{"id":5634,"date":"2022-06-23T12:45:35","date_gmt":"2022-06-23T17:45:35","guid":{"rendered":"https:\/\/www.hospitalcardiologica.com.mx\/?p=3488"},"modified":"2024-01-15T14:07:31","modified_gmt":"2024-01-15T20:07:31","slug":"la-miocardiopatia-hipertrofica-propuesta-de-una-nueva-clasificacion","status":"publish","type":"post","link":"https:\/\/dev.hospitalcardiologica.com.mx\/?p=5634","title":{"rendered":"Hypertrophic cardiomyopathy. Proposal for a new classification"},"content":{"rendered":"\n[et_pb_section][et_pb_row][et_pb_column type=\u00bb4_4&#8243;][et_pb_text]\n\t\t\t\t<!-- divi:gallery {\"ids\":[3511]} -->\n<ul class=\"wp-block-gallery columns-1 is-cropped\"><li class=\"blocks-gallery-item\"><figure><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/Hypertrophic-cardiomyopathy.-Proposal-for-a-new-classification-1024x577.png\" alt=\"\" data-id=\"3511\" data-link=\"https:\/\/www.hospitalcardiologica.com.mx\/la-miocardiopatia-hipertrofica-propuesta-de-una-nueva-clasificacion\/hypertrophic-cardiomyopathy-proposal-for-a-new-classification-2\/\" class=\"wp-image-3511\"\/><\/figure><\/li><\/ul>\n<!-- \/divi:gallery -->\n\n<!-- divi:paragraph {\"align\":\"left\"} -->\n<p style=\"text-align:left\"><strong>Hypertrophic cardiomyopathy (HCM)<\/strong> is a clinical\ncondition, but its name has been subjected to frequent changes over the years,\nlargely because of its morphological and functional heterogeneity, which leads\nthe clinician who is focused on its study to have difficulty in understanding\nhow to diagnose it and when and how to treat it. Regarding its name, it has\nbeen called in more than 75 different ways, and it has being classified with\ndifficulty through echocardiography for more than 40 years. Today, it is\nnecessary to understand that the diverse phenotypic behavior, as well as the\nevolutionary stages of the disease, must be approached in a practical and\neffective way, so that it easier to understand its clinical behavior and\nprognosis, as well as the therapeutic needs in each particular case. We review\nthe aspects related to the name of the condition and propose a new <strong>&nbsp;<\/strong>that\ncould provide the clinical and surgical cardiologist a better understanding of <strong>Hypertrophic cardiomyopathy (HCM)<\/strong> in\nits various morphological and functional aspects<em>. <\/em><\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:image {\"id\":3526} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/INTRODUCCION-1-1024x44.jpg\" alt=\"\" class=\"wp-image-3526\"\/><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:paragraph -->\n<p>The nomenclature and <strong>Classification of Cardiomyopathies<\/strong> have had constant changes since 1961, when Goodwin et al. published what may be considered the first descriptive article of the clinical aspects of <strong>Cardiomyopathies<\/strong>, which from the pathophysiological point of view were divided into congestive, constrictive and \/ or obliterative and obstructive. As early as 1957, Bridgen had coined the term <strong><em>\u00abCardiomyopathy\u00bb<\/em><\/strong> when referring to non-coronary heart disease, restricting the term \u00abmyocarditis\u00bb only to encompass patients with inflammatory disease of infectious etiology. In 1980, the World Health Organization (WHO) defined cardiomyopathies as a disease of the cardiac muscle whose cause was unknown and in 1995 the WHO together with the International Society and Federation of Cardiology (ISFC) developed the joint work (\u201cTask Force\u201d) for the Definition and <strong>Classification<\/strong> of <strong>Cardiomyopathies (CM),<\/strong> and expanded the <strong>classification<\/strong> to include all the diseases that affected the cardiac muscle (<strong>myocardial<\/strong> diseases associated with myocardial dysfunction) taking into account both, the etiology and the dominant pathophysiological pattern, and they included in it: dilated <strong>cardiomyopathy<\/strong>, <strong>hypertrophic cardiomyopathy (HCM<\/strong>), restrictive <strong>cardiomyopathy<\/strong> and for the first time they added arrhythmogenic right ventricular <strong>cardiomyopathy<\/strong>, which had been described in 1982. &nbsp;It was until 2006, when Maron et al., endorsed by the American Heart Association (AHA), proposed a <strong>classification <\/strong>and sub-classification, where primary <strong>cardiomyopathy<\/strong> (which affects only or primarily the heart muscle) could be named according to its origin as genetic, mixed and acquired, providing a description of each one. <strong>Hypertrophic cardiomyopathy <\/strong>was defined as a genetic primary <strong>CM<\/strong>, and its origin was attributed to various mutations of sarcomeric proteins encoded by 11 genes. In 2011, The American College of Cardiology (ACC), together with the AHA, endorsed their <strong>classification<\/strong> published 5 years before, with the participation of Maron himself. Two years later, the MOGE(S) <strong>classification <\/strong>for<strong> Cardiomyopathies<\/strong> appeared, and it included a phenogenotypic nomenclature system endorsed by the World Heart Federation (WHF), and which attempted to use a descriptive system of nomenclature and notation applied to diagnosis in the clinical practice (like the one used in oncological diseases) based on the knowledge of the genetics and pathophysiology of each <strong>cardiomyopathy<\/strong>, and they also placed the acronym S to refer to the functional class of the described condition.&nbsp; Despite everything, in the European Guidelines for the Diagnosis and Treatment of <strong>Hypertrophic<\/strong> <strong>Cardiomyopathy<\/strong> published in 2014, little value was given to the MOGE(S) <strong>Classification<\/strong>, and they adopted the recommendations of the ESC itself. They defined them with morphological and functional criteria with the family \/ genetic and non-family \/ non-genetic subtypes regardless of the presence of extra-cardiac disease. <strong>Hypertrophic Cardiomyopathy<\/strong> was defined by the presence of an increase in the thickness of the left ventricular wall which cannot be explained by abnormal overload conditions <strong>(Figure 1<\/strong>).<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:image {\"id\":3520} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/Classification-of-cardiomyopathies-according-to-the-European-Society-of-Cardiology-in-2008.jpg\" alt=\"\" class=\"wp-image-3520\"\/><figcaption> <strong><em>Figure 1. Classification<\/em><\/strong><em> of <strong>cardiomyopathies<\/strong> according to the European Society of Cardiology in 2008. HCM: hypertrophic cardiomyopathy, DCM: dilated <strong>cardiomyopathy<\/strong>, ARVC: arrhythmogenic right ventricular <strong>cardiomyopathy<\/strong>, RCM: restrictive <strong>cardiomyopathy<\/strong>. <\/em> <\/figcaption><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:image {\"id\":3524} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/2-HIPERTROPHIC-CARD-1-1024x44.jpg\" alt=\"\" class=\"wp-image-3524\"\/><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:paragraph -->\n<p>The first description of <strong>Hypertrophic Cardiomyopathy <\/strong>was made by Schmincke et al. in 1907 in autopsy results.In 1957, Brock called it aortic subvalvular stenosis and in the same year, Donald Teare published his descriptive article of nine autopsy cases, which he had described as asymmetric cardiac <strong>hypertrophy<\/strong> in young adults; seven had suffered sudden death. He described the disorganization of the myocardial fibers for the first time and he even classified it as a muscular hamartoma. <\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>In 1962 in Mexico, Fishleder et al. described the clinical, auscultatory and exploratory findings in patients that they considered had a dynamic subaortic stenosis.In 1964, Braunwald, Morrow et al. delineated the condition that they called idiopathic hypertrophic subaortic stenosis, based on the analyzes of 64 patients, which included Morrow himself, who described the well-known Morrow Myectomy, and who suffered the disease. <sup>14<\/sup> That same year, Cohen et al. called it Obstructive <strong>Hypertrophic Cardiomyopathy<\/strong> for the first time.&nbsp; It should be mentioned here that, to date, the disease has been called in more than 75 different ways, which has generated greater confusion in its understanding. <\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>Today we know that <strong>Hypertrophic Cardiomyopathy<\/strong>\nis a hereditary disease transmitted in an autosomal dominant manner,\ncharacterized by an inexplicable <strong>hypertrophy<\/strong>\nof the myocardium, which has an estimated phenotypic prevalence of 1 in 500 (2\nper 1,000) in an urban adult population with a similar prevalence in different\ncontinents and countries and a possible genotypic prevalence of 1 in 200 (5 per\n1,000) which places it probably as the most common of the genetic heart\ndiseases.To support this last hypothesis, there are several avenues\nof evidence, such as the fact that pathogenic sarcomere genes are more common\nin the general population than previously thought, as well as the fact that the\ngenetic tests with a greater capacity that are carried out today have defined a\nnew subgroup of patients, who don\u2019t have clinical expression or left\nventricular <strong>hypertrophy<\/strong> (<em>positive\ngenotype, negative phenotype<\/em>); and on the other hand, thanks to the image\ntechnology currently used, such as cardiac magnetic resonance imaging (MRI),\nthe recognition of some <strong>Hypertrophic Cardiomyopathy<\/strong>\nphenotypes that are difficult to delineate by means of 2D echocardiography, is\nmore feasible. In addition, it should be remembered that previous prevalence\nstudies did not consider the hereditary nature of the disease, whereas now it\nis common to perform a family detection. So far, a little more than 11 genes,\nwhich may encode more than 1500 mutations in cardiac sarcomere proteins have\nbeen identified. Around 60% of young and adult patients with <strong>Hypertrophic\nCardiomyopathy<\/strong> have one of these mutations and 5-10% are caused by\nanother type of metabolic or neuromuscular genetic alteration. Its origin is\nstill unknown in 25-30% of the patients.<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:image {\"id\":3529} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/CLASSIFICATION-OF-HYPERTR-1024x44.jpg\" alt=\"\" class=\"wp-image-3529\"\/><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:paragraph {\"align\":\"left\"} -->\n<p style=\"text-align:left\">The WHO determined to use the term <strong>hypertrophic cardiomyopathy<\/strong> as it is considered the most<br> accurate term to describe this primary <strong>hypertrophy<\/strong> that can occur with or without dynamic left<br> ventricular outflow tract obstruction (LVOTO). Therefore, today it has been classified from the<br> hemodynamic point of view, into two large groups:<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p><strong>The Obstructive Form: <\/strong><\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p><strong>Hypertrophic<\/strong>\nobstructive <strong>cardiomyopathy<\/strong> (HOCM),\nwhich shows an obstruction to the LVOT which can be present at rest (<em>persistent<\/em>),\ncan be <em>latent<\/em> (absent at rest but provoked by some maneuver or effort)\nor <em>labile<\/em> (variable). The first two (resting and latent) represent 70%\nof the cases. The two most common forms of obstruction are the one that is\nclassified as subaortic (which is more frequent and is related to an LVOT\nobstruction, and the mid-ventricular, in which the obstruction, in case it is present,\nis precisely mid-ventricular). The LVOT obstruction may be conditioned either\nby the systolic anterior motion (SAM) of the anterior leaflet or posterior\nleaflet of the mitral valve, or it may be conditioned by alterations or\nmalposition of the papillary muscle and \/ or the chordae tendineae (tendinous\ncords), which by a drag (Venturi effect) causes an incomplete support on the\nseptum, which also frequently favors the appearance of insufficiency of the mitral\nvalve. The <em>mid-ventricular<\/em>\nobstruction can be caused by an abnormal insertion of the anterior papillary\nmuscle or by excessive mid-ventricular <strong>hypertrophy<\/strong>\nor by the papillary muscle itself, with a pathological alignment. Both may\ncoexist in the same patient. There may also exist an obstruction in the right\nventricular outflow tract, and it is seldom considered important.<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>In general, patients with the obstructive type of the disease are more symptomatic and have a worse prognosis. LVOT obstruction is closely related to higher mortality caused by obstruction or by sudden death. In the asymptomatic or slightly symptomatic patient, the magnitude of the obstruction loses predictive value for mortality and on the contrary, in the highly symptomatic patient, mortality is higher regardless of the degree of the obstruction.<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p><strong>The non-Obstructive Form:<\/strong><\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>The non-obstructive <strong>hypertrophic cardiomyopathy<\/strong> (nHCM) is characterized by\ndisproportionate <strong>hypertrophy<\/strong> of the\nventricular wall, but it is not possible to demonstrate an obstruction at any\nlevel at rest, and it may not be caused by maneuvers such as the Valsalva maneuver\nor exercise. These patients generally have a more benign and less symptomatic\ncourse than patients with the obstructive form.<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:image {\"id\":3534} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/PROGRESSION-STAGES-OF-HYPER-1024x44.jpg\" alt=\"\" class=\"wp-image-3534\"\/><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:paragraph -->\n<p>In 2012, Olivotto I. et al.described 4 <strong>Hypertrophic\nCardiomyopathy<\/strong> progression patterns, which they classified into\nStages I to IV, which are an excellent description of what the natural history\nof the disease usually is. They allow a clear understanding of the\npathophysiological process of the condition. These patterns are:<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:list -->\n<ul><li><strong>STAGE I<\/strong> (<strong>HCM\nin the nonhypertrophic phase<\/strong>), it is characterized by the absence of <strong>hypertrophy<\/strong> of the left ventricle (LV)\nin the context of the subject who has the genotype, usually detected in a\nsystematic family study of a patient who has the disease. The phenotypic\nmanifestation in the patient with the genetic alteration usually manifests itself\nduring the 2nd decade of his life and it may even appear in later stages. An\nimportant point to consider is that we are not referring to the patient who has\nthe genotype and who has a negative phenotype (genotype + \/ phenotype -) for\nthe rest of his life. In this stage. the patient usually has some\nelectrocardiographic manifestations, diastolic dysfunction, and slight dilation\nof the left atrium, as well as abnormalities of the subvalvular apparatus in\nthe echocardiogram (ECHO).<\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:list -->\n<ul><li><strong>STAGE II<\/strong> (<strong>Classic\nHCM phenotypically<\/strong>) it refers to the stage in which phenotypic expression\nbecomes manifest, with a hyperdynamic LV, with a LV expulsion fraction\n(LVEF)&gt; 65%, in the absence of fibrosis. 75% of the patients will enter into\nthis stage, depending on the penetrance of the causal genetic mutation.\nTypically, regional and asymmetric <strong>hypertrophy<\/strong>\nis observed, most often involving the anterior basal <em>septum<\/em> and the\nbasal portion of the anterior free wall of the LV. The anatomic patterns of <strong>hypertrophy<\/strong> may be multiple (see below).\nMicroscopically, <strong>myocardial <\/strong>fiber\nderangement, microvascular remodeling and incipient fibrosis appear. In this\nstage, the LV is usually small, hypercontractile, and with an LVEF usually\ngreater than 65%. The fibrosis determined by MRI, and late gadolinium\nenhancement (LGE) is usually 2% in a (low) average. This stage usually lasts\nfor years or decades.<\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:list -->\n<ul><li><strong>STAGE III (adverse remodeling)<\/strong>, this stage of the disease has been called by some as \u00abadverse\nremodeling\u00bb and it is defined by the presence of unfavorable structural\nmodifications superimposed on the classic pattern of <strong>Hypertrophic cardiomyopathy<\/strong>,\na consequence of an increase in myocardial fibrosis and the consequent\ndepression of the systolic function. It is important to mention that apparently\nthis is not an expected average behavior in a patient with <strong>Hypertrophic cardiomyopathy<\/strong>\nas time goes by, but rather a selective pathway followed by approximately 15-20%\nof the patients, of which a small proportion, will progress to a severe\ndysfunction and heart failure. It has also been observed that this adverse\nremodeling is more prevalent in complex genotypes (patients with multiple\nmutations), which could reflect a profound disorder of sarcomere mechanics and\ncardiomyocyte energetics. The development of both, the extension and the time\nof evolution of this adverse remodeling are very heterogeneous, and it is\npossible to observe it in any age (including childhood and adolescence) and it\nwill progress to a severe dysfunction and heart failure in some cases in a short\ntime or, as in the majority of the cases, it occurs gradually evolving over\nyears or decades. Of course, these patients will go through intermediate stages\nof progression that go from the hypercontractility phase to the reduced left\nventricular systolic function (LVEF) phase, which includes a moderate reduction\nin LVEF, moderate to significant diastolic dysfunction and a progressive\ndilation of the left atrium, an increase in the percentage of fibrosis measured\nby RT, severe microvascular dysfunction, progressive thinning of the LV walls,\nappearance of atrial fibrillation, spontaneous reduction or loss of LVOT\nobstruction, and the appearance of apical aneurysm. Not all of these, but some\ncoexist in the same patient, and this entails the presence of a poor evolution\nand progression towards adverse remodeling.<\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:paragraph -->\n<p>In general, this remodeling model behaves in a variable way with the\nappearance of moderate to large areas of intramyocardial fibrosis that can be\nconfluent or in patches, which replace significant portions of the LV, usually\nfrom the middle portions of the wall that tend to radiate towards the\nsubendocardium (although they can be transmural). This causes the LV wall to be\nthinner and it creates cicatrization or repair processes. Finally, it seems that\neverything is a consequence of microvascular ischemia, cardiomyocyte energy\ndepletion and apoptosis that leads to a progressive loss of myocytes that are\nreplaced by fibrous tissue.<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:list -->\n<ul><li><strong>STAGE IV<\/strong> (<strong>excessive\ndysfunction<\/strong>), although it is rare, it is characterized by significant LVEF\ndeterioration (&lt;50%), significant fibrosis and LV dilation with clinical\nmanifestations of heart failure. Although it may be considered as an\n\u201cend-stage\u201d disease, some people have called it a <strong>\u201cburned out\u201d<\/strong> phase and it corresponds to ~5% of patients. Maron BJ\net al.had already defined this stage, when in 1998, they described\nthe progression of some patients with <strong>Hypertrophic Cardiomyopathy<\/strong> to\nsystolic dysfunction, in whom the wall thickness was reduced by approximately\n25% in 5-6 years (from 20 to 15 mm in average) at a rate of 1 to 2 mm per year,\nand the LV cavity measured in diastole, dilated 20% in this period (from 45 to\n55 mm in average) at a rate of 1 to 1.5 mm per year. <strong>(Fig. 2).<\/strong><\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:paragraph -->\n<p>\n\nA\nvery important aspect is that in this stage, they cataloged two types of\npatients. The first type was defined as <em>\u00abdilated hypokinetic\u00bb<\/em>\ncharacterized by an increased volume and remodeling with LV sphericity, and\nsometimes it was difficult to differentiate it from cases with dilated <strong>cardiomyopathy<\/strong> of idiopathic type.\nUsually at this stage the LVOT obstruction has disappeared. It is common to\nfind pulmonary arterial hypertension, biventricular dilation, and mitral\nregurgitation due to dilation of the valve ring (annulus). The second form was\ncalled <em>\u201chypokinetic-restrictive\u201d<\/em> characterized by a small and rigid LV\ncavity with significant diastolic dysfunction that simulates restrictive <strong>cardiomyopathy<\/strong>; in these patients,\nsystolic function was slightly compromised, and it was possible to distinguish\nsome degree of asymmetry in the thickness of the LV wall. It is now known that\nthis last form is related to some specific type of mutations such as TPM1, MYL3\nand MYL2. Although Olivotto et al.<sup>23<\/sup> did not define it this way,\nMelacini P. et al. described a third pattern in terminal patients,\ncharacterized by progressive heart failure because of <em>\u201cpersistence of LVOT\nobstruction\u201d<\/em>, which eventually conditions dilation and systolic dysfunction\nof the LV, without the total disappearance of the obstruction. These patients\nare represented by older individuals (50 \u00b1 14 years at diagnosis). The onset of\nsymptoms after diagnosis is also short (4 \u00b1 6 years) although once started,\nthey rapidly evolve to an advanced functional class (1 \u00b1 2 years).\n\n\n\n<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:image {\"id\":3537} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/Development-of-Progression-Patterns-of-Left-Ventricular-Hypertrophy-in-the-Patient-who-has-HCM-Genotype.jpg\" alt=\"Development of Progression Patterns of Left Ventricular Hypertrophy in the Patient who has Hypertrophic Cardiomyopathy Genotype. LVEF: left ventricular ejection fraction. \" class=\"wp-image-3537\"\/><figcaption> <strong><em>Figure 2.<\/em><\/strong><em> Development of Progression Patterns of Left Ventricular <strong>Hypertrophy<\/strong> in the Patient who has <strong>Hypertrophic Cardiomyopathy<\/strong> Genotype. LVEF: left ventricular ejection fraction.<\/em> <\/figcaption><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:image {\"id\":3548} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/DISTRIBUTION-AND-CLASIFIC-1024x44.jpg\" alt=\"\" class=\"wp-image-3548\"\/><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:paragraph -->\n<p>In <strong>Hypertrophic Cardiomyopathy<\/strong>, the distribution of LV <strong>hypertrophy<\/strong> is characteristically asymmetric and particularly\nheterogeneous, it can encompass a wide range of wall thickening patterns, from\nextensive and diffuse to mild and segmental, and without a single morphological\nexpression considered typical or classical. However, for a better clinical\nunderstanding, there has been an effort to subclassify these patterns in such a\nway that it is possible to understand which could be the dominant <strong>hypertrophic<\/strong> point, and thus expect to\na certain degree, a predictable clinical evolution. In spite of their\ndiversity, the LV <strong>hypertrophy<\/strong>\npatterns are generally not extensive and usually involve &lt;50% of its wall in\nhalf of the patients, and their extension is less in a significant minority.<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>Although the phenotypic characteristics were initially described by\nautopsy findings and later by 2D ECHO analysis, the first formal attempt to\nclassify <strong>Hypertrophic Cardiomyopathy<\/strong> according to its anatomical characteristics was made\nby Maron BJ et al. in 1981, through the analysis of 125 patients with the\ndisease, who underwent a 2D ECHO. They defined 4 dominant LV hypertrophy\ndistribution patterns, which were called Type I &#8211; IV based on their location:<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:list -->\n<ul><li><strong>Type I <\/strong>(10% of the\ncases),<strong> <\/strong>it is\ncharacterized by having <strong>hypertrophy<\/strong> confined only to the anterior\nportion of the LV <em>septum<\/em>,<\/li><li><strong>Type II<\/strong> (20% of the cases), it corresponds to patients with <strong>hypertrophy<\/strong> of the entire ventricular <em>septum<\/em> (anterior and posterior segment)\nbut not to the LV free wall,<\/li><li><strong>Type III<\/strong> (the most frequent), it corresponds to\nhypertrophy of basal portions of both the septum and the LV free wall (52% of\nthe patients), and of these, a small proportion (25 in 65 patients) had a\npredominance of <strong>hypertrophy<\/strong> in the\napical regions; and finally,<\/li><li><strong>Type IV<\/strong> (18% of the patients), with involvement\nof other LV regions and without showing hypertrophy of the anterior basal\nportion of the ventricular <em>septum<\/em>. <\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:paragraph -->\n<p>&nbsp;<strong>(Fig. 3).<\/strong><\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>They confirmed that previous studies performed by M-mode\nechocardiography significantly underestimated (up to 5 mm) the maximum\nthickness of the septal or free LV wall. That same year, Yamaguchi H et al.\npublished the ventriculographic and echocardiographic findings of 30 Japanese\npatients with apical <strong>Hypertrophic\nCardiomyopathy<\/strong>. They had a marked\napical obliteration together with \u00abgiant\u00bb negative T waves in the\nelectrocardiogram with high voltage QRS and a thickness of the apex wall &gt;\n15 mm. In Maron&#8217;s Description, patients with apical HCM in Type III and IV had\nbeen included, but it did not include concentric hypertrophy. Maron himself in\n1985, described 2 patients with posterobasal LV free wall <strong>hypertrophy<\/strong> with evidence of obstruction. This morphological type\nwas not included in the classification. One year later (1986) Candel-Riera et\nal. added two types to the <strong>classification<\/strong>\nproposed by Maron:<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:list -->\n<ul><li><strong>Type V<\/strong> which corresponded to concentric <strong>hypertrophy<\/strong>, and<\/li><li><strong>Type VI<\/strong> which corresponded to the apical <strong>hypertrophy<\/strong> described by Yamaguchi.<\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:paragraph -->\n<p> In the year 2000, Romero-Farina et al. compared Maron&#8217;s echocardiographic <strong>classification<\/strong> with <strong>myocardial<\/strong> morphology analyzed by <strong>myocardial<\/strong> tomography scan (SPET). Although their power of spatial resolution was lower than the ECHO and the other techniques such as MRI, they considered that allowing the distribution of <strong>hypertrophy<\/strong> to be observed, facilitated the <strong>classification<\/strong> of patients into different morphological types. They analyzed 119 patients and found that only in 64% of them, the ECHO was able to facilitate the measurement of all the LV segments, and with the SPET they obtained a more complete visualization of all the segments in the short axis, so although the spatial resolution did not allow them to accurately measure the thickness of the walls, it made it possible to establish which morphological type each case corresponded to. They confirmed that the most frequent type was Maron&#8217;s type III (74% of the cases), but in 25% of the cases the ECHO made a mistake in defining the <strong>classification<\/strong> fundamentally in the same type. They also found that 4 patients could not be classified within type I &#8211; VI (they had septal and inferior <strong>hypertrophy<\/strong>). <\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:image {\"id\":3549} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/Marons-original-classification-of-hypertrophic-cardiomyopathy-by-2D-echocardiography.-Type-I-to-IV.-Modified-from-Maron-BJ.-jpg.jpg\" alt=\"Maron's original classification of hypertrophic cardiomyopathy by 2D echocardiography. Type I to IV. (Modified from Maron BJ et al.) \" class=\"wp-image-3549\"\/><figcaption><strong><em>Figure 3. <\/em><\/strong><em>Maron&#8217;s original <strong>classification<\/strong> of <strong>hypertrophic cardiomyopathy<\/strong> by 2D echocardiography. Type I to IV. (Modified from Maron BJ et al.)<\/em> <\/figcaption><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:image {\"id\":3551} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/RIGHT-VENTRICLE-1-1024x44.jpg\" alt=\"\" class=\"wp-image-3551\"\/><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:paragraph -->\n<p>In 2007, Maron et al. described the involvement\nof the right ventricle (RV) when studying 46 patients with <strong>Hypertrophic Cardiomyopathy <\/strong>who\nunderwent MRI and they compared them with 22 healthy individuals carefully\nanalyzing the thickness of the wall of both ventricles. They found that the\nmaximum RV wall thickness was greater in <strong>Hypertrophic Cardiomyopathy<\/strong>\npatients compared to the control group (7 \u00b1 2 vs 5 \u00b1 1 mm, p &lt;0.001),\nincluding 15 (33%) with a maximum thickness \u2265 8 mm, and four (9%) with extreme <strong>hypertrophy<\/strong> (\u2265 10 mm). They\ndemonstrated a close correlation between the degree of LV <strong>hypertrophy <\/strong>and RV <strong>hypertrophy<\/strong>.\nThe greater the hypertrophy of the former, the greater the <strong>hypertrophy<\/strong> of the latter (R2 = 0.4, p &lt;0.001). The presence of\nRV hypertrophy was never included in Maron&#8217;s <strong>classification.<\/strong>\n\nIn the same way, in 2010, Keeling et al.\npublished the case of a patient with <strong>Hypertrophic Cardiomyopathy<\/strong> in whom\nthey detected RV <strong>hypertrophy<\/strong> through\nMRI but who also had apical fibrosis and fibrosis of the free wall of this\nventricle, which had been detected by RT. It is now known that in addition to\nRV wall <strong>hypertrophy<\/strong>, it is common to\nfind a prominence of some RV structures, such as the supraventricular crest\n(Wolf&#8217;s spur) that is located between the pulmonary and right atrioventricular\norifices and that can lead to confusion when measuring right septal thickness.\nThe most important portion to evaluate is the right septal basal portion and\nthe basal portion of the RV free wall, which can sometimes condition RV outflow\nobstruction and it requires surgical treatment.\n\n\n\n<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:image {\"id\":3552} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/APICAL-ANEURISM-1024x44.jpg\" alt=\"\" class=\"wp-image-3552\"\/><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:paragraph -->\n<p>Apical <strong>Hypertrophic Cardiomyopathy<\/strong>,\ninitially described by Sakamoto et al., and later discussed masterfully by\nYamaguchi et al. is a phenotypic variant apparently modulated by environmental\nand genetic factors, but in general its diagnosis is a challenge when only ECO\n2D is used. Although the apical LV involvement is a <em>sine qua non<\/em> component in the apical form of <strong>HCM<\/strong>, some mid-ventricular segments may also be hypertrophied (this\nis one of the mixed morphological subtypes), in which mid-ventricular\nobstruction with obliteration may occur of the LV cavity. These patients may\npresent an apical aneurysm (AA), which is usually another aspect that is\ndifficult to diagnose, and which is usually underdiagnosed and undervalued. In\npatients with apical <strong>Hypertrophic Cardiomyopathy<\/strong>, the\npresence of AA can be detected in 2% to 28% of patients (there is a higher\nincidence in patients with obstructive mid-ventricular <strong>hypertrophy<\/strong>). This anomaly corresponds to a small segment of the LV\napex, with a thin, dyskinetic or akinetic wall, with a relatively narrow neck\nthat communicates with the basal or medial portions of the LV. Patients with AA\nassociated with mid-ventricular <strong>hypertrophy\n<\/strong>represent an important subgroup of patients who, in addition to being\nusually underdiagnosed if MRI is not used in their analysis, have special\nprognostic and therapeutic implications. MRI has demonstrated that AA is\nusually made up of fibrous tissue and that RT can be infiltrated into the\nadjacent septum and free wall, representing a \u201cnest\u201d which fosters ventricular\ntachyarrhythmias and thus increases the risk of sudden death. In 2008, Maron et\nal. demonstrated that AA patients had a higher risk of progressing to heart\nfailure, having sudden death, generating systemic embolism and having apical\nthrombi. The average risk of adverse clinical consequences in these patients\nwas 10.5% per year, which is considerably higher than the amount reported in the\ntotality of the patients with <strong>Hypertrophic Cardiomyopathy<\/strong>. On\nHolter monitoring, more than 40% of these patients had monomorphic nonsustained\nventricular tachycardia, which is considered high risk for sudden death in\npatients with <strong>HCM<\/strong>. AA may also be\npresent in patients with pure apical H<strong> Hypertrophic Cardiomyopathy<\/strong>.<strong>(Figure\n4)<\/strong><\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:image {\"id\":3553} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/Classic-phenotypes-and-subtypes-of-mid-ventricular-and-apical-hypertrophic-cardiomyopathy-873x1024.jpg\" alt=\"\" class=\"wp-image-3553\"\/><figcaption> <br><strong><em>Figure 4. <\/em><\/strong><em>Classic phenotypes and subtypes of mid-ventricular and apical hypertrophic cardiomyopathy. <strong>A: <\/strong>isolated apical form (Type III), it is the traditional phenotype, limited to the apical segments of the LV, it may have an apical aneurysm (Type IIIa). <strong>B: <\/strong>mixed balanced form, in which the contiguous (mid-ventricular), and rarely the basal portions, are also hypertrophied, although apical hypertrophy predominates (Type III). It may or may not have an apical aneurysm. <strong>C: <\/strong>phenotype with isolated mid-ventricular hypertrophy, without involvement of the apical segments (Type II). It may or may not have an obstruction and an apical aneurysm. <strong>D: <\/strong>predominantly mid-ventricular form, in which this region has a greater hypertrophy (Type II), but the LV apex is also hypertrophied and it has an obstruction. It may have an apical aneurysm (Type IIa-o). (Modified from Jan et al.). <\/em> <\/figcaption><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:paragraph -->\n<p>The presence of mid-ventricular obstruction with cavity obliteration\nis frequent and it is only possible to observe it in apical <strong>Hypertrophic\nCardiomyopathy<\/strong> of the mixed type (mid-ventricular involvement) and\nin severe cases. the obliteration of the cavity persists until the end of the\ndiastole, and it is associated with the presence of a paradoxical diastolic\nflow <em>jet<\/em> towards AA, which is usually\na marker of poor prognosis.<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:image {\"id\":3555} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/CONTEMPORARY-ANALYSIS-1024x44.jpg\" alt=\"\" class=\"wp-image-3555\"\/><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:paragraph -->\n<p>In 2009, Maron et al. characterized the\ndistribution pattern of LV <strong>hypertrophy <\/strong>using\nMRI, seeking to define more precisely the phenotypic expression of these\npatients. They studied 333 patients who had <strong>Hypertrophic Cardiomyopathy<\/strong>\nwith MRI. They considered that since this offered a great spatial resolution\nand a complete anatomical reconstruction of the LV, it would allow them to\nevaluate the precise distribution of <strong>hypertrophy<\/strong>.\nIt was thus possible to define that the contiguous basal portions of the\nanterior free wall and the ventricular septum (number 1 in the clock of the\nshort-axis plane), it constituted the regions with a predominance of thickening\n(77%) that corresponded to the distribution known as Maron Type III.They found\nthat just over half of the patients had areas of <strong>hypertrophy<\/strong> distributed over \u2265 50% of the entire LV chamber\n(diffuse <strong>hypertrophy<\/strong>), and that a\nminority had focal or regional areas of <strong>hypertrophy<\/strong>.\n12% of the patients had only 1 or 2 hypertrophied LV segments, and they were\nclassified as <em>focal involvement<\/em>, which were not even enough to show an\nincrease in the calculated total LV mass. They found a <em>moderate involvement<\/em>\nthat represented between 13% and 49% of the entire LV (3 to 7 segments) in 34%\nof the patients, and finally <em>diffuse\ninvolvement<\/em> (\u2265 8 segments), in other words, &gt; 50% of the entire LV, in\n54% of patients. Frequently, the phenotypic expression was non-contiguous\nsegmental <strong>hypertrophy<\/strong>, which created\nabrupt changes in wall thickness (in patches separated by non-hypertrophied\nregions), which were present in up to 15% of the patients, and which they describe\nas a <em>lumpy aspect<\/em>. In this last group, it was common to find\ncombinations of <strong>hypertrophy<\/strong> in\npatches of the basal anterior <em>septum<\/em>\nand in the apical anterior wall, as well as the basal anterior <em>septum<\/em> with the posterior medial <em>septum<\/em>.<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>In this study, Maron et al. also demonstrated\nthat by means of RT, it was possible to identify and quantify \u00abin\nvivo\u00bb the presence of <strong>myocardial<\/strong>\nfibrosis which is so common in patients with <strong>HCM<\/strong>. They also found that the extent of <strong>hypertrophy<\/strong> (number of hypertrophied segments) was related to the\npresence of LVOT obstruction and to a greater deterioration in their functional\nclass of heart failure. The greater the <strong>hypertrophy<\/strong>,\nthe greater the degree of obstruction and the greater the clinical\ndeterioration.<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>In this study, various <strong>hypertrophy<\/strong> patterns were defined as follows:<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>a) <strong>Hypertrophy<\/strong> of the LVseptum\npreserving the free wall,<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>b) Focal <strong>hypertrophy<\/strong> of the anterior basal portion of the LV <em>septum<\/em>,<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>c) LV apex <strong>hypertrophy<\/strong>, <\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>d) Segmental <strong>hypertrophy<\/strong> predominantly of the anterolateral LV wall with normal\nanterior <em>septum<\/em>,<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>e) Massive asymmetric <strong>hypertrophy<\/strong> of the anterior wall of the\nLV <em>septum<\/em>, without involvement of the posterior septal portions,<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>f) Diffuse <strong>hypertrophy<\/strong> with involvement of the <em>septum<\/em> and the\nanterolateral wall.<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>Furthermore, they concluded that using 2D ECHO,\nLV wall thickness was underestimated in some patients, since the epicardial\nborder of the free wall was frequently not adequately visualized. They\nconcluded that MRI is the optimal method to precisely define the morphological\ncharacteristics in the patient with <strong>Hypertrophic Cardiomyopathy<\/strong>.\nSince then, no more has been said about Maron&#8217;s echocardiographic phenotypic <strong>classification<\/strong>, which has been\nforgotten by many people.<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>Since then, more than an anatomical <strong>classification<\/strong>, the concept of\nphenotype has been used to refer to the morphological and functional aspects of\n<strong>Hypertrophic\nCardiomyopathy<\/strong>. The most common morphologies of the <em>septum<\/em> and the distribution of\nhypertrophy in the left ventricular wall in patients with <strong>Hypertrophic Cardiomyopathy<\/strong>\n(phenotypic expression) are shown in <strong>Figure 5<\/strong>. In fact, this distribution has been\nused to subdivide the condition into these more commonly identified 4 groups.<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>As it has already been mentioned, although\nthere are four phenotypic types which are considered as the most frequent in\nterms of the location of <strong>hypertrophy<\/strong>,\nsuch as basal sigmoid <strong>hypertrophy<\/strong>\n(with LVOT obstruction), reverse curvature hypertrophy (which usually\ncorresponds to mid-ventricular <strong>hypertrophy<\/strong>,\nand may have mid-ventricular obstruction and \/ or AA), apical and neutral <strong>hypertrophy<\/strong>; in general, some of them\nmay coexist in the same patient, or even have atypical or mixed localization\ncomponents. A greater extent of left ventricular <strong>hypertrophy <\/strong>has been associated with a younger age and a mitral\nvalve with a higher degree of SAM of the valve and outflow obstruction but it has\nnot been shown to be related to the magnitude of the symptoms or to the gender.<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>Another important point related to the findings\nof Maron et al. through the analysis of the MRIis that today, it\nmay not be possible to evaluate the patient with <strong>Hypertrophic Cardiomyopathy<\/strong>\nand plan an adequate therapeutic strategy, without a correct non-invasive\nanatomical diagnosis through a detailed analysis of the MRI, which allows to\nspecify the site or LV portion with greater <strong>hypertrophy<\/strong>, as well as the coexistence of morphological\nalterations of the mitral subvalvular apparatus.<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:image {\"id\":3556} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/The-most-common-morphologies-of-the-HCM-showing-the-frequency-of-presentation-and-their-anatomicalcharacteristics.jpg\" alt=\"\" class=\"wp-image-3556\"\/><figcaption><strong><em>Figure 5. <\/em><\/strong><em>The most common morphologies of the <strong>HCM<\/strong>, showing the frequency of presentation and their anatomical characteristics. SIGMOID: prominent basal septal protuberance, concave septum and ovoid left ventricular cavity; REVERSE CURVATURE: convex septum, increasing left ventricular cavity; APICAL: hypertrophy of the apical portion \u00b1 middle segments, \u201cAce of spades\u201d shaped cavity (More frequent in Asia); NEUTRAL: uniform hypertrophic septum. <\/em> <\/figcaption><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:image {\"id\":3557} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/proposal-for-a-new-anatomic-functional-cL-1-1024x44.jpg\" alt=\"\" class=\"wp-image-3557\"\/><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:paragraph -->\n<p>Five forms of phenotypic expression have been identified that are\nconsidered the most common in the early stages of <strong>Hypertrophic Cardiomyopathy<\/strong>, and one form was identified in late stages of the disease. On the\nother hand, there are many reports that have made it possible to define the\nmost common morphological manifestations of the disease and now we know that in\naddition to the LV, the RV may be involved and there may also be an obstruction\nof the latter&#8217;s outflow tract. Furthermore, it is known that a late phenotypic\nmanifestation (end stage) of the disease may be an LV dilation phase with\nsignificant systolic dysfunction <em>(burned-out)<\/em>.\nIt is known that there is a group of patients with LVOT obstruction (some at\nrest and others with patent obstruction) and others with mid-ventricular\nobstruction, and a minority without obstruction at any level. Finally, there\nare patients who develop LV AA as a serious complication. For this reason, it\nis increasingly necessary to have an anatomical-functional <strong>classification<\/strong> scheme, which allows each patient to be classified\ninto a group that could also have different therapeutic and prognostic\nimplications. For this reason, we are proposing the use of a <strong>classification<\/strong> system that facilitates\nits understanding in a clear and practical way. The proposal is to classify the\nmorphological findings into six Types <strong>(Fig.6):<\/strong><\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:list -->\n<ul><li><strong>Type <\/strong><strong>I,<\/strong> would correspond to the \u201csigmoid\u201d variety\nwith <strong>hypertrophy<\/strong> of the basal\nsegments (anterior and \/ or posterior) of the septum and the free anterior\nwall, which corresponds to the most frequent (40 to 50% of cases). This is\ncharacterized by a prominent basal septal bulge, a concave medial septum, and\nan ovoid left ventricular cavity <strong>(Figure 6a).<\/strong> 40%\nof type I patients will have a detectable obstruction at rest (persistent) and\n30% will have an obstruction provoked by some maneuver (latent), in other\nwords, 70% will have an obstruction. This last group of patients will be those\nthat may be defined as having obstructive <strong>Hypertrophic Cardiomyopathy<\/strong>\n(oHCM).<\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:list -->\n<ul><li><strong>Type <\/strong><strong>II,<\/strong> corresponds to patients with mid-ventricular\n<strong>hypertrophy<\/strong> (reverse curvature) and\nit represents 30 to 40% of all patients. They may also have mid-ventricular\nobstruction, or this obstruction be absent (\u2265 30 mmHg peak instantaneous\ngradient in 9.4%). <strong>(Figure 6b).<\/strong> There\nis a subgroup of patients in whom mid-ventricular hypertrophy is accompanied by\napical hypertrophy, although to a lesser degree. They may or may not have AA,\nbut this type is the one that develops it most frequently (28%).<\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:list -->\n<ul><li><strong>Type <\/strong><strong>III,<\/strong> corresponds to patients with apical\nhypertrophy, which represent approximately 10% of the cases <strong>(Figure 6c).<\/strong>\nIn these patients, the hypertrophy may be \u00abpurely\u00bb apical, or\nit may be accompanied by moderate mid-ventricular hypertrophy and very rarely\nby basal <strong>hypertrophy<\/strong> (mixed form)\nand may or may not have AA.<\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:list -->\n<ul><li><strong>Type <\/strong><strong>IV,<\/strong> is the group of patients with diffuse,\nneutral <strong>hypertrophy<\/strong>, without\nobstruction and without a specific segmental pattern. It corresponds to\napproximately 10% of the cases. Usually, these cases, will not be obstructive\n(nHCM). <strong>(Figure\n6d)<\/strong><\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:list -->\n<ul><li><strong>Type <\/strong><strong>V,<\/strong> corresponds to those patients who have mixed\npatterns; in other words, areas of <strong>hypertrophy<\/strong>\nin patches in various LV sites, and which could be difficult to classify into\none of the four types already described, which usually may only be identified\nby MRI <strong>(Figure\n6e).<\/strong><\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:list -->\n<ul><li><strong>Type <\/strong><strong>VI,<\/strong> refers to the patient who is in the dilated\nphase of the disease (<em>burned-out<\/em>),\nwhere it has been clearly defined, either genetically or with previous imaging\nstudies, that he had <strong>Hypertrophic Cardiomyopathy<\/strong> of\nany type and that finally the ventricle dilated and entered a phase of\nsignificant systolic dysfunction (Type VId) <strong>(Figure 6f).<\/strong> These patients may rarely have a \u201crestrictive\u201d\nend-stage form (Type VIr) or persist despite dilatation with some degree of LVOT\nobstruction (Type VIo).<\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:paragraph -->\n<p>On the other hand, it is proposed in this <strong>classification<\/strong> to use additional acronyms, which include three\nfundamental aspects of the disease:<\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:list -->\n<ul><li><strong>First, <\/strong>whether there is an\n<em>obstruction<\/em>. If so, the lowercase letter \u201co\u201d must be used for\nobstruction, after the corresponding type and a hyphen. If the patient has\nbasal septal <strong>hypertrophy<\/strong>, he would be type I, but if he has either a\npersistent or latent obstruction, he would be type I-o. If he doesn\u2019t have a\ndetectable obstruction, he would be type I-n (adding the letter \u201cn\u201d which means\nnon-obstructive).<\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:list -->\n<ul><li><strong>Second,<\/strong> whether\nthere is an <em>apical aneurysm.<\/em> If so, the lowercase letter \u201ca\u201d\nmeaning aneurysm, would be added. Thus, if the patient has mid-ventricular\nhypertrophy, he would be type II, but if there is mid-ventricular obstruction\nand apical aneurysm, he would be Type IIa-o, and if there is no obstruction,\nbut if there is apical aneurysm, he would be Type IIa-n.<\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:list -->\n<ul><li><strong>Third<\/strong>, whether\nthere is <em>RV involvement<\/em>. In\nthe presence of right ventricular <strong>hypertrophy<\/strong>,\nthe capital letter \u201cR\u201d would be added at the end of the text (R comes from\nRight). For example, in the latter case with mid-ventricular <strong>hypertrophy<\/strong>, with obstruction and\napical aneurysm, if there were RV involvement, it would be Type IIaR-o. <strong>(Figure 6).<\/strong><\/li><\/ul>\n<!-- \/divi:list -->\n\n<!-- divi:image {\"id\":3563} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/cardio-a-color-2-1024x912.jpg\" alt=\"\" class=\"wp-image-3563\"\/><figcaption><strong><em>Figure 6.<\/em><\/strong><em> Proposal for a new anatomic-functional classification of hypertrophic cardiomyopathy. It is classified from type I to type V, according to the predominant location of the hypertrophied area of the Left Ventricle (LV). Type I (sigmoid) and Type II (reverse curve or mid-ventricular) are the most frequent. In the classification, they are presented as Type VI, when an evolutionary stage of the disease has appeared which is characterized by having an LV Ejection Fraction &lt;50%; in other words, the patient has entered a stage of excessive dysfunction and may be classified as Type VId (LV dilation), Type VIr (with restrictive pattern) or Type VIo (persistence of obstructive pattern, but with LV dilation). When the right ventricle is involved, the capital letter \u201cR\u201d is added at the end of the Type. If there is an apical aneurysm, the letter \u201ca\u201d is added after the Type (See the text and the examples in the table). (Modified from Llamas- Esper\u00f3n et al.). <\/em> <\/figcaption><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:image {\"id\":3565} -->\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/CONCLUSIONS-1-1024x44.jpg\" alt=\"\" class=\"wp-image-3565\"\/><\/figure>\n<!-- \/divi:image -->\n\n<!-- divi:paragraph -->\n<p>This proposal seeks to facilitate the morphological and therefore\npathophysiological understanding of the patient with <strong>Hypertrophic Cardiomyopathy<\/strong>, in such a way that, classifying him within in a\nparticular Type, the therapeutic needs, both pharmacological and surgical, as\nwell as their prognostic implications, can be understood. <\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:paragraph -->\n<p>The management and treatment of <strong>Hypertrophic Cardiomyopathy<\/strong> has evolved since the first descriptions and thanks to the risk\nstratification models derived from registries and publications regarding a\ngreater number of patients, we now have facilities for the more precise\nidentification of patients at high risk of sudden death and future\ncomplications. Through the early recognition and directed management thanks to\na morphological and functional <strong>classification<\/strong>,\nit is possible to identify the therapeutic needs and the prognostic\nimplications in each particular case. <\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:image {\"id\":3495,\"align\":\"center\",\"width\":137,\"height\":137} -->\n<div class=\"wp-block-image\"><figure class=\"aligncenter is-resized\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/337946.png\" alt=\"\" class=\"wp-image-3495\" width=\"137\" height=\"137\"\/><figcaption><a href=\"http:\/\/cmca.mx\/wp-content\/uploads\/2022\/06\/Hypertrophic-cardiomyopathy.-Proposal-for-a-new-classification.pdf\">Download<\/a><\/figcaption><\/figure><\/div>\n<!-- \/divi:image -->\n\n<!-- divi:paragraph -->\n<p><\/p>\n<!-- \/divi:paragraph -->\n\n<!-- divi:core-embed\/youtube {\"url\":\"https:\/\/www.youtube.com\/watch?v=VpJpezxCuM0\",\"type\":\"video\",\"providerNameSlug\":\"youtube\",\"className\":\"wp-embed-aspect-4-3 wp-has-aspect-ratio\"} -->\n<figure class=\"wp-block-embed-youtube wp-block-embed is-type-video is-provider-youtube wp-embed-aspect-4-3 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\n<iframe loading=\"lazy\" title=\"2nd International Conference on Cardiology. Paris, France Dr. Guillermo Llamas Esper\u00f3n\" width=\"1080\" height=\"810\" src=\"https:\/\/www.youtube.com\/embed\/VpJpezxCuM0?feature=oembed\"  allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen><\/iframe>\n<\/div><\/figure>\n<!-- \/divi:core-embed\/youtube -->\t\t[\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section]\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"on","_et_pb_old_content":"\n\t\t\t\t<!-- wp:gallery {\"ids\":[3511]} -->\n<ul class=\"wp-block-gallery columns-1 is-cropped\"><li class=\"blocks-gallery-item\"><figure><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/Hypertrophic-cardiomyopathy.-Proposal-for-a-new-classification-1024x577.png\" alt=\"\" data-id=\"3511\" data-link=\"https:\/\/www.hospitalcardiologica.com.mx\/la-miocardiopatia-hipertrofica-propuesta-de-una-nueva-clasificacion\/hypertrophic-cardiomyopathy-proposal-for-a-new-classification-2\/\" class=\"wp-image-3511\"\/><\/figure><\/li><\/ul>\n<!-- \/wp:gallery -->\n\n<!-- wp:paragraph {\"align\":\"left\"} -->\n<p style=\"text-align:left\"><strong>Hypertrophic cardiomyopathy (HCM)<\/strong> is a clinical\ncondition, but its name has been subjected to frequent changes over the years,\nlargely because of its morphological and functional heterogeneity, which leads\nthe clinician who is focused on its study to have difficulty in understanding\nhow to diagnose it and when and how to treat it. Regarding its name, it has\nbeen called in more than 75 different ways, and it has being classified with\ndifficulty through echocardiography for more than 40 years. Today, it is\nnecessary to understand that the diverse phenotypic behavior, as well as the\nevolutionary stages of the disease, must be approached in a practical and\neffective way, so that it easier to understand its clinical behavior and\nprognosis, as well as the therapeutic needs in each particular case. We review\nthe aspects related to the name of the condition and propose a new <strong>&nbsp;<\/strong>that\ncould provide the clinical and surgical cardiologist a better understanding of <strong>Hypertrophic cardiomyopathy (HCM)<\/strong> in\nits various morphological and functional aspects<em>. <\/em><\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:image {\"id\":3526} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/INTRODUCCION-1-1024x44.jpg\" alt=\"\" class=\"wp-image-3526\"\/><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:paragraph -->\n<p>The nomenclature and <strong>Classification of Cardiomyopathies<\/strong> have had constant changes since 1961, when Goodwin et al. published what may be considered the first descriptive article of the clinical aspects of <strong>Cardiomyopathies<\/strong>, which from the pathophysiological point of view were divided into congestive, constrictive and \/ or obliterative and obstructive. As early as 1957, Bridgen had coined the term <strong><em>\"Cardiomyopathy\"<\/em><\/strong> when referring to non-coronary heart disease, restricting the term \"myocarditis\" only to encompass patients with inflammatory disease of infectious etiology. In 1980, the World Health Organization (WHO) defined cardiomyopathies as a disease of the cardiac muscle whose cause was unknown and in 1995 the WHO together with the International Society and Federation of Cardiology (ISFC) developed the joint work (\u201cTask Force\u201d) for the Definition and <strong>Classification<\/strong> of <strong>Cardiomyopathies (CM),<\/strong> and expanded the <strong>classification<\/strong> to include all the diseases that affected the cardiac muscle (<strong>myocardial<\/strong> diseases associated with myocardial dysfunction) taking into account both, the etiology and the dominant pathophysiological pattern, and they included in it: dilated <strong>cardiomyopathy<\/strong>, <strong>hypertrophic cardiomyopathy (HCM<\/strong>), restrictive <strong>cardiomyopathy<\/strong> and for the first time they added arrhythmogenic right ventricular <strong>cardiomyopathy<\/strong>, which had been described in 1982. &nbsp;It was until 2006, when Maron et al., endorsed by the American Heart Association (AHA), proposed a <strong>classification <\/strong>and sub-classification, where primary <strong>cardiomyopathy<\/strong> (which affects only or primarily the heart muscle) could be named according to its origin as genetic, mixed and acquired, providing a description of each one. <strong>Hypertrophic cardiomyopathy <\/strong>was defined as a genetic primary <strong>CM<\/strong>, and its origin was attributed to various mutations of sarcomeric proteins encoded by 11 genes. In 2011, The American College of Cardiology (ACC), together with the AHA, endorsed their <strong>classification<\/strong> published 5 years before, with the participation of Maron himself. Two years later, the MOGE(S) <strong>classification <\/strong>for<strong> Cardiomyopathies<\/strong> appeared, and it included a phenogenotypic nomenclature system endorsed by the World Heart Federation (WHF), and which attempted to use a descriptive system of nomenclature and notation applied to diagnosis in the clinical practice (like the one used in oncological diseases) based on the knowledge of the genetics and pathophysiology of each <strong>cardiomyopathy<\/strong>, and they also placed the acronym S to refer to the functional class of the described condition.&nbsp; Despite everything, in the European Guidelines for the Diagnosis and Treatment of <strong>Hypertrophic<\/strong> <strong>Cardiomyopathy<\/strong> published in 2014, little value was given to the MOGE(S) <strong>Classification<\/strong>, and they adopted the recommendations of the ESC itself. They defined them with morphological and functional criteria with the family \/ genetic and non-family \/ non-genetic subtypes regardless of the presence of extra-cardiac disease. <strong>Hypertrophic Cardiomyopathy<\/strong> was defined by the presence of an increase in the thickness of the left ventricular wall which cannot be explained by abnormal overload conditions <strong>(Figure 1<\/strong>).<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:image {\"id\":3520} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/Classification-of-cardiomyopathies-according-to-the-European-Society-of-Cardiology-in-2008.jpg\" alt=\"\" class=\"wp-image-3520\"\/><figcaption> <strong><em>Figure 1. Classification<\/em><\/strong><em> of <strong>cardiomyopathies<\/strong> according to the European Society of Cardiology in 2008. HCM: hypertrophic cardiomyopathy, DCM: dilated <strong>cardiomyopathy<\/strong>, ARVC: arrhythmogenic right ventricular <strong>cardiomyopathy<\/strong>, RCM: restrictive <strong>cardiomyopathy<\/strong>. <\/em> <\/figcaption><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:image {\"id\":3524} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/2-HIPERTROPHIC-CARD-1-1024x44.jpg\" alt=\"\" class=\"wp-image-3524\"\/><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:paragraph -->\n<p>The first description of <strong>Hypertrophic Cardiomyopathy <\/strong>was made by Schmincke et al. in 1907 in autopsy results.In 1957, Brock called it aortic subvalvular stenosis and in the same year, Donald Teare published his descriptive article of nine autopsy cases, which he had described as asymmetric cardiac <strong>hypertrophy<\/strong> in young adults; seven had suffered sudden death. He described the disorganization of the myocardial fibers for the first time and he even classified it as a muscular hamartoma. <\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>In 1962 in Mexico, Fishleder et al. described the clinical, auscultatory and exploratory findings in patients that they considered had a dynamic subaortic stenosis.In 1964, Braunwald, Morrow et al. delineated the condition that they called idiopathic hypertrophic subaortic stenosis, based on the analyzes of 64 patients, which included Morrow himself, who described the well-known Morrow Myectomy, and who suffered the disease. <sup>14<\/sup> That same year, Cohen et al. called it Obstructive <strong>Hypertrophic Cardiomyopathy<\/strong> for the first time.&nbsp; It should be mentioned here that, to date, the disease has been called in more than 75 different ways, which has generated greater confusion in its understanding. <\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>Today we know that <strong>Hypertrophic Cardiomyopathy<\/strong>\nis a hereditary disease transmitted in an autosomal dominant manner,\ncharacterized by an inexplicable <strong>hypertrophy<\/strong>\nof the myocardium, which has an estimated phenotypic prevalence of 1 in 500 (2\nper 1,000) in an urban adult population with a similar prevalence in different\ncontinents and countries and a possible genotypic prevalence of 1 in 200 (5 per\n1,000) which places it probably as the most common of the genetic heart\ndiseases.To support this last hypothesis, there are several avenues\nof evidence, such as the fact that pathogenic sarcomere genes are more common\nin the general population than previously thought, as well as the fact that the\ngenetic tests with a greater capacity that are carried out today have defined a\nnew subgroup of patients, who don\u2019t have clinical expression or left\nventricular <strong>hypertrophy<\/strong> (<em>positive\ngenotype, negative phenotype<\/em>); and on the other hand, thanks to the image\ntechnology currently used, such as cardiac magnetic resonance imaging (MRI),\nthe recognition of some <strong>Hypertrophic Cardiomyopathy<\/strong>\nphenotypes that are difficult to delineate by means of 2D echocardiography, is\nmore feasible. In addition, it should be remembered that previous prevalence\nstudies did not consider the hereditary nature of the disease, whereas now it\nis common to perform a family detection. So far, a little more than 11 genes,\nwhich may encode more than 1500 mutations in cardiac sarcomere proteins have\nbeen identified. Around 60% of young and adult patients with <strong>Hypertrophic\nCardiomyopathy<\/strong> have one of these mutations and 5-10% are caused by\nanother type of metabolic or neuromuscular genetic alteration. Its origin is\nstill unknown in 25-30% of the patients.<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:image {\"id\":3529} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/CLASSIFICATION-OF-HYPERTR-1024x44.jpg\" alt=\"\" class=\"wp-image-3529\"\/><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:paragraph {\"align\":\"left\"} -->\n<p style=\"text-align:left\">The WHO determined to use the term <strong>hypertrophic cardiomyopathy<\/strong> as it is considered the most<br> accurate term to describe this primary <strong>hypertrophy<\/strong> that can occur with or without dynamic left<br> ventricular outflow tract obstruction (LVOTO). Therefore, today it has been classified from the<br> hemodynamic point of view, into two large groups:<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p><strong>The Obstructive Form: <\/strong><\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p><strong>Hypertrophic<\/strong>\nobstructive <strong>cardiomyopathy<\/strong> (HOCM),\nwhich shows an obstruction to the LVOT which can be present at rest (<em>persistent<\/em>),\ncan be <em>latent<\/em> (absent at rest but provoked by some maneuver or effort)\nor <em>labile<\/em> (variable). The first two (resting and latent) represent 70%\nof the cases. The two most common forms of obstruction are the one that is\nclassified as subaortic (which is more frequent and is related to an LVOT\nobstruction, and the mid-ventricular, in which the obstruction, in case it is present,\nis precisely mid-ventricular). The LVOT obstruction may be conditioned either\nby the systolic anterior motion (SAM) of the anterior leaflet or posterior\nleaflet of the mitral valve, or it may be conditioned by alterations or\nmalposition of the papillary muscle and \/ or the chordae tendineae (tendinous\ncords), which by a drag (Venturi effect) causes an incomplete support on the\nseptum, which also frequently favors the appearance of insufficiency of the mitral\nvalve. The <em>mid-ventricular<\/em>\nobstruction can be caused by an abnormal insertion of the anterior papillary\nmuscle or by excessive mid-ventricular <strong>hypertrophy<\/strong>\nor by the papillary muscle itself, with a pathological alignment. Both may\ncoexist in the same patient. There may also exist an obstruction in the right\nventricular outflow tract, and it is seldom considered important.<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>In general, patients with the obstructive type of the disease are more symptomatic and have a worse prognosis. LVOT obstruction is closely related to higher mortality caused by obstruction or by sudden death. In the asymptomatic or slightly symptomatic patient, the magnitude of the obstruction loses predictive value for mortality and on the contrary, in the highly symptomatic patient, mortality is higher regardless of the degree of the obstruction.<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p><strong>The non-Obstructive Form:<\/strong><\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>The non-obstructive <strong>hypertrophic cardiomyopathy<\/strong> (nHCM) is characterized by\ndisproportionate <strong>hypertrophy<\/strong> of the\nventricular wall, but it is not possible to demonstrate an obstruction at any\nlevel at rest, and it may not be caused by maneuvers such as the Valsalva maneuver\nor exercise. These patients generally have a more benign and less symptomatic\ncourse than patients with the obstructive form.<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:image {\"id\":3534} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/PROGRESSION-STAGES-OF-HYPER-1024x44.jpg\" alt=\"\" class=\"wp-image-3534\"\/><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:paragraph -->\n<p>In 2012, Olivotto I. et al.described 4 <strong>Hypertrophic\nCardiomyopathy<\/strong> progression patterns, which they classified into\nStages I to IV, which are an excellent description of what the natural history\nof the disease usually is. They allow a clear understanding of the\npathophysiological process of the condition. These patterns are:<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:list -->\n<ul><li><strong>STAGE I<\/strong> (<strong>HCM\nin the nonhypertrophic phase<\/strong>), it is characterized by the absence of <strong>hypertrophy<\/strong> of the left ventricle (LV)\nin the context of the subject who has the genotype, usually detected in a\nsystematic family study of a patient who has the disease. The phenotypic\nmanifestation in the patient with the genetic alteration usually manifests itself\nduring the 2nd decade of his life and it may even appear in later stages. An\nimportant point to consider is that we are not referring to the patient who has\nthe genotype and who has a negative phenotype (genotype + \/ phenotype -) for\nthe rest of his life. In this stage. the patient usually has some\nelectrocardiographic manifestations, diastolic dysfunction, and slight dilation\nof the left atrium, as well as abnormalities of the subvalvular apparatus in\nthe echocardiogram (ECHO).<\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:list -->\n<ul><li><strong>STAGE II<\/strong> (<strong>Classic\nHCM phenotypically<\/strong>) it refers to the stage in which phenotypic expression\nbecomes manifest, with a hyperdynamic LV, with a LV expulsion fraction\n(LVEF)&gt; 65%, in the absence of fibrosis. 75% of the patients will enter into\nthis stage, depending on the penetrance of the causal genetic mutation.\nTypically, regional and asymmetric <strong>hypertrophy<\/strong>\nis observed, most often involving the anterior basal <em>septum<\/em> and the\nbasal portion of the anterior free wall of the LV. The anatomic patterns of <strong>hypertrophy<\/strong> may be multiple (see below).\nMicroscopically, <strong>myocardial <\/strong>fiber\nderangement, microvascular remodeling and incipient fibrosis appear. In this\nstage, the LV is usually small, hypercontractile, and with an LVEF usually\ngreater than 65%. The fibrosis determined by MRI, and late gadolinium\nenhancement (LGE) is usually 2% in a (low) average. This stage usually lasts\nfor years or decades.<\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:list -->\n<ul><li><strong>STAGE III (adverse remodeling)<\/strong>, this stage of the disease has been called by some as \"adverse\nremodeling\" and it is defined by the presence of unfavorable structural\nmodifications superimposed on the classic pattern of <strong>Hypertrophic cardiomyopathy<\/strong>,\na consequence of an increase in myocardial fibrosis and the consequent\ndepression of the systolic function. It is important to mention that apparently\nthis is not an expected average behavior in a patient with <strong>Hypertrophic cardiomyopathy<\/strong>\nas time goes by, but rather a selective pathway followed by approximately 15-20%\nof the patients, of which a small proportion, will progress to a severe\ndysfunction and heart failure. It has also been observed that this adverse\nremodeling is more prevalent in complex genotypes (patients with multiple\nmutations), which could reflect a profound disorder of sarcomere mechanics and\ncardiomyocyte energetics. The development of both, the extension and the time\nof evolution of this adverse remodeling are very heterogeneous, and it is\npossible to observe it in any age (including childhood and adolescence) and it\nwill progress to a severe dysfunction and heart failure in some cases in a short\ntime or, as in the majority of the cases, it occurs gradually evolving over\nyears or decades. Of course, these patients will go through intermediate stages\nof progression that go from the hypercontractility phase to the reduced left\nventricular systolic function (LVEF) phase, which includes a moderate reduction\nin LVEF, moderate to significant diastolic dysfunction and a progressive\ndilation of the left atrium, an increase in the percentage of fibrosis measured\nby RT, severe microvascular dysfunction, progressive thinning of the LV walls,\nappearance of atrial fibrillation, spontaneous reduction or loss of LVOT\nobstruction, and the appearance of apical aneurysm. Not all of these, but some\ncoexist in the same patient, and this entails the presence of a poor evolution\nand progression towards adverse remodeling.<\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:paragraph -->\n<p>In general, this remodeling model behaves in a variable way with the\nappearance of moderate to large areas of intramyocardial fibrosis that can be\nconfluent or in patches, which replace significant portions of the LV, usually\nfrom the middle portions of the wall that tend to radiate towards the\nsubendocardium (although they can be transmural). This causes the LV wall to be\nthinner and it creates cicatrization or repair processes. Finally, it seems that\neverything is a consequence of microvascular ischemia, cardiomyocyte energy\ndepletion and apoptosis that leads to a progressive loss of myocytes that are\nreplaced by fibrous tissue.<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:list -->\n<ul><li><strong>STAGE IV<\/strong> (<strong>excessive\ndysfunction<\/strong>), although it is rare, it is characterized by significant LVEF\ndeterioration (&lt;50%), significant fibrosis and LV dilation with clinical\nmanifestations of heart failure. Although it may be considered as an\n\u201cend-stage\u201d disease, some people have called it a <strong>\u201cburned out\u201d<\/strong> phase and it corresponds to ~5% of patients. Maron BJ\net al.had already defined this stage, when in 1998, they described\nthe progression of some patients with <strong>Hypertrophic Cardiomyopathy<\/strong> to\nsystolic dysfunction, in whom the wall thickness was reduced by approximately\n25% in 5-6 years (from 20 to 15 mm in average) at a rate of 1 to 2 mm per year,\nand the LV cavity measured in diastole, dilated 20% in this period (from 45 to\n55 mm in average) at a rate of 1 to 1.5 mm per year. <strong>(Fig. 2).<\/strong><\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:paragraph -->\n<p>\n\nA\nvery important aspect is that in this stage, they cataloged two types of\npatients. The first type was defined as <em>\"dilated hypokinetic\"<\/em>\ncharacterized by an increased volume and remodeling with LV sphericity, and\nsometimes it was difficult to differentiate it from cases with dilated <strong>cardiomyopathy<\/strong> of idiopathic type.\nUsually at this stage the LVOT obstruction has disappeared. It is common to\nfind pulmonary arterial hypertension, biventricular dilation, and mitral\nregurgitation due to dilation of the valve ring (annulus). The second form was\ncalled <em>\u201chypokinetic-restrictive\u201d<\/em> characterized by a small and rigid LV\ncavity with significant diastolic dysfunction that simulates restrictive <strong>cardiomyopathy<\/strong>; in these patients,\nsystolic function was slightly compromised, and it was possible to distinguish\nsome degree of asymmetry in the thickness of the LV wall. It is now known that\nthis last form is related to some specific type of mutations such as TPM1, MYL3\nand MYL2. Although Olivotto et al.<sup>23<\/sup> did not define it this way,\nMelacini P. et al. described a third pattern in terminal patients,\ncharacterized by progressive heart failure because of <em>\u201cpersistence of LVOT\nobstruction\u201d<\/em>, which eventually conditions dilation and systolic dysfunction\nof the LV, without the total disappearance of the obstruction. These patients\nare represented by older individuals (50 \u00b1 14 years at diagnosis). The onset of\nsymptoms after diagnosis is also short (4 \u00b1 6 years) although once started,\nthey rapidly evolve to an advanced functional class (1 \u00b1 2 years).\n\n\n\n<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:image {\"id\":3537} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/Development-of-Progression-Patterns-of-Left-Ventricular-Hypertrophy-in-the-Patient-who-has-HCM-Genotype.jpg\" alt=\"Development of Progression Patterns of Left Ventricular Hypertrophy in the Patient who has Hypertrophic Cardiomyopathy Genotype. LVEF: left ventricular ejection fraction. \" class=\"wp-image-3537\"\/><figcaption> <strong><em>Figure 2.<\/em><\/strong><em> Development of Progression Patterns of Left Ventricular <strong>Hypertrophy<\/strong> in the Patient who has <strong>Hypertrophic Cardiomyopathy<\/strong> Genotype. LVEF: left ventricular ejection fraction.<\/em> <\/figcaption><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:image {\"id\":3548} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/DISTRIBUTION-AND-CLASIFIC-1024x44.jpg\" alt=\"\" class=\"wp-image-3548\"\/><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:paragraph -->\n<p>In <strong>Hypertrophic Cardiomyopathy<\/strong>, the distribution of LV <strong>hypertrophy<\/strong> is characteristically asymmetric and particularly\nheterogeneous, it can encompass a wide range of wall thickening patterns, from\nextensive and diffuse to mild and segmental, and without a single morphological\nexpression considered typical or classical. However, for a better clinical\nunderstanding, there has been an effort to subclassify these patterns in such a\nway that it is possible to understand which could be the dominant <strong>hypertrophic<\/strong> point, and thus expect to\na certain degree, a predictable clinical evolution. In spite of their\ndiversity, the LV <strong>hypertrophy<\/strong>\npatterns are generally not extensive and usually involve &lt;50% of its wall in\nhalf of the patients, and their extension is less in a significant minority.<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>Although the phenotypic characteristics were initially described by\nautopsy findings and later by 2D ECHO analysis, the first formal attempt to\nclassify <strong>Hypertrophic Cardiomyopathy<\/strong> according to its anatomical characteristics was made\nby Maron BJ et al. in 1981, through the analysis of 125 patients with the\ndisease, who underwent a 2D ECHO. They defined 4 dominant LV hypertrophy\ndistribution patterns, which were called Type I - IV based on their location:<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:list -->\n<ul><li><strong>Type I <\/strong>(10% of the\ncases),<strong> <\/strong>it is\ncharacterized by having <strong>hypertrophy<\/strong> confined only to the anterior\nportion of the LV <em>septum<\/em>,<\/li><li><strong>Type II<\/strong> (20% of the cases), it corresponds to patients with <strong>hypertrophy<\/strong> of the entire ventricular <em>septum<\/em> (anterior and posterior segment)\nbut not to the LV free wall,<\/li><li><strong>Type III<\/strong> (the most frequent), it corresponds to\nhypertrophy of basal portions of both the septum and the LV free wall (52% of\nthe patients), and of these, a small proportion (25 in 65 patients) had a\npredominance of <strong>hypertrophy<\/strong> in the\napical regions; and finally,<\/li><li><strong>Type IV<\/strong> (18% of the patients), with involvement\nof other LV regions and without showing hypertrophy of the anterior basal\nportion of the ventricular <em>septum<\/em>. <\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:paragraph -->\n<p>&nbsp;<strong>(Fig. 3).<\/strong><\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>They confirmed that previous studies performed by M-mode\nechocardiography significantly underestimated (up to 5 mm) the maximum\nthickness of the septal or free LV wall. That same year, Yamaguchi H et al.\npublished the ventriculographic and echocardiographic findings of 30 Japanese\npatients with apical <strong>Hypertrophic\nCardiomyopathy<\/strong>. They had a marked\napical obliteration together with \"giant\" negative T waves in the\nelectrocardiogram with high voltage QRS and a thickness of the apex wall &gt;\n15 mm. In Maron's Description, patients with apical HCM in Type III and IV had\nbeen included, but it did not include concentric hypertrophy. Maron himself in\n1985, described 2 patients with posterobasal LV free wall <strong>hypertrophy<\/strong> with evidence of obstruction. This morphological type\nwas not included in the classification. One year later (1986) Candel-Riera et\nal. added two types to the <strong>classification<\/strong>\nproposed by Maron:<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:list -->\n<ul><li><strong>Type V<\/strong> which corresponded to concentric <strong>hypertrophy<\/strong>, and<\/li><li><strong>Type VI<\/strong> which corresponded to the apical <strong>hypertrophy<\/strong> described by Yamaguchi.<\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:paragraph -->\n<p> In the year 2000, Romero-Farina et al. compared Maron's echocardiographic <strong>classification<\/strong> with <strong>myocardial<\/strong> morphology analyzed by <strong>myocardial<\/strong> tomography scan (SPET). Although their power of spatial resolution was lower than the ECHO and the other techniques such as MRI, they considered that allowing the distribution of <strong>hypertrophy<\/strong> to be observed, facilitated the <strong>classification<\/strong> of patients into different morphological types. They analyzed 119 patients and found that only in 64% of them, the ECHO was able to facilitate the measurement of all the LV segments, and with the SPET they obtained a more complete visualization of all the segments in the short axis, so although the spatial resolution did not allow them to accurately measure the thickness of the walls, it made it possible to establish which morphological type each case corresponded to. They confirmed that the most frequent type was Maron's type III (74% of the cases), but in 25% of the cases the ECHO made a mistake in defining the <strong>classification<\/strong> fundamentally in the same type. They also found that 4 patients could not be classified within type I - VI (they had septal and inferior <strong>hypertrophy<\/strong>). <\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:image {\"id\":3549} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/Marons-original-classification-of-hypertrophic-cardiomyopathy-by-2D-echocardiography.-Type-I-to-IV.-Modified-from-Maron-BJ.-jpg.jpg\" alt=\"Maron's original classification of hypertrophic cardiomyopathy by 2D echocardiography. Type I to IV. (Modified from Maron BJ et al.) \" class=\"wp-image-3549\"\/><figcaption><strong><em>Figure 3. <\/em><\/strong><em>Maron's original <strong>classification<\/strong> of <strong>hypertrophic cardiomyopathy<\/strong> by 2D echocardiography. Type I to IV. (Modified from Maron BJ et al.)<\/em> <\/figcaption><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:image {\"id\":3551} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/RIGHT-VENTRICLE-1-1024x44.jpg\" alt=\"\" class=\"wp-image-3551\"\/><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:paragraph -->\n<p>In 2007, Maron et al. described the involvement\nof the right ventricle (RV) when studying 46 patients with <strong>Hypertrophic Cardiomyopathy <\/strong>who\nunderwent MRI and they compared them with 22 healthy individuals carefully\nanalyzing the thickness of the wall of both ventricles. They found that the\nmaximum RV wall thickness was greater in <strong>Hypertrophic Cardiomyopathy<\/strong>\npatients compared to the control group (7 \u00b1 2 vs 5 \u00b1 1 mm, p &lt;0.001),\nincluding 15 (33%) with a maximum thickness \u2265 8 mm, and four (9%) with extreme <strong>hypertrophy<\/strong> (\u2265 10 mm). They\ndemonstrated a close correlation between the degree of LV <strong>hypertrophy <\/strong>and RV <strong>hypertrophy<\/strong>.\nThe greater the hypertrophy of the former, the greater the <strong>hypertrophy<\/strong> of the latter (R2 = 0.4, p &lt;0.001). The presence of\nRV hypertrophy was never included in Maron's <strong>classification.<\/strong>\n\nIn the same way, in 2010, Keeling et al.\npublished the case of a patient with <strong>Hypertrophic Cardiomyopathy<\/strong> in whom\nthey detected RV <strong>hypertrophy<\/strong> through\nMRI but who also had apical fibrosis and fibrosis of the free wall of this\nventricle, which had been detected by RT. It is now known that in addition to\nRV wall <strong>hypertrophy<\/strong>, it is common to\nfind a prominence of some RV structures, such as the supraventricular crest\n(Wolf's spur) that is located between the pulmonary and right atrioventricular\norifices and that can lead to confusion when measuring right septal thickness.\nThe most important portion to evaluate is the right septal basal portion and\nthe basal portion of the RV free wall, which can sometimes condition RV outflow\nobstruction and it requires surgical treatment.\n\n\n\n<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:image {\"id\":3552} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/APICAL-ANEURISM-1024x44.jpg\" alt=\"\" class=\"wp-image-3552\"\/><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:paragraph -->\n<p>Apical <strong>Hypertrophic Cardiomyopathy<\/strong>,\ninitially described by Sakamoto et al., and later discussed masterfully by\nYamaguchi et al. is a phenotypic variant apparently modulated by environmental\nand genetic factors, but in general its diagnosis is a challenge when only ECO\n2D is used. Although the apical LV involvement is a <em>sine qua non<\/em> component in the apical form of <strong>HCM<\/strong>, some mid-ventricular segments may also be hypertrophied (this\nis one of the mixed morphological subtypes), in which mid-ventricular\nobstruction with obliteration may occur of the LV cavity. These patients may\npresent an apical aneurysm (AA), which is usually another aspect that is\ndifficult to diagnose, and which is usually underdiagnosed and undervalued. In\npatients with apical <strong>Hypertrophic Cardiomyopathy<\/strong>, the\npresence of AA can be detected in 2% to 28% of patients (there is a higher\nincidence in patients with obstructive mid-ventricular <strong>hypertrophy<\/strong>). This anomaly corresponds to a small segment of the LV\napex, with a thin, dyskinetic or akinetic wall, with a relatively narrow neck\nthat communicates with the basal or medial portions of the LV. Patients with AA\nassociated with mid-ventricular <strong>hypertrophy\n<\/strong>represent an important subgroup of patients who, in addition to being\nusually underdiagnosed if MRI is not used in their analysis, have special\nprognostic and therapeutic implications. MRI has demonstrated that AA is\nusually made up of fibrous tissue and that RT can be infiltrated into the\nadjacent septum and free wall, representing a \u201cnest\u201d which fosters ventricular\ntachyarrhythmias and thus increases the risk of sudden death. In 2008, Maron et\nal. demonstrated that AA patients had a higher risk of progressing to heart\nfailure, having sudden death, generating systemic embolism and having apical\nthrombi. The average risk of adverse clinical consequences in these patients\nwas 10.5% per year, which is considerably higher than the amount reported in the\ntotality of the patients with <strong>Hypertrophic Cardiomyopathy<\/strong>. On\nHolter monitoring, more than 40% of these patients had monomorphic nonsustained\nventricular tachycardia, which is considered high risk for sudden death in\npatients with <strong>HCM<\/strong>. AA may also be\npresent in patients with pure apical H<strong> Hypertrophic Cardiomyopathy<\/strong>.<strong>(Figure\n4)<\/strong><\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:image {\"id\":3553} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/Classic-phenotypes-and-subtypes-of-mid-ventricular-and-apical-hypertrophic-cardiomyopathy-873x1024.jpg\" alt=\"\" class=\"wp-image-3553\"\/><figcaption> <br><strong><em>Figure 4. <\/em><\/strong><em>Classic phenotypes and subtypes of mid-ventricular and apical hypertrophic cardiomyopathy. <strong>A: <\/strong>isolated apical form (Type III), it is the traditional phenotype, limited to the apical segments of the LV, it may have an apical aneurysm (Type IIIa). <strong>B: <\/strong>mixed balanced form, in which the contiguous (mid-ventricular), and rarely the basal portions, are also hypertrophied, although apical hypertrophy predominates (Type III). It may or may not have an apical aneurysm. <strong>C: <\/strong>phenotype with isolated mid-ventricular hypertrophy, without involvement of the apical segments (Type II). It may or may not have an obstruction and an apical aneurysm. <strong>D: <\/strong>predominantly mid-ventricular form, in which this region has a greater hypertrophy (Type II), but the LV apex is also hypertrophied and it has an obstruction. It may have an apical aneurysm (Type IIa-o). (Modified from Jan et al.). <\/em> <\/figcaption><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:paragraph -->\n<p>The presence of mid-ventricular obstruction with cavity obliteration\nis frequent and it is only possible to observe it in apical <strong>Hypertrophic\nCardiomyopathy<\/strong> of the mixed type (mid-ventricular involvement) and\nin severe cases. the obliteration of the cavity persists until the end of the\ndiastole, and it is associated with the presence of a paradoxical diastolic\nflow <em>jet<\/em> towards AA, which is usually\na marker of poor prognosis.<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:image {\"id\":3555} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/CONTEMPORARY-ANALYSIS-1024x44.jpg\" alt=\"\" class=\"wp-image-3555\"\/><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:paragraph -->\n<p>In 2009, Maron et al. characterized the\ndistribution pattern of LV <strong>hypertrophy <\/strong>using\nMRI, seeking to define more precisely the phenotypic expression of these\npatients. They studied 333 patients who had <strong>Hypertrophic Cardiomyopathy<\/strong>\nwith MRI. They considered that since this offered a great spatial resolution\nand a complete anatomical reconstruction of the LV, it would allow them to\nevaluate the precise distribution of <strong>hypertrophy<\/strong>.\nIt was thus possible to define that the contiguous basal portions of the\nanterior free wall and the ventricular septum (number 1 in the clock of the\nshort-axis plane), it constituted the regions with a predominance of thickening\n(77%) that corresponded to the distribution known as Maron Type III.They found\nthat just over half of the patients had areas of <strong>hypertrophy<\/strong> distributed over \u2265 50% of the entire LV chamber\n(diffuse <strong>hypertrophy<\/strong>), and that a\nminority had focal or regional areas of <strong>hypertrophy<\/strong>.\n12% of the patients had only 1 or 2 hypertrophied LV segments, and they were\nclassified as <em>focal involvement<\/em>, which were not even enough to show an\nincrease in the calculated total LV mass. They found a <em>moderate involvement<\/em>\nthat represented between 13% and 49% of the entire LV (3 to 7 segments) in 34%\nof the patients, and finally <em>diffuse\ninvolvement<\/em> (\u2265 8 segments), in other words, &gt; 50% of the entire LV, in\n54% of patients. Frequently, the phenotypic expression was non-contiguous\nsegmental <strong>hypertrophy<\/strong>, which created\nabrupt changes in wall thickness (in patches separated by non-hypertrophied\nregions), which were present in up to 15% of the patients, and which they describe\nas a <em>lumpy aspect<\/em>. In this last group, it was common to find\ncombinations of <strong>hypertrophy<\/strong> in\npatches of the basal anterior <em>septum<\/em>\nand in the apical anterior wall, as well as the basal anterior <em>septum<\/em> with the posterior medial <em>septum<\/em>.<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>In this study, Maron et al. also demonstrated\nthat by means of RT, it was possible to identify and quantify \"in\nvivo\" the presence of <strong>myocardial<\/strong>\nfibrosis which is so common in patients with <strong>HCM<\/strong>. They also found that the extent of <strong>hypertrophy<\/strong> (number of hypertrophied segments) was related to the\npresence of LVOT obstruction and to a greater deterioration in their functional\nclass of heart failure. The greater the <strong>hypertrophy<\/strong>,\nthe greater the degree of obstruction and the greater the clinical\ndeterioration.<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>In this study, various <strong>hypertrophy<\/strong> patterns were defined as follows:<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>a) <strong>Hypertrophy<\/strong> of the LVseptum\npreserving the free wall,<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>b) Focal <strong>hypertrophy<\/strong> of the anterior basal portion of the LV <em>septum<\/em>,<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>c) LV apex <strong>hypertrophy<\/strong>, <\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>d) Segmental <strong>hypertrophy<\/strong> predominantly of the anterolateral LV wall with normal\nanterior <em>septum<\/em>,<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>e) Massive asymmetric <strong>hypertrophy<\/strong> of the anterior wall of the\nLV <em>septum<\/em>, without involvement of the posterior septal portions,<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>f) Diffuse <strong>hypertrophy<\/strong> with involvement of the <em>septum<\/em> and the\nanterolateral wall.<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>Furthermore, they concluded that using 2D ECHO,\nLV wall thickness was underestimated in some patients, since the epicardial\nborder of the free wall was frequently not adequately visualized. They\nconcluded that MRI is the optimal method to precisely define the morphological\ncharacteristics in the patient with <strong>Hypertrophic Cardiomyopathy<\/strong>.\nSince then, no more has been said about Maron's echocardiographic phenotypic <strong>classification<\/strong>, which has been\nforgotten by many people.<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>Since then, more than an anatomical <strong>classification<\/strong>, the concept of\nphenotype has been used to refer to the morphological and functional aspects of\n<strong>Hypertrophic\nCardiomyopathy<\/strong>. The most common morphologies of the <em>septum<\/em> and the distribution of\nhypertrophy in the left ventricular wall in patients with <strong>Hypertrophic Cardiomyopathy<\/strong>\n(phenotypic expression) are shown in <strong>Figure 5<\/strong>. In fact, this distribution has been\nused to subdivide the condition into these more commonly identified 4 groups.<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>As it has already been mentioned, although\nthere are four phenotypic types which are considered as the most frequent in\nterms of the location of <strong>hypertrophy<\/strong>,\nsuch as basal sigmoid <strong>hypertrophy<\/strong>\n(with LVOT obstruction), reverse curvature hypertrophy (which usually\ncorresponds to mid-ventricular <strong>hypertrophy<\/strong>,\nand may have mid-ventricular obstruction and \/ or AA), apical and neutral <strong>hypertrophy<\/strong>; in general, some of them\nmay coexist in the same patient, or even have atypical or mixed localization\ncomponents. A greater extent of left ventricular <strong>hypertrophy <\/strong>has been associated with a younger age and a mitral\nvalve with a higher degree of SAM of the valve and outflow obstruction but it has\nnot been shown to be related to the magnitude of the symptoms or to the gender.<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>Another important point related to the findings\nof Maron et al. through the analysis of the MRIis that today, it\nmay not be possible to evaluate the patient with <strong>Hypertrophic Cardiomyopathy<\/strong>\nand plan an adequate therapeutic strategy, without a correct non-invasive\nanatomical diagnosis through a detailed analysis of the MRI, which allows to\nspecify the site or LV portion with greater <strong>hypertrophy<\/strong>, as well as the coexistence of morphological\nalterations of the mitral subvalvular apparatus.<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:image {\"id\":3556} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/The-most-common-morphologies-of-the-HCM-showing-the-frequency-of-presentation-and-their-anatomicalcharacteristics.jpg\" alt=\"\" class=\"wp-image-3556\"\/><figcaption><strong><em>Figure 5. <\/em><\/strong><em>The most common morphologies of the <strong>HCM<\/strong>, showing the frequency of presentation and their anatomical characteristics. SIGMOID: prominent basal septal protuberance, concave septum and ovoid left ventricular cavity; REVERSE CURVATURE: convex septum, increasing left ventricular cavity; APICAL: hypertrophy of the apical portion \u00b1 middle segments, \u201cAce of spades\u201d shaped cavity (More frequent in Asia); NEUTRAL: uniform hypertrophic septum. <\/em> <\/figcaption><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:image {\"id\":3557} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/proposal-for-a-new-anatomic-functional-cL-1-1024x44.jpg\" alt=\"\" class=\"wp-image-3557\"\/><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:paragraph -->\n<p>Five forms of phenotypic expression have been identified that are\nconsidered the most common in the early stages of <strong>Hypertrophic Cardiomyopathy<\/strong>, and one form was identified in late stages of the disease. On the\nother hand, there are many reports that have made it possible to define the\nmost common morphological manifestations of the disease and now we know that in\naddition to the LV, the RV may be involved and there may also be an obstruction\nof the latter's outflow tract. Furthermore, it is known that a late phenotypic\nmanifestation (end stage) of the disease may be an LV dilation phase with\nsignificant systolic dysfunction <em>(burned-out)<\/em>.\nIt is known that there is a group of patients with LVOT obstruction (some at\nrest and others with patent obstruction) and others with mid-ventricular\nobstruction, and a minority without obstruction at any level. Finally, there\nare patients who develop LV AA as a serious complication. For this reason, it\nis increasingly necessary to have an anatomical-functional <strong>classification<\/strong> scheme, which allows each patient to be classified\ninto a group that could also have different therapeutic and prognostic\nimplications. For this reason, we are proposing the use of a <strong>classification<\/strong> system that facilitates\nits understanding in a clear and practical way. The proposal is to classify the\nmorphological findings into six Types <strong>(Fig.6):<\/strong><\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:list -->\n<ul><li><strong>Type <\/strong><strong>I,<\/strong> would correspond to the \u201csigmoid\u201d variety\nwith <strong>hypertrophy<\/strong> of the basal\nsegments (anterior and \/ or posterior) of the septum and the free anterior\nwall, which corresponds to the most frequent (40 to 50% of cases). This is\ncharacterized by a prominent basal septal bulge, a concave medial septum, and\nan ovoid left ventricular cavity <strong>(Figure 6a).<\/strong> 40%\nof type I patients will have a detectable obstruction at rest (persistent) and\n30% will have an obstruction provoked by some maneuver (latent), in other\nwords, 70% will have an obstruction. This last group of patients will be those\nthat may be defined as having obstructive <strong>Hypertrophic Cardiomyopathy<\/strong>\n(oHCM).<\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:list -->\n<ul><li><strong>Type <\/strong><strong>II,<\/strong> corresponds to patients with mid-ventricular\n<strong>hypertrophy<\/strong> (reverse curvature) and\nit represents 30 to 40% of all patients. They may also have mid-ventricular\nobstruction, or this obstruction be absent (\u2265 30 mmHg peak instantaneous\ngradient in 9.4%). <strong>(Figure 6b).<\/strong> There\nis a subgroup of patients in whom mid-ventricular hypertrophy is accompanied by\napical hypertrophy, although to a lesser degree. They may or may not have AA,\nbut this type is the one that develops it most frequently (28%).<\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:list -->\n<ul><li><strong>Type <\/strong><strong>III,<\/strong> corresponds to patients with apical\nhypertrophy, which represent approximately 10% of the cases <strong>(Figure 6c).<\/strong>\nIn these patients, the hypertrophy may be \"purely\" apical, or\nit may be accompanied by moderate mid-ventricular hypertrophy and very rarely\nby basal <strong>hypertrophy<\/strong> (mixed form)\nand may or may not have AA.<\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:list -->\n<ul><li><strong>Type <\/strong><strong>IV,<\/strong> is the group of patients with diffuse,\nneutral <strong>hypertrophy<\/strong>, without\nobstruction and without a specific segmental pattern. It corresponds to\napproximately 10% of the cases. Usually, these cases, will not be obstructive\n(nHCM). <strong>(Figure\n6d)<\/strong><\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:list -->\n<ul><li><strong>Type <\/strong><strong>V,<\/strong> corresponds to those patients who have mixed\npatterns; in other words, areas of <strong>hypertrophy<\/strong>\nin patches in various LV sites, and which could be difficult to classify into\none of the four types already described, which usually may only be identified\nby MRI <strong>(Figure\n6e).<\/strong><\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:list -->\n<ul><li><strong>Type <\/strong><strong>VI,<\/strong> refers to the patient who is in the dilated\nphase of the disease (<em>burned-out<\/em>),\nwhere it has been clearly defined, either genetically or with previous imaging\nstudies, that he had <strong>Hypertrophic Cardiomyopathy<\/strong> of\nany type and that finally the ventricle dilated and entered a phase of\nsignificant systolic dysfunction (Type VId) <strong>(Figure 6f).<\/strong> These patients may rarely have a \u201crestrictive\u201d\nend-stage form (Type VIr) or persist despite dilatation with some degree of LVOT\nobstruction (Type VIo).<\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:paragraph -->\n<p>On the other hand, it is proposed in this <strong>classification<\/strong> to use additional acronyms, which include three\nfundamental aspects of the disease:<\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:list -->\n<ul><li><strong>First, <\/strong>whether there is an\n<em>obstruction<\/em>. If so, the lowercase letter \u201co\u201d must be used for\nobstruction, after the corresponding type and a hyphen. If the patient has\nbasal septal <strong>hypertrophy<\/strong>, he would be type I, but if he has either a\npersistent or latent obstruction, he would be type I-o. If he doesn\u2019t have a\ndetectable obstruction, he would be type I-n (adding the letter \u201cn\u201d which means\nnon-obstructive).<\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:list -->\n<ul><li><strong>Second,<\/strong> whether\nthere is an <em>apical aneurysm.<\/em> If so, the lowercase letter \u201ca\u201d\nmeaning aneurysm, would be added. Thus, if the patient has mid-ventricular\nhypertrophy, he would be type II, but if there is mid-ventricular obstruction\nand apical aneurysm, he would be Type IIa-o, and if there is no obstruction,\nbut if there is apical aneurysm, he would be Type IIa-n.<\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:list -->\n<ul><li><strong>Third<\/strong>, whether\nthere is <em>RV involvement<\/em>. In\nthe presence of right ventricular <strong>hypertrophy<\/strong>,\nthe capital letter \u201cR\u201d would be added at the end of the text (R comes from\nRight). For example, in the latter case with mid-ventricular <strong>hypertrophy<\/strong>, with obstruction and\napical aneurysm, if there were RV involvement, it would be Type IIaR-o. <strong>(Figure 6).<\/strong><\/li><\/ul>\n<!-- \/wp:list -->\n\n<!-- wp:image {\"id\":3563} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/cardio-a-color-2-1024x912.jpg\" alt=\"\" class=\"wp-image-3563\"\/><figcaption><strong><em>Figure 6.<\/em><\/strong><em> Proposal for a new anatomic-functional classification of hypertrophic cardiomyopathy. It is classified from type I to type V, according to the predominant location of the hypertrophied area of the Left Ventricle (LV). Type I (sigmoid) and Type II (reverse curve or mid-ventricular) are the most frequent. In the classification, they are presented as Type VI, when an evolutionary stage of the disease has appeared which is characterized by having an LV Ejection Fraction &lt;50%; in other words, the patient has entered a stage of excessive dysfunction and may be classified as Type VId (LV dilation), Type VIr (with restrictive pattern) or Type VIo (persistence of obstructive pattern, but with LV dilation). When the right ventricle is involved, the capital letter \u201cR\u201d is added at the end of the Type. If there is an apical aneurysm, the letter \u201ca\u201d is added after the Type (See the text and the examples in the table). (Modified from Llamas- Esper\u00f3n et al.). <\/em> <\/figcaption><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:image {\"id\":3565} -->\n<figure class=\"wp-block-image\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/CONCLUSIONS-1-1024x44.jpg\" alt=\"\" class=\"wp-image-3565\"\/><\/figure>\n<!-- \/wp:image -->\n\n<!-- wp:paragraph -->\n<p>This proposal seeks to facilitate the morphological and therefore\npathophysiological understanding of the patient with <strong>Hypertrophic Cardiomyopathy<\/strong>, in such a way that, classifying him within in a\nparticular Type, the therapeutic needs, both pharmacological and surgical, as\nwell as their prognostic implications, can be understood. <\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:paragraph -->\n<p>The management and treatment of <strong>Hypertrophic Cardiomyopathy<\/strong> has evolved since the first descriptions and thanks to the risk\nstratification models derived from registries and publications regarding a\ngreater number of patients, we now have facilities for the more precise\nidentification of patients at high risk of sudden death and future\ncomplications. Through the early recognition and directed management thanks to\na morphological and functional <strong>classification<\/strong>,\nit is possible to identify the therapeutic needs and the prognostic\nimplications in each particular case. <\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:image {\"id\":3495,\"align\":\"center\",\"width\":137,\"height\":137} -->\n<div class=\"wp-block-image\"><figure class=\"aligncenter is-resized\"><img src=\"https:\/\/www.hospitalcardiologica.com.mx\/wp-content\/uploads\/2022\/06\/337946.png\" alt=\"\" class=\"wp-image-3495\" width=\"137\" height=\"137\"\/><figcaption><a href=\"http:\/\/cmca.mx\/wp-content\/uploads\/2022\/06\/Hypertrophic-cardiomyopathy.-Proposal-for-a-new-classification.pdf\">Download<\/a><\/figcaption><\/figure><\/div>\n<!-- \/wp:image -->\n\n<!-- wp:paragraph -->\n<p><\/p>\n<!-- \/wp:paragraph -->\n\n<!-- wp:core-embed\/youtube {\"url\":\"https:\/\/www.youtube.com\/watch?v=VpJpezxCuM0\",\"type\":\"video\",\"providerNameSlug\":\"youtube\",\"className\":\"wp-embed-aspect-4-3 wp-has-aspect-ratio\"} -->\n<figure class=\"wp-block-embed-youtube wp-block-embed is-type-video is-provider-youtube wp-embed-aspect-4-3 wp-has-aspect-ratio\"><div class=\"wp-block-embed__wrapper\">\nhttps:\/\/www.youtube.com\/watch?v=VpJpezxCuM0\n<\/div><\/figure>\n<!-- \/wp:core-embed\/youtube -->\t\t","_et_gb_content_width":"","content-type":"","footnotes":""},"categories":[9,1],"tags":[],"_links":{"self":[{"href":"https:\/\/dev.hospitalcardiologica.com.mx\/index.php?rest_route=\/wp\/v2\/posts\/5634"}],"collection":[{"href":"https:\/\/dev.hospitalcardiologica.com.mx\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dev.hospitalcardiologica.com.mx\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dev.hospitalcardiologica.com.mx\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dev.hospitalcardiologica.com.mx\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5634"}],"version-history":[{"count":1,"href":"https:\/\/dev.hospitalcardiologica.com.mx\/index.php?rest_route=\/wp\/v2\/posts\/5634\/revisions"}],"predecessor-version":[{"id":5649,"href":"https:\/\/dev.hospitalcardiologica.com.mx\/index.php?rest_route=\/wp\/v2\/posts\/5634\/revisions\/5649"}],"wp:attachment":[{"href":"https:\/\/dev.hospitalcardiologica.com.mx\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5634"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dev.hospitalcardiologica.com.mx\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5634"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dev.hospitalcardiologica.com.mx\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5634"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}