Miocardiopatía Hipertrófica en ausencia de criterios de hipertrofia. Serie de casos / Hypertrophic cardiomyopathy in the absence of hypertrophy criteria. Case series

La miocardiopatía hipertrófica (MCH) es la miocardiopatía hereditaria más frecuente, su principal expresión fenotípica consiste en hipertrofia ventricular izquierda (HVI) en ausencia de condiciones de carga que la justifiquen. Cuando existe una variante genética patogénica se denomina MCH sarcomérica. Los criterios diagnósticos más aceptados son HVI ≥ 15 mm en cualquier segmento o ≥ 13 en ciertas condiciones, criterios que tienen tres inconvenientes: 1) La HCM es una patología donde la HVI es evolutiva, existiendo otros elementos más precoces, pero menos precisos, como criptas, bandas musculares y alteraciones de la válvula mitral y músculos papilares; 2) Pacientes de baja estatura pueden no alcanzar estos umbrales; 3) La MCH apical no queda siempre bien representada usando estos grosores, requiriendo indexar por tamaño del paciente y/o considerar la HVI relativa (relación grosor apical / basal que no debe superar 1). Presentamos una serie de casos con genotipo confirmado para MCH que no cumplen los criterios de HVI aceptados para MCH y donde se debe individualizar el diagnóstico considerando los tres elementos señalados.

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac condition; its phenotypic expression consists of ventricular hypertrophy (LVH) unrelated to loading conditions. In patients with a genetic pathogenic variant, the condition is termed sarcomeric HCM. Current diagnostic criteria are based on absolute left ventricular thickness, requiring ≥15 mm in any segment or ≥13 mm in particular conditions. These criteria have three pitfalls: 1) HCM is an evolving disease where LVH occurs gradually, with other early -but less precisephenotypic expressions such as myocardial crypts, muscular bands, or mitral and papillary muscle alterations; 2) Patients with short stature tend to have less LVH and do not reach the proposed thickness threshold. 3) Apical HCM is not correctly addressed in this cut-off as the heart tapers from base to apex, warranting indexing wall thickness to body size and using relative LVH in the apex (ratio from apex/base, abnormal,>1). This small case series includes three patients with a pathogenic genetic variant for HCM that doesn't satisfy the current criteria of LVH. For its precise assessment, the aforementioned points must be considered.

Changing Concept of Hypertensive Heart Disease

Arterial hypertension leads to both structural and functional changes of the heart. Hypertensive heart disease (HHD) is characterized by complex changes in myocardial structure (e.g., enhanced cardiomyocyte growth, excessive cardiomyocyte apoptosis, accumulation of interstitial and perivascular collagen fibers, disruption of endomysial and perimysial collagen network) that cause the remodeling of the myocardium. In the 1970s, hypertrophic growth of cardiomyocytes is compensatory to reduce wall stress on the ventricular wall imposed by pressure overload. Recent data from animal studies suggest that inhibition of ventricular hypertrophy was not associated with ventricular dilatation or reduced wall motion despite elevated wall stress. The genetic complexity (gene-gene and/or gene-environment interactions) may modulate left ventricular mass and transcriptional regulators are participated in pathologic myocardial growth. Many hormones and cytokines lead to a profibrotic and inflammatory environment. Excess of ventricular collagen in hypertensive patients is the result of both increased collagen synthesis by fibroblasts and stimulated myofibroblasts, and unchanged or decreased collagen degradation by matrix metalloproteinase. Several biochemical markers of myocardial remodeling will prove to be useful. The development of noninvasive methods like echoreflectivity, cardiac magnetic resonance imaging, speckle tracking echocardiography, and cardiac molecular imaging would enable broader application. Meta-analysis showed that there was a significant difference among medication classes in decreasing left ventricular mass.