CONICET | Buscador de Institutos y Recursos Humanos

Objetive: To investigate the pathogenesis of dilation in patients (p) with hypertrophic cardiomyopathy (HCM) who progressed to the dilated phase of HCM (DHCM) and were submitted to heart transplantation. Methods: Diagnosis of HCM was based on ecocardiographic findings and presence of fiber disarray in endomyocardial biopsy. In explanted hearts from 7 p with DHCM the extent of arteriolar dysplasia and fibrosis were determined in Masson trichrome-stained tissue sections involving the whole left ventricle (LV) wall at the mid-zone between the apex and the mitral annulus. The amount of fibrosis and proportion of intramural dysplasic arterioles were determined with a digital analysis system. Results: Age 40.6 ± 10 (32 - 56 years), 5 males, diastolic LV diameter 61.3 ± 11.8 mm. The hearts weighed 393 (260-755 g). The epicardial coronary arteries had a patent lumen. Replacement patchy fibrosis was distributed in 37.6 ± 12.6% of the LV wall and 87.5 ± 14.6% of the intramural arterioles were dysplasic (figure). Many arterioles, especially within the fibrosis areas presented complete luminal occlusion. All hearts presented areas with fiber disarray and myocyte hypertrophy Figure Conclusions: All p with DHCM presented a severe arteriolar disease and replacement of more than 1/3 of the LV mass by fibrous tissue, it can be hypothesized that dilation leading to heart failure is the consequence of a remodeling process secondary to chronic ischemia and myocyte death. This observation confirming other published reports pose the possibility that the new strategies for increasing the heart microcirculation, either by gene therapy or cell transplant, may be beneficial for preventing or ameliorating dilation and heart failure in HCM

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