Histological assessment of apoptotic cell death in cardiomyopathies

Apoptosis in the myocardium is complex and often difficult to recognise. My ocyte apoptosis is scattered across the myocardial wall and is restricted t o individual cells. In the present study, we describe the amount of apoptos is in 50 endomyocardial biopsies taken from 50 patients with dilated cardio myopathy, in 14 hearts with hypertrophic cardiomyopathy and in five hearts with arrhythmogenic dysplasia of the right ventricle. As a control group, 1 5 endomyocardial biopsies from 15 transplanted hearts (of live patients) we re used. Apoptosis was immunohistochemically determined in paraffin section s with the TUNEL method. In each specimen the TUNEL index was calculated as the percentage of TUNEL-positive nuclei among a total number of 200 counte d nuclei. Cellular morphology was assessed in conjunction with TUNEL staini ng. The mean percentage of TUNEL-positive myocardial cells varied from 4% f or dilated cardiomyopathy to 17.5% for arrhythmogenic right ventricle dyspl asia and 18.5% for hypertrophic cardiomyopathy, whereas no signs of apoptot ic myocardial cell death were found in normal subjects. The numbers of apop totic cells in dilated cardiomyopathy specimens were significantly lower by comparison with both those of hypertrophic cardiomyopathy and those of arr hythmogenic right ventricular dysplasia specimens. it is evident that apopt osis constitutes a major biological phenomenon in the development of at lea st some heart diseases, but its role in their pathophysiology has yet to be delineated.