Electron microscopic investigation of endomyocardial biopsy samples in hypertrophy and cardiomyopathy. A semiquantitative study in 48 patients.

Electron microscopic and statistical analyses of 66 right ventricular biopsies from 48 patients were undertaken to investigate whether quantitative differences exist between those patients with "ordinary" myocardial hypertrophy and those suffering from a form of cardiomyopathy. The electron microscopic changes were scored and correlated with hemodynamic variables such as ejection fraction (EF), left ventricular end-diastolic pressure (LVEDP) and length of history. The patients were followed for an average of 22.5 months, permitting an assessment of prognosis. The results show that the three diagnostic groups--"ordinary" hypertrophy, hypertrophic cardiomyopathy (HOCM) and congestive cardiomyopathy (COCM)--overlap, but crossover of sarcomeres is more frequent in patients in whom HOCM is diagnosed. Except for a tenuous relationship between EF, and the electron microscopy (EM) (r = -0.46, p less than 0.1) and between LVEDP and EM score (r = 0.61, p less than 0.01), in the COCM group, no correlation could be established between EF, LVEDP and length of history when the patients were grouped according to histologic or clinical diagnosis. This study shows that the various claims regarding relationships between morphologic changes and the functional status of patients or prognosis cannot be confirmed.