Value of endomyocardial biopsy.

The role of endomyocardial biopsy may be restricted to the diagnosis of myocarditis. On the other hand, a broad utilization of the biopsy technique may be championed by those who believe that the light and electron microscopic characteristics of the tissue are important and that the biochemical features of the tissue may hold important clues to the diagnosis and therapy of dilated cardiomyopathy. The popularity of endomyocardial biopsy arises from the ease and safety of the procedure. Light microscopy of the tissue is useful not only to diagnose myocarditis but also to discover infiltrative cardiomyopathies and to characterize the dilated cardiomyopathies by the amount of fibrosis and cellular hypertrophy. Electron microscopy supplies more detailed information on the myofibrils, nuclei, tubular structures, mitochondria, glycogen, and lipofuscin. At present, these data are clinically applicable only to the anthracycline cardiomyopathies. On an investigational basis, subcellular characteristics may help us better understand the etiology and pathogenesis of dilated cardiomyopathy. The greatest promise lies in the biochemical assessment of tissue, which may uncover single or multiple biochemical abnormalities in heart failure. Although the clinical usefulness of endomyocardial biopsy is quite restricted at present, its future looks quite promising.