The role of myocardial biopsy in cardiac diagnosis.
With the advent of cardiac catheterization, cardioangiography, and selective coronary arteriography, specific types of cardiac disease can be recognized and clearly defined. This is appropriate because myocardial biopsy alone rarely plays a major role in cardiac diagnosis. Excluding Aschoff's nodules in patients with rheumatic valve disease, the light microscopic findings in patients with rheumatic heart disease, congenital heart disease, pericardial disease, hypertensive and arteriosclerotic heart disease are similar and nonspecific. In these, interstitial fibrosis and/or myocardial hypertrophy is the dominant tissue diagnosis. Occasionally a pericardial and myocardial specimen is helpful to distinguish constrictive pericarditis and restrictive cardiomyopathy. Myocardial biopsy has provided the only method for diagnosis in a small number of patients with normal hemodynamics, normal coronary arteriograms and normal ventriculograms. The patients were studied because of chest pain and/or cardiac arrhythmias. Supraventricular and/or ventricular arrhythmias were encountered. In these patients the tissue diagnosis was interstital fibrosis and/or myocardial hypertrophy. These findings are consistent with primary myocardial disease which was not recognized clinically or by angiographic studies. The procedure seems to play a major role in the diagnosis of specific types of primary myocardial disease. It is valuable in the recognition of glycogen storage disease, amyloidosis, hemochromatosis, and myocarditis. On the basis of current experience, the indications for myocardial biopsies depend on the need for a tissue diagnosis in determining the management of the patient and the availability of adequately trained personnel to perform the procedure and manage the complications.