Profiles of biopsy-proven cases with myocarditis.

Fifty-seven patients with unexplained dilated hearts and congestive heart failure were studied clinically and by endomyocardial biopsy of the left ventricle. Of the patients, 61% had histologic evidence of active lymphocytic myocarditis. The sudden onset of heart failure, often with arrhythmias, if preceded by a viral-like illness indicated a high chance of finding inflammatory infiltration in the biopsy material. No abnormal accumulation of immunoglobulin was found in these patients with dilated cardiomyopathy and myocarditis. Immunosuppressive therapy did not always bring about improvement.