Granulomatous myocarditis. Diagnosis by endomyocardial biopsy and response to corticosteroids in two patients.

Granulomatous involvement of the myocardium is of uncertain etiology, rarely diagnosed premorbidly, and the response to therapy is unknown. We report two patients with granulomatous disease apparently isolated to the myocardium, one presenting with cardiac arrest secondary to ventricular tachycardia, one with heart block. In both cases, the clinical rhythm was substantiated by electrophysiologic studies and neither case had evidence of significant myocardial dysfunction. In both, treatment was instituted with orally administered prednisone. One patient died suddenly two months following onset of therapy. Limited autopsy demonstrated no evidence of granulomatous involvement of the myocardium. The other patient is alive without clinical arrhythmias on amiodarone therapy; however, inducible ventricular tachycardia persists. Repeat endomyocardial biopsy in this patient demonstrated no granulomatous disease. These cases are discussed and the literature reviewed.