Unexpected myocardial disease in patients with life threatening arrhythmias.

It is not unusual for an individual without recognisable clinical heart disease to have a life threatening arrhythmia. This report describes the results of endomyocardial biopsy in twelve patients who presented with life threatening arrhythmias and normal or near normal cardiac function. The eight men and four women (mean age 35) presented with ventricular tachycardia or fibrillation (nine cases), high grade heart block with inadequate ventricular escape (two cases), and dangerous ventricular extrasystoles (Lown grade 4, one case). In ten of the twelve patients symptoms had been present for less than or equal to 6 months at presentation. No patient had a normal electrocardiogram. Electrophysiological testing confirmed the clinical arrhythmia in all but three patients. Endomyocardial biopsy demonstrated lymphocytic myocarditis in two patients, granulomatous myocarditis in two patients, small vessel vasculitis in one patient, and cardiomyopathic changes in six patients. In one patient the biopsy specimen was normal. Endomyocardial biopsy is a valuable diagnostic tool in patients with unexplained life threatening arrhythmias. In this study half the patients had a treatable form of heart muscle disease.