ENDOMYOCARDIAL BIOPSY FINDINGS IN PATIENTS WITH VENTRICULAR ARRHYTHMIAS OF UNKNOWN ORIGIN

To evaluate possible occult myocardial disease in patients with ventri cular arrhythmias of unknown origin, over 11 years right ventricular e ndomyocardial biopsies (EMB) were performed on 80 consecutive such pat ients (29 Females, 51 Males; median age 42 years). Seventy-one (89%) h ad ventricular tachycardia or fibrillation, 7 (9%) had complex ventric ular arrhythmias, and 2 (3%) had premature ventricular beats. None sho wed clinical evidence of congestive heart failure or significant coron ary artery or valvular disease. Endomyocardial biopsies revealed patho logic changes in 70 out of 80 patients (88%). Of the 70 affected, 39 ( 56%) had nonspecific changes consistent with cardiomyopathy (e.g., myo fiber hypertrophy, interstitial and perivascular fibrosis, and vascula r sclerosis); 6 (9%) had active myocarditis (Myo); 7 (10%) had borderl ine Myo; 7 (10%) had small vessel disease; 6 (9%) had changes consiste nt with arrhythmogenic cardiomyopathy; 2 (3%) had amyloidosis; 2 (3%) had microfibrillar cardiomyopathy, and one (1.0%) showed intravascular organizing thrombus. Thus, EMB reveals a variety of abnormalities in the majority of patients presenting with ventricular arrhythmias witho ut clinical evidence of structural heart disease.