Incidence of myocarditis in patients with dilated cardiomyopathy

Abstract

We performed right ventricular endomyocardial biopsies in 23 patients with dilated cardiomyopathy aged 45 +/- 14 years. All patients had congestive heart failure of unknown etiology dating up to one year before the procedure (57% less than 3 months). NYHA functional class was II in 5, III in 12 and IV in 6 patients. All patients had evidence of systolic dysfunction and a dilated left ventricle (LV diastolic dimension 68 +/- 11 and systolic dimension 55 +/- 11). Definite evidence of myocarditis, based on findings of inflammatory infiltrate and cellular damage, was found in 6 patients (26%), borderline myocarditis in 9 and abnormalities consistent with dilated cardiomyopathy in 8. The incidence of myocarditis here reported is lower than previously figures based on findings of more than 5 lymphocytes per high power field. In this series, clinical and functional aspects of heart failure did not differ in patients with or without evidence of myocarditis.