Arrhythmogenic right ventricular cardiomyopathy: Clinicopathologic correlation based on a revised definition of pathologic patterns

Different morphologic features of arrhythmogenic right ventricular cardiomy opathy (ARVC) have been described. However, it is still unclear whether the y correspond to distinct forms of the same disease. A pathologic study was performed on a series of ARVC (15 from heart transplant and 12 from autopsy ) from 2 Italian referral university hospitals. Based on both myocellular f eatures and the nature of myocardial replacement, hearts were divided into 2 groups: infiltrative, with a lacelike pattern of transmural fatty infiltr ation and strands of normal residual cardiomyocytes (n = 11); and cardiomyo pathic, with massive myocardial replacement by fibro fatty tissue and cardi omyopathic changes (such as hypertrophy and myofibril loss) of residual car diomyocytes (n = 16). Hearts from the infiltrative group were mostly obtain ed at autopsy of patients who died suddenly. Fatty substitution was limited almost exclusively to the right ventricle. Mitral valve dysplasia (prolaps e or cleft) was frequently present. Hearts from the cardiomyopathic group c ame mainly from heart transplants for congestive heart failure. Fibro fatty replacement was more extensive, usually biventricular. Active myocarditis and features suggestive of myocardial transdifferentiation were also observ ed. Despite these differences in clinical outcome and morphologic features, patients from the 2 groups showed similar mean age, sex distribution, occu rrence of threatening ventricular arrhythmias, and prevalence of family his tory of sudden death, arrhythmias, or cardiomyopathy. Infiltrative and card iomyopathic patterns represent different clinical and pathologic subsets of ARVC. Myocellular features are an important clue in the distinction betwee n the two entities. The differentiation between the 2 patterns is feasible on endomyocardial biopsy and could give important prognostic information. H um PATHOL 32:1078-1086. Copyright (C) 2001 by W.B. Saunders Company.