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

Different morphologic features of arrhythmogenic right ventricular cardiomyopathy (ARVC) have been described. However, it is still unclear whether they 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 features and the nature of myocardial replacement, hearts were divided into 2 groups: infiltrative, with a lacelike pattern of transmural fatty infiltration and strands of normal residual cardiomyocytes (n = 11); and cardiomyopathic, with massive myocardial replacement by fibro fatty tissue and cardiomyopathic changes (such as hypertrophy and myofibril loss) of residual cardiomyocytes (n = 16). Hearts from the infiltrative group were mostly obtained at autopsy of patients who died suddenly. Fatty substitution was limited almost exclusively to the right ventricle. Mitral valve dysplasia (prolapse or cleft) was frequently present. Hearts from the cardiomyopathic group came 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 observed. Despite these differences in clinical outcome and morphologic features, patients from the 2 groups showed similar mean age, sex distribution, occurrence of threatening ventricular arrhythmias, and prevalence of family history of sudden death, arrhythmias, or cardiomyopathy. Infiltrative and cardiomyopathic patterns represent different clinical and pathologic subsets of ARVC. Myocellular features are an important clue in the distinction between the two entities. The differentiation between the 2 patterns is feasible on endomyocardial biopsy and could give important prognostic information. Copyright 2001 by W.B. Saunders Company