Clinical and Pathologic Study of Two Siblings with Arrhythmogenic Right Ventricular Cardiomyopathy

ARVC is a cardiomyopathy in which the right ventricular myocardium is replaced by fibroadipose tissue. Males are affected slightly more often than females and, in those cases which are familial, the pattern of inheritance is usually autosomal dominant with incomplete penetrance. We examined the hearts of two sisters, ages 17 and 14, with no family history of heart disease. The older sibling, who was previously considered healthy, died suddenly, while the younger sibling developed congestive heart failure and received a cardiac transplant. An autopsy of the older sibling and examination of the younger siblingʹs excised heart revealed severe examples of ARVC with minor differences. A thick cap of fibroadipose tissue covered most, if not all, of each right ventricle and was transmural in some areas. Microscopically, left ventricles contained extensive myocyte disarray and multifocal fibrosis. The coronary arteries displayed intimal hyperplasia with disruption of the internal elastic lamina, similar to fibromuscular dysplasia. These two cases comprise a unique familial grouping in a polymorphic disease. Despite the male predominance and autosomal dominant inheritance in ARVC, the only members affected in this family were female, and an autosomal dominant pattern of inheritance, even with incomplete penetrance, would be unusual. In addition, we identified changes in the coronary arteries similar to fibromuscular dysplasia and corroborated recently reported changes in the left ventricle of patients with ARVC, providing evidence that this disease, in its most severe form, involves the entire heart.