Abstract 5934: Arrhythmogenic Right Ventricular Cardiomyopathy Due to Desmosomal Gene Mutations Is a Progressive Biventricular Disease

Abstract

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited disease characterized by a gradual loss of myocytes with fibro-fatty replacement. Mutations of gene encoding desmosomal proteins have been demonstrated in up to 50% of probands. The aim of this study was to assess the morphologic spectrum and the relative role of viruses on genotyped ARVC hearts. Design: Fourteen ARVC hearts (10 M/4 F, age range 7–64, mean 30 yrs), coming from sudden death (8), cardiac transplantation (4), heart failure (1) and extracardiac death (1) were investigated. Familial recurrence of ARVC was ascertained in 12 (86%). Genetic screening identified pathogenetic mutations in plakophilin-2 (5), desmoplakin (4), desmoglein-2 (2) and plakoglobin (3). Five hearts from patients with in ryanodine receptor 2 (Ryr2) gene mutations were also investigated. Morphopathologic investigation consisted of gross examination, histology, immunohistochemistry and molecular pathology (PCR) for cardiotropic viruses. Result: Cardiac involvement was biventricular in all but 1 case, a 7 year old girl who died of extracardiac causes and presented a structurally normal heart. Ventricular myocardium abnormalities consisted of fibro-fatty replacement in 12 cases and of subepicardial myocyte necrosis with acute inflammation and granulation tissue in a 15 year old boy who died suddenly. Inflammatory infiltrates were evident in 93% of cases, either diffuse (23%) or focal (77%), and mostly consisted of T-lymphocytes and macrophages. Molecular investigation was negative in all but one with Hepatitis C virus (7%). Ryr2 gene hearts showed only mild fatty infiltration confined to the antero-apical wall of the right ventricle. Conclusion: ARVC hearts from patients with desmosomal gene mutations are characterized by biventricular myocardial atrophy and fibro-fatty replacement. In early adolescence, the phenotype can be either absent or consistent with acute myocyte damage without fibro-fatty replacement, thus confirming the progressive nature of the disease. While myocarditis is a usual feature, viral genome is exceptionally detected in the myocardium as to support the reactive nature of inflammation. The pathologic features of Ryr2 hearts are not in keeping with ARVC.