The role of endomyocardial biopsy in ARVC: looking beyond histology in search of new diagnostic markers.

The Role of Endomyocardial Biopsy in ARVC.  Arrhythmogenic right ventricular cardiomyopathy (ARVC) is characterized by a high incidence of ventricular tachyarrhythmias and sudden cardiac death that appear early in the natural history of the disease and may precede significant ventricular remodeling. The classical pathology of ARVC is degeneration of right ventricular free wall myocardium and its replacement by fat and fibrous tissue. The clinical presentation may be highly variable, however, and genetic penetrance is typically low which makes definitive diagnosis difficult, especially in early stages of the disease. Endomyocardial biopsy (EMB) has not been used widely in the diagnosis of ARVC, in part because pathological changes are usually most conspicuous in the epicardium of the right ventricular free wall and tend to spare the endocardium and interventricular septum. Thus, diagnostic pathological features of ARVC are often not seen in conventional septal biopsies. Diagnostic yield may be increased by sampling the RV free wall or by using 3-dimensional electroanatomic voltage mapping to identify affected areas, but these approaches can carry increased risk and require specialized equipment and experience. Moreover, diagnostic pathological changes may not be apparent in early disease despite an increased risk of arrhythmias and sudden death. This review considers the role of EMB in the diagnosis of ARVC and highlights recent advances in identifying potential tissue biomarkers that arise early in the disease process and occur diffusely throughout the myocardium. Analysis of conventional EMB using such biomarkers could improve diagnostic sensitivity and accuracy but widespread clinical application of this approach requires further validation.