Arrhythmogenic Right Ventricular Cardiomyopathy vs. Cardiac Sarcoidosis - A Tissue Diagnosis Makes All The Difference

Abstract

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is primarily an autosomal dominant structural abnormality where fibro fatty replacement of cardiac myocytes results in tachyarrhythmias and sudden death. Sarcoidosis, on the other hand, is a multisystem granulomatous disease of unknown aetiology characterized by non-caseating granulomas in involved organs. ARVC can be mimicked both clinically and radiologically by cardiac sarcoidosis. In some cases differentiating the diagnoses is only made at biopsy or autopsy. A 31 year old Irish male presented to a regional hospital with a one hour history of palpitations and mild chest discomfort. Emergency department (ED) electrocardiograph (ECG) revealed ventricular tachycardia (VT). Direct current cardioversion of 150 kilojoules was given due to haemodynamic instability and resulted in reversion to normal sinus rhythm. Following this, he was treated as a non ST-segment elevation myocardial infarction and referred to a tertiary referral centre for coronary artery angiography. Normal angiography and echocardiogram prompted cardiac magnetic resonance imaging (MRI) which demonstrated right ventricular outflow tract scarring consistent with either a primary diagnosis of ARVC or cardiac sarcoidosis. Initially, a diagnosis of sarcoidosis was deemed less likely on the basis of normal laboratory findings and absence of other clinical manifestations of extra cardiac sarcoidosis. However, an endovascular biopsy was taken from the right ventricle and tissue diagnosis was made of isolated cardiac sarcoidosis and corticosteroids were commenced.