Cardiac sarcoidosis mimicking arrhythmogenic right ventricular dysplasia with high defibrillation threshold requiring subcutaneous shocking coil implantation.

Cardiac involvement in patients with sarcoidosis has been reported in up to 25–39% of patients and is responsible for up to 85% of deaths attributed to the disease, often due to sudden cardiac death. An established diagnosis of cardiac sarcoidosis (CS) portends an ominous prognosis, with an estimated five year-survival of 44%. We report a case that was initially diagnosed as arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C), but extra-cardiac biopsies later on were consistent with sarcoidosis and a final diagnosis of CS was made. The patient received an implantable cardioverter defibrillator (ICD) with a subcutaneous lead array implant for high defibrillation threshold (DFT). Exclusive right ventricular (RV) involvement is atypical for CS. The predominant RV involvement based on echocardiogram, cardiac magnetic resonance imaging (MRI) and right precordial electrocardiogram changes can lead to misdiagnosis as ARVD/C based on the modified task force criteria. Cardiac sarcoidosis is an under-diagnosed disease and the delay in its diagnosis and appropriate therapy can lead to a fatal outcome. High defibrillation thresholds have not been previously reported in patients with CS, but given the natural progression of the disease and the limitations in current pharmacotherapy, implanters who diagnose and treat such patients must be prepared to deal with this issue.