Cardiac Sarcoidosis - Arrhythmias, Inflammation and Anti-inflammatory Drug Therapy

The prevalence of cardiac involvement in patients with systemic sarcoidosis ranges from 3.7 to 54.9% depending on the population studied (asymptomatic or symptomatic), imaging techniques used and criteria used for diagnosis.[1] Though cardiac involvement may be asymptomatic, common cardiac manifestations include conduction abnormalities usually complete atrioventricular block, ventricular arrhythmias, heart failure, atrial tachyarrhythmias and sudden cardiac death. Rarely, isolated cardiac sarcoidosis without manifestations related to other organs occurs and presents difficulties in the diagnosis. Since the yield of endomyocardial biopsy for cardiac sarcoidosis is low, due to patchy and focal involvement of myocardium, the diagnosis of cardiac sarcoidosis is often made by presence of cardiac manifestations along with tissue diagnosis from other organs. No international consensus guidelines or diagnostic criteria for cardiac sarcoidosis exist except for the Japanese Ministry of Health and Welfare Criteria. [2,3] To compound the difficulties with the diagnosis, tuberculosis affecting the heart can have very similar clinical [ventricular tachycardia (VT), lymphnode enlargement], radiological (mediastinal adenopathy, lung lesions) and imaging features [(mid myocardial scar, delayed enhancement on magnetic resonance imaging (MRI) or focal uptake of 18flouro-deoxyglucose (FDG) on positron emission computerized tomography (PET CT)]. The histology showing caseating granulomas (in lung or node biopsy) or positive stain or culture for acid-fast bacilli and/or positive DNA-PCR for Mycobacterium tuberculosis in the tissue can indicate the correct diagnosis of tuberculosis and guide appropriate disease specific therapy.[4] The differentiation is important since steroid administration without anti-tubercular therapy can result in flaring of the tuberculosis if underlying tuberculosis was present. A high index of suspicion is essential for the diagnosis of both tuberculosis and sarcoidosis of the heart. There is also a possibility of co-existence of the two diseases (tuberculosis-sarcoidosis overlap), especially in developing countries like India with high prevalence of tuberculosis.