Relationship between arrhythmogenesis and disease activity in cardiac sarcoidosis

Background In patients with cardiac sarcoidosis, ventricular arrhythmias and/or conduction disturbances are frequently observed and sometimes fatal. However, few reports on disease activity and arrhythmic events in cardiac sarcoidosis are available. Objective The purpose of this study was to investigate the relationship between disease activity and arrhythmic events in cardiac sarcoidosis and the effect of corticosteroid therapy. Methods The study population consisted of 15 cardiac sarcoidosis patients with new-onset symptomatic arrhythmia, including eight patients admitted once for complete atrioventricular block (CAVB), five patients admitted once for sustained ventricular tachycardia (VT), and two patients admitted twice for two arrhythmic events (one for CAVB and the other for sustained VT). Disease activity was evaluated by gallium-67 citrate (Ga) scintigraphy. All patients with positive Ga uptake were treated with corticosteroids, and arrhythmic events were evaluated by repeat Holter recordings. Results Positive uptake of Ga was observed in 8 (80%) of the 10 CAVB events and in 1 (14%) of the 7 sustained VT events (80% vs 14%, P = .02). Corticosteroids abolished myocardial Ga uptake in all nine patients with positive Ga uptake. After corticosteroid therapy was started, AV conduction improved in 5 of 9 CAVB patients (including 8 patients with new-onset CAVB and one patient with history of CAVB). However, ventricular arrhythmias were not improved after corticosteroid therapy. Conclusion In cardiac sarcoidosis patients, CAVB develops mainly during the active phase of the disease. Early treatment with corticosteroids might improve AV conduction disturbance. However, sustained VT is not closely linked with disease activity and frequently develops in the advanced stage of disease.