Isolated cardiac sarcoidosis: Clinical characteristics, diagnosis and treatment

•Cardiac sarcoidosis is a fatal condition requiring early and intensive treatment.•There are many sarcoidosis patients whose clinical manifestation is isolated to the heart.•Diagnosis of this condition is needed to be made based on cardiac manifestations.•Combination of imaging tests is effective for diagnosis.•Pharmacological and nonpharmacological treatments have altered the prognosis.

Sarcoidosis is a systemic disease characterized by the development of noncaseating epithelioid granulomas in multiple organs. Despite extensive investigations over a long period of time, the etiology of this disease remains unknown. Cardiac involvement of this disease is the most ominous complication leading to fatal outcome. Recently, attention has been focused on isolated cardiac sarcoidosis, which exists without clinically apparent sarcoidosis elsewhere. One of the critical issues of isolated cardiac sarcoidosis is difficulty in diagnosis, since existence of the cardiac lesion should be detected from cardiac manifestations alone. Because specificity of biomarkers or sensitivity of histological examination of biopsied sample is very low, diagnosis of isolated cardiac sarcoidosis mainly depends on imaging modalities. In this review article we summarized current knowledge on the pathogenesis of sarcoidosis, clinical features of cardiac sarcoidosis especially that isolated to the heart by showing some typical cases. Utilities and problems of diagnostic imaging tests for this condition including echocardiography, cardiac magnetic resonance imaging, and fluorodeoxyglucose-positron emission tomography are discussed. Advances in pharmacological and nonpharmacological treatment for cardiac sarcoidosis have improved the prognosis of cardiac sarcoidosis to a great deal; however, there are many issues that remain to be solved in the management of isolated cardiac sarcoidosis.