Diagnosis and treatment of cardiac sarcoidosis

Sarcoidosis is a systemic granulomatous disease of unknown aetiology. The frequency of cardiac involvement (cardiac sarcoidosis (CS)) varies in the different geographical regions, but it has been reported that it is an absolutely important prognostic factor in this disease. Complete atrioventricular block is the most common, and ventricular tachycardia/ventricular fibrillation the second most common arrhythmia in this disease, both of which are associated with cardiac sudden death. Diagnosing CS is sometimes difficult because of the non-specific ECG and echocardiographic findings, and CS is sometimes misdiagnosed as dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy or an idiopathic ventricular aneurysm, and therefore, endomyocardial biopsy is important, but has a low sensitivity. Another problem is the recognition of isolated types of CS. Recently, MRI and ¹⁸F-fluorodeoxyglucose positron emission tomography have been demonstrated to be useful tools for the non-invasive diagnosis of CS as well as therapeutic evaluation tools, but are still unsatisfactory. Treatment of CS is usually done by corticosteroid therapy to control inflammation, prevent fibrosis and protect from any deterioration of the cardiac function, but the long-term outcome is still in debate. Despite the advancement of non-pharmacological approaches for CS (pacing, defibrillators and catheter ablation) to improve the prognosis, there are still many issues remaining to resolve diagnosing and managing CS. Here, we attempt a review of the clinical evidence, with special focus on the current understanding of this disease and showing the current strategies and remaining problems of diagnosing and managing CS.