Cardiac sarcoidosis: The chameleon of cardiology

Sarcoidosis is a multisystemic granulomatous disease of unknown etiology, characterized by the formation of non-caseating granulomas in multiple organs. Cardiac involvement, an important cause of morbidity and mortality in these patients, has been generating interest in cardiology, because it is a cause of heart failure, atrioventricular blocks, and ventricular arrhythmias with unfavorable prognosis; however, there are specific treatments with the potential to change the natural history of this condition. The main challenge of cardiac sarcoidosis (CS) is diagnosis, given that the gold standard method of endomyocardial biopsy has limited sensitivity due to the focal nature of the pathology. Accordingly, cardiovascular imaging methods play the role of guiding most diagnoses of CS. In this scenario, knowledge about these methods, their main findings, and their rational use are essential to the diagnosis of this disease with such diverse presentations. Electrocardiogram and echocardiography are practical and widely available exams; however, they provide greater diagnostic capacity in patients with clinically manifest disease. On the other hand, to identify incipient forms, which are often silent, it is necessary to use advanced imaging methods, such as positron emission tomography with ¹⁸F-fluorodeoxyglucose and cardiac magnetic resonance, which primarily identify signs of active inflammatory activity and fibrosis, respectively. Despite the advances in these imaging methods, due to the lack of studies comparing them with the gold standard (endomyocardial biopsy), the diagnosis of CS currently remains a major challenge. (author)