Cardiac Sarcoidosis: Pathophysiology and Diagnostic–Therapeutic Processes

Sarcoidosis is a rare inflammatory disorder of unknown etiology, characterized by the formation of non-caseating granulomas in affected organs. Additionally, sarcoidosis typically involves multiple systems, with the lungs and thoracic lymph nodes being most commonly affected. While many cases are self-limited and resolve spontaneously, cardiac involvement, although relatively uncommon, can be particularly severe. Indeed, cardiac sarcoidosis may lead to life-threatening arrhythmias, severe heart failure, or sudden cardiac death, significantly impacting prognosis. Meanwhile, the heterogeneity of presentation and disease course can make diagnosis and treatment challenging. An endomyocardial biopsy (EMB) is considered the gold standard for diagnosing cardiac sarcoidosis (CS); despite its high specificity, the sensitivity of this technique is low owing to the often focal and patchy cardiac involvement in sarcoidosis. New imaging techniques, such as fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) and cardiac magnetic resonance (CMR) imaging, can provide valuable information for the accurate diagnosis of CS and can be useful for evaluating treatment response and prognosis. Immunosuppressive treatments, particularly corticosteroids, are considered the cornerstone of therapy for CS. However, randomized clinical trials are lacking, and treatment decisions are based on cohort studies and consensus opinions. Moreover, the optimal strategy for determining when to initiate, how long to continue, and what dosage to use for immunosuppressive therapy remains uncertain.