Severe Acute Decompensated Heart Failure in a Patient with Cardiac Sarcoidosis

<b>Introduction:</b> Cardiac sarcoidosis (CS) is a rare but potentially life-threatening manifestation of systemic sarcoidosis, often leading to arrhythmias, conduction abnormalities, or heart failure. Diagnosis is challenging due to nonspecific symptoms and the need for advanced imaging or biopsy. <b>Case Presentation:</b> We describe a 49-year-old man admitted with severe decompensated heart failure (NYHA IV). He had a history of complete heart block treated with pacemaker implantation and subsequent CRT-D upgrade. On admission, echocardiography revealed biventricular dysfunction with severe mitral and tricuspid regurgitation. Cardiac MRI demonstrated extensive non-ischemic late gadolinium enhancement. Blood cultures grew methicillin-sensitive <i>Staphylococcus aureus</i> (MSSA) and intravenous antibiotics were initiated. Despite diuretics and inotropes, his condition deteriorated. Corticosteroid therapy was started due to high suspicion of sarcoidosis. Endomyocardial biopsy confirmed CS. The patient developed neuropsychiatric complications and, despite urgent listing for heart transplantation, died during hospitalization. <b>Conclusions:</b> This case highlights the diagnostic and therapeutic challenges of CS, the limitations of corticosteroid therapy in advanced disease, and the importance of early recognition with advanced imaging modalities.