Left atrial dominant cardiac sarcoidosis presenting with supraventricular tachycardia and left atrial myocardial damage: A case report.

UNLABELLED: A 61-year-old woman presented to our hospital with palpitations and dyspnea persisting for several months. Electrocardiography revealed atrial tachycardia, and X-ray revealed bilateral hilar enlargement. Computed tomography (CT) was performed for suspected sarcoidosis of the respiratory system, which revealed hilar lymph node enlargement in the bilateral lungs. 18F-Fluorodeoxyglucose (18F-FDG)-positron emission tomography-CT revealed abnormal 18F-FDG uptake in the hilar lymph nodes, liver, and left atrium (LA), but not in the left ventricle. Contrast-enhanced cardiac magnetic resonance imaging revealed late gadolinium enhancement (LGE) in the LA. Mediastinal lymph node, transbronchial lung, and right ventricular biopsies were performed, but no specific pathological findings were observed. Echocardiography-guided liver biopsy was also performed, which revealed non-caseating epithelioid granulomas. We definitively diagnosed systemic sarcoidosis, including cardiac lesions. Following the initiation of immunosuppressive therapy, abnormal 18F-FDG uptake in the liver, lymph nodes, and LA resolved, and atrial tachycardia improved, likely owing to the suppression of atrial inflammation. However, LGE in the LA persisted after immunosuppressive therapy, suggesting that structural damage had persisted. In this case, multimodality imaging helped us understand the disease state and post-treatment course.

LEARNING OBJECTIVE: The main site of cardiac sarcoidosis involvement is the left ventricle, and cases in which inflammation is confined to the left atrium are rare. In left atrial dominant cardiac sarcoidosis, clinical manifestations are often limited to supraventricular tachycardia. Although immunosuppressive therapy controlled the arrhythmia, multimodality imaging revealed that left atrial structural damage persisted, even after inflammation had improved. These findings highlight the clinical importance of recognizing left atrial dominant cardiac sarcoidosis, as irreversible atrial damage may persist despite adequate treatment.