138 Abstract Background: Sarcoidosis is a systemic inflammatory disorder that can cause sarcoidosis-associated cardiac autonomic dysfunction (SCAD), often overlooked despite its impact. Current guidelines for sarcoidosis diagnosis and management lack specific recommendations for SCAD assessment. [ 123I]- Meta-iodobenzylguanidine ([123I]MIBG) scintigraphy, a technique for assessing cardiac sympathetic innervation, offers potential diagnostic value for diagnosing SCAD. Aim: This retrospective study explores the role of [123I]MIBG scintigraphy in detecting SCAD among patients with unexplained cardiac symptoms. It focuses on its potential to provide complementary diagnostic information in patients where established imaging techniques, such as [18F]fluoro-2-deoxyD-glucose positron emission tomography/computed tomography (FDG PET/CT) and cardiac magnetic resonance imaging (CMR), fail to detect cardiac sarcoidosis. Methods: Sarcoidosis patients referred to the St. Antonius Hospital (2017-2024) who underwent [123I]MIBG scintigraphy were included. Collected data encompassed demographics, SCAD-symptoms, cardiac imaging findings, and carvedilol treatment outcomes. [123I]MIBG abnormalities were defined as a heart-to-mediastinal ratio ≤1.6 or a washout rate ≥20%. Results: Among 46 patients, 44% exhibited abnormal [123I]MIBG results consistent with SCAD, whereas only 5% had cardiac abnormalities on FDG PET/CT and CMR imaging. No significant differences were observed in clinical characteristics between patients with normal and abnormal [123I]MIBG findings. Of the 16 patients treated with carvedilol, 80% reported symptom improvement although 50% experienced side effects. Conclusion: [123I]MIBG scintigraphy demonstrates diagnostic value in identifying SCAD, particularly in patients with inconclusive conventional imaging despite pronounced clinical symptoms. These findings emphasize the need for further research validating the role of [123I]MIBG scintigraphy in clinical practice and to develop tailored personalized therapeutic strategies for SCAD. Introduction Sarcoidosis is a systemic inflammatory disorder characterized by noncaseating granulomas that can affect various organs, including the lungs, skin, eyes, and the heart.1 Alongside organ-specific symptoms, patients often report non-organ-specific symptoms such as fatigue, fever, weight loss and pain.2,3 Small fiber neuropathy (SFN) is frequently associated with sensory complaints such as, pain, but also with symptoms of autonomic dysfunction, such as dizziness and heart rhythm disturbances which can significantly impair quality of life.3–5 This broad spectrum of symptoms and systemic involvement makes sarcoidosis a challenging condition to manage.6 One of the potentially life-threatening complications of sarcoidosis is cardiac sarcoidosis, caused by granulomatous infiltration of the myocardium. This can result in conduction abnormalities, ventricular arrhythmias, and left ventricular dysfunction, with symptoms ranging from dyspnea and dizziness to severe cardiovascular events.1,7 Comprehensive diagnostic evaluation, including cardiac magnetic resonance imaging (CMR) and, [18F]fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography (FDG PET/CT), is critical for assessing myocardial involvement.8 The symptoms of cardiac sarcoidosis caused by granulomas, may closely resemble those of sarcoidosis-associated cardiac autonomic dysfunction (SCAD). However, the latter cannot be identified through the imaging techniques such as CMR or FDG PET/CT. This distinction aligns with current guidelines for the diagnosis and management of cardiac sarcoidosis, which emphasize the role 9 144 9
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