[I]-Meta-Iodobenzylguanidine Scintigraphy in Sarcoidosis: Exploring Cardiac Autonomic Dysfunction in Patients with Unexplained Cardiac Symptoms.

: Sarcoidosis is a systemic inflammatory disease that can cause cardiac autonomic dysfunction (SCAD), often underrecognized despite its clinical importance. While [F]fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography ([F]FDG PET/CT) and cardiac magnetic resonance imaging (CMR) assess cardiac involvement, [I]-meta-iodinebenzylguanidine ([I]MIBG) scintigraphy evaluates cardiac sympathetic innervation, offering complementary insights to potentially improve SCAD detection and management. This retrospective study explores the role of [I] 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 [F]FDG PET/CT and CMR, fail to detect cardiac sarcoidosis. : Sarcoidosis patients referred to the St. Antonius Hospital (2017-2024) who underwent [I]MIBG scintigraphy were included. Collected data encompassed demographics, SCAD symptoms, cardiac imaging findings, and carvedilol treatment outcomes. [I] MIBG abnormalities were defined as a heart-to-mediastinal ratio ≤1.6 or a washout rate ≥20%. : Among the final cohort of 40 sarcoidosis patients with unexplained cardiac symptoms and normal [F]FDG PET/CT and CMR findings, 19 patients (48%) showed abnormal [I] MIBG scintigraphy results suggestive of SCAD. No significant differences were observed in clinical characteristics between patients with normal and abnormal [I]MIBG findings. Of the 16 patients treated with carvedilol, 88% reported symptom improvement, although 50% experienced side effects. : [I]MIBG scintigraphy revealed abnormalities in a substantial number of sarcoidosis patients with unexplained cardiac symptoms despite normal [F]FDG PET/CT and CMR. These findings indicate a potential role for [I]MIBG in detecting SCAD, but prospective studies are needed to confirm their clinical significance.