4780Visualisation of left atrial sympathetic activity distribution and its physiological variation over time in healthy individuals

Background: A novel cardiac gamma camera utilises physiologic uptake of Iodine-123 Meta-iodobenzylguanidine (123I –mIBG) to visualise cardiac sympathetic innervation. Physiologic uptake of 123I –mIBG provides anatomical quantification of autonomic nervous system (ANS) structures with discrete uptake areas (DUA) located in the left atrium (LA) corresponding to main ganglionated plexi (GP) clusters, that have previously not been able to be visualised in healthy subject. Purpose: Understanding patterns of left atrial sympathetic activity in healthy individuals and their variation over time. Methods: Ten healthy individuals (4 male, mean age 37.8±14) underwent cardiac computed tomography and 123I –mIBG isotope nuclear imaging. The two image datasets were merged to generate a detailed anatomical map of cardiac sympathetic innervation. Specific activity (corrected for volume) from each DUA was measured, as well as the mediastinal specific activity (corrected for volume), to describe the ratio between DUA and the mediastinum. Nuclear imaging was repeated after 5 -7 days, with no apparent change in the subject's condition, and compared with baseline imaging. The study was approved by local Ethics Committee and all participants signed informed consent.