Introduction: Cardiac sympathetic activity is involved in the initiation and maintenance of atrial fibrillation. A novel technique that evaluates the atrial accumulation of 123I-MIBG may be able to assess the atrial sympathetic innervation. The purpose of this study was to visually evaluate the modification of sympathetic innervation caused by multiple catheter ablations. Methods: The total study cohort comprised 32 patients with atrial fibrillation. 21 patients underwent only one ablation using a balloon catheter (cryoballoon in 10 patients; hot balloon in 11 patients) (group 1), while 11 patients underwent multiple radiofrequency catheter ablation procedures (three procedures in 6 patients; four procedures in 5 patients) (group 2). In all patients, the left atrial sympathetic activity was evaluated using MIBG images obtained using a novel solid-state whole-body scanner (VERITON). For local quantitative evaluation, the site with the strongest discrete MIBG accumulation was automatically recognized by the computer and compared in pre- and post-procedural images. Results: In all patients, the total left atrial MIBG accumulation value after ablation (6.64х10 4 ±1.65х10 4 PROPCNTS) was significantly lower than that before ablation (7.74х10 4 ±2.25х10 4 PROPCNTS, p=0.0289). At the site with the strongest discrete MIBG accumulation, the MIBG accumulation after ablation was decreased in 19 patients, unchanged in 9, increased in 3, and shifted in 1. The total left atrial MIBG accumulation value before ablation was significantly lower in group 2 (5.74х10 4 ±1.40х10 4 PROPCNTS) than group 1 (6.67х10 4 ±1.57х10 4 PROPCNTS, p=0.0485). Conclusions: The MIBG accumulation in the left atrium decreased after catheter ablation. Furthermore, preoperative evaluation revealed a significant decrease in MIBG accumulation after multiple ablation procedures. This suggests that multiple catheter ablation of the left atrium modifies the sympathetic innervation.