Visualisation and radiofrequency ablation of sympathetic innervation loci in the left atrium in patients with paroxysmal atrial fibrillation

Abstract

Introduction: A novel cardiac gamma camera utilizes the radiopharmaceutical Iodine-123-Meta-iodobenzylguanidine ( 123 I-MIBG) to visualize cardiac sympathetic innervation. Physiological accumulation of 123 I-mIBG provides an anatomical quantitative determination ofthestructuresoftheautonomicnervoussystem(ANS)withdiscreteuptakeareas(DUA)ofsympatheticactivitylocatedintheleftatrium (LA) corresponding to the main ganglionic plexi (GP) clusters that could not previously be visualized. Aim: to visualize the DUA of the heart in patients with paroxysmal atrial fibrillation (AF) and to assess the effect of radiofrequency ablation (RFA) on DUA in LA. Materials and Methods. Computed tomography (CT) of the heart and radionuclide imaging with 123 I-mIBG were performed in 15 patients with paroxysmal AF. The results of the study were combined with preliminary taken CT images to create a detailed anatomical map of the sympathetic activity of the heart. The processed images were combined with the 3D reconstruction of the LA, obtained with the navigation system (CARTO 3, CARTO RMT). In DUA, high-frequency stimulation (HFS) followed by RF ablation was performed using the current recommended parameters. Results. Forty-eight DUA (median 3 [3; 3]) were identified. Average activity of DUA was 1315 [1171; 1462] cnt/sec/ml. Positive response to HFS in the DUA was obtained in 8 (53.3%) patients. Prior to ablation, no response was received to HFS in areas of LA outside the DUA. After ablation, there was no response to HFS in the DUA sites. At repeated scans 3 DUA (median 0 [0; 0]; p<0.001 compared with preoperative data) were observed. Activity of DUA significantly decreased to 819 [684; 955] cnt/sec/ml (p<0.001 as compared with preoperative data). Thirteen of 13 of 15 patients (87%) had no AF/AT/AFL recurrences for 6 month follow up. Conclusion. In patients with AF, the areas of sympathetic activity in LA can be visualized by physiological localized uptake of 123 I-mIBG. Radiofrequency catheter ablation can target the identified sympathetic innervation structures in AF patients precisely and effectively.