Endocardial botulinum toxin injection into ganglionated plexi in order to reduce atrial fibrillation inducibility

Objective. Prior animal studies suggest that botulinum toxin injection into the epicardial fat pads can suppress atrial fibrillation (AF) inducibility. The purpose of the present study was to assess the efficacy and safety of endocardial botulinum toxin injection into epicardial fat pads and intramyocardial left atrial ganglionated plexi (GP) for preventing AF. Methods. Twenty-four dogs were separated into 3 groups: endocardial approach for botulinum toxin (Xeomin, Germany) injection into epicardial fat pads and intramyocardial GPs; endocardial approach for placebo injection (0.9% normal saline; control 1; n = 8) and epicardial approach for botulinum toxin injection (control 2; n = 8). Results. A mean of 6.9±1.7 intramyocardial injections (10 U/0.2 mL at each) and 3 injections (50 U/1 mL at each) were administered into each site exhibiting a positive vagal response and into each epicardial fat pad in all groups (p>0.05 between groups). The injections of botulinum toxin demonstrated dramatic prolongation of ERP in all PV-atrial junctions. This effect correlated with less pronounced ERP shortening in response to vagal nerve stimulation. Suppression of AF inducibility was observed at 7 days after endocardial botulinum toxin injections. The level of AF inducibility was: at 7 days - 57% (p0.05 for all). The effect of AF suppression disappeared at 3 months. No procedure-related complications occurred. Conclusion. Botulinum toxin injection into intramyocardial GPs and epicardial fat pads by an endocardial approach is feasible and safe. It provides complete removal of cardiac vagal responses and reliably reduces vulnerability to atrial fibrillation.