B-PO04-078 DRIVING MECHANISMS IN PERSISTENT ATRIAL FIBRILLATION DEMONSTRATE MULTI-MONTH STABILITY IN A CANINE MODEL

Abstract

Previous studies suggest persistent atrial fibrillation (AF) is maintained by focused mechanisms, or drivers, outside the pulmonary veins. Single mapping sessions during AF to locate drivers for ablation have had limited success in improving over pulmonary vein isolation. Little is known about the development of drivers over time, but this development may explain current difficulties in driver-based ablation. To characterize the development of drivers in a canine model of persistent AF. We captured high-density left atrial voltage maps from a rapid-paced canine paced model of persistent AF (n=9, 1 yr. mongrel, 29±3 kg). To assess the progression of AF with time, we conducted these mapping sessions at 1, 3, and 6 months post-implant during AF using an Orion catheter and the Rhythmia mapping system (Boston Scientific). The mapping catheter was held at sites distributed in the atrium for 4 minutes each, such that the entire substrate was well covered. We examined each site for the existence of stable focal and reentrant mechanisms as guided by dominant frequency maps. For each mapping session, we measured 15.5±3.7 sites (n=357) and found an average of 1.9±0.8 drivers (n=39). ANOVA analysis showed the mean number of drivers to be stable over time (p=0.004). While duration of AF is associated with remodeling of the atrial substrate, these results support the surprising finding that the number of active drivers remains stable from the first month through at least 6 months of paced AF. This is promising for ablation as it shows a limited number of driving sites for treatment even as AF develops.