Background: Introduction Oxidative Stress(OS) is a mechanism underlying atrial fibrillation(AF) correlated with electrical and structural remodeling in AF. We hypothesized that reactive oxygen species(ROS) are dynamically involved in the creation of vulnerable substrate with electrograms(EGMs) of high ROS, being uniquely sensitive to acute ROS scavenging.
Objective: We assessed the spatial and temporal characteristics of AF EGMs within each sub-region of the left and right atrium with greatest change in response to acute ROS inhibition.
Methods: AF was induced in 10 dogs by rapid atrial pacing(RAP) for 6 weeks. Epicardial high-density mapping was performed (130electrodes, inter-elec dist 2.5mm) before and after administration of N-acetylcysteine(NAC), a ROS scavenger. AF electrogram(EGM) characteristics were analyzed in 6 different regions of the left and right atrium. Sub-regions with>30% change in the Dominant Frequency(DF) delta maps (FigureA) were analyzed.
Results: NAC led to a significant decrease in DF in nearly all atrial regions. Sub-regions (figure B) that showed >30% reduction in DF after NAC administration had sizes of 54.76±48.65mm²(median 37.5mm²). These ‘hot spots’ were consistently present at all-time points from 30min-3h, with the largest number of hot spots being located in the left atrial free wall, followed by the posterior left atrium. FigureA shows a representative ROS ‘hot spot’ in the LAA. Greatest changes in DF appeared at 134±63(median 120)min after NAC.
Conclusion: Acute scavenging of ROS selectively reduces AF dominant frequency in ‘hot spot’ sub-regions that remain stable over time .These ‘hot spot’ regions may be new potential target for ablation. $$graphic_{07404D20-E705-4B4C-87B0-378938A2C063}$$