Abstract 17050: Pulmonary Vein Isolation Leads to Decreased Stability of Rotational Activities in Atrial Regions Remote From the Site of Ablation - A New Mechanism by Which Pulmonary Vein Isolation Leads to Beneficial Remodeling in the Atria

Introduction: Pulmonary vein isolation (PVI) is thought to be efficacious in patients with paroxysmal and persistent atrial fibrillation (AF). However, the underlying mechanisms by which PVI leads to beneficial atrial remodeling are not clear. Hypothesis: We hypothesized that PVI leads to beneficial atrial remodeling by affecting electrophysiological characteristics at sites ‘remote’ from the site of ablation. We examined the effect of PVI on stability of rotational activity throughout both atria. Methods: AF was induced in 12 dogs by rapid atrial pacing for 3-6 weeks. PVI was performed in 3 dogs, 9 dogs were used as controls. Epicardial high-density mapping was performed (117 electrodes, inter-elec. distance 2.5mm) before and after PVI. The AF characteristics were analyzed in 6 regions in the left (LA) and right atrium (RA): Cycle length (CL), stability, number of observed rotational activities based on local activation time (LAT) maps. Results: Multiple interacting rotational activities were detected in all regions with highest stability in the appendages (Figure A). PVI led to a significant increase in CL (range: 2.26 %-14.1%) in all regions (Figure B). Stability of rotational activity decreased (baseline vs after PVI) in all atrial regions: LAA (594±344ms, median 525ms vs 354±126ms, median 300ms), PLA (564±491ms, median 360ms vs 180±25ms, median 180ms), LAFW (323±248ms, median 240ms vs 240±70ms, median 240ms), in PRA (260±1167ms, median 210ms vs 239±75ms, median 240ms), RAA (1521±1301ms, median 975ms vs 457±251ms, median 450ms), P<=0.05 for all comparisons, RAFW (1521±1301ms, median 975ms vs 457±251ms, median 450ms, P=0.46) (Figure C). PVI reduced number of observed rotational activities by 25.76% in all regions (P>0.5). Conclusions: PVI significantly reduces the stability of rotational drivers in atrial regions remote from the site of ablation. We believe we have discovered a new mechanism by which PVI leads to beneficial remodeling in both the LA and RA.