Abstract 741: Atrial Fibrillation Begets Atrial Fibrillation: Acute Autonomic Remodeling Leads to Enhanced Inducibility for Atrial Fibrillation
Introduction: There have been many forms of remodeling reported to play a role in the concept of “atrial fibrillation (AF) begets atrial fibrillation.” The role of intrinsic cardiac nervous system (ICNS) in this remodeling process was evaluated in this study.
Methods: Continuous rapid pacing (1200 bpm, 2× threshold, TH) was performed at the left atrial appendage to maintain AF. Group 1 (N=7): 6-hours of pacing followed by ganglionated plexi (GP) ablation, both left and right side; Group 2 (N=7): GP ablation followed by 6-hours of pacing. At 2x and 10x TH, the effective refractory period (ERP) and window of vulnerability (WOV), i.e., longest-shortest coupling of premature stimulus which induced AF in milliseconds (ms), were measured at the left atrium, right atrium and pulmonary veins (PVs) every hour during the 6-hours of pacing before and after GP ablation.
Results: In group 1 (rapid pacing with GP intact) ERP progressively shortened in the first two hours and then stabilized both at 2×TH and 10×TH (Figure 1A⇓), however, WOV progressively widened throughout the time period (Figure 1B⇓). After GP ablation, ERP was significantly longer than prior to ablation and AF could not be induced (WOV=0, p<0.01) at any pacing site at either 2×TH or 10×TH (Figure 1B⇓). In group 2 (initial GP ablation), ERP exhibited a slightly increasing trend as the pacing time increased. AF could not be induced in 6/7 dogs during the 6-hour pacing, and was inducible in 1/7 with a cumulative WOV of only 10 ms.
Conclusion: The ICNS is crucial for the process of “AF begets AF” in the acute stages of remodeling by rapid atrial pacing.