Abstract Body (Do not enter title and authors here):
Background:
Ablate-and-pace strategies for permanent atrial fibrillation (AF) have shown mortality benefit with biventricular pacemakers (BiV). The mechanism of benefit is not well understood, but may involve cardiac remodeling. We sought to characterize the effects of AV junction ablation (AVJA) in patients receiving BiV or conduction system pacing (CSP) devices on valvular regurgitation.

Objective:
To evaluate the effects of AVJA in permanent AF on valvular regurgitation as measured by standard 2D echocardiography.

Methods:
Consecutive patients undergoing BiV/CSP after AVJA for permanent AF with tricuspid regurgitation (TR) and/or mitral regurgitation (MR) between January 2018 and January 2023 at our institution were analyzed. Ejection fraction (EF), TR severity, and MR severity were compared pre-AVJA and post-AVJA.

Results:
A total of 102 patients met the above criteria. Median clinical follow up time was 902 days (IQR 578-1537 days) from AVJA. In patients with at least 1+ MR at baseline (N=65), there was significant improvement in MR severity post-AVJA (p=0.003). At baseline, 51% of patients had 1+ MR, 36% of patients had 2+ MR, 10% of patients had 3+, and 3% of patients had 4+ MR. Post AVJA, 45% (29 patients) had improvement in MR severity, 40% (26 patients) had no change, and 15% (10 patients) worsened. The greatest improvement was seen in patients with reduced baseline EF(defined as EF<50%). All 3+ and 4+ MR improved to at least 2+ MR post-AVJA in this subset. In patients with at least 2+ TR at baseline (N=28), there was also significant improvement in TR severity (p=0.029).

Conclusion:
AVJA with physiologic pacing in patients with permanent AF is associated with improvement in MR and TR severity.