Predictors of Sinus Rhythm Maintenance After Catheter Ablation in Atrial Fibrillation Patients With Significant Atrial Functional Mitral Regurgitation.

Background: Atrial functional mitral regurgitation (FMR) results from left atrial enlargement and dysfunction, typically observed in patients with atrial fibrillation (AF). Predictors of sinus rhythm maintenance after catheter ablation in atrial FMR patients are not well understood. Methods and Results: We retrospectively reviewed 1,410 consecutive patients who underwent initial catheter ablation for AF at Kobe University Hospital between January 2014 and December 2022. Of these patients, 56 (4%; mean [±SD] age 68±8 years; 68% male) had significant (moderate, n=48; severe, n=8) atrial FMR based on pre-ablation transesophageal echocardiography. At follow-up echocardiography, a reduction in the left atrial diameter (LAd) was observed in 30 patients, whereas improvement in mitral regurgitation (MR) was noted in 26. During a mean follow-up period of 835 days, AF recurred in 23 (41%) patients. Kaplan-Meier curves for AF recurrence did not differ based on LAd reductions or MR improvements alone. However, recurrence rates were significantly lower in patients who achieved both LAd reduction and MR improvement than in those who did not achieve both changes (P=0.0259). Multivariate analysis revealed that the combination of LAd reduction and MR improvement was the only significant predictor of a decrease in AF recurrence (hazard ratio 0.275; 95% confidence interval 0.091-0.826; P=0.021). Conclusions: In AF patients with significant atrial FMR, achieving both LAd reduction and MR improvement after ablation is important to reduce the risk of AF recurrence.