The Association Between Significant Mitral Regurgitation and Atrial Fibrillation Recurrence Post-Ablation

<b>Background:</b> Atrial fibrillation (AF) is a common tachyarrhythmia associated with increased morbidity. AF frequently occurs alongside mitral regurgitation (MR). Although the impact of MR severity on AF is well proven, its effect on AF recurrence post-ablation is unclear and was the focus of our study. <b>Methods:</b> Retrospective single-center cohort of patients who underwent AF catheter ablation from 2014 to 2024. Pre-procedural transthoracic echocardiograms evaluated pre-ablation baseline MR severity. Patients with 'significant' MR (defined as moderate-severe or severe MR) were compared to those with 'non-significant' MR. Univariate Kaplan-Meier (KM) survival analysis, multivariable Cox proportional hazards models, and inverse probability treatment weighting (IPTW) method were applied to assess the association between baseline MR and AF recurrence post-ablation. <b>Results:</b> Among 444 patients undergoing AF ablation, 28 (6.3%) had 'significant' baseline MR. Over median follow-up of 19 months, 104 (23.4%) patients experienced AF recurrence. Univariate and KM survival analyses showed a non-significant trend for increased AF recurrence among patients with 'significant' MR. Applying KM analysis on balanced IPTW pseudo-population revealed robust association between 'significant' MR and AF recurrence post-ablation (HR = 2.41, 95% CI 1.80-3.22, <i>p</i> < 0.001). Multivariate analysis, performed on IPTW-adjusted pseudo-population, including age, gender, LA diameter, LVEF, and AF type, showed 'significant' MR to be independently associated with AF recurrence post-ablation (HR = 2.11, 95% CI 1.43-5.73, <i>p</i> = 0.003). <b>Conclusions:</b> Use of IPTW pseudo-population suggests a significant association between baseline MR severity, regardless of its etiology, and AF recurrence post-ablation. This association should be confirmed by future larger studies.