Aims: Mitral regurgitation (MR) causes left atrium (LA) enlargement and subsequent atrial fibrillation (AF). The presence of MR may increase recurrence rates after AF ablation. The purpose of this study was to determine the impact of MR on recurrence rates after catheter ablation of AF.
Methods and results: We compared 95 patients with moderate or greater baseline MR (defined by MR jet area to LA area ratio ≥ 0.2) and AF undergoing ablation to 95 randomly selected patients without significant MR undergoing AF ablation. Electrocardiographic recurrence at 1-year follow-up was the primary outcome. Patients in the MR cohort had mean MR/LA ratio 0.37 vs. 0.09 in controls (P< 0.0001). Mitral regurgitation patients had larger LA dimension (4.5 vs. 4.1 cm, P< 0.0001) and more persistent AF (71 vs. 28%, P< 0.0001). Mitral regurgitation patients had higher recurrence rates than controls (61 vs. 46%, P= 0.04). The degree of MR was higher in patients with recurrence (MR/LA ratio 0.25 vs. 0.20, P= 0.03), as was LA dimension (4.5 vs. 4.1 cm, P< 0.0001). In multivariate analyses, only LA size was an independent predictor of recurrence (odds ratio 2.9 per centimetre increase in LA dimension, P= 0.005). Fifty-five percent of MR patients had normal leaflet motion, with MR likely due to atrial remodelling secondary to AF.
Conclusion: Mitral regurgitation was associated with increased AF recurrence after AF ablation, but its impact was mediated by LA size. Left atrium size was the only independent predictor of AF recurrence. The high percentage of MR that was likely secondary to AF may have impacted our findings and deserves further study.