Impact of Residual Functional Mitral Regurgitation After Atrial Fibrillation Ablation on Clinical Outcomes in Patients With Left Ventricular Systolic Dysfunction.

Functional mitral regurgitation (FMR) negatively impacts the prognosis in patients with atrial fibrillation (AF) and reduced left ventricular (LV) ejection fraction (LVEF). Although structural reverse remodeling after AF ablation can reduce FMR severity, the prognostic impact of FMR and its evolution remain unclear. Of 491 patients with baseline LVEF <50% who underwent first-time AF ablation, 134 patients (27%) had grade 2 to 4 FMR at baseline. Among them, 88 patients (66%) exhibited FMR improvement to grade 0 to 1 FMR 6 months after AF ablation. Conversely, among 357 with baseline grade 0 to 1 FMR, 13 patients (3.6%) exhibited FMR worsening to grade 2 to 4 FMR despite AF ablation. Assessment with multidetector computed tomography revealed that an increase in the left atrial emptying fraction (odds ratio 3.55 per 10% increase; 95% confidence interval 2.12 to 5.95) and a reduction in the LV end-diastolic volume index (1.35 per 10-ml/m decrease; 1.04 to 1.76) were identified as contributors to the FMR improvement. During a follow-up of 43 months, patients with postprocedural grade 2 to 4 FMR more frequently experienced hospitalizations for heart failure or cardiovascular death than those with grade 0 to 1 FMR (30.5% vs 4.6%, log-rank p <0.001). An age-adjusted multivariate Cox regression analysis including baseline and postprocedural FMR revealed that postprocedural grade 2 to 4 FMR (hazard ratio, 3.24; 95% confidence interval 1.43 to 7.35) was significantly associated with unfavorable events. In conclusion, AF ablation modified and often improved FMR severity in patients with reduced LVEF. Residual grade 2 to 4 FMR 6 months after AF ablation was associated with a poor prognosis.