[Clinical characteristics and prognosis of patients with atrial functional mitral regurgitation]

Objective: To investigate the clinical characteristics and prognosis of atrial functional mitral regurgitation (AFMR). Methods: This was a single-center retrospective study. Patients hospitalized at Sun Yat-sen Memorial Hospital of Sun Yat-sen University between January 2020 and March 2022 and diagnosed with significant functional mitral regurgitation were enrolled. According to the type of regurgitation, patients were divided into the AFMR group and the ventricular functional mitral regurgitation (VFMR) group. Clinical and echocardiographic data were compared between the two groups. The patients were followed up until April 2024. The primary endpoint was all-cause mortality, and the secondary endpoint was the composite of cardiac death and hospitalization for heart failure. Survival was compared between the two groups using Kaplan-Meier survival curves. Cox proportional hazards regression analysis was performed to identify factors associated with all-cause mortality in patients with functional mitral regurgitation. Results: The study cohort consisted of 269 patients, with a median age of 66.0 (57.5, 76.0) years, among whom 172 (63.9%) were male. Patients were divided into the AFMR group (n=61, 22.7%) and the VFMR group (n=208, 77.3%). Compared with the VFMR group, the AFMR group had a higher proportion of female patients, older age, a higher prevalence of atrial fibrillation, lower prevalences of coronary artery disease, fewer patients with heart failure symptoms, and a lower proportion of prior visits to cardiovascular departments (all P<0.05). Compared with the VFMR group, the AFMR group demonstrated significantly larger anteroposterior left atrial diameter, right atrial transverse diameter, and right ventricular transverse diameter, along with a higher LVEF and a higher prevalence of moderate or greater tricuspid regurgitation (all P<0.05). The follow-up duration was 24.6 (5.8, 37.6) months. The AFMR group exhibited lower all-cause mortality (21.3% (13/61) vs. 38.9% (81/208), P=0.011) and a lower rate of the composite endpoint of cardiac death and heart failure hospitalization (24.6% (15/61) vs. 42.8% (89/208), P=0.010) than the VFMR group. Kaplan-Meier survival analysis also revealed that the AFMR group had a higher cumulative event-free survival rate than the VFMR group (P_log-rank=0.002). Multivariate Cox proportional-hazards regression analysis demonstrated that age (HR=1.038, 95%CI 1.019-1.057, P<0.001), cerebrovascular disease (HR=2.014, 95%CI 1.200-3.382, P=0.008), AFMR (HR=0.341, 95%CI 0.175-0.667, P=0.002), and moderate or greater tricuspid regurgitation (HR=2.297, 95%CI 1.467-3.596, P<0.001) were independent predictors of all-cause mortality in patients with functional mitral regurgitation. Conclusions: Compared with VFMR, AFMR is more common among elderly patients, female patients, and patients with atrial fibrillation and is less frequently accompanied by heart failure symptoms. The rates of all-cause mortality and cardiovascular death or hospitalization for heart failure are both lower in the AFMR group than those in the VFMR group.