Clinical Outcomes of Mitral Valve Surgery in Atrial Functional Mitral Regurgitation in the REVEAL-AFMR Registry

The characteristics and treatment strategies of atrial functional mitral regurgitation (AFMR) are poorly understood. To investigate the prevalence, clinical characteristics, and outcomes of mitral valve (MV) surgery in AFMR. This retrospective cohort study, called the Real-World Observational Study for Investigating the Prevalence and Therapeutic Options for Atrial Functional Mitral Regurgitation (REVEAL-AFMR), was conducted across 26 Japanese centers (17 university hospitals, 1 national center, 3 public hospitals, and 5 private hospitals). All transthoracic echocardiography procedures performed from January 1 to December 31, 2019, were reviewed to enroll adult patients (aged ≥20 years) with moderate or severe AFMR, defined by preserved left ventricular function, a dilated left atrium, and an absence of degenerative valvular changes. Data were analyzed from May 8, 2023, to May 16, 2024. Mitral valve surgery, with or without tricuspid valve intervention. The primary composite outcome included heart failure hospitalization and all-cause mortality. In 177 235 patients who underwent echocardiography, 8867 had moderate or severe MR. Within this group, 1007 (11.4%) were diagnosed with AFMR (mean [SD] age, 77.8 [9.5] years; 55.7% female), of whom 807 (80.1%) had atrial fibrillation. Of these patients, 113 underwent MV surgery, with 92 (81.4%) receiving concurrent tricuspid valve surgery. Patients who underwent surgery were younger but had more severe MR (57.5% [n = 65] vs 9.4% [n = 84]; P