OBJECTIVES: Evidence on optimal therapeutic strategies for atrial functional mitral regurgitation (AFMR) remains limited. This study aimed to evaluate patient characteristics, surgical techniques, and outcomes in AFMR patients from the Mini Mitral International Registry (MMIR).

METHODS: Patients undergoing mini mitral surgery for AFMR between 2015 and 2023 were identified. Exclusion criteria included organic lesions, abnormal leaflet motion, reduced left ventricular function, absence of annular dilation, and previous mitral procedures.

RESULTS: Of 7957 patients, 430 (5.4%) met AFMR criteria. The cohort was elderly (median age 73), predominantly female (67.7%), with frequent atrial fibrillation (AF) (69.7%). Mitral repair was performed in 91.4% of patients, all via isolated annuloplasty except 3. Complete rings were used in 97.1%. On multivariable analysis, anterior mitral leaflet (AML) pseudo-prolapse was associated with an increased likelihood of valve replacement (OR 5.3, 95% CI 1.07-9.12). Concomitant tricuspid repair, AF ablation, and left atrial appendage closure were performed in 44.2%, 40.5%, and 25.6%, respectively. At discharge, 99% had none or mild regurgitation; in-hospital mortality and stroke were 2.3% and 1.9%.

CONCLUSIONS: Findings from the MMIR indicate that mitral repair with isolated annuloplasty was the preferred surgical strategy for AFMR, providing satisfactory procedural and early clinical outcomes. The presence of AML pseudo-prolapse reduced the likelihood of valve repair. Overall operative results were favourable, with 99% of patients experiencing no or mild residual mitral regurgitation. These findings may serve as a reference for clinical decision-making in AFMR treatment pathways.