Long-standing atrial fibrillation is associated with atrial functional mitral regurgitation (AFMR) with atriogenic tethering. We compared the outcomes of patch augmentation (PA) and valve replacement (VR) for AFMR.We retrospectively compared the data of 16 patients who underwent PA for AFMR with the data of 15 patients who underwent VR between 2008 and 2021. Patients with a left ventricular ejection fraction (LVEF) of50% were excluded. We also performed atrial plication and left appendage closure if the patients had no weak atrial wall that led to severe bleeding.The median age was 72.5 and 76.0 years in the PA and VR groups, respectively. The PA group had a longer cardiopulmonary bypass time (206PA may achieve comparable outcomes to those of VR for AFMR. Operative procedures should be chosen based on each patient's background. Atrial reduction could be considered to prevent thromboembolic events.