The change in the mitral-septal angle after surgery for atrial functional mitral regurgitation

Objective The optimal surgical strategy for atrial functional mitral regurgitation remains uncertain. Preoperative mitral-septal angle ≤ 70° has been reported as a risk factor for an abnormal vortex pattern in mitral valve repair. This study aimed to elucidate the change in the mitral-septal angle after surgery for atrial functional mitral regurgitation and its effect on the mid-term outcomes. Methods Forty patients underwent mitral valve repair for atrial functional mitral regurgitation. The mitral-septal angle was defined as the angle between the mitral annulus and the anteroseptal wall of the left ventricular mid-portion in the parasternal long-axis view on transthoracic echocardiography. All patients underwent mitral ring annuloplasty. Left atrial plication was performed in nine patients. The mean clinical follow-up period was 42 ± 24 months. Results The ratio of left atrial volume to left ventricular end-systolic volume was negatively correlated with the preoperative mitral-septal angle. The postoperative mitral-septal angles were significantly smaller than the preoperative ones. The mitral-septal angle decreased with a decrease in the mitral annuloplasty ring size. Patients who underwent left atrial plication tended to show an increase in the mitral-septal angle postoperatively. There were no significant differences in mid-term morbidities, including heart failure, requiring re-hospitalization and mortalities between patients with postoperative MSA > 70° and those with postoperative MSA ≤ 70°. Conclusions Mitral ring annuloplasty negatively changed the mitral-septal angle, while left atrial plication may induce a positive change to the mitral-septal angle. An association between the mitral-septal angle and mid-term outcomes was not revealed in this study.