Early and Late Improvement of Mitral Reserve in Selected Patients Undergoing Coronary Artery Bypass Graft with Moderate Ischemic Mitral Regurgitation

Abstract

Objective: The treatment of moderate ischemic mitral regurgitation in patients undergoing coronary artery bypass graft is still debated. Mitral reserve may be simplified as the ratio between the length of anterior and posterior mitral leaflets. The aim of our study was to assess the outcome of ischemic mitral regurgitation in selected patients undergoing coronary artery bypass grafting. We have used the changes in the mitral reserve to assess the improvement of mitral valve leaflets’ motion. Methods: We have been enrolling 52 consecutive patients undergoing coronary artery bypass grafts (CABGs) with mild (1+) to moderate (2+) functional mitral regurgitation (MR) since June 2019. The selection criteria are hypokinesia of left ventricular lateral or posterior-lateral wall, mitral regurgitation ≤ 2+ and revascularization of some branches of circumflex artery. Trans-thoracic echocardiogram was carried out to all patients at baseline, 6 months and 1 year. Statistical analysis was performed with SPSS 23 and non-parametric Wilcoxon test was used. Results: At 6 months, the improvement of mitral reserve (2.33 ± 0.86 vs 2.01 ± 0.64; p=0.041) and ejection fraction (40.8 ± 11.5 vs 45 ± 9.8; p=0.029) and the reduction of mitral anulus (37.5 ± 5.03 vs 34.4 ± 3.34; p=0.013) are statistically significant and they also remain stable at 12 months. Mitral regurgitation degree is reduced at 6 months (1.53 ± 0.74 vs 1.40 ± 0.50; p=0.43) remaining stable at 12 months. Mean follow-up is 7.23 ± 5.22 months. Conclusions: The improvement of mitral reserve represented by the reduction of the ratio between the length of anterior and posterior mitral leaflets, should be explained by the reduction of the tethering of posterior leaflet due to myocardial revascularization. Therefore, we believe that in selected patients with ischemic mitral regurgitation undergoing coronary artery bypass graft, mitral valve shouldn’t be treated.