Influence of isolated coronary artery bypass graft on moderate functional mitral regurgitation.

Introduction: The natural course and clinical significance of moderate mitral regurgitation (MR) in patients undergoing isolated coronary artery bypass graft (CABG) surgery are still debated. This study aimed to determine the course of moderate functional MR after CABG. Methods: In this registry-based cohort, patients who underwent isolated elective CABG at Tehran Heart Center between 2010 and 2017 were included. Transthoracic echocardiography was performed at baseline before CABG and after 12 months of follow-up. The outcomes of interest were both improvement and progression of MR during the study. Results: Among 291 patients with moderate functional MR, the mean age was 66.1±9.6 years, and 204 (70.1%) were males. Most of the study population had extensive coronary disease (240 patients; 82.5% with thee-vessel disease). Moreover, 101 patients (34.7%) had suffered a prior myocardial infarction. The mean LVEF before CABG was 42.0±9.9 and 145 patients (49.8%) had an LVEF≤40% prior to surgery.The median follow-up duration was 10.1 months (9.0-11.2). Only four patients had improvements in MR at follow-up. Eleven patients (3.8%) in the study population showed worsening MR after isolated CABG. In this group of patients, mean LVEF dropped from 44.1±10.9 at baseline to 41.8±11.5 during follow-up Due to the low number of cases with regression and progression, an analysis of predictors of MR change was not performed. Conclusion: This study showed that in patients with moderate functional MR, isolated CABG did not result in significant changes in the degree of MR.