Additional mitral valve procedure and coronary artery bypass grafting versus isolated coronary artery bypass grafting in the management of significant functional ischemic mitral regurgitation: a meta-analysis

Abstract

Functional ischemic mitral regurgitation (IMR) is commonly present following acute myocardial infarction (AMI) and tightly associated with a poorer prognosis. The optimal surgical strategy for the management of significant IMR (≥2+ grade) remains controversial and mitral valve surgery (MVS) at the time of coronary artery bypass grafting (CABG) is still debated. The primary objective of this meta-analysis was to clarify the effects of additional MVS on the prognosis in the patients with significant IMR, compared with isolated CABG. A meta-analysis of eligible studies, reporting concomitant MVS and CABG in comparison with CABG alone in respects to in-hospital mortality, survival and postoperative residual mitral regurgitation (MR) and cardiac functional status, was carried out. The outcomes of interest included in-hospital mortality, one-, three- and five-year survival and postoperative New York Heart Association (NYHA) class, residual MR and left ventricular ejection fraction (LVEF). Pooling 2 randomized controlled trials (RCTs) (N.=175) and 11 observational studies (N.=2661) demonstrated that additional MVS did not significantly influence in-hospital mortality (odds ratio [OR]=1.45, 95% confidence interval [CI] 0.93-2.28, P=0.10) and one- (OR=0.89, 95%CI 0.68-1.15, P=0.37), three- (OR=1.10, 95%CI 0.79-1.55, P=0.56) and five- (OR=0.93, 95%CI 0.73-1.18, P=0.55) year survival in comparison with isolated CABG. And pooling neither RCTs nor observational studies alone presented any evidence of significant difference in in-hospital mortality and survival between the two groups. Additionally, concomitant MVS was associated with increased postoperative LVEF (standard mean differences [SMD]=0.28, 95%CI 0.10-0.46, P<0.01) and decreased postoperative residual MR (SMD=-4.22, 95%CI -6.48 to -1.97, P<0.0001). Similar outcomes were obtained when either RCTs or observational studies were pooled alone. Additional MVS appeared to decrease postoperative NYHA functional class (SMD=-0.48, 95%CI -0.97-0.00, P=0.05) with evident heterogeneity (I2=87.5%, P<0.0001). In the subgroup analysis, MVS significantly reduced postoperative NYHA functional class in RCTs (SMD=-1.32, 95%CI -1.67 to -0.97, P<0.0001) whereas it did not among observational studies (SMD=-0.08, 95%CI -0.27-0.11, P=0.42), and heterogeneity was completely eliminated (for RCTs, I2=0%, P=0.49; for observational studies, I2=0%, P=0.40). Concomitant MVS at the time of CABG is associated with greater improvement in postoperative residual MR and LVEF in the patients with significant IMR. However, the evidence is still lacking of advantages of combined surgery over CABG alone regarding in-hospital mortality, survival and postoperative NYHA function class. Additional RCTs are needed to assess the safety and efficacy outcomes of adding mitral valve procedure in the surgical intervention of significant IMR.