Impact of ischemic mitral regurgitation on long-term outcome of patients with ejection fraction above 0.30 undergoing first isolated myocardial revascularization

Background. We evaluated the impact of ischemic mitral regurgitation (IMR) on long-term outcome of patients with an ejection fraction (EF) exceeding 0.30 undergoing isolated coronary artery bypass grafting (CABG). Methods. From November 1994 to December 2002, 4226 patients (EF > 0.30) underwent a first isolated CABG. Preoperative IMR was present in 1421 (33.6%, group IMR), of which 1254 had mild (1/4) and 167 had moderate (2/4). The remaining 2805 patients (66.4%, group no-IMR) showed no IMR. A nonparsimonious regression model was built to determine the propensity score. Ten-year freedom from death from any cause, cardiac death, and cardiac events was evaluated by the Kaplan-Meier method. Results of Cox analysis were adjusted by entering the propensity score as an independent variable. Results. All patients had similar early mortality (2.1% no-IMR vs 2.5% IMR, p = 0.502) and morbidity (6.5% no-IMR vs 6.6% IMR, p = 0.840). In patients with EF of 0.31 to 0.40, but not in those ones with EF exceeding 0.40, IMR grade was an independent variable for worse long-term freedom from cardiac death (82.8 +/- 3.2 vs 91.4 +/- 2.4; Cox hazard ratio [HR], 2.1 [95% confidence interval (CI), 1.1 to 4.1]; p = 0.0324) and cardiac events (78.6 +/- 3.5 vs 88.5 +/- 2.7; Cox HR, 2.0 [95% CI, 1.1 to 3.7]; p = 0.0174). Conclusions. Mild or moderate IMR in patients with an EF exceeding 0.30 undergoing first isolated CABG influences long-term outcome when EF is 0.31 to 0.40, but not when it exceeds 0.40.