Impact of Moderate Ischemic Mitral Regurgitation After Isolated Coronary Artery Bypass Grafting

Abstract

The aim of the study was to evaluate the clinical and echocardiographic outcomes, at rest and under exercise testing, of patients with moderate ischemic mitral regurgitation (IMR) undergoing isolated coronary artery bypass graft surgery (CABG). Between February 2003 and March 2008, 180 patients with moderate IMR who had isolated CABG were enrolled. Patients were matched 1:2 (n = 360) with patients who underwent isolated CABG without IMR (by propensity score). The study endpoints were freedom from all death, cardiac related-death, late events, and cardiac-related events. Late outcomes and left ventricular remodeling were evaluated according to preoperative percent of ejection fraction. Symptoms and MR grade under exercise test were investigated. Mean follow-up was 30 ± 16 months. The 5-year freedom from all deaths and from cardiac-related deaths among patients without IMR versus with IMR was, respectively, 90.5% ± 1.8% versus 73.7% ± 2.1% (p < 0.001) and 94.2% ± 1.6% versus 79.5% ± 1.5% (p < 0.001). Ischemic mitral regurgitation affects significantly late survival only in patients with ejection fraction 40% or less. The 5-year freedom from cardiac-related events among patients without and with IMR was, respectively, 88.2% ± 2.1% and 62.1% ± 1.2% (p < 0.0001). Patients with IMR experienced more cardiac-related events in comparison with patients without IMR. Ischemic mitral regurgitation promotes left ventricular remodeling in all patients. During exercise testing, the grade of MR moved from mild to moderate in 10 patients (28.5%) and to severe in 5 (14.3%). Among the 42 patients with moderate MR at rest, 32 patients (76%) moved from moderate to severe MR during exercise. Ischemic mitral regurgitation significantly increases the incidence of cardiac-related deaths among patients with ejection fraction 40% or less and the incidence of cardiac-related events, and promotes left ventricular remodeling. Most patients who had at-rest residual mild to moderate MR presented with a worse MR grade under exercise with the appearance of dyspnea.