Impact of Mitral Regurgitation on Exercise Capacity and Clinical Outcomes in Patients with Ischemic Left Ventricular Dysfunction

摘要

There is uncertainty and debate regarding whether ischemic mitral regurgitation (MR) is a secondary epiphenomenon resulting from left ventricular (LV) dysfunction or confers an independent effect on exercise capacity and outcomes. We tested whether ischemic MR negatively impacts exercise capacity, cardiovascular morbidity and mortality in patients with coronary artery disease (CAD) and inferior wall motion abnormality patients, independent of LV dysfunction. Clinical follow-up over 5 years was obtained in 77 patients (age 64±10 years, LVEF 54±11%) with at least mild ischemic MR from CAD and evidence of inferior wall motion abnormality, who had exercise stress testing with perfusion imaging within 24 hours of echocardiography. Patients with active heart failure, ischemia, intrinsic valve disease, pulmonary and vascular disease were excluded. Exercise capacity (METs, peak double product) was tested for relation to MR (vena contracta (VC) and jet area), LV size and function, and pulmonary pressures. Cox proportional hazards analysis assessed whether MR predicted cardiovascular events, including hospitalization for heart failure, acute coronary syndrome, and myocardial infarction, and cardiovascular (CV) and total mortality. Univariate correlation identified MR with both VC (r=−0.674, p<0.0001) and MR jet area (r=−0.575, p<0.0001) as determinants of reduced functional capacity evaluated by METs, with VC the stronger predictor. MR VC > 2 mm (moderate ischemic MR) and age were independent predictors of CV events and death (HR 6.72 for MR, p=0.04). In conclusion, in patients with CAD and LV inferior wall motion abnormality, MR impacts negatively on exercise capacity and is associated with increased cardiovascular morbidity and mortality. This effect appears independent of degree of LV dysfunction.