Impact of mitral regurgitation on exercise capacity and clinical outcomes in patients with ischemic left ventricular dysfunction

Abstract

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 affects exercise capacity and cardiovascular morbidity and mortality in patients with coronary artery disease (CAD) and those with inferior wall motion abnormality independent of LV dysfunction. Clinical follow-up over 5 years was obtained in 77 patients (64 ± 10 years old, LV ejection fraction 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 diseases 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 and total mortalities. Univariate correlation identified MR with VC (r = -0.674, p <0.0001) and MR jet area (r = -0.575, p <0.0001) as determinants of decreased functional capacity evaluated by METs, with VC the stronger predictor. MR VC >2 mm (moderate ischemic MR) and age were independent predictors of cardiovascular events and death (hazard ratio 6.72 for MR, p = 0.04). In conclusion, in patients with CAD and LV inferior wall motion abnormality, MR negatively affects exercise capacity and is associated with increased cardiovascular morbidity and mortality. This effect appears independent of degree of LV dysfunction.