Predictors of long-term outcomes in patients with significant myxomatous mitral regurgitation undergoing exercise echocardiography

Background: Significant myxomatous mitral regurgitation leads to progressive left ventricular (LV) decline, resulting in congestive heart failure and death. Such patients benefit from mitral valve surgery. Exercise echocardiography aids in risk stratification and helps decide surgical timing. We sought to assess predictors of outcomes in such patients undergoing exercise echocardiography.

Methods and results: This is an observational study of 884 consecutive patients (age, 58 ± 14 years; 67% men) with grade III+ or greater myxomatous mitral regurgitation who underwent exercise echocardiography between January 2000 and December 2011 (excluding functional mitral regurgitation, prior valvular surgery, hypertrophic cardiomyopathy, rheumatic valvular disease, or greater than mild mitral stenosis). Clinical and echocardiographic data (mitral regurgitation, LV ejection fraction, LV dimensions, right ventricular systolic pressure) and exercise variables (metabolic equivalents, heart rate recovery at 1 minute after exercise) were recorded. Composite events of death, myocardial infarction, stroke, and progression to congestive heart failure were recorded. Mean LV ejection fraction, indexed LV end-systolic dimension, resting right ventricular systolic pressure, peak stress right ventricular systolic pressure, metabolic equivalents achieved, and heart rate recovery were 58 ± 5%, 1.6 ± 0.4 mm/m(2), 31 ± 12 mm Hg, 46 ± 17 mm Hg, 9.6 ± 3, and 33 ± 14 beats, respectively. During 6.4 ± 4 years of follow-up, there were 87 events. On stepwise multivariable Cox analysis, percent of age/sex-predicted metabolic equivalents (hazard ratio, 0.99; 95% confidence interval, 0.98-0.99; P=0.005), heart rate recovery (hazard ratio, 0.29; 95% confidence interval, 0.17-0.50; P<0.001), resting right ventricular systolic pressure (hazard ratio, 1.03; 95% confidence interval, 1.004-1.05; P=0.02), atrial fibrillation (hazard ratio, 1.91; 95% confidence interval, 1.07-3.41; P=0.03), and LV ejection fraction (hazard ratio, 0.96; 95% confidence interval, 0.92-0.99; P=0.04) predicted outcomes.

Conclusions: In patients with grade III+ or greater myxomatous mitral regurgitation undergoing exercise echocardiography, lower percent of age/sex-predicted metabolic equivalents, lower heart rate recovery, atrial fibrillation, lower LV ejection fraction, and high resting right ventricular systolic pressure predicted worse outcomes.