Exercise Contractile Reserve for Predicting Mortality in Non-Ischemic Ventricular Dysfunction

Objectives: A preserved contractile reserve is a marker of favorable outcome in different cardiac diseases. In some studies, using drugs, an increase in left ventricular (LV) systolic function was associated to better prognosis in patients with dilated cardiomyopathy. We aimed to assess whether a positive contractile reserve (CR) to physical exercise is a marker of good outcome in patients with LV systolic dysfunction not related to coronary artery disease (CAD). Design: From our exercise echocardiography database we extracted patients with LV systolic dysfunction (LVEF ≤45), negative coronary angiography, and absence of a history of CAD. A positive CR was considered when peak LVEF was higher that resting LVEF. The endpoint was overall mortality. Results and Conclusions: Among the 225 patients included, 105 had a positive CR and 120 a negative CR. Resting LV function was similar in patients with positive and negative CR (LVEF 35±8 vs. 34±9; wall motion score index 1.81±0.34 vs. 1.80±0.29; both p=NS). During a follow up of 6.2+4.7 years (25-75th percentiles 2.2-9.5), there were 71 deaths. Ten-year mortality rates were 34% for patients with CR and 67% for patients without CR (p=0.003). After multivariate adjustment that included clinical variables, medications, resting LV function, and exercise testing variables the only predictors of death were age (hazard ratio (HR) 1.07, 95% Confidence Interval (CI) 1.04-1.10, p<0.001), and absence of CR (HR 1.80, 95% CI 1.09-2.98, p=0.02). In conclusion, in patients with non- ischemic LV dysfunction, a positive CR to physical exercise is a marker of better outcome.