Cardiopulmonary and Noninvasive Hemodynamic Responses to Exercise Predict Outcomes in Heart Failure

Background: An impaired cardiac output response to exercise is a hallmark of chronic heart failure (HF). We determined the extent to which noninvasive estimates of cardiac hemodynamics during exercise in combination with cardiopulmonary exercise test (CPX) responses improved the estimation of risk for adverse events in patients with HF. Methods and Results: CPX and impedance cardiography were performed in 639 consecutive patients (mean age 48 +/- 14 years), evaluated for HF. Clinical, hemodynamic, and CPX variables were acquired at baseline and subjects were followed for a mean of 460 +/- 332 days. Patients were followed for the composite outcome of cardiac-related death, hospitalization for worsening HF, cardiac transplantation, and left ventricular assist device implantation. Cox proportional hazards analyses including clinical, noninvasive hemodynamic, and CPX variables were performed to determine their association with the composite endpoint. There were 113 events. Among CPX variables, peak oxygen uptake (VO2) and the minute ventilation (VE)/carbon dioxide production (VCO2) slope were significant predictors of risk for adverse events (age-adjusted hazard ratio [HR] 1.08, 95% confidence interval [CI] 1.05-1.11 for both; P < .001). Among hemodynamic variables, peak cardiac index was the strongest predictor of risk (HR 1.08, 95% CI 1.0-1.16; P = .01). In a multivariate analysis including CPX and noninvasively determined hemodynamic variables, the most powerful predictive model included the combination of peak VO2, peak cardiac index, and the VE/VCO2 slope, with each contributing significantly and independently to predicting risk; an abnormal response for all 3 yielded an HR of 5.1 (P < .001). Conclusions: These findings suggest that noninvasive indices of cardiac hemodynamics complement established CPX measures in quantifying risk in patients with HF. (J Cardiac Fail 2013;19:101-107)