Abstract 20993: Which Test is the Best? Comparison of Functional Tests for Prediction of Poor Outcomes in Heart Failure
Introduction: Peak VO2 is considered the best predictor of adverse outcomes in advanced HF. Several recent publications suggested that VE/VCO2 max is superior to peak VO2. Six minute walk distance is considered generally useful but inferior to either peak VO2 or VE/VCO2 max.
Objective: To compare 6 minute walk, peak VO2 and VE/VCO2max as predictors of adverse outcomes in advanced HF.
Methods: A limited access dataset from the ESCAPE trial provided by the National Heart Lung and Blood Institute (Bethesda, MD) was analyzed. Patients with advanced heart failure and left ventricular ejection fraction less than 30% had 6 minute walk test and cardiopulmonary exercise stress test on admission and at discharge from the hospital. Cardiovascular mortality and cardiovascular readmission rates over 6 months were used as outcomes. We calculated sensitivity, specificity, positive and negative predictive values with the cutoff values of less than 300 meters for 6 minute walk test, peak VO2 less than 13 mL/kg/min, and slope of >34 for VE/VCO2.
Results: A six minute walking distance less than 300 m was the most specific predictor of poor outcomes both at the baseline (decompensated HF) and at discharge (sub compensation/compensation)- see table. It was much more specific than either peak VO2 or VE/VCO2. At the baseline, peak VO2 and VE/VCO2 were equally highly sensitive for poor outcomes. At discharge, peak VO2 was more sensitive predictor of poor outcomes than VE/VCO2 max. In terms of positive predictive value, high baseline VE/VCO2 was the best predictor of future mortality and cardiovascular readmissions, while at discharge all three indicator were approximately equivalent.
Conclusions: Six minutes walk, peak VO2, and VE/VCO2 are complimentary and do not repeat or substitute each other. While 6 minute walk is most specific, sensitivity and positive predictive value are better for VO2 max and VE/VCO2. Table
- © 2010 by American Heart Association, Inc.