Determining the Preferred Percent-Predicted Equation for Peak Oxygen Consumption in Patients With Heart Failure

Abstract

Background— Peak oxygen consumption (V o 2 ) is routinely assessed in patients with heart failure undergoing cardiopulmonary exercise testing. The purpose of the present investigation was to determine the prognostic ability of several established peak V o 2 prediction equations in a large heart failure cohort. Methods and Results— One thousand one hundred sixty-five subjects (70% males; age, 57.0�13.8 years; ischemic etiology, 43%) diagnosed with heart failure underwent cardiopulmonary exercise testing. Percent-predicted peak V o 2 was calculated according to normative values proposed by Wasserman and Hansen (equation), Jones et al (equation), the Cooper Clinic (below low fitness threshold), a Veteran’s Administration male referral data set (4 equations), and the St James Take Heart Project for women (equation). The prognostic significance of percent-predicted V o 2 values derived from the 2 latter, sex-specific equations were assessed collectively. There were 179 major cardiac events (117 deaths, 44 heart transplantations, and 18 left ventricular assist device implantations) during the 2-year tracking period (annual event rate, 10%). Measured peak V o 2 and all percent-predicted peak V o 2 calculations were significant univariate predictors of adverse events (χ 2 ≥31.9, P <0.001) and added prognostic value to ventilatory efficiency (VE/V co 2 slope), the strongest cardiopulmonary exercise testing predictor of adverse events (χ 2 =150.7, P <0.001), in a multivariate regression. The Wasserman/Hansen prediction equation provided optimal prognostic information. Conclusions— Actual peak V o 2 and the percent-predicted models included in this analysis all were significant predictors of adverse events. It seems that the percent-predicted peak V o 2 value derived from the Wasserman/Hansen equations may outperform other expressions of this cardiopulmonary exercise testing variable.