Cardiopulmonary exercise testing for prognosis in chronic heart failure: continuous and independent prognostic value from VE/VCO2 slope and peak VO2

Background Chronic heart failure carries a poor prognosis. Cardiopulmonary exercise testing is useful in predicting survival. We set out to establish the prognostic value of peak VO2 and VE/VCO2 slope across a range of threshold values. Method and Results Three hundred and three consecutive patients with stable chronic heart failure underwent cardiopulmonary exercise testing between 1992 and 1996, Their age was 59 +/- 11 years (mean +/- SD), peak VO2 17.8 +/- 66 ml. kg(-1) min(-1). VE/VCO2 slope 37 +/- 12. Al the end of follow-up in January 1999, 91 patients had died (after a median of 7 months, interquartile range 3-16 months). The median follow-up for the survivors was 47 months (interquartile range 37-57 months). The areas under the receiver-operating characteristic curves for predicting mortality at 2 years were 0.77 for both peak VO2 and VE/VCO2 slope. With peak VO2 and VE/VCO2 slope viewed as continuous variables in the Cox proportional-hazards model, they were both highly significant prognostic indicators, both in univariate analysis and bivariate analysis (P<0.001 for VE/VCO2 slope, P<0.003 for peak VO2). Conclusions Lower peak VO2 implies poorer prognosis across a range of values from 10 to 20 ml . kg(-1) min(-1), without a unique threshold. Gradations of elevation of the VE/VCO2 slope also carry prognostic information over a wide range (30-55), The two parameters are comparable in terms of prognostic power. and contribute complementary prognostic information. (C) 2000 The European Society of Cardiology.