Comparison of ventilatory expired gas parameters used to predict hospitalization in patients with heart failure

Background. Several ventilatory expired gas measures obtained during exercise testing demonstrate prognostic value in the heart failure (HF) population. Comparison of prognostic efficacy between pertinent measures is sparse. Methods. The ability of various expressions of peak oxygen consumption (Vo₂), the relationship between minute ventilation (VE) and carbon dioxide production (Vc0₂), and the partial pressure of end-tidal carbon dioxide (P_ETCO₂) were assessed to determine which measure(s) best predicted cardiac-related hospitalization over a 1-year period in subjects diagnosed with HF. Results. Univariate Cox regression analysis found that several expressions of peak Vo₂, VE-Vco₂ relationship, and P_ETCO₂ were significant predictors of hospitalization. Multivariate Cox regression analysis revealed that the VE/Vco₂ slope significantly predicted hospitalization (χ² = 29.1, P < .00001). Peak Vo₂ and P_ETCO₂ did not provide additional predictive value. Conclusions. The prognostic superiority of the VE/Vco₂ slope over peak Vo₂ may be a result of the latter measure's partial dependence on subject effort and skeletal muscle function.