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 (Vo(2)), the relationship between minute ventilation (VE) and carbon dioxide production (Vco(2)), and the partial pressure of end-tidal carbon dioxide (P(ET)co(2)) 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 Vo(2), VE-Vco(2) relationship, and P(ET)co(2) were significant predictors of hospitalization. Multivariate Cox regression analysis revealed that the VE/Vco(2) slope significantly predicted hospitalization (x(2) = 29.1, P <.00001). Peak Vo(2) and P(ET)co(2) did not provide additional predictive value. Conclusions The prognostic superiority of the VE/Vco(2) slope over peak Vo(2) may be a result of the latter measure's partial dependence on subject effort and skeletal muscle function.