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 (PETCO2) 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 PETCO2 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 PETCO2 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.