Prognostic value of end-tidal carbon dioxide during exercise testing in heart failure

Background The partial pressure of end-tidal carbon dioxide production (PETCO2) at ventilatory threshold (VT) has been shown to be strongly correlated with cardiac output during exercise in patients with heart failure (HF), but few data are available regarding its prognostic utility. Aims The purpose of this study was to assess the ability of PETCO2 to predict cardiac-related events in a group of subjects with HF. Methods One hundred and thirty subjects diagnosed with compensated HF underwent cardiopulmonary exercise testing (CPX). Peak oxygen consumption (VO2), the minute ventilation–carbon dioxide production (VE/VCO2) slope and PETCO2 were determined. Results Receiver operating characteristic (ROC) curve analysis revealed that PETCO2 at the ventilatory threshold (VT) was a significant predictor of cardiac-related events (ROC area = 0.82, p < 0.001). The optimal PETCO2 at a VT threshold value for separating high (≤) and low (>) risk groups was 36.1 mm Hg (77% sensitivity, 69% specificity). In a multivariate Cox regression analysis, PETCO2 at VT added significant predictive value to the VE/VCO2 slope and peak VO2. Conclusion These results indicate that PETCO2 during CPX is a significant predictor of cardiac-related events in patients with HF. Clinical assessment of this variable in patients with HF undergoing CPX may therefore be warranted.