©2012 Wiley Periodicals Inc.

New variables obtained from cardiopulmonary exercise testing (CPX) have received attention in recent years, in particular the partial pressure of end-tidal carbon dioxide (PETCO2). The purpose of this study was to therefore comprehensively assess the ability of resting and exercise PETCO2 to predict major cardiac events in a heart failure (HF) cohort referred for CPX. A total of 963 patients with systolic HF undergoing symptom-limited CPX were included in the analysis. Resting and exercise PETCO2 along with other CPX variables were determined, and patients were followed for major adverse events. With regard to resting measures, multivariate analysis revealed that left ventricular ejection fraction was the most robust prognostic marker (P<.001) while resting PETCO2 added significant predictive value and was retained in the regression (P<.001). When exercise data were considered, the multivariate analysis revealed that the PETCO2 apex during exercise added predictive value and was retained (P<.05). In what is the largest evaluation of PETCO2 in the assessment of systolic HF patients to date, the authors substantiate prior (smaller) studies showing prognostic utility of PETCO2, both as a resting measure (an important potential screening tool) and during exercise. These data add to the rationale to incorporate PETCO2 as a routine monitoring component in HF management.