• Ross Arena, Marco Guazzi, and Jonathan Myers.
• Department of Physical Therapy, Box 980224, Virginia Commonwealth University, Health Sciences Campus, Richmond, Virginia 23298-0224, United States. raarena@vcu.edu
• Int. J. Cardiol. 2007 Apr 12; 117 (1): 103-8.

BackgroundThe partial pressure of end-tidal carbon dioxide production (P(ET)CO2) 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.AimsThe purpose of this study was to assess the ability of P(ET)CO2 to predict cardiac-related events in a group of subjects with HF.MethodsOne 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 P(ET)CO2 were determined.ResultsReceiver operating characteristic (ROC) curve analysis revealed that P(ET)CO2 at the ventilatory threshold (VT) was a significant predictor of cardiac-related events (ROC area=0.82, p<0.001). The optimal P(ET)CO2 at a VT threshold value for separating high (< or =) and low (>) risk groups was 36.1 mm Hg (77% sensitivity, 69% specificity). In a multivariate Cox regression analysis, P(ET)CO2 at VT added significant predictive value to the VE/VCO2 slope and peak VO2.ConclusionThese results indicate that P(ET)CO2 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.

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