title: Prognostic value of end-tidal carbon dioxide during exercise testing in heart failure.
abstract: BACKGROUND
  The 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.
  
  
  OBJECTIVE
  The 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.
  
  
  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 P(ET)CO2 were determined.
  
  
  RESULTS
  Receiver 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.
  
  
  CONCLUSIONS
  These 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.
authors.affiliation: Department of Physical Therapy, Box 980224, Virginia Commonwealth University, Health Sciences Campus, Richmond, Virginia 23298-0224, United States. raarena@vcu.edu
authors.forename: Ross
authors.initials: R
authors.lastname: Arena
authors.forename: Marco
authors.initials: M
authors.lastname: Guazzi
authors.forename: Jonathan
authors.initials: J
authors.lastname: Myers
mesh_terms: D001944:Breath Tests; D002245:Carbon Dioxide / Q000378:metabolism*; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011379:Prognosis; D012044:Regression Analysis; D012680:Sensitivity and Specificity
chemical_list: D002245:Carbon Dioxide