title: Defining the optimal prognostic window for cardiopulmonary exercise testing in patients with heart failure.
abstract: BACKGROUND
  Ventilatory efficiency (VE/VCO(2) slope) and peak oxygen consumption (VO) provide robust prognostic information in patients with heart failure undergoing cardiopulmonary exercise testing (CPX). The purpose of this study is to assess the change in prognostic characteristics of CPX at different time intervals.
  
  
  RESULTS
  Seven hundred ninety-one subjects (74% male, mean age: 60.7+/-12.9 years, ejection fraction: 34.6+/-15.0%, ischemic etiology: 51%) underwent CPX and were tracked for major cardiac events over a 4-year period. All event-free subjects were tracked for at least 3 years. Mean VE/VCO(2) slope and peak VO(2) were 35.0+/-10.0 and 16.0+/-6.4 mL O(2) . kg(-1) . min(-1), respectively. There were a total of 263 major cardiac events (199 deaths, 45 transplants, and 19 left ventricular assist device implantations). Both continuous and dichotomous expressions of the VE/VCO(2) slope and peak VO(2) were prognostically significant up to 18 months post-CPX. Continuous and dichotomous expressions of the VE/VCO(2) slope remained prognostically significant up to 36 months post-CPX, whereas peak VO(2) was not predictive during the third and fourth year of follow-up. In a multivariate analysis, the VE/VCO(2) slope was consistently the superior prognostic marker, whereas peak VO(2) added predictive value and was retained in the regression up to 18 months post-CPX.
  
  
  CONCLUSIONS
  These results indicate that commonly assessed CPX variables retain prognostic value for at least 2 years. The VE/VCO(2) slope is the superior predictor of adverse events throughout follow-up, although peak VO(2) provides additive prognostic information during the first 2 years of follow-up.
authors.affiliation: Department of Physical Therapy, Virginia Commonwealth University, Richmond, VA 23298, USA. raarena@vcu.edu
authors.forename: Ross
authors.initials: R
authors.lastname: Arena
authors.forename: Jonathan
authors.initials: J
authors.lastname: Myers
authors.forename: Joshua
authors.initials: J
authors.lastname: Abella
authors.forename: Sherry
authors.initials: S
authors.lastname: Pinkstaff
authors.forename: Peter
authors.initials: P
authors.lastname: Brubaker
authors.forename: Dalane
authors.initials: D
authors.lastname: Kitzman
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Peberdy
authors.forename: Daniel
authors.initials: D
authors.lastname: Bensimhon
authors.forename: Paul
authors.initials: P
authors.lastname: Chase
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Forman
authors.forename: Marco
authors.initials: M
authors.lastname: Guazzi
mesh_terms: D000328:Adult; D000368:Aged; D002245:Carbon Dioxide / Q000378:metabolism; D015331:Cohort Studies; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000401:mortality / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D011237:Predictive Value of Tests; D011379:Prognosis; D012123:Pulmonary Ventilation / Q000502:physiology*; D016019:Survival Analysis; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide