title: Contribution of peak respiratory exchange ratio to peak VO2 prognostic reliability in patients with chronic heart failure and severely reduced exercise capacity.
abstract: BACKGROUND
  We evaluated the influence of peak respiratory exchange ratio (pRER), as an index of effort adequacy, on peak VO2 prognostic reliability in patients with chronic heart failure (CHF) and reduced exercise capacity, whose peak VO2 may be underestimated because of poor patient motivation.
  
  
  METHODS
  A cardiopulmonary exercise test was performed in 570 patients with CHF (age 60 +/- 10 years, ejection fraction 26% +/- 7%, New York Heart Association class 2.2 +/- 0.6), 193 of whom had a peak VO2 that was >10 but <or=14 mL/kg/min (reduced exercise capacity) and 80 of whom had a peak VO2 <or=10 mL/kg/min (severely reduced exercise capacity).
  
  
  RESULTS
  Seventy-eight events (72 cardiovascular deaths and 6 status I heart transplantations) occurred during follow-up (19.6 +/- 14 months). The 2-year survival rate was 69% in patients with a peak VO2 <or=10 and 83% in patients with a peak VO2 >10 but <or=14 (P <.0001). However, in the group of patients with a peak VO2 <or=10, patients who had a pRER >or=1.15 had a 2-year survival rate of 52%, and this pRER value (but not >or=1, >or=1.05, or >or=1.10) was the only independent predictor of the composite end point (chi(2) = 4.73, P =.03). Conversely, in the group of patients with a peak VO2 <or=10, patients who had a pRER value <1.15 had a survival rate of 83%, which was comparable with that of the group of patients with a peak VO2 >10 but <or=14.
  
  
  CONCLUSIONS
  Patients with CHF and severely reduced exercise capacity should be encouraged to exercise to an RER as close as possible to 1.15, to ascertain their motivation and ensure their peak VO2 prognostic reliability.
authors.affiliation: Division of Cardiology, Salvatore Maugeri Foundation, IRCCS, Veruno Scientific Institute, Veruno, Italy. amezzani@fsm.it
authors.forename: Alessandro
authors.initials: A
authors.lastname: Mezzani
authors.forename: Ugo
authors.initials: U
authors.lastname: Corrà
authors.forename: Enzo
authors.initials: E
authors.lastname: Bosimini
authors.forename: Andrea
authors.initials: A
authors.lastname: Giordano
authors.forename: Pantaleo
authors.initials: P
authors.lastname: Giannuzzi
mesh_terms: D000704:Analysis of Variance; D002303:Cardiac Output, Low / Q000503:physiopathology; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006333:Heart Failure / Q000401:mortality / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008451:Maximal Voluntary Ventilation / Q000502:physiology; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D011379:Prognosis; D011659:Pulmonary Gas Exchange / Q000502:physiology; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric; D015996:Survival Rate; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology