title: Prolonged oxygen uptake kinetics during low-intensity exercise are related to poor prognosis in patients with mild-to-moderate congestive heart failure.
abstract: OBJECTIVE
  To investigate the prognostic value of oxygen uptake (O(2)) kinetics during low-intensity exercise in patients with congestive heart failure.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Tertiary care center.
  
  
  METHODS
  One hundred forty-six consecutive patients (128 men) with chronic heart failure, followed up for a mean (+/- SD) duration of 25 +/- 15 months.
  
  
  METHODS
  A treadmill exercise test was performed with "breath by breath" gas-exchange monitoring. VO(2) kinetics were defined as the VO(2) deficit (ie, Delta VO(2) x time[rest to steady state] - Sigma VO(2)[rest to steady state]) and mean response time (MRT) [ie, VO(2) deficit/Delta VO(2)]. Cardiac death, urgent cardiac transplantation, and hospitalization due to worsening heart failure were considered as the end points.
  
  
  RESULTS
  Thirty patients (21%) died, 11 patients (8%) underwent urgent transplantation, and 32 patients (22%) were hospitalized. In univariate analysis, MRT was the most powerful predictor of survival, survival free of urgent transplantation, and survival free of hospitalization (hazard ratios [HRs] per 10 s, 1.65, 1.72, and 1.61, respectively; all p < 0.0001). The predictive value of MRT exceeded that of peak VO(2) (HR per mL/kg/min, 0.90; p = 0.02, 0.91; p = 0.007, and 0.95; p = 0.08, respectively). In multivariate analysis, MRT (HR per 10 s, 1.73; p = 0.0002), resting systolic BP (HR per 10 mm Hg, 0.65; p = 0.003), and the slope of the ventilatory response to exercise (HR per 10 U, 1.68; p = 0.02) were independent predictors of survival.
  
  
  CONCLUSIONS
  Our results suggest that VO(2) kinetics are strongly related to outcome in heart failure patients. Since it has several additional advantages over peak exercise testing (eg, less time-consuming, less demanding for the patients, less dependent on motivation, and applicable in patients with limitations other than cardiopulmonary disease), it has the potential to become a prognostic test for the assessment of heart failure patients.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, University Hospital, Zurich, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Schalcher
authors.forename: Hans
authors.initials: H
authors.lastname: Rickli
authors.forename: Manuel
authors.initials: M
authors.lastname: Brehm
authors.forename: Daniel
authors.initials: D
authors.lastname: Weilenmann
authors.forename: Erwin
authors.initials: E
authors.lastname: Oechslin
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kiowski
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Brunner-La Rocca
mesh_terms: D019540:Area Under Curve; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000145:classification / Q000378:metabolism / Q000401:mortality; D006439:Hemodynamics; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D011379:Prognosis; D011446:Prospective Studies; D011930:Reaction Time; D012720:Severity of Illness Index; D016019:Survival Analysis