Prolonged oxygen uptake kinetics during low-intensity exercise are related to poor prognosis in patients with mild-to-moderate congestive heart failure.
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.
Schalcher
Christoph
C
Division of Cardiology, Department of Internal Medicine, University Hospital, Zurich, Switzerland.
Rickli
Hans
H
Brehm
Manuel
M
Weilenmann
Daniel
D
Oechslin
Erwin
E
Kiowski
Wolfgang
W
Brunner-La Rocca
Hans Peter
HP
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