Exercise endpoints in patients with chronic heart failure

Background: Peak oxygen consumption ((V) over dot(O2)) is a powerful predic tor of outcome in patients with chronic heart failure. This is not a test t hat is readily clinically available, We therefore sought to establish a met hod of assessing peak (V) over dot(O2) from non-invasively acquired data. M ethods: We analysed the results from incremental treadmill exercise tests i n 60 patients [aged 59.0 (S.D. 12.4) years] with chronic heart failure or l eft ventricular dysfunction [left ventricular ejection fraction (29.6 (15.2 )%)] and 52 control subjects [aged 36.7 (12.3)]. Metabolic gas exchange dur ing exercise was measured with a respiratory mass spectrometer. Heart rate and blood pressure were measured. Results: Peak (V) over dot(O2) was lower in patients than controls [19.9 (7.7) ml/kg/min vs. 38.3 (9.0), P<0.001]. E xercise time (r=0.84, P<0.001), heart rate at peak exercise (r=0.63, P<0.00 01), change in heart rate (r=0.72, P<0.0001), rate pressure product at peak exercise (r=0.64, P<0.0001) and change in systolic blood pressure (r=0.31, P=0.002) all correlated with peak (V) over dot(O2). In a stepwise regressi on model, exercise time was the most powerful predictor of peak (V) over do t(O2) (r(2)=0.79). The only additional independent Variable was change in h eart rate from rest to peak exercise, which increased r(2) to 0.80. In a su rvival analysis, measured peak (V) over dot(O2) and the peak (V) over dot(O 2) estimated from exercise time and change in heart rate had similar predic tive power. Conclusions: In this preliminary study, peak (V) over dot(O2) c an be estimated from non-invasively acquired parameters. Estimated peak (V) over dot(O2) and measured peak (V) over dot(O2) have similar predictive po wer for outcome. Further work is necessary to see if estimated peak (V) ove r dot(O2) is widely applicable in a clinical setting. (C) 2000 Elsevier Sci ence Ireland Ltd. All rights reserved.