Response of the Oxygen Uptake Efficiency Slope to Exercise Training in Patients with Chronic Heart Failure

BACKGROUND: The oxygen uptake efficiency slope (OUES) is a new exercise parameter that provides prognostic power in patients with CHF. Little is known about the effects of exercise training (ET) on OUES. AIM: To describe the response of OUES to 6 months of ET in CHF patients and compare its evolution to that of other exercise variables. METHODS: 35 patients with CHF (NYHA II-III, age 54+/-9y, LVEF 31+/-10%) performed 3 maximal exercise tests, i.e. at the start, middle and end of a 6 month ET program. OUES, PeakVO(2), ventilatory anaerobic threshold (VAT) and slope VE/VCO(2) were determined. RESULTS: OUES, peakVO(2), VAT, slope VE/VCO(2), peak Watt, 6MWT and NYHA-class improved during the first part of the ET period (p<0.05). Only VAT, peak Watt and 6MWT continued to improve during the second part of the ET period (p<0.05) Improvements in OUES correlated better with improvements in peakVO(2) (r=0.77, p<0.001), than changes in other prognostic variables. DISCUSSION: OUES improves significantly after 6 months of ET. Changes in peakVO(2) correlate best with changes in OUES. OUES is sensitive to ET and can be used to evaluate the progression of exercise capacity in CHF patients.