PURPOSE: The oxygen uptake efficiency slope (OUES) is a promising submaximal index of exercise capacity, but its relationships to other indices characterizing physical fitness and ventilatory efficiency have not been widely investigated in heart failure. METHODS: Sixty-three male patients with stable chronic heart failure performed a symptom-limited maximal exercise test on a cycle ergometer. Nineteen of them performed two exercise tests, 6 months apart. The peak oxygen uptake (VO2peak), ventilatory anaerobic threshold (VAT), OUES using all data (OUES(100)) or only the data up to the point where the RER was 1 (OUE(SRER1)), and V(E)-VCO2 slope were determined. RESULTS: OUES(100), OUE(SRER1), and VAT were significantly correlated with measured VO2peak (r = 0.883, r = 0.814, and r = 0.877, respectively). The Bland-Altman limits of agreement between measured VO2peak and the values predicted by calculation from OUES(100), OUE(SRER1), and VAT were ±0.46, ±0.57, and ±0.48 L·min(-1), respectively. The variation in OUE(SRER1) between the first and second tests in the 19 patients was significantly related to the variation in VO2peak but not to the variation in the V(E)-VCO2 slope. CONCLUSIONS: To predict VO2peak in patients with chronic heart failure, the index OUE(SRER1) is not better than the VAT. This, however, does not question the theoretical interest of its calculation because it may provide additional information on the oxygen uptake limitation steps.
PURPOSE: The oxygen uptake efficiency slope (OUES) is a promising submaximal index of exercise capacity, but its relationships to other indices characterizing physical fitness and ventilatory efficiency have not been widely investigated in heart failure. METHODS: Sixty-three male patients with stable chronic heart failure performed a symptom-limited maximal exercise test on a cycle ergometer. Nineteen of them performed two exercise tests, 6 months apart. The peak oxygen uptake (VO2peak), ventilatory anaerobic threshold (VAT), OUES using all data (OUES(100)) or only the data up to the point where the RER was 1 (OUE(SRER1)), and V(E)-VCO2 slope were determined. RESULTS: OUES(100), OUE(SRER1), and VAT were significantly correlated with measured VO2peak (r = 0.883, r = 0.814, and r = 0.877, respectively). The Bland-Altman limits of agreement between measured VO2peak and the values predicted by calculation from OUES(100), OUE(SRER1), and VAT were ±0.46, ±0.57, and ±0.48 L·min(-1), respectively. The variation in OUE(SRER1) between the first and second tests in the 19 patients was significantly related to the variation in VO2peak but not to the variation in the V(E)-VCO2 slope. CONCLUSIONS: To predict VO2peak in patients with chronic heart failure, the index OUE(SRER1) is not better than the VAT. This, however, does not question the theoretical interest of its calculation because it may provide additional information on the oxygen uptake limitation steps.