Oxygen Uptake Efficiency Slope, Aerobic Fitness, and (V) over dotE-(V) over dotCO2 Slope in Heart Failure

ANTOINE-JONVILLE, S., A. PICHON, A. VAZIR, M. I. POLKEY, and M. J. DAYER. Oxygen Uptake Efficiency Slope, Aerobic Fitness, and (V) over dot(E)-(V) over dotCO(2) Slope in Heart Failure. Med. Sci. Sports Exerc., Vol. 44, No. 3, pp. 428-434, 2012. 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 ((V) over dotO(2peak)), ventilatory anaerobic threshold (VAT), OUES using all data (OUES100) or only the data up to the point where the RER was 1 (OUESRER1), and (V) over dot(E)-(V) over dotCO(2) slope were determined. Results: OUES100, OUESRER1, and VAT were significantly correlated with measured (V) over dotO(2peak) (r = 0.883, r = 0.814, and r = 0.877, respectively). The Bland-Altman limits of agreement between measured (V) over dotO(2peak) and the values predicted by calculation from OUES100, OUESRER1, and VAT were +/- 0.46, +/- 0.57, and +/- 0.48 L.min(-1), respectively. The variation in OUESRER1 between the first and second tests in the 19 patients was significantly related to the variation in (V) over dotO(2peak) but not to the variation in the (V) over dot(E)-(V) over dotCO(2) slope. Conclusions: To predict (V) over dotO(2peak) in patients with chronic heart failure, the index OUESRER1 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.