Abstract 3954: Exercise Training Increases Oxygen Uptake Efficiency in Heart Failure
Background The oxygen uptake efficiency slope (OUES), measured during a symptom-limited exercise test, is a novel measure of cardiopulmonary function. This parameter is attractive because it is independent of exercise intensity. Hence, actual attainment of maximal workload during a test is not required. Compared to other exercise-test derived variables like VO2peak, OUES has a high prognostic value in chronic heart failure (CHF). Exercise training increases VO2peak in CHF patients. We hypothesized that exercise training also improves OUES.
Methods We randomized 28 NYHA class II-III CHF patients into an exercise training group X (N= 20; 19M/1F; age 62 ± 8 yrs; LVEF 35 ± 6%) and a control group C (N=8; 7M/1F; age 61 ± 10 yrs; LVEF 29 ± 9%). A symptom-limited exercise test was done at baseline and repeated after two weeks (group C) or after completion of a 10-week training program (group X). OUES was computed by a linear least squares regression from the oxygen uptake on the logarithm of the ventilation. The differences between the data of the baseline measurement and the remeasurement of group X and group C were compared by an unpaired t-test.
Results The results are summarized in the Table⇓. Exercise training increased VO2peak by 15% and OUES by 17% (P(XvsC)< 0.05).
Conclusion According to expectation, exercise training increased VO2peak. Our data confirmed the hypothesis that exercise training also increases the prognostic parameter OUES. This finding is of great potential interest. Multiple factors affect the maximal load attained during a symptom-limited maximal exercise test. As a consequence, individual VO2peak values are relatively unreliable. Contrastingly, OUES is a more consistent parameter, as it is load independent. Follow-up studies should demonstrate if OUES improvements induced by exercise training are associated with improved prognosis.