Key result
Bisoprolol therapy for 6 months did not significantly improve oxygen uptake recovery time constants compared to placebo in patients with chronic heart failure (112.6 ± 27 s vs 97.3 ± 31 s).
Why the study?
Does bisoprolol improve postexercise oxygen uptake kinetics and exercise capacity in patients with chronic heart failure?
RCT (n=25)
Does bisoprolol improve postexercise oxygen uptake kinetics and exercise capacity in patients with chronic heart failure?
Absolute Event Rate: 112.6% vs 97.3%
In patients with chronic heart failure, 6 months of bisoprolol therapy reduces resting and maximal heart rates but does not significantly affect exercise capacity or oxygen uptake recovery kinetics.
Bisoprolol does not improve postexercise oxygen uptake kinetics in chronic heart failure; challenges assumptions tying beta-blockade to better exercise recovery.
Background: Beta-blocking agents have recently been demonstrated to improve survival in chronic heart failure (CHF), but a debate exists regarding the influence of beta-blockade on exercise capacity in these patients. The time delay for oxygen uptake to return to baseline after exercise (VO₂ recovery kinetics) has been shown to be related to the severity of CHF, skeletal muscle metabolic abnormalities and prognosis. We performed the present study to determine the effect of beta-blockade on VO₂ recovery kinetics in patients with CHF. Methods: Twenty-five patients with CHF were randomized to 6 months of bisoprolol (n = 10, ejection fraction = 27 ± 6%) or placebo (n = 15, ejection fraction = 25 ± 5%) therapy. Bisoprolol dosage was titrated in accordance with the Cardiac Insufficiency Bisoprolol Study protocol. Before and after the study period, oxygen uptake kinetics in recovery from maximal exercise were calculated and expressed as the slope of a single exponential relation between oxygen uptake and time during the first 3 min of recovery. Results: Resting and maximal heart rates were reduced after bisoprolol therapy, by 17 (p < 0.05) and 14 (p = 0.08) beats/min, respectively. Maximal oxygen uptake was unchanged in the bisoprolol (19.0 ± 4.9 vs. 19.9 ± 4.3 ml/kg/min) and placebo (18.9 ± 3.6 vs. 19.4 ± 3.6 ml/kg/min) groups. The time constants in recovery were reduced by modest and insignificant amounts in both groups (127.2 ± 41 vs. 112.6 ± 27 s for bisoprolol and 119.5 ± 55 vs. 97.3 ± 31 s for placebo). The time constant in recovery was poorly related to peak VO₂ (r = –0.10). Conclusion: In patients with CHF, beta-blockade does not influence exercise capacity or oxygen uptake recovery kinetics. While this study confirms the suppression of sympathetic drive which has been shown to have beneficial effects in CHF, these results suggest that beta-blockade has minimal effects on indices of exercise tolerance, including VO₂recovery time.
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Gianrossi et al. (2001) conducted an RCT in chronic heart failure (n=25). bisoprolol vs. placebo was evaluated on oxygen uptake kinetics in recovery from maximal exercise (time constant). Bisoprolol therapy for 6 months did not significantly improve oxygen uptake recovery time constants compared to placebo in patients with chronic heart failure (112.6 ± 27 s vs 97.3 ± 31 s).
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