Cardioselective β blockers are considered to have little impact on lung function at rest in patients with chronic obstructive pulmonary disease (COPD). However, their effects on dynamic hyperinflation, an important mechanism contributing to symptoms and exercise tolerance in patients with COPD, have not been evaluated. Twenty-seven patients with moderate to severe COPD (forced expiratory volume in 1 second 52 ± 13% predicted) completed pulmonary function tests, echocardiography, maximal exercise tests, and cycle endurance tests at baseline. Inspiratory capacity was measured at 2-minute intervals during the cycle endurance test to quantify dynamic hyperinflation. Pulmonary function and cycle endurance testing were repeated after 14 days of bisoprolol 10 mg/day and 14 days of placebo in a randomized, double-blind, placebo-controlled, crossover trial. The extent of dynamic hyperinflation at peak isotime exercise with bisoprolol and placebo was compared. Peak isotime was defined as the latest time point that was reached during the 2 cycle endurance tests. Changes in inspiratory capacity from rest to peak isotime were different with bisoprolol compared to placebo (-0.50 ± 0.35 vs -0.41 ± 0.33 L, p = 0.01). Exercise duration tended to be lower with bisoprolol compared to placebo (305 ± 125 vs 353 ± 172 seconds, p = 0.11). The magnitude of change in exercise duration between the bisoprolol and placebo conditions was correlated with the magnitude of change in inspiratory capacity (r = 0.57, p <0.01). In conclusion, bisoprolol was associated with modest worsening dynamic hyperinflation, whereas exercise duration remained unchanged in patients with moderate to severe COPD. The magnitude of these effects was small and should not contraindicate the use of bisoprolol in patients with COPD.
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