Background: Several β-blockers, with different pharmacological characteristics, are available for heart failure (HF) treatment. We compared Carvedilol (β1-β2-α-blocker), Bisoprolol (β1-blocker), and Nebivolol (β1-blocker, NO-releasing activity).
Methods: Sixty-one moderate HF patients completed a cross-over randomized trial, receiving, for 2 months each, Carvedilol, Nebivolol, Bisoprolol (25.6 ± 12.6, 5.0 ± 2.4 and 5.0 ± 2.4 mg daily, respectively). At the end of each period, patients underwent: clinical evaluation, laboratory testing, echocardiography, spirometry (including total DLCO and membrane diffusion), O2/CO2 chemoreceptor sensitivity, constant workload, in normoxia and hypoxia (FiO2=16%), and maximal cardiopulmonary exercise test.
Results: No significant differences were observed for clinical evaluation (NYHA classification, Minnesota questionnaire), laboratory findings (including kidney function and BNP), echocardiography, and lung mechanics. DLCO was lower on Carvedilol (18.3 ± 4.8*mL/min/mmHg) compared to Nebivolol (19.9 ± 5.1) and Bisoprolol (20.0 ± 5.0) due to membrane diffusion 20% reduction (*=p<0.0001). Constant workload exercise showed in hypoxia a faster VO2 kinetic and a lower ventilation with Carvedilol. Peripheral and central sensitivity to CO2 was lower in Carvedilol while response to hypoxia was higher in Bisoprolol. Ventilation efficiency (VE/VCO2 slope) was 26.9 ± 4.1* (Carvedilol), 28.8 ± 4.0 (Nebivolol), and 29.0 ± 4.4 (Bisoprolol). Peak VO2 was 15.8 ± 3.6*mL/kg/min (Carvedilol), 16.9 ± 4.1 (Nebivolol), and 16.9 ± 3.6 (Bisoprolol).
Conclusions: β-Blockers differently affect several cardiopulmonary functions. Lung diffusion and exercise performance, the former likely due to lower interference with β2-mediated alveolar fluid clearance, were higher in Nebivolol and Bisoprolol. On the other hand, Carvedilol allowed a better ventilation efficiency during exercise, likely via a different chemoreceptor modulation. Results from this study represent the basis for identifying the best match between a specific β-blocker and a specific HF patient.
Keywords: Chemoreflex; Hypoxia; Ventilation efficiency; β-Blockers.
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