The Effect of beta-blockade on objectively measured physical fitness in patients with abdominal aortic aneurysms - A blinded interventional study

Background: Perioperative beta-blockade is widely used, especially before vascular surgery; however, its impact on exercise performance assessed using cardiopulmonary exercise testing (CPET) in this group is unknown. We hypothesized that betablocker therapy would significantly improve CPET-derived physical fitness in this group. Methods: We recruited patients with abdominal aortic aneurysms (AAA) of <5.5 cm under surveillance. All patients underwent CPET on and off beta-blockers. Patients routinely prescribed beta-blockers underwent a first CPET on medication. Beta-blockers were stopped for one week before a second CPET. Patients not routinely taking beta-blockers underwent the first CPET off treatment, then performed a second CPET after commencement of bisoprolol for at least 48 h. Oxygen uptake (V O₂ ) at estimated lactate threshold (σ^_L) and V O₂ at peakwere primary outcome variables. Alinear mixed-effects modelwas fitted to investigate any difference in adjusted CPET variables on and off beta-blockers. Results: Forty-eight patients completed the study. No difference was observed in V O₂ at σ^_L and V O₂ at peak; however, a significant decrease in V_E=V CO₂ at ^σ_L and peak, an increase in workload at ^σ_L, O₂ pulse and heart rate both at ^σ_L and peak was found with beta-blockers. Patients taking beta-blockers routinely (chronic group) had worse exercise performance (lower V O₂ ). Conclusions: Beta blockade has a significant impact on CPET-derived exercise performance, albeit without changing V O₂ at ^σ_L and V O₂ at peak. This supports performance of preoperative CPET on or off beta-blockers depending on local perioperative practice. Clinical trial registration: NCT 02106286.