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

Abstract

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 VE=V CO2 at ^σL and peak, an increase in workload at ^σL, O2 pulse and heart rate both at ^σL 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 ^σL 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.