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

West MA, Parry M, Asher R, Key A, Walker P, Loughney L, et al.

Br J Anaesth. Feb24; 2015.

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 beta-blocker 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 ([Formula: see text]) at estimated lactate threshold ([Formula: see text]) and [Formula: see text] at peak were primary outcome variables. A linear mixed-effects model was 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 [Formula: see text] at [Formula: see text] and [Formula: see text] at peak; however, a significant decrease in [Formula: see text] at [Formula: see text] and peak, an increase in workload at [Formula: see text], O2 pulse and heart rate both at [Formula: see text] and peak was found with beta-blockers. Patients taking beta-blockers routinely (chronic group) had worse exercise performance (lower [Formula: see text]).
CONCLUSIONS: Beta blockade has a significant impact on CPET-derived exercise performance, albeit without changing [Formula: see text] at [Formula: see text] and [Formula: see text] at peak. This supports performance of preoperative CPET on or off beta-blockers depending on local perioperative practice. CLINICAL TRIAL REGISTRATION: NCT 02106286.