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

West, M. A.; Parry, M.; Asher, R.; Key, A.; Walker, P.;
Loughney, L.; Pintus, S.; Duffy, N.; Jack, S.; Torella, F..

British Journal of Anaesthesia, June 2015, Vol. 114 Issue: Number 6
p878-878, 1p;

Abstract: <sec><st>Background</st> 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. </sec>
<sec><st>Methods</st> 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 (<f>$${\dot{V}}_{{\mathrm{O}}_{2}}$$</f>) at
estimated lactate threshold (<f>$${\hat{\theta }}_{L}$$</f>) and
<f>$${\dot{V}}_{{\mathrm{O}}_{2}}$$</f> 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. </sec>
<sec><st>Results</st> Forty-eight patients completed the study. No
difference was observed in <f>$${\dot{V}}_{{\mathrm{O}}_{2}}$$</f> at
<f>$${\hat{\theta }}_{L}$$</f> and
<f>$${\dot{V}}_{{\mathrm{O}}_{2}}$$</f> at peak; however, a significant
decrease in <f>$${\dot{V}}_{E}/{\dot{V}}_{{\mathrm{CO}}_{2}}$$</f> at
<f>$${\hat{\theta }}_{L}$$</f> and peak, an increase in workload at
<f>$${\hat{\theta }}_{L}$$</f>, O<inf>2</inf> pulse and heart rate both
at <f>$${\hat{\theta }}_{L}$$</f> and peak was found with
beta-blockers. Patients taking beta-blockers routinely (chronic group)
had worse exercise performance (lower
<f>$${\dot{V}}_{{\mathrm{O}}_{2}}$$</f>). </sec>

Conclusions</st>Beta blockade has a significant impact on
CPET-derived exercise performance, albeit without changing
<f>$${\dot{V}}_{{\mathrm{O}}_{2}}$$</f> at <f>$${\hat{\theta
}}_{L}$$</f> and <f>$${\dot{V}}_{{\mathrm{O}}_{2}}$$</f> at peak. This
supports performance of preoperative CPET on or off beta-blockers
depending on local perioperative practice.