Abstract: We included two studies in this review, both of which were double-blind, randomised controlled trials comparing perioperative beta-adrenergic blockade (metoprolol) with placebo, on cardiovascular outcomes in people undergoing major non-cardiac vascular surgery. We included 599 participants receiving beta-adrenergic blockers (301 participants) or placebo (298 participants). The overall quality of studies was good. However, one study did not report random sequence generation or allocation concealment techniques, indicating possible selection bias, and the other study did not report outcome assessor blinding and was possibly underpowered. It should be noted that several of the outcomes were only reported in a single study and neither of the studies reported on vascular patency/graft occlusion, which reduces the quality of evidence to moderate. There was no evidence that perioperative beta-adrenergic blockade reduced all-cause mortality (OR 0.62, 95% CI 0.03 to 15.02), cardiovascular mortality (OR 0.34, 95% CI 0.01 to 8.32), non-fatal myocardial infarction (OR 0.83, 95% CI 0.46 to 1.49; P value = 0.53), arrhythmia (OR 0.70, 95% CI 0.26 to 1.88), heart failure (OR 1.71, 95% CI 0.40 to 7.23), stroke (OR 2.67, 95% CI 0.11 to 67.08), composite cardiovascular events (OR 0.87, 95% CI 0.55 to 1.39; P value = 0.57) or re-hospitalisation at 30 days (OR 0.86, 95% CI 0.48 to 1.52). However, there was strong evidence that beta-adrenergic blockers increased the odds of intra-operative bradycardia (OR 4.97, 95% CI 3.22 to 7.65; P value < 0.00001) and intra-operative hypotension (OR 1.84, 95% CI 1.31 to 2.59; P value = 0.0005). This meta-analysis currently offers no clear evidence that perioperative beta-adrenergic blockade reduces postoperative cardiac morbidity and mortality in people undergoing major non-cardiac vascular surgery. There is evidence that intra-operative bradycardia and hypotension are more likely in people taking perioperative beta-adrenergic blockers, which should be weighed with any benefit.

Plain-language summary: We identified two studies that evaluated beta-blockers giving during surgery (perioperatively) in people undergoing major non-cardiac vascular surgery, with follow-up data on cardiovascular outcomes. A total of 599 participants were randomised to receive beta-blockers (301 participants) or placebo (298 participants). Both studies were double-blind (neither participants nor surgeon were aware of the treatment), randomised controlled trials evaluating the beta-blocker, metoprolol. The results of the analysis offered no clear evidence that perioperative beta-blockers reduced death from any cause (all-cause mortality), cardiovascular death, non-fatal heart attack, irregular heartbeat (arrhythmia), heart failure, stroke, combined cardiovascular events or re-hospitalisation at 30 days. There was evidence to support that beta-blockers increased the risk of intra-operative low heart rate (bradycardia) and low blood pressure (hypotension). These complications should be weighed with any benefit when considering the use of beta-blockers in this population. Study quality was good for both trials. One trial did not adequately describe their randomisation techniques and the other trial did not report whether the outcome assessors were blinded to the treatment group, and was possibly underpowered. With only two studies included, several of the outcomes only had data from a single study, and neither of the studies reported on blockage or obstruction of blood vessels (vascular patency/graft occlusion), reducing the quality of evidence to moderate.