The Controversy of Peri-operative ß-blockade: What Should I Do?

Beta-adrenergic blockers for perioperative cardiac risk reduction in people undergoing vascular surgery

BACKGROUND

People undergoing major vascular surgery have an increased risk of postoperative cardiac complications. Beta-adrenergic blockers represent an important and established pharmacological intervention in the prevention of cardiac complications in people with coronary artery disease. It has been proposed that this class of drugs may reduce the risk of perioperative cardiac complications in people undergoing major non-cardiac vascular surgery.

OBJECTIVES

To review the efficacy and safety of perioperative beta-adrenergic blockade in reducing cardiac or all-cause mortality, myocardial infarction, and other cardiovascular safety outcomes in people undergoing major non-cardiac vascular surgery.

SEARCH METHODS

The Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (January 2014) and the Cochrane Central Register of Controlled Trials (CENTRAL; 2013, Issue 12). We searched trials databases and checked reference lists of relevant articles.

SELECTION CRITERIA

We included prospective, randomised controlled trials of perioperative beta-adrenergic blockade of people over 18 years of age undergoing non-cardiac vascular surgery.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection and data extraction. We resolved disagreements through discussion. We performed meta-analysis using a fixed-effect model with odds ratios (ORs) and 95% confidence intervals (CIs).

MAIN RESULTS

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).

AUTHORS' CONCLUSIONS

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.