Perioperative beta-blockade -the evidence at last!

A/Prof Kate Leslie

Department of Anaesthesia and Pain Management, Royal Melbourne Hospital,Melbourne,Australia

Perioperative cardiac events, such as myocardial infarction, cardiac arrest and cardiac death, represent a great burden on health care resources in developed nations. Perioperative beta-blockade has been the subject of many randomized trials, several systematic reviews (1-3) and an influential clinical practice guideline (4).The review of Devereaux et al. (3) included 22 trials with 2,437 patients. Perioperative beta-blockers did not affect any individual outcome and had a marginal statistically significant beneficial effect on cardiovascular mortality, non-fatal myocardial infarction and non-fatal cardiac arrest combined, RR 0.44 (95% CI: 0.20 – 0.97), and the authors argued that the current evidence was inconclusive (3).The relative risks for bradycardia (2.27 [95% CI: 1.53 – 3.36]) and hypotension (1.27 [95% CI: 1.04 – 1.56]) needing treatment reached statistical significance.The subsequently-completed DIPOM study of beta-blockade in diabetic patients having noncardiac surgery, which had a negative result, was not included (5).

A randomized trial in 8,351 at-risk patients having noncardiac surgery (the POISE study) has just been completed and the results were presented at the American Heart Association meeting in Orlando Florida in November 2007. Patients were randomised to metoprolol or placebo for 30 days.The primary endpoint was cardiac death, non•fatal MI and non-fatal cardiac arrest.The risk of the primary outcome was significantly lower in the metoprolol group (6.9% vs. 5.8%; p = 0.04).This was mainly due to a decreased risk of MI in the metoprolol patients (5.1% vs. 3.6%; p = 0.0007). However, there was an increased risk of stroke (1% vs. 0.5%; p = 0.005) and death (3.1% vs. 2.3%; p = 0.03) in metoprolol-treated patients, possibly due to a higher rate of significant hypotension (15% vs. 10%; p <0.0001).The advantages and disadvantages of perioperative beta-blockers need to be considered carefully before initiating new beta-blocker treatment.

References

1. Auerbach A, Goldman L. Beta-blockers and reduction of cardiac events in non-cardiac surgery. JAMA 2002;287:1435-44.
2. Stevens R, Burri H,Tramer M. Pharmacologic myocardial protection in patients undergoing noncardiac surgery: a quantitative systematic review.Anesth Analg 2003;97:623-33.
3. Devereaux P, BeattieW, Choi P et al. How strong is the evidence for the use of perioperative beta-blockers in non-cardiac surgery? Systematic review and meta-analysis of randomised controlled trials. BMJ 2005;331:313-21.
4. Eagle K, Berger P, Calkins H et al.ACC/AHA guideline update for perioperative cardiovascular evaluation for noncardiac surgery- executive summary a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation 2002;105:1257-67.
5. Juul A. Randomized blinded trial on perioperative metoprolol versus placebo for diabetic patients undergoing noncardiac surgery. Presented at Late-Breaking Clinical Trials I,American Heart Association Scientific Sessions, New Orleans, USA, November 7-10 (abstract), 2004.
6. Investigators TPT. Rationale, design, and organization of the PeriOperative ISchemic Evaluation (POISE) Trial:A randomized controlled trial of metoprolol versus placebo in patients undergoing noncardiac surgery.Am J Heart 2006;152:223-30.