A meta-analysis of perioperative beta blockade: What is the actual risk reduction?

Background. The use of beta blockers in surgical patients has been suggested to decrease perioperative cardiac events. However, the overall risk reduction, on the basis of solely aggregate data from randomized studies, is unknown. The objective is to evaluate the effect of perioperative beta blockade in non-cardiac surgery,for Protection against mortality or cardiac events. Methods. We performed a formal meta-analysis. The Medline database was searched for articles published from 1966-2004 by using the terms perioperative, beta blocker, surgery, and noncardiac. Inclusion criteria were randomized controlled trials evaluating perioperative beta blockade in noncardiac surgery. Studies were evaluated independently by 2 researchers. Cochrane Collaboration Software (Review Manager 4.2) was used to calculate relative risk (RR), risk difference (RD), and 95 % confidence interval (CI). Six distinct postoperative adverse events were analyzed. Results. Eligible studies included 6 randomized controlled trials evalualing perioperative beta blockade in patients undergoing noncardiac surgery. These studies evaluated a total of 632 patients: 354 received perioperative beta blockade and 278 did not. Results for the 6 postoperative outcomes are shown. Postoperative outcome RR (95% CI) RD (95% CI) Perioperative overall mortality 0.52(0.20, 1.35) -0.04 (- 0.09, 0.01) Perioperative cardiac mortality 0.25(0.07, 0.87) -0.05 (- 0.10, -0.01) Long-term overall mortality 0.33(0.14, 0.74) -0.09 (- 0.16, -0.03) Long-term cardiac mortality 0.16(0.05, 0.53) -0.10 (- 0.15, -0.04) Myocardial infarction 0.14(0.04, 0.47) -0.07 (- 0.11, -0.03) Myocardial ischemia 0.47(0.34, 0.65) -0.18 (- 0.25, -0.10) The 2 largest effects were a decrease in long-term cardiac mortality from 12% to 2% and a decrease in myocardial ischemia from 33 % to 15 %. All outcomes except perioperative overall mortality had improvements (P <.02), which favor the use of perioperative beta blockade. Conclusions. This report highlights for the first time the aggregated risk reduction from all published randomized controlled trials, and shows the Protection of Peroperative beta blockade against both short-term complications and mortality.