Level 1: Likely reliable evidence
A recent systematic review analyzed 33 randomized trials comparing oral and IV beta blockers with various control conditions (other drugs, placebo, or no intervention) in 12,306 patients having noncardiac surgery (Lancet. 2008;372:1962-1976). In meta-analyses limited to high-quality trials, patients taking beta blockers had lower rates of nonfatal MI (3.1% vs. 4.4%, P=.001, NNT 80) and myocardial ischemia (4.1% vs. 7.2%, P<.0001, NNT 23) compared with patients randomized to control conditions. However, beta blockers were associated with increased rates of nonfatal stroke (0.68% vs. 0.32%, P=0.004, NNH 275). All-cause mortality was also increased for beta blockers (2.8% vs. 2.3%, P=.044, NNH 164), as were rates of perioperative bradycardia and hypotension that required treatment. There were no significant differences in either cardiovascular mortality (1.5% vs. 1.4%) or heart failure (2.9% vs. 2.5%).