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Abstract
Trials of beta blockers in patients undergoing non-cardiac surgery have reported conflicting
results. This randomised controlled trial, done in 190 hospitals in 23 countries,
was designed to investigate the effects of perioperative beta blockers.
We randomly assigned 8351 patients with, or at risk of, atherosclerotic disease who
were undergoing non-cardiac surgery to receive extended-release metoprolol succinate
(n=4174) or placebo (n=4177), by a computerised randomisation phone service. Study
treatment was started 2-4 h before surgery and continued for 30 days. Patients, health-care
providers, data collectors, and outcome adjudicators were masked to treatment allocation.
The primary endpoint was a composite of cardiovascular death, non-fatal myocardial
infarction, and non-fatal cardiac arrest. Analyses were by intention to treat. This
trial is registered with ClinicalTrials.gov, number NCT00182039.
All 8351 patients were included in analyses; 8331 (99.8%) patients completed the 30-day
follow-up. Fewer patients in the metoprolol group than in the placebo group reached
the primary endpoint (244 [5.8%] patients in the metoprolol group vs 290 [6.9%] in
the placebo group; hazard ratio 0.84, 95% CI 0.70-0.99; p=0.0399). Fewer patients
in the metoprolol group than in the placebo group had a myocardial infarction (176
[4.2%] vs 239 [5.7%] patients; 0.73, 0.60-0.89; p=0.0017). However, there were more
deaths in the metoprolol group than in the placebo group (129 [3.1%] vs 97 [2.3%]
patients; 1.33, 1.03-1.74; p=0.0317). More patients in the metoprolol group than in
the placebo group had a stroke (41 [1.0%] vs 19 [0.5%] patients; 2.17, 1.26-3.74;
p=0.0053).
Our results highlight the risk in assuming a perioperative beta-blocker regimen has
benefit without substantial harm, and the importance and need for large randomised
trials in the perioperative setting. Patients are unlikely to accept the risks associated
with perioperative extended-release metoprolol.