The quality of evidence is downgraded by study limitations (unclear allocation concealment and blinding).
A Cochrane review[Abstract]1 included 63 studies with a total of 85 550 subjects (mean age 57.4 years) with suspected or diagnosed myocardial infarction (MI). Fifty-six studies commenced beta-blockers during the acute phase of acute MI and 7 studies during the subacute phase.
At the time point less than 3 months follow-up: Beta-blockers reduced risk of reinfarction (RR 0.82, 98% CI 0.73 to 0.91; 18 studies, n=67 562) compared to placebo or no intervention; absolute risk reduction (ARR) 0.5%, NNTB 196. They had little or no effect on all-cause mortality (RR 0.94, 97.5% CI 0.90 to 1.00; 46 studies, n=80 452; ARR 0.4%) and cardiovascular mortality (RR 0.99, 95% CI 0.91 to 1.08; 1 study, n=45 852, ARR 0.4%). It was uncertain whether beta-blockers had a beneficial or harmful effect on angina (RR 0.70, 98% CI 0.25 to 1.84; 3 studies, n=98).
At maximum follow-up beyond 3 months: Beta-blockers reduced risk of all-cause mortality (RR 0.93, 97.5% CI 0.86 to 0.99; 21 studies, n=25 210; ARR 1.1%, NNTB 91), and cardiovascular mortality (RR 0.90, 98% CI 0.83 to 0.98; 14 studies, n=22 457; ARR 1.2%, NNTB 83) compared to placebo or no intervention. There was no statistically significant difference in major adverse cardiovascular events (RR 0.81, 97.5% CI 0.40 to 1.66; 4 studies, n=475), reinfarction (RR 0.89, 98% CI 0.75 to 1.08; 14 studies, n=6 825), and angina (RR 0.64, 98% CI 0.18 to 2.0; 2 studies, n=844).
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Primary/Secondary Keywords