BACKGROUND: Debate exists regarding the efficacy of â-blockers in myocardial infarction and their required duration of usage in contemporary practice. METHODS: We conducted a MEDLINE/EMBASE/CENTRAL search for randomized trials evaluating â-blockers in myocardial infarction enrolling at least 100 patients. The primary outcome was all-cause mortality. Analysis was performed stratifying trials into reperfusion era (>50% undergoing reperfusion and/or receiving aspirin/statin) or pre-reperfusion era trials. RESULTS: Sixty trials with 102003 patients satisfied the inclusion criteria. In the acute myocardial infarction trials, a significant interaction (Pinteraction=0.02) was noted such that â-blockers reduced mortality in the pre-reperfusion[Incident Rate Ratio (IRR)=0.86, 95% CI 0.79-0.94] but not in the reperfusion era(IRR=0.98, 95% CI 0.92-1.05). In the pre-reperfusion era, â-blockers reduced cardiovascular mortality(IRR=0.87, 95% CI 0.78-0.98), myocardial infarction(IRR=0.78, 95% CI 0.62-0.97), and angina(IRR=0.88, 95% CI 0.82-0.95) with no difference for other outcomes. In the reperfusion era, â-blockers reduced myocardial infarction(IRR=0.72, 95% CI 0.62-0.83) (NNTB=209) and angina(IRR=0.80, 95% CI 0.65-0.98) (NNTB=26) at the expense of increase in heart failure(IRR=1.10, 95% CI 1.05-1.16) (NNTH=79), cardiogenic shock(IRR=1.29, 95% CI 1.18-1.41) (NNTH=90) and drug discontinuation(IRR=1.64, 95% CI 1.55-1.73) with no benefit for other outcomes. Benefits for recurrent myocardial infarction and angina in the reperfusion era appeared to be short-term (30-days). CONCLUSIONS: In contemporary practice of treatment of myocardial infarction, â-blockers have no mortality benefit but reduce recurrent myocardial infarction and angina (short-term) at the expense of increase in heart failure, cardiogenic shock and drug discontinuation. The guidelines should reconsider the strength of recommendations for â-blockers post myocardial infarction.
American Journal of Medicine, 2014, Vol 127, Issue 10, p. 939-953