β-blockers in myocardial infarction: An overview
It has been >20 years since the double-blind BHAT (β-Blocker Heart Attack Trial) showed that the β-blocker propranolol reduced the rate of mortality when initiated in the first week following myocardial infarction (MI). Despite an overall 23% reduction in the risk of mortality with β-blockers in long-term trials of acute MI, uncertainty has remained about the benefits of acute aggressive use of β-blockers, including those administered intravenously, compared with more gentle initiation of oral β-blocker in the hours following presentation with ACS. COMMIT/CCS-2 (Clopidogrel and Metoprolol in MI Trial/Second Chinese Cardiac Study) was a landmark study that had important implications for the use of β-blockers in the management of acute MI (AMI). The trial showed that a class of drugs widely thought to be safe, highly effective, and widely recommended can have adverse effects that negate their benefits. Thus, β-blockers should be used in AMI, but generally orally and with caution, especially in patients with signs and/or symptoms of acute heart failure. There is little direct evidence to show that the routine use of β-blockers in the acute phase (first 24-48 h) of non-ST-segment elevation ACS (NSTEACS) has more than an anti-anginal effect. There is a need for further randomized trial evidence of the effects of early β-blocker use in patients with NSTEACS.