Immediate β-blockade in patients with myocardial infarctions: is there evidence of benefit?

STUDY OBJECTIVE: The American Heart Association recommends the initiation of β-blockade to all patients with an ST-segment elevation myocardial infarction (STEMI) without contraindications to β-blocking agents. The present study seeks to systematically review the medical literature to determine the efficacy of treating STEMI patients with a β-blocker within the first 24 hours.

METHODS: We searched databases for articles through MEDLINE with the PubMed interface and from 1966 through May 2009 and EMBASE from 1980 to August 2009 with the Ovid Technologies interface, using a search strategy derived from the following PICO (Patient-Intervention-Comparator-Outcome) clinical question: In patients presenting with STEMI (P), does immediate treatment with β-blockers (I) followed by standardized care beginning on day 2 or 3 compared with placebo or no treatment followed by standardized care on day 2 or 3 (C) reduce the risk of death, reinfarction, or cardiogenic shock (O)? The methodological quality of the studies was assessed.

RESULTS: From more than 2,000 references identified in the search, only a single randomized trial met the inclusion criteria. There were no statistically significant differences in mortality; the relative risk for the combined endpoint (mortality and reinfarction) was 0.67 (95% confidence interval 0.44 to 1.03) at 6 days and 0.74 (95% confidence interval 0.53 to 1.06) at 6 weeks. Outcomes for cardiogenic shock were not reported.

CONCLUSION: Evidence from a single randomized trial failed to demonstrate a reduction in mortality or reinfarction with administration of β-blocker within the first 24 hours after STEMI.