Early intravenous then oral metoprolol in 45 852 patients with acute myocardial infarction: randomised placebo-controlled trial
Topic: Beta-blockers in acute coronary syndrome
Aim:
- Determine benefits of early beta-blocker therapy in the emergency treatment of myocardial infarction (MI) when add to standard interventions (eg, aspirin and fibrinolytic therapy).
Design:
- Prospective, multi-centered, double blinded, randomized clinical trial
Treatment:
- Metoprolol (up to 15 mg intravenous then 200 mg oral daily for up to 4 weeks)
Control:
- Placebo
Cohort:
- 45,852 patients
Inclusion criteria:
- ST elevation, LBBB, or ST depression within 24 hours of the onset of symptoms of suspected acute MI
Exclusion criteria:
- Not considered to have clear indications for, or contraindications to, an of the study treatments.
- Scheduled for primary PCI
Follow up:
- 4 weeks
Primary endpoint:
- The composite of death, reinfarction, or cardiac arrest (including ventricular fibrillation); and death from any cause during the scheduled treatment period.
Secondary endpoint:
- Reinfarction, ventricular fibrillation, other cardiac arrest, cardiogenic shock, and related conditions.
Main results:
- Mean age 61, 28% were women.
- Neither of the co-primary outcomes was significantly reduced by allocation to metoprolol.
- Death, reinfarction, or cardiac arrest occurred in 2166 (9.4%) in the metoprolol group vs 2261 (9.9%) in the placebo group (OR 0.96, CI 0.90-1.01; p=0.1).
- For death alone, there were 1774 (7.7%) deaths in the metoprolol group versus 1797 (7.8%) in the placebo group (OR 0.99, CI 0.92-1.05; p=0.69).
- Treatment with metoprolol, compared to placebo, was associated with less reinfarction (464 [2.0%] vs 568 [2.5%]; OR 0.82, 0.72-0.92; p=0.001) and ventricular fibrillation (581 [2.5%] vs 698 [3.0%]; OR 0.83, 0.75-0.93; p=0.001).
- Patient treated with metoprolol had significantly greater incidence of cardiogenic shock (1141 [5.0%] vs 885 [3.9%]; OR 1.30, 1.19-1.41; p<0.00001). This occurred mainly during days 0-1.
TAKE AWAY: Early use of beta blockers in acute MI in those treated with standard therapy (thrombolytics and aspirin) reduced rates of re-infarction and ventricular fibrillation, at the expense of significantly increase rates of cardiogenic shock.
