Metoprolol in Acute myocardial infarction - MIAMI


Early metoprolol for 15-day mortality in acute myocardial infarction.


To evaluate effects of early administration of metoprolol for acute myocardial infarction.

Study Design

Study Design:

Patients Screened: 26,439
Patients Enrolled: 5,778
Mean Follow Up: 1 year
Mean Patient Age: 60
Female: 22.4

Patient Populations:

Electrocardiographic (ECG) signs of AMI and chest pain for ≥ 15 min
Symptom onset within the previous 24 h.


Current treatment with a beta blocker or calcium-channel blocker.
Heart rate less than or equal to 65 beats/min.
Systolic blood pressure less than or equal to 105 mm Hg.
Contraindications to metoprolol therapy.

Primary Endpoints:

Mortality at 15 days

Secondary Endpoints:

Development of AMI
Serum enzyme activity
Electrocardiographic signs of AMI
Late or recurrent AMI
Treatment of chest pain
Adverse events

Drug/Procedures Used:

Metoprolol, 15mg IV, followed by 200mg daily in divided oral doses.

Principal Findings:

Of the 5778 patients included, 2901 were allocated to placebo and 2877 to metoprolol. Definite AMI was confirmed in 4127 patients.

There were 142 deaths in the placebo group (4.9%) and 123 deaths in the metoprolol group (4.3%). This relative difference of 13 per cent had 95% confidence limits of -8 to +33 per cent, which was not statistically significant (P = 0.29).

After the initial 15-day study period, all patients received metoprolol in an open fashion. One-year mortality was 10.6% for patients who were randomized to early metoprolol compared to 10.7% for patients randomized to placebo.


The MIAMI data conflicts with the ISIS-1 data, which suggested a benefit for early beta blocker therapy in acute myocardial infarction. In MIAMI only 15% received treatment within 6 hours, while in ISIS 38% were treated within 4 hours. It is therefore likely that in most patients enrolled in MIAMI the infarcts were completed before intervention was started. Thus, taken together, the study results emphasize the importance of early initiation of beta-blockade therapy.


1. Eur Heart J 1985;6:199-211. Final results
2. J Intern Med 1990;228:125-31. One-year mortality and morbidity
3. J Intern Med 1991;230:233-8. Long-term prognosis

Keywords: Myocardial Infarction, Chest Pain, Electrocardiography, Metoprolol

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