Myocardial infarction: early thrombolysis saves more lives.

Clinical bottom line (level 1a)

  1. Patients with a suspected myocardial infarction who receive thrombolysis within 1 hour are less likely to die (NNT = 15 at 35 days) .
  2. Patients receive benefit up to 12 hours after symptom onset, but the reduction in mortality is less as time from symptom onset increases.
Boersma et al: Lancet 1996; 348: 771-775
Expires February 2003

The study

Systematic review of all randomised controlled trials of
  • Patients: suspected myocardial infarction
  • Intervention: thrombolytic therapy compared with placebo or control
  • Outcome: death within 35 days


Articles found in ?all languages using MEDline, 1983 to 1993 (search terms: ? )

Selection criteria: not given
Appraisal criteria: not given
Articles excluded if:

  • less than 100 patients


22 studies found involving 50246 patients. 11 studies used in the NNT analysis.

The evidence

time from symptom-onset to thrombolysis
Outcome Time to outcome ARR
(95% CI)		NNT
(95% CI)
one hour 35 days 6.5%
(3.8% to 9.3%)		 15
(11 to 26)
2 to 3 hours 35 days 3.7%
(2.0% to 5.5%)		 27
(18 to 50)
3 to 6 hours 35 days 2.9%
(1.9% to 4.0%)		 38
(27 to 51)
6 to 12 hours 35 days 1.8%
(0.7% to 2.9%)		 56
(34 to 190)
12 to 24 hours 35 days 0.9%
(-0.5% to 2.2%)		 110
(NNT = 45 to infinity;
NNH = 200 to infinity)

  • A sensitivity analysis did not alter the result.
  • Aspirin should not be forgotten in the rush to thrombolyse

Citation

  1. Boersma E, Maas AC, Deckers JW, et al: Early thrombolytic treatment in acute myocardial infarction: reappraisal of the golden hour. Lancet 1996; 348: 771-775
Search Terms: thrombolysis and myocard* in Cochrane
Contributor: Chris Ball and Clare Wotton, February 2000
Reviewer: Clare Liddy

Clinical Question.
Patient myocardial infarction
Intervention or Exposure time to thrombolysis
Outcome death