Myocardial infarction: long-term beta-blockers reduce death and reinfarction.

Clinical bottom line (level 1a)

  1. Patients with an acute or recent myocardial infarction who take a beta-blocker for at least 2 years compared with control are less likely to die (NNT = 44 at 2 years) or have another infarction (NNT = 110 at 2 years) .
  2. Patients on beta-blockers are more likely to stop their medication (NNH = 86 at 2 years) .
  3. There is no clear effect on short-term mortality.
Freemantle et al: British Medical Journal 1999; 318: 1730-1737
Expires March 2003

The study

Systematic review of all randomised controlled trials of
  • Patients: acute or recent myocardial infarction
  • Intervention: beta-blockers (started before or after MI, and may have been started intravenously) compared with control
  • Outcome: death, reinfarction, withdrawal



Articles found in all languages using Medline, Embase, Biosis, Healthstar, Sigle, IHTA, conference papers index, Derwent drug file, dissertation abstracts, Pascal, international pharmaceutical abstracts, and science citations index, 1966 to 1997 (search terms: not given ) and by searching reference lists of retrieved studies, existing bibliographies and reviews.

Selection criteria: see above
Appraisal criteria: not given: by 2 independent reviewers
Articles excluded if:

  • crossover study
  • treatment for less than 1 day
  • not patients with MI


82 studies found involving 54234 patients.

The evidence

Outcome Time to outcome CER OR
(95% CI)		 NNT
(95% CI)
death unknown 1560/14584
(10.7%)		 0.96
(0.85 to 1.08) 		260
(NNT = 130 to infinity;
NNH = 69 to infinity)
death 2 years 1306/12117
(10.8%)		 0.77
(0.69 to 0.85) 		44
(32 to 68)
reinfarction 2 years 698/8779
(8.0%)		 110
(63 to 330)

  • More patients withdrew from beta-blockers than placebo ARI: 1.16% (95% CI: 0.56% to 1.76%) giving NNH of 86 (95% CI: 57 to 180)

Comments

  1. Treatment with an initial intravenous dose of beta-blockers was not clearly associated with a greater reduction in mortality than treatment with oral medication alone.
  2. Neither drugs with increased cardioselectivity nor intrinsic sympathomimetic activity was clearly associated with a reduction in mortality.
  3. Only 4 drugs were found to be significantly associated with a reduction in mortality - propranolol, timolol, metoprolol and acebutolol. These were also the drugs most commonly used in the studies.
  4. No odds ratio was reported for the reinfarction or withdrawal rate.

Citation

  1. Freemantle N, Cleland J, Young P, et al: beta-blockade after myocardial infarction: systematic review and meta regression analysis. British Medical Journal 1999; 318: 1730-1737
Contributor: Chris Ball and Clare Wotton, February 2000
Reviewer:

Clinical Question.
Patient acute or recent myocardial infarction
Intervention or Exposure beta-blockers
Comparison control
Outcome death, reinfarction, withdrawal