Myocardial infarction: early beta-blocker therapy reduced recurrent chest pain and reinfarction.

Clinical bottom line (level 1b)

  1. Patients with a myocardial infarction who had beta-blockers immediately compared with waiting 6 days were less likely to have recurrent chest pain (NNT = 19 at 6 days) or a reinfarction (NNT = 42 at 6 days) , (NNT = 37 at 6 weeks) .
  2. There was no clear effect on reinfarction at 12 months.
  3. There was no clear effect on mortality at 6 days, 6 weeks or 12 months.
Roberts et al: Circulation 1991; 83 (2): 422-437
Expires March 2003

The study

?blinded ?concealed randomised trial with intention-to-treat
Setting: 25 acute hospitals, USA

1434 patients (aged mean 55, 85% male) with an acute myocardial infarction

Excluded if
  • on beta-blocker, verapamil or diltiazem on admission
  • presented > 4 hours after symptom onset
  • aged > 75
  • implanted pacemaker; heart block
  • resting ventricular rate < 55 beats/minute
  • systolic blood pressure consistently < 100 mmHG
  • evidence of pulmonary oedema
  • history of asthma; wheezing; or COPD requiring steroids or beta-agonist inhalers


Note:
  • Patients were factorially randomised to invasive therapy or conservative therapy, and immediate or delayed beta-blockade.


Control Group: (n = 714, 714 analysed): delayed beta-blocker therapy: on day 6 post-infarction, oral metoprolol 50 mg twice daily for 24 hours then 100 mg twice daily
Experimental Group: (n = 720, 720 analysed): immediate beta-blocker therapy: intravenous metoprolol three 5 mg doses given at 2 minutes intervals immediately following tPA. 15 minutes after third dose (and no evidence of AV block or bronchospasm), patients had 50 mg orally every 12 hours for 24 hours, increased to 100 mg orally every 12 hours
Patients were treated with tPA, heparin and aspirin and were randomised to routine angiography and PTCA or angiography only if recurrent ischaemic symptoms.
84% followed for 12 months
Outcome notes:
  • death : at 6 days
  • fatal or nonfatal reinfarction : at 6 days
  • recurrent chest pain : at 6 days
  • death : at 6 weeks
  • fatal or nonfatal reinfarction : at 6 weeks
  • fatal or nonfatal reinfarction : at 12 months
  • death : at 12 months

The evidence

Outcome Time to outcome CEREERRRR
(95% CI)		ARR
(95% CI)		NNT
(95% CI)
death 6 days 17
(2.38%)		 17
(2.36%)		 1%
(-93% to 49%)		 0.02%
(-1.56% to 1.59%)		 5000
(NNT = 63 to infinity;
NNH = 64 to infinity)
fatal or nonfatal reinfarction 6 days 36
(5.04%)		 19
(2.64%)		 48%
(10% to 70%)		 2.40%
(0.42% to 4.39%)		 42
(23 to 240)
recurrent chest pain 6 days 170
(23.8%)		 134
(18.6%)		 22%
(4% to 36%)		 5.20%
(0.97% to 9.42%)		 19
(11 to 100)
death 6 weeks 25
(3.50%)		 26
(3.61%)		 -3%
(-77% to 40%)		 -0.11%
(-2.03% to 1.81%)		 -900
(NNT = 55 to infinity;
NNH = 49 to infinity)
fatal or nonfatal reinfarction 6 weeks 51
(7.14%)		 32
(4.44%)		 38%
(4% to 60%)		 2.70%
(0.283% to 5.11%)		 37
(20 to 350)
fatal or nonfatal reinfarction 12 months 67
(9.38%)		 60
(8.33%)		 11%
(-24% to 36%)		 1.05%
(-1.89% to 3.99%)		 95
(NNT = 25 to infinity;
NNH = 53 to infinity)
death 12 months 35
(4.90%)		 34
(4.72%)		 4%
(-53% to 39%)		 0.18%
(-2.04% to 2.40%)		 560
(NNT = 42 to infinity;
NNH = 49 to infinity)

Citation

  1. Roberts R, Rogers WJ, Mueller HS, et al: Immediate versus deferred beta-blockade following thrombolytic therapy in patients with acute myocardial infarction: results of thrombolysis in myocardial infarction (TIMI) II-B study. Circulation 1991; 83 (2): 422-437
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Contributor: Chris Ball and Clare Wotton, February 2000
Reviewer:

Clinical Question.
Patient myocardial infarction
Intervention or Exposure immediate metoprolol
Comparison delayed metoprolol
Outcome death, reinfarction, chest pain