Myocardial infarction: invasive management increased death in non-Q-wave infarctions.

Clinical bottom line (level 1b)

  1. Patients with acute non-Q-wave myocardial infarction who were given invasive management were more likely to die than those given conservative management (NNH = 21 at 12 months) .
  2. Patients who were given invasive management were more likely to suffer the combined outcome of death or nonfatal infarction (NNH = 18 at 12 months) .
Boden et al: New England Journal of Medicine 1998; 338 (25): 1785-1792
Expires March 2003

The study

Unblinded concealed randomised trial with intention-to-treat
Setting: 15 Veterans Affairs centres, USA

920 patients (aged mean 62 years, 97% male) evolving non-Q-wave acute myocardial infarction, creatine kinase MB isoenzymes >1.5 times the upper limit of normal for the hospital

Excluded if
  • serious coexisting conditions
  • ischaemic complications that placed them at very high risk while in the coronary care unit
  • new abnormal Q waves (or R waves) on serial electrocardiograms

Note:
  • Patients were stratified according to age, previous MI, use of thrombolytic therapy, anterior location infarct and ST-segment depression on entry ECG-how random?


Control Group: (n = 458, 458 analysed): conservative management strategy- radionuclide ventriculography to assess left ventricular function as the initial noninvasive test, followed by a symptom-limited treadmill exercise test with planar thallium scintigraphy or thallium scintigraphy with single-photon emission computed tomography, before discharge. Patients who were unable to exercise to a level of at least 5 metabolic equivalents received iv dipyridamole and then underwent perfusion scintigraphy.
Experimental Group: (n = 462, 462 analysed): early invasive management strategy- coronary angiography soon after randomisation as diagnostic test, and the management guidelines of TIMI IIIB for revascularisation were followed. Patients with single-vessel coronary artery disease had balloon angioplasty or, rarely, directional atherectomy, whereas those with multivessel disease had bypass surgery recommended.
Enteric-coated aspirin (325 mg per day) was given to all patients, as was long-acting diltiazem (180-300 mg per day). Patients could receive any other standard medication during hospitalisation, if necessary.
100% followed for 12 months

The evidence

Outcome Time to outcome CEREERRRR
(95% CI)		ARR
(95% CI)		NNH
(95% CI)
mortality 12 months 36
(7.86%)		 58
(12.6%)		 -60%
(-137% to -8%)		 -4.69%
(-8.59% to -0.79%)		 21
(12 to 130)
death or nonfatal infarction 12 months 85
(18.6%)		 111
(24.0%)		 -29.0%
(-66.0% to -1.00%)		 -5.47%
(-10.7% to -0.19%)		 18
(9 to 530)
 

Citation

  1. Boden WE, O'Rourke RA, Crawford MH, et al: Outcomes in patients with acute non-Q-wave myocardial infarction randomly assigned to an invasive as compared with a conservative management strategy. New England Journal of Medicine 1998; 338 (25): 1785-1792
Contributor: Clare Wotton and Musab Hayatli, March 2000
Reviewer: Dwight Peretz

Clinical Question.
Patient acute non-Q-wave MI
Intervention or Exposure invasive management
Comparison conservative management
Outcome mortality or nonfatal infarction