Unstable angina, non-Q wave MI: troponin I did not predict mortality.

Clinical bottom line (level 2b)

  1. Raised troponin I levels did not usefully predict mortality in patients with unstable angina or non-Q wave myocardial infarction.
  2. Patients with ST-depression within 24 hours of admission were at increased risk of dying (NNT = 15 at 42 days) .
Antman et al: New England Journal of Medicine 1996; 335: 1342-1349
Expires June 2003

The study

Prospective cohort study with objective outcomes, adjusted for confounding factors, not validated in an independent set of patients.

Setting: 31 hospitals, USA and Canada

1404h patients (aged range 21 to 79 years; mean 58, 66% male) unstable angina or non-Q wave myocardial infarction defined as:
  • chest pain at rest lasting between 5 minutes and 6 hours occurring within 24 hours of enrollment
  • and objective evidence of ischaemia: one of: ECG changes- ST elevation >=1 mm in two contiguous leads for <30 minutes, or persistent ST depression >=1 mm, or T wave inversion during an episode of rest pain within the last seven days; history of MI, >=70% luminal diameter stenosis on previous coronary angiogram; positive exercise thallium scintigraphy


Excluded if
  • treatable cause of unstable angina
  • MI in previous 21 days
  • coronary arteriography within last 30 days
  • PTCA <36 months
  • prior CABG
  • pulmonary oedema, systolic blood pressure >180 mmHg, diastolic blood pressure >100 mmHg
  • left bundle branch block
  • co-existing severe illness
  • woman of childbearing age
  • anticoagulants
  • contraindication to thrombolysis or heparin


    • All patients had conventional medical therapy for unstable angina:
    • beta-blocker (metoprolol 50 mg po every 12 hours)
    • calcium antagonist (diltiaem 30 mg po every 6 hours)
    • long-acting nitrate (isosorbide dinitrate 10 mg po every 8 hours) or larger dosease and supplemented by nitroglycerin
    • heparin- 5000 units iv bolus and a maintenance infusion so aPTT 1.5-2.0
    • aspirin 325 mg po once daily started on second day and continued for a year


    Multivariate regression was used to adjust for confounding factors.

    100% followed for 42 days
    Outcomes studied:
  • death

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    death 42 days 29/1404 2.07%
    (1.32% to 2.81%)

    prognostic factor for
    death     		time to outcome control rate (%) adjusted OR
    (95% CI)    		 NNF+
    (95% CI)
    ST depression on entry into study 42 days /
    (2.07%)     		4.63
    (2.02 to 10.6)     		15
    (6 to 49)
    age >=65 42 days /
    (2.07%)     		2.34
    (1.11 to 4.96)     		38
    (13 to 450)
    raised troponin I 42 days /
    (2.07%)     		1.03
    (1.00 to 1.05)     		1600
    (990 to inf)

    Comments

    1. Troponin levels correlate well with prognosis, but this correlation is explained by the effect of previously known factors, and adds nothing itself

    Citation

    1. Antman EM, Tanasijevic MJ, Thompson B, et al: Cardiac-specific troponin I levels to predict the risk of mortality in patients with acute coronary syndromes. New England Journal of Medicine 1996; 335: 1342-1349
    Search Terms: troponin in Cochrane
    Contributor: Chris Ball and Clare Wotton, June 2000
    Reviewer: William Rhoton

    Clinical Question.
    Patient angina or MI
    Intervention or Exposure ST depression, older age, raised troponin
    Outcome death