Myocardial infarction: anterior: abnormal QRS complexes on admission ECG increased the risk of dying.

Clinical bottom line (level 1b)

  1. One in eight patients with an acute myocardial infarction died in hospital.
  2. The risk of dying was increased if the QRS on admission ECG was abnormal.
Birnbaum et al: Chest 1993; 103 (6): 1681-1687
Expires March 2003

The study

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

Setting: coronary care unit, acute hospital, Israel

147 patients (aged 37 to 86; mean 64, 76% male) early evolving anterior myocardial infarction (diagnosed as chest pain for at least 30 minutes with associated changes in cardiac enzymes and serial ECGs)

Excluded if
  • inversion of T wave, an abnormal Q wave present or a bundle branch block
  • history or ECG evidence of previous anterior MI



    • Factors studied:
  • ECG changes, Killip functional class, age, sex


    • 74% received thrombolysis. All patients were treated with iv heparin and isosorbide dinitrate.

    A logistic regression analysis was used to adjust for confounding factors.

    ?100% followed for length of hospital stay
    Outcomes studied:
  • death
  • death with type A ECG: tall symmetric abnormal T waves in the involved leads without ST elevation or major changes in the terminal portion of the QRS
  • death with type B ECG: abnormal T waves and ST elevation in 2 more adjacent leads without major changes in the terminal portion of the QRS
  • death with type C ECG: abnormal T waves and ST elevation, with distortion of the terminal portion of the QRS complex in 2 or more adjacent leads

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)    		 NNF
    (95% CI)
    death length of hospital stay 19/147 13%
    (7.5% to 18%)    		 8
    (5 to 13)
    death with type A ECG: length of hospital stay 0/12 0.0%
    (0.0% to 22%)    		 -
    (5 to infinity)
    death with type B ECG: length of hospital stay 2/77 2.6%
    (0.0% to 6.2%)    		 39
    (16 to infinity)
    death with type C ECG: length of hospital stay 17/58 29%
    (18% to 41%)    		 3
    (2 to 6)

    • The risk of dying was increased with
      • initial ECG pattern
      • sex

    Comments

    1. The therapy given in this study no longer matches current practice. In addition the study involved few patients, making these results less certain.

    Citation

    1. Birnbaum Y, Sclarovsky S, Blum A, et al: Prognostic significance of the initial electrocardiographic pattern in a first acute anterior wall myocardial infarction. Chest 1993; 103 (6): 1681-1687
    Contributor: Chris Ball and Clare Wotton, February 2000
    Reviewer:

    Clinical Question.
    Patient anterior myocardial infarction
    Intervention or Exposure changes on initial ECG
    Outcome death