Myocardial infarction: inferior: heart block was not clearly associated with dying.

Clinical bottom line (level 2b)

  1. Around 3% of patients with an inferior myocardial infarction died within the next 21 days.
  2. Patients with an inferior myocardial infarction who developed second or third degree heart block within 24 hours of admission were not clearly at an increased risk of dying.
Berger et al: Journal of the American College of Cardiology 1992; 20: 533-540
Expires March 2003

The study

Inception cohort study with objective outcomes, adjusted for confounding factors, validated in an independent set of patients.

Setting: acute hospitals, USA

1786 patients (aged mean 57, 82% male) with an inferior myocardial infarction (> 0.1 mV ST elevation in at least 2 of the 3 inferior leads II, III, aVF)

Excluded if
  • aged > 75
  • MI not confirmed on serial ECG or elevation of CK to twice normal
  • implantable permanent pacemaker
  • dilated cardiomyopathy
  • prior cardiac surgery
  • recent prolonged cardiopulmonary resuscitation
  • left bundle branch block
  • history of cerebrovascular disease
  • blood pressure > 180/110 mmHg
  • bleeding disorder
  • operation within 2 weeks, PTCA or trauma within 6 months
  • any other serious illness



    • Factors studied:
  • age, sex, prior MI, hypotension, atrial fibrillation, pulmonary edema or shock, history of diabetes mellitus, use of beta-blockers before study entry, second or third heart block


    • All patients received tPA

    Cox proportional hazards model used to adjust for confounding factors.

    ?100% followed for 21 days
    Outcomes studied:
  • death

    • This data comes from a randomised controlled trial comparing early angiography and angioplasty with no intervention unless ischemia could not be controlled by medical therapy or was provoked on exercise testing.

    The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)    		 NNF
    (95% CI)
    death 21 days 53/1786 3.0%
    (2.2% to 3.8%)    		 34
    (27 to 46)

    • Only pulmonary edema or shock on admission was found to be an independent predictor of mortality.

    Comments

    1. 12% of patients with inferior MI had heart block. Heart block was not associated with an increased risk of dying.

    Citation

    1. Berger PB, Ruocco NA, Ryan TJ, et al: incidence and prognostic implications of heart block complicating inferior myocardial infarction treated with thrombolytic therapy: results from TIMI II. Journal of the American College of Cardiology 1992; 20: 533-540
    Contributor: Chris Ball and Bob Phillips, October 2000
    Reviewer:

    Clinical Question.
    Patient inferior myocardial infarction
    Intervention or Exposure heart block
    Outcome death