Myocardial infarction: age over 70, cardiac arrest, Killip class and anterior MI increased the risk of dying following a ventricular arrhythmia.

Clinical bottom line (level 1b)

  1. Two-thirds of patients who have a late ventricular arrhythmia after myocardial infarction were alive at 2 years.
  2. Patients were at increased risk of dying with a ventricular arrhythmia less than 6 weeks after MI if they were over 70 years old, had a cardiac arrest, were in Killip class III or IV or had an anterior MI.
  3. Multiple previous MIs have no clear effect on mortality risk, and Killip class had no clear effect on mortality risk in the late-arrythmia group.
Willems et al: Journal of the American College of Cardiology 1990; 16: 521-530
Expires March 2003

The study

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

Setting: 13 cardiology departments, The Netherlands

390 patients (aged 59% between 50-70yrs, 89% male) documented sustained ventricular tachycardia or fibrillation occurring > or = 48 hours after the onset of myocardial infarction

Excluded if
  • if none of the following occurred during the arrhythmia: palpitation, chest pain, dyspnoea, dizziness, syncope or cardiac arrest
  • tachyarrhythmia attributed to pump failure, ischaemia or imbalance of serum electrolytes
  • arrhythmia caused by proarrhythmic effects of an antiarrhythmic drug
  • asymptomatic tachycardia
  • tachycardia of supraventricular instead of ventricular origin



    • Factors studied:
  • non-significant factors studied included gender, age, referral status, postinfarct angina, conduction abnormalities and index arrythmia variables
  • age >70 years
  • cardiac arrest during index arrhythmia
  • Killip class III or IV during the semiacute phase of infarction
  • anterior MI
  • multiple previous MIs
  • cardiac arrest
  • Killip class III or IV
  • multiple previous MIs


    • Initial treatment with an antiarrhythmic drug followed by a second and third if previous ones were ineffective. The first two drugs were preferably class I antiarrhythmic drugs, such as procainamide, quinidine, disopyramide, flecainide and propafenone. Amiodarone was used as the third drug.

    Multivariate analysis using the Cox survival proportional hazards model was used to adjust for confounding factors.

    100% followed for 2 years
    Outcomes studied:
  • total mortality
  • mortality- first VT/VF less than 6 weeks after MI
  • mortality- first VT/VF more than 6 weeks after MI

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    total mortality 2 years 133/390 34.1%
    (29.4% to 38.8%)
    mortality- first VT/VF less than 6 weeks after MI 2 years 68/161 42.2%
    (34.6% to 49.9%)
    mortality- first VT/VF more than 6 weeks after MI 2 years 72/229 31.4%
    (25.4% to 37.5%)

    prognostic factor for
    mortality- first VT/VF less than 6 weeks after MI     		time to outcome control rate (%) adjusted OR
    (95% CI)    		 NNF+
    (95% CI)
    age >70 years 2 years 68/161
    (42.2%)     		4.5
    (2.6 to 7.7)     		3
    (2 to 4)
    cardiac arrest 2 years 68/161
    (42.2%)     		1.7
    (1.0 to 2.8)     		8
    (1 to 4)
    Killip class III or IV 2 years 68/161
    (42.2%)     		3.5
    (1.5 to 4.4)     		3
    (3 to 10)
    anterior MI 2 years 68/161
    (42.2%)     		2.2
    (1.2 to 3.9)     		5
    (3 to 22)
    multiple previous MIs 2 years 68/161
    (42.2%)     		1.6
    (0.9 to 2.7)     		9
    (-39 to 4)

    prognostic factor for
    mortality- first VT/VF more than 6 weeks after MI     		time to outcome control rate (%) adjusted OR
    (95% CI)    		 NNF+
    (95% CI)
    cardiac arrest 2 years 72/229
    (31.4%)     		1.7
    (1.1 to 2.9)     		8
    (4 to 48)
    Killip class III or IV 2 years 72/229
    (31.4%)     		1.7
    (0.8 to 3.4)     		8
    (-22 to 3)
    multiple previous MIs 2 years 72/229
    (31.4%)     		1.4
    (0.8 to 2.4)     		13
    (-22 to 5)

    Comments

    1. Numbers needed to follow are over-estimated due the control rate used being the overall control rate for mortality.

    Citation

    1. Willems AR, Tijssen JGP, van Capelle FJL, et al: Determinants of prognosis in symptomatic ventricular tachycardia or ventricular fibrillation late after myocardial infarction. Journal of the American College of Cardiology 1990; 16: 521-530
    Contributor: Clare Wotton and Bob Phillips, October 1999
    Reviewer:

    Clinical Question.
    Patient ventricular tachycardia or fibrillation late after myocardial infarction
    Intervention or Exposure risk factors
    Comparison no risk factors
    Outcome survival