Myocardial infarction: non-Q-wave MI and hypertension increased the risk of reinfarction.

Clinical bottom line (level 1b)

  1. A third of patients who had a myocardial infarction had another infarct within 10 years.
  2. Two thirds of patients who had a myocardial infarction died within 10 years.
  3. Patients were at increased risk of reinfarction within 10 years after myocardial infarction, if they had: a non-Q-wave MI or hypertension prior to the MI.
Berger et al: Journal of the American Medical Association 1992; 268: 1545-1551
Expires March 2003

The study

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

Setting: multicentre, USA

363 patients (aged range 36 to 89 years; mean 67, 63% male) first acute myocardial infarction

Excluded if
  • interpretation of ECG was obscured by the presence of a left bundle branch block or ventricular pacemaker at the time of initial MI
  • coronary artery bypass surgery prior to first MI
  • first MI unrecognised



Factors studied:
  • age, sex, angina, heart failure and cardiovascular disease (non-significant)
  • hypertension
  • non-Q-wave MI (designated on the basis of a history of prolonged ischaemic chest pain and elevation of cardiac enzymes in the absence of the development of Q-waves on serial ECGs)




Multivariate analysis was used to adjust for confounding factors.

99.9% followed up for a mean of 5.1 years, adjusted followed for 10 years
Outcomes studied:
  • reinfarction
  • all-cause mortality

The evidence

outcome time to outcome number of patients/total number %
(95% CI)
reinfarction 10 years 114/363 31.4%
(26.6% to 36.2%)
all-cause mortality 10 years 228/363 62.8%
(57.8% to 67.8%)

prognostic factor for
reinfarction 		time to outcome control rate (%) adjusted OR
(95% CI)		 NNF+
(95% CI)
hypertension 10 years 175/363
(48.2%) 		1.8
(1.1 to 3.2) 		7
(4 to 42)
non-Q-wave MI 10 years 76/278
(27.3%) 		1.8
(1.1 to 3.1) 		8
(18 to 52)

Comments

  1. While this is a reliably performed study, its applicability to current patients is, however, confounded by at least two factors: None of the patients received thrombolytic treatment at that time and secondary prevention was much less developed during the study period. Thrombolysis as well as early coronary angioplasty blur the distinction between Q- and non-Q-infarctions, and modern secondary prevention with aspirin, ACE-inhibitors, beta-blockers and statins changes and improves the prognosis of patients with myocardial infarction.
  2. Effective secondary prevention is, nevertheless, the priority for all coronary patients to improve their prognosis.

Citation

  1. Berger CJ, Murabito JM, Evans JC, et al: Prognosis after first myocardial infarction: Comparison of Q-wave and non-Q-wave myocardial infarction in the Framingham Heart Study. Journal of the American Medical Association 1992; 268: 1545-1551
Contributor: Clare Wotton and Bob Phillips, October 1999
Reviewer: Timo Strandberg

Clinical Question.
    Patient first myocardial infarction
    Intervention or Exposure non-Q-wave MI
    Comparison Q wave MI
    Outcome all cause mortality and reinfarction