Myocardial infarction: cardiac enzyme changes diagnose most cases within 24 hours.

Clinical bottom line (level 1b)

  1. A third of patients with suspected myocardial infarction in immediate care facilities will have had one.
  2. Provisional diagnosis of myocardial infarction at 24 hours with the use of routine clinical criteria helps to rule in myocardial diagnosis.
Lee et al: Annals of Internal Medicine 1987; 106 (2): 181-186
Expires March 2003

The study

Setting: intensive or immediate care units at three teaching and threee community hospitals, USA

1460 patients (aged mean 64, 63% male) anterior, precordial or left-sided chest pain unexplained by obvious trauma or abnormalities on chest roentgenograms

Independent blinded reference standard, applied in all patients from a consecutive appropriate spectrum.
Reference standard:
  • final diagnosis using routine clinical criteria
Diagnostic test: provisional diagnosis at 24 hours- creatine kinase-MB abnormalities, lactate dehydrogenase isoenzyme increase, total creatine kinase elevations, presence of ECG showing development of new pathologic Q waves (at least 0.04 seconds duration) and a decrease in the amplitude of the following R wave as compared with emergency room ECG, or a scintiscan showing focal uptake of technetium-99m stannous pyrophosphate in the cardiac area where the serum enzyme peak might have occurred before hospitailsation and if the patient had no earlier history of myocardial infarction or valvular calcification.

The evidence

pre-test probability of myocardial infarction: 30%, (95% CI: 27% to 32%)

diagnostic test number of patients sensitivity for
myocardial infarction
(95% CI)
provisional diagnosis at 24 hours with enzymes etc. 415 96.3%
(94.5% to 98.1%)
total 431

Comments

  1. These criteria were prospectively validated in another set of 275 patients: 97% were diagnosed based on cardiac enzyme changes within 24 hours (95% CI: 95% to 99%). 99% were diagnosed based on cardiac enzyme changes or recurrent chest pain within 24 hours (95% CI: 97% to 100%).

Citation

  1. Lee TH, Rouan GW, Weisberg MC, et al: Sensitivity of routine clinical criteria for diagnosing myocardial infarction within 24 hours of hospitalization. Annals of Internal Medicine 1987; 106 (2): 181-186
Contributor: Clare Wotton and Chris Ball, January 2000
Reviewer: Dwight Peretz

Clinical Question.
Patient chest pain
Intervention or Exposure routine clinical criteria within 24 hours
Comparison routine clinical criteria after 24 hours
Outcome myocardial infarction