• J Mair, J Smidt, P Lechleitner, F Dienstl, and B Puschendorf.
• Department of Internal Medicine, University of Innsbruck School of Medicine, Austria.
• Coron. Artery Dis. 1995 Jul 1;6(7):539-45.

BackgroundAccurate diagnosis of impending acute myocardial infarction (AMI) in patients presenting at an emergency department with acute chest pain is essential for proper triage and treatment. We have developed an algorithm for the early diagnosis of AMI.MethodsThe diagnostic performances of ECG, creatine kinase (CK) and creatine kinase isoenzyme MB (CKMB) activities, CKMB mass, myoglobin, and cardiac troponin T (cTnT) were compared for early diagnosis of AMI in 60 non-traumatic chest pain patients (22 AMI, 29 unstable angina, nine other diseases) on presentation to an internal medicine emergency department and 1 h thereafter. The classification and regression trees method was used for data analysis and revealed the following results.ResultsIn patients with electrocardographic signs of acute transmural myocardial ischaemia on admission (mostly regional ST-segment elevations), biochemical markers could not improve the diagnostic accuracy either on admission or 1 h later. By contrast, in patients with non-diagnostic ECG, CKMB mass concentration measured 1h after admission was the best discriminator between AMI and non-AMI patients (discriminator value 5.8 micrograms/l) and was superior to ECG and all other biochemical markers tested. This algorithm for diagnosing AMI is characterized by 96% sensitivity, 90% specificity, 84% positive predictive value, 97% negative predictive value, 92% accuracy, 0.05 negative likelihood ratio, and 9.1 positive likelihood ratio.ConclusionThe classification procedure obtained allows accurate rapid and early diagnosis of AMI and could therefore be a valuable diagnostic aid to physicians of emergency medicine.

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