• G J Kost, J D Kirk, and K Omand.
• Department of Clinical Chemistry, University of California, Davis, Health System, USA.
• Arch. Pathol. Lab. Med. 1998 Mar 1;122(3):245-51.

ObjectiveTo design a strategy for cardiac injury marker testing in the diagnosis of acute myocardial infarction.DesignProspective study. Group I (n=54 patients): evaluation of clinical performance. Specimens collected at 0, 3, 6, and 12 (+/-1.5) hours after presentation. World Health Organization criteria were used for diagnosis of acute myocardial infarction. Group II (n=57 patients): evaluation of temporal evolution. Time intervals 0 to 1.5, 1.5 to 4.5, 4.5 to 7.5, and 7.5 to 13.5 hours. Patients identified by positive creatine kinase-MB (CK-MB) mass or myoglobin. Fourteen patients in Group I qualified for Group II. Hence, the total number of patients was 97.SettingA team of laboratorians and clinicians at the University of California, Davis, hospital assessed the clinical performance and temporal evolution of serial CK-MB isoform, troponin I, and troponin T results in comparison to parallel CK-MB mass and myoglobin results.Main Outcome MeasuresGroup I: sensitivity, specificity, and positive and negative predictive values. Group II: the time interval of the first positive result for each cardiac injury marker. Strategy and conclusions were based on study results and a literature review.ParticipantsEmergency department patients with acute onset of chest pain and other complaints, possibly indicative of myocardial ischemia, who were under evaluation for admission.ResultsTwenty-seven cases of acute myocardial infarction were documented. Group I: troponin I had the highest specificity (100%) and the highest positive predictive value (100%); troponin I, troponin T, and CK-MB mass had the highest sensitivity (90.0%); and the negative predictive values of troponin I, troponin T, and CK-MB mass were comparable (97.8%, 97.6%, and 97.6%, respectively). Group II: early diagnosis (within 1.5 hours) was provided by both CK-MB isoforms and CK-MB mass, and then by myoglobin and troponins, in order of decreasing frequency.ConclusionsCreatine kinase-MB mass, myoglobin, and troponin I were selected as the cardiac injury markers of choice at our institution. The strategy calls for serial testing of myoglobin and CK-MB mass initially-and serially if warranted by heightened clinical suspicion--with troponin I added if indicated for (1) specific confirmation, (2) late presentation, or (3) risk stratification.

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