• G X Brogan, J E Hollander, C F McCuskey, H C Thode, J Snow, A Sama, and J L Bock.
• Department of Emergency Medicine, University Medical Center, State University of New York, Stony Brook 11794-8350, USA. gbrogan@epo.som.sunysb.edu
• Acad Emerg Med. 1997 Jan 1;4(1):6-12.

ObjectiveTo compare a new assay for cardiac troponin 1 (cTn-1) with an assay for creatine kinase-MB (CK-MB) for the diagnosis of acute myocardial infarction (AMI).MethodsA prospective cross-sectional study of patients presenting with symptoms consistent with cardiac ischemia was performed at a university teaching hospital. Serum sampling for cTn-1 and CK-MB was performed at 0, 1, 3, 8, and 16 hours after presentation. Normal values were defined as CK-MB < or = 7 ng/mL and a relative index < or = 2%, cTn-I < or = 1.4 ng/mL. Final diagnosis was made using World Health Organization criteria, including standard enzyme sampling. Consecutive patients with AMI were compared with a randomly selected subset of patients without AMI to determine the sensitivity and specificity of cTn-I and CK-MB assays for AMI, stratified by time from symptom onset. The ability of the biochemical cardiac markers obtained within 6 hours of symptom onset to predict later complications or need for interventions was assessed using odds ratios (ORs).ResultsThirty-five patients who had AMI were compared with 136 patients who did not have AMI. The sensitivities and specificities of the cTn-I and CK-MB assays, stratified by time from symptom onset, were: [table: see text]. Patients who had elevations in either CK-MB or cTn-I within 6 hours of symptom onset were at increased risk for cardiovascular complications and/or interventions (CK-MB, OR 5.8; cTn-I, OR 6.3).ConclusioncTn-I was as sensitive and specific for AMI as was CK-MB in ED patients who presented within 24 hours of symptom onset. However, cTn-I was more sensitive in patients who presented > or = 24 hours after symptom onset. Elevations of either marker within 6 hours of symptom onset predict an increased risk of complications and/or need for interventions.

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