Premium
Evaluation of a New Assay for Cardiac Troponin I vs Creatine Kinase‐MB for the Diagnosis of Acute Myocardial Infarction
Author(s) -
Brogan Gerard X.,
Hollander Judd E.,
McCuskey Charles F.,
Thode Henry C.,
Snow Jeffrey,
Sama Andrew,
Bock Jay L.
Publication year - 1997
Publication title -
academic emergency medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.221
H-Index - 124
eISSN - 1553-2712
pISSN - 1069-6563
DOI - 10.1111/j.1553-2712.1997.tb03636.x
Subject(s) - medicine , myocardial infarction , creatine kinase , cardiology , troponin , troponin i , odds ratio , prospective cohort study , troponin t , creatine
Objective : To compare a new assay for cardiac troponin I (cTn‐I) with an assay for creatine kinase‐MB (CK‐MB) for the diagnosis of acute myocardial infarction (AMI). Methods : A prospective cross‐sectional study of patients presenting with symptoms consistent with cardiac ischemia was performed at a university teaching hospital. Serum sampling for cTn‐I and CK‐MB was performed at 0, 1, 3, 8, and 16 hours after presentation. Normal values were defined as CK‐MB ≤ 7 ng/mL and a relative index ≤ 2%, cTn‐I ≤ 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 the 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). Results : Thirty‐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: 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). Conclusion : cTn‐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 ≥ 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.