Combination (multiple) testing for myocardial infarction using myoglobin, creatine kinase-2 (mass), and troponin T.
We retrospectively determined the mass concentrations of myoglobin, creatine kinase-2 (CK-2), and troponin T in serial samples from 80 patients with confirmed myocardial infarction (MI) and 60 non-MI patients. Results from receiver operating characteristic curve analyses show that all three tests are comparable in their diagnostic utility within the first 12 h of infarction. Decision thresholds were selected at a constant rule-in specificity of 95% and rule-out sensitivities of 95% at, respectively, 3-6, 6-9, and 9-12 h intervals after the onset of symptoms. Test sensitivities and specificities were compared for each, used as: a single test; two-test parallel combination; three-test parallel combination; two-test series combination; and three-test series combination. Our results from combination testing indicate what for the early diagnosis of MI, a single serum myoglobin measurement has diagnostic utility at 3 h after the onset of symptoms, and myoglobin and CK-2 (mass) in combination later than 3 h following the onset of symptoms. Serum troponin T is diagnostically similar to CK-2 (mass), although it has superior cardiac-tissue specificity, but it is not as yet commercially available as a "stat" test. Therefore, we recommend using troponin T as a confirmatory test 9 h after the onset of MI. Based on our findings, we suggest a testing algorithm for the early biochemical diagnosis of MI.
Bhayana
V
V
Department of Laboratory Medicine, University Hospital, University of Western Ontario, London, Canada.
Cohoe
S
S
Pellar
T G
TG
Jablonsky
G
G
Henderson
A R
AR
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D003402:Creatine Kinase / Q000097:blood*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis*; D009211:Myoglobin / Q000097:blood*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014336:Troponin / Q000097:blood*; D020107:Troponin T
D015415:Biomarkers; D007527:Isoenzymes; D009211:Myoglobin; D014336:Troponin; D020107:Troponin T; D003402:Creatine Kinase