The acute coronary syndrome diagnosis and prognostic evaluation by troponin I is influenced by the test system affinity to different troponin complexes.
It was suggested recently that cardiac troponins are released as T-I-C complexes and then further degraded to T and I-C. It is not known whether the various affinity to the T-I-C and I-C complex of different troponin I test systems influence the diagnostic and prognostic value of the test results in clinical practice. We studied 162 patients (61.3 S.D. 11.1 years) with suspected acute myocardial infarction (AMI) in a single center study. AMI was confirmed in 109 patients. Blood samples were taken at admission, after 1, 2, 4, 8, 12 and 24 h. Troponin I (TnI) was measured using the OPUS plus (TnI-O, cut-off 1.6 microg/l) and the Stratus II (TnI-S, cut-off 1.5 microg/l) analyzers. TnI-O has high affinity to the binary (I-C) and TnI-S to the ternary (T-I-C) troponin complex. A 6-month follow-up with respect to death and recurrent AMI was performed. The sensitivity (SE) and specificity (SP) for AMI diagnosis were 82.6 and 86.8% for TnI-S; 75.2 and 92.5% for TnI-O 0-2 h after admission. The ROC analysis showed a slightly better curve for TnI-S at 4 h (P<0.05). Logistic regression analysis shows prediction of 6 months outcome by 0-24 h serial TnI-S measurements (odds ratio 5.21, P=0.0356), and serial TnI-O measurements (odds ratio 4.92, P=0.0186). High affinity to the ternary troponin complex enhances the diagnostic but not the prognostic value of a test system. Indeed, the resulting differences are small but underline the need for standardization of biochemical markers.
Möckel
M
M
Department of Medicine, University Hospital Charité/Campus Virchow-Klinikum, Humboldt University, Berlin, Germany. martin.moeckel@charite.de
Heller
G
G
Berg
K
K
Klefisch
F
F
Danne
O
O
Müller
C
C
Störk
T V
TV
Frei
U
U
Wu
A H
AH
D000208:Acute Disease; D015415:Biomarkers; D003327:Coronary Disease / Q000175:diagnosis* / Q000401:mortality; D003404:Creatinine / Q000097:blood; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D005455:Fluorescent Antibody Technique; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis; D009206:Myocardium / Q000737:chemistry*; D011237:Predictive Value of Tests; D011379:Prognosis; D014336:Troponin / Q000737:chemistry*; D019210:Troponin I / Q000032:analysis*
D015415:Biomarkers; D014336:Troponin; D019210:Troponin I; D003404:Creatinine