The acute coronary syndrome diagnosis and prognostic evaluation by troponin I is influenced by the test system affinity to different troponin complexes
M. Mockel et al., The acute coronary syndrome diagnosis and prognostic evaluation by troponin I is influenced by the test system affinity to different troponin complexes, CLIN CHIM A, 293(1-2), 2000, pp. 139-155
It was suggested recently that cardiac troponins are released as T-I-C comp
lexes and then further degraded to T and I-C. It is not known whether the v
arious affinity to the T-I-C and I-C complex of different troponin T test s
ystems 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 sus
pected 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(R) plus
(TnI-O, cut-off 1.6 mu g/l) and the Stratus(R) II (TnI-S, cut-off 1.5 mu g/
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 a
ffinity to the ternary troponin complex enhances the diagnostic but not the
prognostic value of a test system. Indeed, the resulting differences are s
mall but underline the need for standardization of biochemical markers. (C)
2000 Elsevier Science B.V. All rights reserved.