Cardiac troponin 1: a highly sensitive and specific cardiac marker

ABSTRACT

The aim of the present study was to evaluate the early diagnostic sensitivity and specificity of cardiac troponin I [cTnI] as compared to the routinely used cardiac enzymes [total CK and CK-MB] in acute chest pain patients presenting to the Emergency Department [ED] within the first six hours of onset of pain. This study was conducted on 17 acute myocardial infarction [AMI] patients presenting to the Emergency Department [ED] within the first six hours from onset of chest pain, in addition to 36 non-AMI patients [11 patients with unstable angina, as well as 15 patients suffering from CRF and 10 patients with traumatic muscle injury]. The results were compared with those of 10 healthy age- and sex-matched control subjects. CTnI [measured by a chemiluminescent technique on Immulite system] proved to be the superior marker for early and accurate diagnosis of AMI during the first six hours of onset of chest pain as evidence by ROC curve analysis. The area under the curve [AUC] for cTnI was 0.955, that for CK-MB was 0.925, meanwhile that for total CK was 0.769. The optimum cutoff level of cTnI was 1.6 ng/ml. At this level, cTnI showed a diagnostic efficacy of 94.1%, 95.6%, respectively, with diagnostic efficacy of 95.2%. Although CK-MB showed a similar diagnostic sensitivity [94.1%], it had a much lower specificity [77.8%], hence resulting in a much lower diagnostic efficacy [82.3%], compared to cTnI. Total CK, on the other hand, showed a very low sensitivity [70.6%] and specificity [80%] with diagnostic efficacy of 82.3%