Clinical significance of minor elevation of cardiac troponin I

Abstract

Background : Cardiac troponin I (cTnI) is known as a sensitive and specific marker for myocardial ischemia. The purposes of this study are to establish cut-off values of cTnI for acute myocardial infarction (AMI) and to analyze clinical significance of minor elevation of cTnI. Methods : Two hundred and four patients from whom cTnI was measured at Ewha Womans University Dongdaemun hospital from January to March, 2006 were enrolled in the study. cTnI was measured using Dimension RxL (Dade Behring, USA). The lower limit of detection (LLD), 10% CV value, 99th percentile of healthy individuals, and cut-off value for AMI by ROC curve analysis were determined. Results : LLD, 10% CV value, and 99th percentile of cTnI were 0.00 ng/mL, 0.10 ng/mL, and 0.07 ng/mL, respectively. The cut-off value of peak cTnI for AMI by ROC curve analysis was 0.13 ng/mL with the sensitivity, specificity, and AUC of 90.9%, 87.7%, and 0.921, respectively. The peak value of cTnI of patients with ischemic heart disease (IHD) was higher than that of the patients without IHD (P<0.05). According to the above reference and cut-off values of the initial cTnI, patients were categorized into four groups; ≤0.05 ng/mL (group 1), 0.06-0.09 ng/mL (group 2), 0.10-0.59 ng/mL (group 3), ≥0.60 ng/mL (group 4), and compared frequencies of AMI, IHD, cardio vascular disease (CVD) and death after 1 month among groups. Frequencies of AMI, IHD, CVD, and death after 1 month were significantly increased as the cTnI concentrations were increased (P<0.05). Conclusions : Minor elevation of cTnI value, even in group 3 was significantly associated with high incidence of AMI, IHD, CVD, and death rate after 1 month.