Comparison of diagnostic performance of cardiac troponin I on the IMMULITE system with other automated troponin I assays in minor myocardial damage.

An analytical and clinical evaluation of cardiac troponin I (cTnI) on the IMMULITE system is presented. The assay results were compared with those of the Stratus II and the Dimension RxL-HM. A between-run imprecision CV < 20% was found at a cTnI concentration of 0.23 microg/L (functional limit of detection). On the basis of a reference study including 215 patients without ischemic heart disease (97.5th percentile: 0.294 microg/L) and 36 patients clinically classified as having stable angina pectoris (<0.22 microg/L) a preliminary cutoff level of 0.3 microg/L was defined. Assay linearity, sample stability, influence of sample material and method comparison studies were performed. In patients with Duchenne's disease, chronic hemodialysis treatment, pulmonary embolism, coronary artery bypass surgery and minimally cardiac surgery the cTnI results of the IMMULITE agreed better with the Dimension RxL-HM than with the Stratus II data. Of 142 samples from patients with unstable angina 67 samples were classified as cTnI positive with the IMMULITE, 76 with the Dimension RxL-HM, and 62 with the Stratus II. In conclusion, the new assay is sensitive for the determination of cTnI and easy to perform within 45 min.