Quantitative bedside assay for cardiac troponin T: A complementary method to centralized laboratory testing

Abstract

Background: In the evaluation of chest pain patients, whole blood bedside assays of highly specific cardiac molecules may be an attractive alternative to centralized clinical chemistry testing. We now report on an optimized test strip device for cardiac troponin T (cTnT) that can be analyzed by a cardiac reader for quantitative assessment of the test result. Methods and Results: The cTnT test strip reader measures, via a CCD camera, the reflectance of the signal line. For quantitative analysis, a calibration curve was constructed from 1030 samples of 252 consecutive patients with acute coronary syndromes. In a method comparison of 140 samples, the quantitative results of the cTnT test strip reader correlated closely with the results of the cTnT ELISA (r = 0.98; y = 0.85x + 0.002). Within-run and day-to-day (n = 10) mean CVs were between 11% and 16%, respectively. The cross-reactivity with skeletal troponin T was <0.02%. In patients with myocardial infarction, 45% and 91% of all samples were positive on admission and at 4-8 h after the onset of symptoms, respectively. ROC curve analysis demonstrated a comparable efficiency of the cTnT test strip reader and the laboratory-based cTnT ELISA in patients with suspected myocardial infarction. Conclusions: It is now possible to quantitatively determine cTnT at the patient's bedside with a rapid and convenient test device. This will facilitate the diagnostic work up of patients with suspected myocardial cell necrosis.