An improved rapid troponin T test with a decreased detection limit: a multicentre study of the analytical and clinical performance in suspected myocardial damage

In a multicentre study, we evaluated the analytical and diagnostic performance of the second version of the TROPT rapid test (TROPT 2, CARDIACT in the US). We tested TROPT 2 on 796 blood samples from 487 patients admitted on suspicion of myocardial infarction between 1 and 72 h after onset of symptoms and determined cTnT ELISA and CK MB mass in the corresponding serum samples. Frequency distributions of the results with TROPT 2 showed a detection limit of 0.18 microgram/l (for 50% positive results) as determined by the quantitative cTnT ELISA method. In a total of 796 samples the sensitivities in the detection of myocardial infarction (WHO criteria) 8-12 h after onset of symptoms were highest for cTnT ELISA (98%), followed by the rapid assay and CK MB mass (92%). A subgroup of 87 patients was primarily classified by the WHO criteria for definite infarction. Based on the maximum values within each patient time-series, diagnostic sensitivities for infarction were 100% for TROPT2, cTnT ELISA and CK MB mass. The corresponding specificities were 90%, 82% and 100%, respectively. After reclassification summarizing all cases of myocardial damage (acute and subacute myocardial infarctions and minor myocardial damage) the sensitivities were 87% (TROPT2), 100% (cTnT ELISA) and 71% (CK MB mass). The specificities of all three markers were 100%. Over 50% of all cases of minor myocardial damage were detected by TROPT 2. The clinical evaluation showed that the diagnostic performance of TROPT 2 is only slightly lower than that of cTnT ELISA.