Diagnosing acute coronary syndrome

High-sensitivity cardiac troponin (TnT hs) assays identify and measure troponin (Tn) at previously undetectable levels, enabling earlier diagnosis of acute coronary syndrome (ACS). The new generation of assays raises questions about what information should be reported to provide meaningful data for their use in the clinical setting. With a view to arriving at a general consensus on an initial protocol for the practical use of its Elecsys TnT hs assay, Roche hosted a meeting in June 2010 for biochemists and clinicians from the north-west of the UK to share their views. Chaired by Dr Martin Myers, consultant clinical biochemist at the Royal Preston Hospital, the meeting also heard from Dr Evangelos Giannitsis, professor of cardiology at the University Hospital, Heidelberg, whose chest pain clinic routinely uses TnT hs to test patients presenting with symptoms of ACS. The universal revised definition of myocardial infarction (MI) requires a rise and/or fall of cardiac troponin (cTn) to be demonstrated in patients with symptoms of ACS, with at least one value above the 99th percentile of the upper reference limit measured with a coefficient of variation (CV) <10%.1 The new generation of TnT and TnI tests are claimed to be the first troponin assays to meet this level of sensitivity and precision (Table 1).

Units of measurement

There was general consensus that units should be reported in ng/L rather than pg/mL, ng/mL, or ?g/L, as the limits of detection have reached very small numbers. It was noted, however, that users need to be aware that different units are used for point-of-care (POC) troponin tests, which currently are less sensitive, and play a different role in the clinical setting.