Sensitive cardiac troponin assays: sense and sensibility.

To meet the criteria defined in the universal definition of acute myocardial infarction (AMI), sensitive assays for cardiac troponins I and T have recently been introduced into clinical medicine. Such assays are commonly understood to have a detection limit ,99th percentile of a reference population and a total imprecision at the 99th percentile ≤10%. The analytical performance of these assays, i.e. the detection limit and imprecision profile, is clearly improved compared with previous generation assays. Among clinicians, however, there has been scepticism as to whether use of more sensitive assays represents a clinically significant improvement. Initial clinical studies of patients with acute chest pain and suspected acute coronary syndromes (ACS) demonstrated that sensitive assays provide enhanced diagnostic accuracy, particularly in patients with a short duration from symptom onset to hospital admission. Thus, the principal advantage of the sensitive assays is, not surprisingly given their name, the enhanced sensitivity to identify troponin elevation in early presenters. The enhanced sensitivity comes at a cost, however, i.e. decreased specificity. This decreased specificity has raised concerns among both emergency room physicians and cardiologists who fear that an increased rate of patients with troponin elevation of causes other than ACS will complicate triage in the emergency room and lead to overdiagnosis of AMI. Moreover, there are concerns that use of sensitive troponin assays with reduced specificity will lead to an increasing number of requests for cardiological assessment of patients with an elevated troponin test result from other departments. It has also been argued that the problem of decreased specificity has been underestimated because published studies, in particular those from specialized chest pain units or invasive centres, may not accurately reflect the patients seen in the emergency rooms of general hospitals, where older patients with complex comorbidities and higher troponin levels are frequently seen.