How to use high-sensitivity cardiac troponin assays in everyday clinical practice

High-sensitivity cardiac troponin (hs-cTn) assays are increasingly being employed in many countries, however a generally accepted definition of high-sensitivity is still pending. These assays enable cTn measurement with a high degree of analytical sensitivity which can be in the single digit concentration range of ng/L or below. These assays have a low coefficient of variation (CV) of ≤10% at the 99^th percentile upper reference value which is the recommended medical decision limit. One of the most important advantages of these new assays is that they allow novel, more rapid approaches to rule in or rule out acute coronary syndromes (ACS) than is possible with the contemporary cTn assays still more commonly used in practice. hs-cTn is also more sensitive for the detection of myocardial damage unrelated to acute myocardial ischaemia. However, the increase in early diagnostic sensitivity of hs-cTn assays for ACS comes at the cost of a reduced specificity because more patients with acute or chronic myocardial injury without overt acute myocardial ischemia are detected then with contemporary cTn assays. As hs-cTn assays are increasingly being adopted in clinical practice and more hs-cTn assays are being developed, this chapter attempts to synthesize the available data to make recommendations for their routine use and to indicate where sufficient clinical data are still lacking.