Early diagnosis of acute myocardial infarction (AMI) in patients presenting with acute chest pain improves clinical outcome. Moreover, rapid exclusion of AMI is important to triage patients in view of limited resources in the emergency department. High-sensitivity cardiac troponin (hs-cTn) assays are increasingly being used in many countries worldwide; however, a generally accepted definition of high-sensitivity is still pending. These assays enable cTn measurement with a high degree of analytical sensitivity with a low analytical imprecision at the low measuring range of cTn assays (coefficient of variation of < 10% at the 99th percentile upper reference limit). Measurement of cardiac troponin levels, as a marker of myocyte necrosis, is essential for diagnosing, AMI.1 Compared with sensitive troponin assays, high-sensitivity troponin assays enhance the accuracy and speed of the diagnosis, 1- 4 improve outcome, and are cost-effective. 5 Recent studies suggest that AMI can be diagnosed earlier than 3 hours, when values below the 99th percentile are used as cutoff values. This concept was incorporated into the 2015 European Society of Cardiology guidelines for NSTEMI as an alternative to the standard approach.8 we aimed to develop an algorithm for accurate and rapid exclusion and diagnosis of AMI after 1 hour using a cutoff below the 99th percentile and compare it with the recommended 3-hour approach. 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 (ACSs) than with previous cTn assay generations which are still more commonly used in practice worldwide. hs-cTn is also more sensitive for the detection of myocardial damage unrelated to acute myocardial ischemia. Therefore, the increase in early diagnostic sensitivity of hs-cTn assays for ACS comes at the cost of a reduced ACS specificity, because more patients with other causes of acute or chronic myocardial injury without overt myocardial ischemia are detected than with previous cTn assays. As hs-cTn assays are increasingly being adopted in clinical practice and more hs-cTn assays are being developed, this review attempts to synthesize the available clinical data to make recommendations for their everyday clinical routine use.
