High-sensitivity troponin allows accurate rapid diagnosis and discharge but it is not a substitute for a comprehensive patient evaluation

High-sensitivity cardiac troponin (hscTn) assays are replacing the older generation methods for the detection of acute myocardial injury. The key advantage is the higher sensitivity and diagnostic accuracy of hscTn assays, leading to a more rapid confirmation or exclusion of acute myocardial infarction (AMI). The 2015 European Society of Cardiology (ESC) guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation (NSTE-ACS) recommend the use of a 0 h/3 h algorithm, but 0 h/1 h rule-in and rule-out protocols have also been proposed [1]. The positive predictive value for MI is 75–80%, mainly due to the confounding effects of a few other cardiac conditions (dysrhythmias, heart failure, etc.) and many other non-cardiac diseases associated with increased hscTn (pulmonary embolism, infections, renal dysfunction, etc.). In a busy Accident & Emergency Department (A&E), where time and space come at a premium, but missing a diagnosis has awkward consequences, the negative predictive value for AMI is very important. This exceeds 98%, allowing the identification of candidates for early discharge and outpatient management [2,3,4]. In patients presenting to A&E > 3 h after symptom onset, one sample should be sufficient to exclude AMI, and several studies show that the diagnosis of AMI is unlikely in case of undetectable hscTn serum levels [5,6,7,8,9]. Still ruling out myocardial injury based on a single hscTn determination irrespective of the presentation time is controversial.