High-sensitivity cardiac troponin and the early rule out of myocardial infarction: time for action

Chest pain is one of the most frequent presenting complaints in patients attending the emergency department, with almost 1 million attendances across the UK every year.1 The priority of the attending clinician is to promptly reach a diagnosis, as early intervention with medical therapy has been shown to reduce morbidity and mortality in patients with myocardial infarction. However, as few as 1 in 10 patients with chest pain actually have a diagnosis of myocardial infarction, with the majority presenting due to alternative diagnoses. Therefore, the safe and early rule out of myocardial infarction may be helpful by facilitating a refocused clinical evaluation, with targeted investigations for alternative differential diagnoses. This can also provide confidence that patients with typical anginal symptoms have not had myocardial infarction and may be safely triaged for outpatient investigation. High-sensitivity cardiac troponin assays were first introduced across Europe and Australasia in 2010. There are now several high-sensitivity assays available for use, all of which offer a magnitude improvement in performance over the previous generation. A number of diagnostic algorithms have been written which exploit the performance of these assays for detection of cardiac troponin at low concentration. For example, in patients with suspected acute coronary syndrome with a non-ischaemic ECG and a high-sensitivity cardiac troponin I or T concentration <5 ng/L (measured using the Abbott ARCHITECT or Siemens Atelleca hs-cTnI, or the Roche Elecsys hs-cTnT assays), both negative predictive value and sensitivity are extremely high, missing as few as 1 in every 200 patients tested and stratifying between 30% and 50% of patients as low risk.2–4 The High-Sensitivity Cardiac Troponin on Presentation to Rule-Out Myocardial Infarction (HiSTORIC) trial evaluated this approach in a stepped-wedge cluster randomised controlled trial, reporting at the European Society of Cardiology (ESC) Congress in 2019, demonstrating implementation of an early …