 The investigators propose to evaluate whether the use of the HighSTEACS pathway in patients with suspected acute coronary syndrome reduces length of stay and allows more patients to be safely discharged from the Emergency Department. This pathways utilizes high-sensitivity cardiac troponin I testing and will rule out myocardial infarction if troponin concentrations are 5 ngL on presentation, with further testing indicated at 3 hours only in those presenting early or with troponin concentrations between 5 ngL and the 99th centile. 