High-Sensitivity Cardiac Troponin On Presentation to Rule Out Myocardial Infarction

Standard care across all sites during the validation phase will rule out myocardial infarction in those with presentation troponin below the 99th centile with greater than 6 hours of symptoms at the time of blood sampling. In those with less than 6 hours of symptoms, a second test will be measured 6- 12 hours after presentation.

Standard care or HighSTEACS pathway.

Implementation of the HighSTEACS pathway to rule out myocardial infarction in patients with suspected acute coronary syndrome. Myocardial infarction will be ruled out if presentation cardiac troponin concentrations are \<5 ng/L in those with at least 2 hours of symptoms at the time of blood sampling. In patients with less than two hours of symptoms, or where cardiac troponin concentrations are between 5ng/L and the 99th centile, repeat testing will be recommended at 3 hours. Myocardial infarction will be ruled out at 3 hours if cardiac troponin concentrations are unchanged (\<3 ng/L change) and remain ≤99th centile on retesting. Those remaining ≤99th centile on retesting but demonstrating a significant change will require admission for further testing at 6-12 hours.