Ruling out acute myocardial infarction based on a single high-sensitivity troponin measurement in the emergency department: a clinical practice review

Emergency departments (EDs) around the world are under increasing pressure, with overcrowding increasing preventable errors, patient discomfort, violence and aggression, staff burnout, and patient morbidity and mortality. Chest pain is one of the most common reasons that patients present to the ED. Accelerated diagnostic pathways use clinical assessment, electrocardiograms and cardiac biomarkers to help emergency medicine providers to quickly and accurately identify patients who are at low risk of myocardial infarction, and who therefore can be safely discharged, whilst ensuring that high-risk patients receive prompt and appropriate care. Accelerated diagnostic pathways decrease ED length of stay, which may reduce overcrowding. The diagnosis of acute myocardial injury has previously required at least two cardiac troponin measurements to be taken at least 6–12 hours apart. More recently, the use of accelerated diagnostic pathways in conjunction with high sensitivity cardiac troponin assays, allow a single sample measuring very low troponin concentration to be used to exclude acute myocardial injury. This enables the early discharge of a significant number of patients presenting to EDs with possible acute coronary syndrome, therefore decreasing ED overcrowding and improving patient flow. This clinical practice review describes the clinical perspective of ED specialists which differs from that of cardiologists and clinical chemists. We summarise the development of decision-making pathways for the assessment of chest pain, and describe the current changes taking place in pathway use involving single test rule out of acute myocardial infarction in the ED. The purpose of this clinical practice review is to provide clinical biochemists with an understanding of how emergency clinicians use and approach cardiac troponin results within the ED.