Acute chest pain is responsible for one in four emergency medical admissions in the United Kingdom,1 and these figures are probably similar in most Western countries. People with chest pain are rightly encouraged to seek help early, and attendances to emergency departments are rising. Emergency departments are responsible for quickly identifying and treating people with acute myocardial infarction and unstable angina, and for evaluating people with a lower likelihood of acute coronary syndrome.

Identifying which patients at low risk of acute coronary syndrome can be safely sent home and which patients need further observation and investigation is not easy, especially when the consequences of misdiagnosis include infarction, arrhythmia, and death. The strategy of evaluating such patients in a chest pain unit based within or near the emergency department is used in 30% of emergency …