Chest pain accounts for 2%–4% of all new attendances at emergency departments (ED) in the United Kingdom.^{1, 2} Chest pain can be the presenting complaint in a myriad of disorders ranging from life threats such as acute myocardial infarction (AMI) to mild self limiting disorders such as muscle strain. Possible cardac chest pain can be viewed as a continuum, ranging from total global AMI to simple short lived angina. Within this spectrum lie the acute coronary syndromes with critical cardiac ischaemia and minimal myocardial damage.

Nationally over 129 000 deaths a year are attributable to ischaemic heart disease.³ AMI case mortality is currently 45% with over 70% of these dying before they reach medical care.⁴ One in eight patients with unstable angina will infarct within two weeks without appropriate treatment. In the UK around 30% of patients with chest pain are admitted and 70% discharged from the ED¹ while in the United States 60% are admitted and 40% discharged.⁴ Despite such high admission rates 3%–4% of AMI are inadvertently discharged from US EDs. In the UK significantly fewer patients are admitted; while the number of missed AMIs is unknown, recent evidence suggests that some 6% of patients discharged from EDs may have prognostically significant myocardial damage.⁵

Mortality for patients with AMI differs greatly between admitted and discharged patients (6% versus 25%).⁶ Missed AMI accounts for 20% of US emergency medicine related litigation dollars.⁷ Many interventions including drug therapy and surgery reduce mortality in patients with AMI.^8–11 However, the patient can only benefit if correctly identified.

Although it is essential to identify all patients with AMI and unstable angina, it is also important to control costs and not subject patients to unnecessary investigations, inpatient care and resultant psychological stress. …