Chest pain is a common cause of accident and emergency (A&E) presentation. In the United States, it accounts for 5–6% of new emergency department attendances.^{1, 2} The principal challenge in these patients is to identify those with an acute coronary syndrome (ACS). Early diagnosis allows effective treatment and inadvertent discharge may have disastrous consequences for patient and doctor: in the United States, between 2–5% of acute myocardial infarctions (AMI) are discharged from the emergency department and 20% of malpractice claims against emergency physicians relate to the management of ACS.³

The problem with the A&E assessment of these patients lies in the limitations of diagnostic tests for acute coronary ischaemia—initial ECG is diagnostic of AMI in only 40–65% of patients and is even less useful in unstable angina.⁴ Despite recent advances, serum markers for myocardial necrosis detect, at best, 66% of AMIs on arrival.⁵ Faced with these diagnostic difficulties and the consequences of misdiagnosis, A&E physicians have a low threshold for admitting patients with chest pain in whom the diagnosis is not immediately clear. Some 60–65% of these patients have an eventual diagnosis of non-cardiac chest pain³ and while serious pathology is diagnosed in a minority, this traditional approach to chest pain is both time consuming and expensive.

It is against this background that the concept of A&E based chest pain evaluation units emerged—the aim being to provide medically equivalent care at a lower cost for A&E chest pain patients with a probability for ACS that is low, but not sufficiently low to allow discharge. The concept originated in, and has been almost exclusively confined to, the United States. The first chest pain evaluation unit was set up in 1981 and, by 1997, 15% of emergency departments in the US had followed suit.⁶ The …