Introduction
Coronary artery disease (CAD) remains the biggest cause of mortality in the UK, causing around 80 000 deaths each year.1 Accurate diagnosis of CAD in patients presenting with stable recent onset chest pain is important to aid the management of this disease. Advances in diagnostic technologies, such as myocardial perfusion imaging, stress echocardiography, MRI and cardiac CT have increased the investigative options available to aid the diagnosis of CAD. Nevertheless, selecting the appropriate investigations to aid cost-effective and accurate diagnosis of CAD remains a challenge.
In 2010, the National Institute for Health and Care Excellence (NICE) published Clinical Guideline 95 (CG95),2 advocating risk stratification of patients using ‘CADScore’ to guide appropriate cardiac investigations for chest pain of recent onset. This risk score is calculated based on the symptoms, age, sex, risk factors (including diabetes, smoking and hyperlipidaemia) and ECG findings of the patient. The NICE guideline proposes that for people without confirmed CAD, in whom stable angina cannot be diagnosed or excluded based on clinical assessment alone, further diagnostic testing would be recommended as follows:
If the pretest likelihood for CAD is high (61–90%), consider invasive coronary angiography as the first-line diagnostic investigation, if appropriate.
If the pretest risk is intermediate (30–60%), consider functional imaging.
If the pretest risk of CAD is low (10–29%), offer cardiac CT as the first-line diagnostic investigation.
The guideline also recommends the depreciation of exercise ECG as a diagnostic test and the elimination of screening tests for the lowest risk patients or those with non-cardiac chest pain. The recommended investigations according to the guideline is summarised in table 1.
In the UK, the Rapid Access Chest Pain Clinic (RACPC) is a cardiologist-led service assessing patients with recent onset chest pain. CG95 was implemented in July 2010 in the RACPC at the University College London Hospitals NHS Foundation Trust in London, a tertiary cardiology centre. The impact of the implementation of the guideline on service provision in this RACPC, in terms of number of investigations and the cost consequence, was evaluated. Despite the higher costs of the new recommended initial investigations compared to previous first-line investigations, such as exercise ECG, it was hypothesised that the implementation of the guideline would reduce average cost of the patient's diagnostic journey and would reduce the number of investigations per patient due to better diagnostic accuracy, thus allowing for better patient safety.