Role of Cardiac CT in Rapid Access Chest Pain Clinics (RADICAL)

Study Objectives: * To assess the diagnostic accuracy and cost effectiveness of non-invasive coronary angiogram by Cardiac CT in the diagnosis of coronary artery disease in patients with angina, in the setting of Rapid Access Chest Pain clinics * To formulate an optimal diagnostic algorithm in terms of accuracy and cost effectiveness for diagnosis of CAD in patients with chest pain. Study Setting: \- Rapid Access Chest Pain clinics in 3 NHS hospitals (Barnet, Chase Farm and the Royal Free hospitals) Target Population: \- Patients with new onset, stable exertional angina presenting to Rapid Access Chest Pain clinics. Study Design and Methodology: This trial is designed as a prospective randomized case - control study. 600 patients who meet the study criteria will be recruited from Rapid Access Chest Pain Clinics. The patients will be randomized into 2 cohorts (study and control) of 300 each. All patients will undergo stress - ECG at the referring hospital. Patients in the control group will receive the 'standard clinical care'. Their management is not altered by their inclusion in the trial. All patients in the study group will undergo CT coronary Angiography at the Clinical Imaging and Research Centre based at the Wellington Hospital. Patients with obstructive coronary artery disease (defined as \>50% stenosis in left main coronary artery or \>70% stenosis in one of the other major epicardial coronary arteries) will be referred for invasive coronary angiography +/- revascularization. Patients with intermediate (50-70%) coronary stenosis will be referred to myocardial perfusion scan (MPS). Patients with significant reversible ischemia on MPS will be referred to invasive coronary angiography +/- revascularization. Patients who do not have evidence of significant reversible ischemia on MPS and those with \<50% stenosis on CT coronary angiogram will be discharged on appropriate medications. All patients will be followed up for 12 months after recruitment. Information will be gathered regarding clinical events (non-fatal/fatal MI, acute coronary syndrome, hospitalization, emergency/elective revascularization) and quality of life as per SF-36 questionnaire. All the diagnostic and therapeutic procedures underwent by each patient in both cohorts will be recorded. The cost-effectiveness of each CT coronary angiography will be calculated by using the NHS reference costs. Primary outcome measure: The total cost of diagnosis for current diagnostic strategy being used in the Rapid Access Chest Pain Clinics and a new strategy involving the use of CT coronary angiography in the investigation of patients with angina. Secondary outcome measures: * Diagnostic Accuracy of CT coronary angiography * Prognostic value of CT coronary angiography * Number of normal angiograms in each cohort * Number of angiograms not followed by revascularization in each cohort * Quality of life as assessed by SF-36 Questionnaire For calculating cost effectiveness, NHS reference costs will be used. Thus, the costs and benefits will be considered from the NHS perspective