 MEASUREMENT OF COSTSOUTCOMES: Primary end-point will be one-year all-cause death or recurrent type 1 MI. Secondary endpoints: 1. Hospital stay, coronary care stay; 2. Proportion of patients receiving invasive coronary angiography during index hospitalisation; 3. Proportion of patients receiving coronary revascularisation during index hospitalisation; 4. Proportion of patients receiving subsequent unplanned coronary revascularisation after index hospitalisation; 5. Proportion of patients receiving invasive coronary angiography despite no significant lesion on CTCA; 6. Proportion of patients prescribed ACS therapies andor discharged on secondary prevention treatment during index hospitalisation; 7. Rehospitalisationpresentation with chest pain within 12 months; 8. Patient symptoms and quality of life up to 12 months; 9. NHS resource utilisation; 10. Patient satisfaction. Safety: 1. Proportion of patients with allergyanaphylaxisacute kidney injury; 2. Proportion of patients with alternative diagnoses e.g. aortic dissection or incidental but potentially concerning e.g. malignancy; 3. Total radiation exposure in each arm. Cost effectiveness: estimated in terms of the lifetime incremental cost per quality-adjusted life year QALY gained. 