SECURE Trial: Stress Echocardiography With Carotid Ultrasound vs Routine CT Coronary Angiography in Chronic Coronary Syndrome for Endpoints

Inclusion Criteria: 1. Age \> 18 years old 2. Patients referred to RACPC and judged by the reviewer to require a further imaging investigation, either SE or CTCA, to evaluate a suspected diagnosis of CAD 3. AND 1. Have a PTP score ≥ 5%, as calculated using ESC guidelines OR 2. Have clinical history in keeping with 'typical' angina symptoms, as judged by the investigator, in patients with a PTP score \<5% - With 'typical' symptoms, as per ESC guidelines, being all three of the following i) Constricting symptoms in the front of the chest or in the neck, jaw, shoulder or arm ii) Precipitated by physical exertion iii) Relieved by rest or nitrates within 5 minutes 4. Able to give informed consent to participate in the study and its follow up Exclusion Criteria: 1. Patients with diagnosed ACS that require urgent or emergency treatment or hospitalisation for inpatient investigations. 2. Known history of obstructive CAD (Previous MI, PCI or CABG) or previous invasive angiography with evidence of ≥ 50% stenosis in any epicardial vessel. 3. Patients who have undergone invasive or non-invasive, functional or anatomical (Including CAC score) testing for detection of CAD within the previous 1 year of clinical assessment. 4. Documented allergy to iodinated contrast or documented allergy to both ultrasound contrasts used at LNWH Trust; Luminity® (Perflutren) and SonoVue® (Sulphur Hexafluoride) or the constitutes 5. Contraindications to undergoing CTCA, including but not limited to; * eGFR \< 40 ml/min * Contraindications to beta-blockers including but not limited to, documented allergy or significant airways disease in the judgement of the investigator. * Exceeding CT scanner weight tolerance 6. Contraindications to undergoing SE, including but not limited to; * Known cardiomyopathic process (Hypertrophic cardiomyopathy (HCM)) with resting gradient \> 50mmHg or severe valvular lesion * Severe uncontrolled hypertension (≥180/100mmHg) 7. Known pregnancy 8. Unable to provide informed consent