Risk Characterization of Non-culprit Vessels in Patients Undergoing Primary PCI for ST-elevation MI in Multivessel Disease

Inclusion Criteria: 1. Ability to provide written informed consent (post PPCI) 2. Age 18 years to 85 years 3. Presentation of acute STEMI within 12 hours of symptom on-set 4. Culprit artery PPCI 5. Coronary stenosis of \> 50% diameter stenosis by visual estimation in NIRA with a minimum diameter of 2.5mm Exclusion Criteria: 1. Cardiogenic shock 2. Decompensated heart failure requiring intubation, inotropes, or intra-aortic balloon counter pulsation 3. Refractory ventricular arrhythmia 4. Previous coronary artery bypass surgery (CABG) 5. Stent thrombosis and in stent restenosis 6. An intention before inclusion into the study to revascularize a non-culprit lesion 7. Active malignancy or inflammatory disorders such as rheumatoid arthritis or inflammatory bowel disease 8. Severe valvular heart disease requiring surgery 9. Planned surgical revascularisation 10. Active participation in another study/trial 11. \< 12 months life expectancy 12. Contraindication to CTCA * Presence of internal defibrillator * Known allergy to iodinated contrast * Pregnancy * Contraindication to intravenous beta blockade * Contraindication to acute sublingual nitrate administration * Mechanical prosthetic heart valve * Advanced renal impairment (creatinine \>200) * Significant valve disease (sever aortic stenosis or regurgitation; severe mitral regurgitation) Angiographic exclusion criteria 1. NIRA stenosis of 50% or more in the left main stem or the ostia of both the left anterior descending and circumflex arteries 2. \< TIMI (thrombolysis in myocardial infarction) flow grade 3 in the NIRA, 3. Evidence of thrombus in the NIRA.