1-month vs 12-month DAPT for ACS Patients Who Underwent PCI Stratified by IVUS: IVUS-ACS and ULTIMATE-DAPT Trials

Inclusion Criteria: Enrollment into the study will require meeting at least one of these clinical syndromes within 1 month. * Unstable angina, defined as rest pain for 5-30 minutes or deteriorative exertional angina with either a) transient ST segment depression or elevation, or b) angiography showing a visually estimated diameter stenosis ≥90% or a ruptured plaque or thrombotic lesion * Non-ST elevation myocardial infarction (NSTEMI), defined as positive troponin consistent with clinical syndrome. * ST elevation MI (STEMI) Exclusion Criteria: * Unable or unwilling to provide informed consent * Stroke within 3 months or any permanent neurologic deficit, and prior intracranial bleed, or any intracranial disease such as aneurysm or fistula * Previous coronary artery bypass graft (CABG) * Any planned surgery within 90 days * Any reason why any antiplatelet therapy might need to be discontinued within 12 months * Severe chronic kidney disease defined as an estimated glomerular filtration rate (eGFR) \< 20 ml/min/1.73m\^2 * Need for chronic oral anticoagulation (warfarin/coumadin or direct oral anticoagulants) * Platelet count \< 100,000 mm\^3 * Contraindication to aspirin * Contraindication to ticagrelor * Liver cirrhosis * Women of child-bearing potential * Life expectancy \< 1 year * Any condition likely to interfere with study processes including medication compliance or follow-up visits (e.g. dementia, alcohol abuse, severe frailty, long distance to travel for follow-up visits, etc.)