OCT Versus Angiography for Culprit Lesion Revascularization in Acute Myocardial Infarction PatiEnts

Inclusion Criteria: * Subject must be at least 19 years of age * Acute ST-segment elevation myocardial infarction (STEMI) \*STEMI: ST-segment elevation ≥0.1 mV in ≥2 contiguous leads or documented newly developed left bundle-branch block1 * Primary percutaneous coronary intervention (PCI) in \< 12 h after the onset of symptoms for STEMI patients * Subject is able to verbally confirm understandings of risks, benefits and treatment alternatives of receiving invasive physiologic evaluation and PCI and he/she or his/her legally authorized representative provides written informed consent prior to any study related procedure. Exclusion Criteria: * Target lesions not amenable for PCI by operators' decision * Ostial lesions located in left main vessel or right coronary artery (left main body or distal bifurcation lesions can be enrolled by operator's discretion) * Creatinine clearance ≤30 ml/min/1.73 m2 and not on dialysis (chronic dialysis dependent patients are eligible for enrolment regardless of creatinine clearance) * Cardiogenic shock (Killip class IV) at presentation * Intolerance to Aspirin, Clopidogrel, Prasugrel, Ticagrelor, Heparin, or Everolimus * Known true anaphylaxis to contrast medium (not allergic reaction but anaphylactic shock) * Pregnancy or breast feeding * Non-cardiac co-morbid conditions are present with life expectancy \<2 year or that may result in protocol non-compliance (per site investigator's medical judgment) * Unwillingness or inability to comply with the procedures described in this protocol