Ticagrelor Versus Clopidogrel in Left Ventricular Remodeling After ST-segment Elevation Myocardial Infarction

Inclusion Criteria: * 18 years and older. * First-time onset STEMI patients uneventfully treated with primary PCI within 12 hours of onset of symptom. * Infarct-related artery with TIMI 0, 1, or 2 grade flow at the time of initial diagnostic angiography (before wire passage). * proximal or mid-portion lesion of epicardial coronary artery. Exclusion Criteria: * Previous history of myocardial infarction. * Left bundle branch block on ECG at the time of screening. * Cardiogenic shock at the time of randomization. * Refractory ventricular arrhythmias or atrial fibrillation. * New York Heart Association class IV congestive heart failure. * Severe or malignant hypertension (SBP\> 180 and/or DBP\> 120 mmHg). * Fibrinolytic therapy. * History of hemorrhagic stroke. * Intracranial neoplasm, arteriovenous malformation, or aneurysm. * Ischemic stroke within 3 months prior to screening. * Platelet count \< 100,000/mm3 or hemoglobin \< 10 g/dL. * A need for oral anticoagulation therapy that cannot be safely discontinued for the duration of the study. * Women who are known to be pregnant, have given birth within the past 90 days, or are breast-feeding. * Unable to cooperate with protocol requirements and follow-up procedures. * A history of P2Y12 receptor inhibitor pretreatment (at least prior 1 month). * An increased risk of bradycardia. * Concomitant therapy with a strong cytochrome P-450 3A inhibitor or inducer.