Effects of Postconditioning On Myocardial Reperfusion

Inclusion Criteria General Inclusion Criteria * Subject must be at least 18 years of age. * Subject is able to verbally confirm understandings of risks, benefits and treatment alternatives of receiving postconditioning and he/she or his/her legally authorized representative provides written informed consent prior to any study related procedure * Diagnosis of STEMI 1. presence of chest pain for more than 30 minutes but less than 12 hours after symptom onset 2. ST-segment elevation more than 1 mm in at least 2 contiguous leads Angiographic Inclusion Criteria * Target lesion(s) must be located in a native coronary artery * Target lesion(s) must be amenable for percutaneous coronary intervention * TIMI flow grade of infarct related arteries \<2 General Exclusion Criteria * Patients with hemodynamic instability or those with cardiogenic shock * Target lesion is located in left main stem * Rescue PCI after thrombolysis or facilitated PCI * Non-cardiac co-morbid conditions are present with life expectancy \<1 year or that may result in protocol non-compliance (per site investigator's medical judgment) * Female of childbearing potential, unless a recent pregnancy test is negative, who possibly plan to become pregnant any time after enrollment into this study