The purpose of this study is to evaluate the efficacy and safety of 5mg maintenance dose (MD) of prasugrel in patients with acute myocardial infarction (AMI) who underwent percutaneous coronary intervention (PCI) with BiomatrixTM stent.

About 1400 patients derived from Korean patients with acute coronary syndrome (ACS) receiving percutaneous coronary intervention (PCI) with BES(Biolimus-eluting stent, BiomatrixTM) in a routine manner will be enrolled in the investigators trial.

These patients will be randomized 1:1 to either prasugrel 5mg once daily MD or clopidogrel 75mg once daily MD after successful PCI with BES .

The investigators excluded the patients with age ≥75 years, body weight <60 kg, or history of TIA (transient ischemic attack) or stroke. Follow-up data will be collected until 1-year after index procedure.

Primary efficacy end-point defined as the composite of cardiac death, non-fatal MI, stent thrombosis and ischemic driven target vessel revascularization and safety end-points as BARC (the Bleeding Academic Research Consortium) type ≥ 2 bleeding.

Inclusion Criteria:

• Patients who can undergo percutaneous coronary intervention with Biomatrix stent with no history of TIA or stroke,
• 75 years old or younger,
• body weight of 60 kg or more and diagnosed with acute coronary syndrome

Exclusion Criteria:

• Patients with history of TIA or stroke,
• 75 years old or older,
• body weight of 60 kg or under,
• hypersensitivity to or contraindicated for heparin, aspirin, clopidogrel, prasugrel or contrast media