To compare low dose (1mg) pitavastatin and high dose (4mg) pitavastatin on neointimal hyperplasia and atherosclerosis progression by using optical coherence tomography (OCT) and near-infrared spectroscopy (NIRS) at 12 months follow-up and on clinical adverse cardiovascular events during 3-year follow-up.

• Patients with non-ST elevation ACS will be randomized into pitavastatin 1mg or 4mg after everolimus-eluting stent implantation with OCT and NIRS study.
• 12 months follow-up coronary angiography with OCT and NIRS will be performed to compare neointimal hyperplasia and atherosclerosis progression.
• 36 months clinical follow-up for major adverse cardiovascular events (cardiac death, all-cause death, myocardial infarction, stroke, target lesion revascularization) will be compared.
• Safety issues such as bleeding rates, abnormal liver function will be compared

Inclusion Criteria:

1. Provision of informed consent prior to any study specific procedures
2. Patients between the age of 30 to 79
3. Non-ST elevation Acute coronary syndrome with successful everolimus eluting stent implantation (with TIMI flow grade 3 after the procedure)

Exclusion Criteria:

1. Hypersensitivity to pitavastatin
2. Unable to perform OCT and NIRS
3. Serum creatinine > 2.0 mg/dL.
4. Steroid or hormone replacement therapy
5. Hemoglobin A1c >9%
6. Type 1 diabetes
7. Decreased serum platelet level (< 100,000/uL)
8. Need for chronic oral anticoagulant therapy or chronic low-molecular-weight heparin
9. Life expectancy less than a year
10. Renal failure requiring dialysis or anticipated need for dialysis during the course of the study
11. Any condition which in the opinion of the investigator would make it unsafe or unsuitable for the patient to participate in this study
12. Involvement in the planning and/or conduct of the study
13. Left ventricular ejection fraction < 40%
14. Hepatic dysfunction (aspartate aminotransferase or alanine aminotransferase > twice the upper limit)
15. Gastrointestinal disorder such as Crohn's disease
16. Alcohol abuse
17. Known pregnancy, breast-feeding, or intend to become pregnant during the study period