This study is a prospective randomized trial to evaluate and compare the quantitative and qualitative characteristics of neointimal formation between high and low efficacy statin treatment after drug eluting stent (DES) implantation, in patients with homogeneous or heterogeneous neointimal pattern accessed by Optical Coherence Tomography (OCT). The investigators postulate that high efficacy statin could have superior effect on modification of neointimal pattern, compared with lower efficacy statin. Our main hypothesis is that Atorvastatin 40mg, high efficacy statin might have superior effect on modification of neointimal pattern evaluated by serially followed OCT, compared with pravastatin 20mg in patients with DES implantation.

Inclusion Criteria:

• Patient is ≥ 20 years old
• Patients who received OCT related to clinical needs or the end point of other study
• Patients who received DES within 1 year before OCT evaluation
• Patients with homogenous or hetero neointimal pattern by OCT
• Non-statin user and moderate or low efficacy statin user

Exclusion Criteria:

• Refuse to participate
• Contraindication to statin treatment
• Women with current or potential childbearing
• Life expectancy <1 year
• High efficacy statin user (Atorvastatin 80mg or Rosuvastatin 20mg)