The purpose of this study is to evaluate the feasibility, safety, and effectiveness of EndeavorTM ResoluteTM and Xience VTM stent implantation in patients with restenosis following drug-eluting stent (DES) implantation. The investigators will evaluate clinical, angiographic and intravascular ultrasound (IVUS) assessment of 9-month efficacy of EndeavorTM ResoluteTM or Xience VTM implantation in DES restenosis and assess the vascular changes of re-treatment with DES for DES restenosis using follow-up IVUS analysis. In addition, the investigators will evaluate the effectiveness of retreatment with EndeavorTM ResoluteTM or Xience VTM stent implantation in patients with restenosis after DES

Inclusion Criteria:

• In-stent restenosis (over 50% by quantitative angiographic analysis) following all types of DES; only insegment restenotic lesions without ISR are not included
• Evidence of myocardial ischemia due to restenosis (e.g., stable, unstable angina, recent infarction, silent ischemia, positive functional study or a reversible changes in the ECG with or without ischemia) or over 70% by quantitative angiographic analysis
• Repeat revascularization, needed with another stent (single stent implanted lesion, lesion length no more than 28mm )
• IVUS available lesions
• Non-emergent conditions
• Patients confirmed about study enrollment and 9 month followup angiogram and IVUS

Exclusion Criteria:

Lesion & Procedural exclusion criteria

• IVUS unavailable lesion

• Restenotic lesions following PCI of de novo lesion like as below;

  • left main lesions
  • BMS restenotic lesion
  • vein graft lesion

• Restenotic lesions following 2.25mm DES implantation

• Prior history of repeat DES implantation for DES restenosis (only conventional or cutting ballooning treatment for DES restenosis is included in this study)

• Simultaneous implantation of different types of DES on restenotic or another de novo lesions (Only same DES implantation is allowed on the restenotic or another de novo lesions)

• Patients with little possibility of performing follow-up angiogram and IVUS

General exclusion criteria

• Contraindication to anti-platelet agents & Bleeding history within prior 3 months
• Prior history or current presentation of DES thrombosis
• Age over 80 years
• Known hypersensitivity or contraindication to any of the following medications: Heparin, Aspirin, Clopidogrel, Zotarolimus, Everolimus
• Severe hepatic dysfunction (3 times normal reference values)
• Serum creatinine level over 2.0 mg/dL or end-stage renal diseases on dialysis
• LVEF less than 30%
• Pregnant women or women with potential childbearing
• An elective surgical procedure is planned that would necessitate interruption of clopidogrel during the first 9 months
• Life expectancy 1 year