OPTIMIZE-APT: Tailored Versus Conventional Antiplatelet Therapy After Intravascular Imaging-guided Drug-eluting Stent Implantation

Objectives: To assess the safety of tailored antiplatelet therapy (short DAPT followed by P2Y12 inhibitor alone strategy) in patients who received optimized DES implantation guided by intravascular imaging (IVUS or OCT) Hypothesis: Tailored antiplatelet strategy (short DAPT followed by P2Y12 inhibitor alone) is superior to conventional antiplatelet strategy in terms of clinically relevant bleeding and noninferior for ischemic composite adverse events in patients who received intravascular imaging-guided optimized DES implantation. (Optimized stent evaluated by on-site IVUS/OCT could act as an essential criterion for decision making for tailored antithrombotic strategy)

Inclusion Criteria: 1. Men or women ≥19 years 2. Typical chest pain or objective evidence of myocardial ischemia suitable for PCI 3. Significant de novo coronary artery lesions suitable for DES implantation 4. Patients who underwent optimized stent implantation either by IVUS or OCT * Using IVUS * MSA \>5.5 mm2, or MSA \>90% of the MLA at the distal reference segment * Plaque burden \4.5 mm2, or MSA \>90% of the MLA at the distal reference segment * No significant malapposition * No significant edge dissection†; thrombus or plaque protrusion occupying \< 10% of the stent area (\*Significant malapposition is defined as strut separation ≥ 0.3 mm from the vessel wall extending over a length \> 3 mm. †Significant dissection is defined as a dissection penetrating the medial layer and extending over more than one quadrant.) 5. The patient or guardian agrees to the study protocol and the schedule of clinical follow-up, and provides informed, written consent, as approved by the appropriate Institutional Review Board/Ethical Committee of the respective clinical site Exclusion Criteria: 1. Angiographic exclusion criteria: any of the followings 1. Bypass graft lesions 2. Lesions in which impaired delivery of imaging catheters is expected: * Extreme angulation (≥90°) proximal to or within the target lesion. * Excessive tortuosity (≥ two 45° angles) proximal to or within the target lesion. * Heavy calcification proximal to or within the target lesion. 2. In-stent restenosis 3. Hypersensitivity or contraindication to device material and its degradants and cobalt, chromium, nickel, platinum, tungsten, acrylic and fluoro polymers that cannot be adequately pre-medicated. 4. Persistent thrombocytopenia (platelet count \