• ① Subject must be at least 19 years of age

• ② Subject who can verbally confirm understandings of risks, benefits and treatment alternatives and he/she or his/her legally authorized representative provides written informed consent prior to any study related procedure

• ③ Patients undergoing elective PCI as follows:

‣ True bifurcation lesion (Medina 1,1,1/1,0,1/0,1,1) with side branch ≥2.5 mm size

⁃ Chronic total occlusion (≥3 months) as target lesion

⁃ PCI for unprotected left main disease (left main ostium, body, or distal bifurcation including non-true bifurcation lesions)

⁃ Long coronary lesions (expected stent length ≥38 mm)

⁃ Multi-vessel PCI (≥2 vessels treated at one PCI session)

⁃ Multiple stent needed (≥3 stents per patient)

⁃ In-stent restenosis lesion as target lesion

⁃ Severely calcified lesion (encircling calcium in angiography)

⁃ Ostial lesions of left anterior descending artery, left circumflex artery, or right coronary artery