The purpose of this study is to verify whether additional administration of Alirocumab exerts a stronger stabilizing effect on the vulnerable plaque in CAD, compared with statin alone administration in patients receiving PCI. Therefore, the change in maxLCBI (4 mm) of the coronary artery 9 months after administration by addition administration of Alirocumab is evaluated as the main evaluation item as compared with statin administration alone for patients who have CAD and received PCI. Also, change of plaque properties is compared with baseline and evaluated. This study is a single-center, randomized, open-label study, using alirocumab, rosuvastatin as test drugs. Based on the findings obtained in this study, it is possible to clarify the mechanism of stabilization of the plaque in a patient with coronary artery disease, which in turn suppresses the progress of plaque in coronary artery disease, resulting in primary or secondary There is a possibility that it can contribute to prevention.

The investigators investigate the change in the maxLCBI (4 mm) value calculated by NIRS-IVUS at the time of PCI and at the treatment evaluation after 9 months compared with the group of Alirocumab(Alirocumab75mg/2week+losuvastatin10mg/daily) and standard treatment (losuvastatin10mg/daily alone). And also the investigators evaluate LCBI(lesion), Angle of a lipid core, EEM CSA, Lumen CSA, Minimum lumen diameter, Plaque burden, Lesion length by NIRS-IVUS.

Inclusion Criteria:

• Patients who underwent PCI for ACS or stable coronary heart disease
• Patients with LDL-C ≥70 mg/dL under daily 10mg rosuvastatin
• Patients who remained 25-75% stenosis with coronary angiography
• Patients who obtained analyzable images and calculated maxLCBI (4 mm) with NIRS-IVUS
• Patients aged ≥20 years old at PCI
• Patients who agree to be enrolled in the trial give signed written informed consent

Exclusion Criteria:

• Patients who have been treated previously with at least one dose of any anti-PCSK9 monoclonal antibody
• Patients had uncontrolled hypertension (systolic blood pressure >180 mmHg or diastolic blood pressure >110 mmHg) between the time of PCI and randomization visit
• Known hypersensitivity to alirocumab or rosuvastatin
• All contraindications to alirocumab and/or rosuvastatin as displayed in the respective national product labeling for these treatments
• Known history of hemorrhagic stroke
• Currently under treatment for cancer
• Patients on lipoprotein apheresis
• Patients with severe liver or renal dysfunction
• Pregnant or breastfeeding women
• Patients recognized as inadequate by attending physician