The presence of coronary atherosclerotic vulnerable plaque significantly impacts the clinical outcomes of patients diagnosed with coronary artery disease (CAD). However, the influence of PCSK9 inhibitors on stabilizing coronary atherosclerotic plaques in individuals with early-onset CAD, evaluated through optical coherence tomography (OCT), remains inadequately understood. Moreover, there is a notable absence of relevant randomized controlled trials investigating this phenomenon. This current study represents a single-center, randomized, controlled, open-label trial conducted among Asian patients with early-onset CAD. Its principal objective was to explore the effects of PCSK9 inhibitors on coronary atherosclerotic plaque morphology as assessed by OCT.

Following initial percutaneous coronary intervention (PCI) for culprit lesions in patients with early-onset coronary artery disease (CAD) and ≥2 additional lesions meeting baseline lipid criteria, optical coherence tomography (OCT) was employed to evaluate non-culprit lesion sites for detailed characterization of plaque features including calcification, fibrosis, fibrolipid deposition, necrosis, minimum fibrous cap thickness (mFCT), and maximum lipid arc (MLA). Subsequently, patients were randomized in a 1:1 ratio to receive either intensive statin therapy alone or a combination of PCSK9 inhibitor with moderate-intensity statin therapy, using a random number allocation method. After 1 year of treatment and follow-up, OCT reassessment of non-culprit vessel critical lesions was conducted, documenting plaque characteristics such as calcification, fibrosis, fibrolipid content, necrosis, as well as stability parameters like mFCT and MLA at lesion sites. OCT findings were compared longitudinally within each treatment group and between groups receiving PCSK9 inhibitor combined with statin therapy versus intensive statin therapy alone. Baseline clinical profiles, biochemical markers, imaging findings, and incidence of adverse cardiovascular events during the follow-up period were also meticulously recorded for all enrolled early-onset CAD patients.

Inclusion Criteria:

• Men aged 18-55 years and women aged 18-65 years;
• CAD patients with coronary angiographically confirmed lesions in ≥2 vessels; at least one vessel was critically diseased (50-70% stenosis level);
• LDL-C >3.4 mmol/L without regular statin therapy or LDL-C >1.8 mmol/L after 4 weeks of statin lipid-lowering therapy.

Exclusion Criteria:

• Known allergies or contraindications to PCSK9 inhibitors and/or statin therapy;
• Prior use of PCSK9 inhibitors;
• Prior history of hemorrhagic stroke;
• Prior coronary artery bypass grafting or coronary intervention;
• Inability to perform OCT imaging or unclear imaging;
• Severe renal insufficiency (creatinine clearance < 30 mL/min);
• Severe hepatic dysfunction;
• Baseline triglycerides > 5.6 mmol/L;
• Pregnant or lactating women;
• Life expectancy not exceeding 1 year;
• In the judgment of the investigator, unsuitable for this study for any reason.

IPD will be made available on reasonable request to the official agencies.