This multicenter observational study investigates whether lipid and lipoprotein subfractions measured by Vertical Auto Profile (VAP) are associated with coronary in-stent restenosis after percutaneous coronary intervention (PCI). The study includes a retrospective cross-sectional component in patients with prior PCI who undergo repeat coronary angiography and a prospective follow-up component in patients undergoing index PCI. Serum samples obtained from routine clinical blood collection will be used for VAP testing without additional blood draws.

This is a multicenter observational cohort study designed to evaluate the association between VAP-measured lipid and lipoprotein subfractions and in-stent restenosis (ISR) after PCI across ASCVD risk strata.

The study includes two components.

Retrospective cross-sectional component:

Adults aged 18 years or older with prior successful implantation of second-generation drug-eluting stents who undergo repeat coronary angiography at participating centers will be screened. Eligible participants must have complete clinical data for ASCVD risk assessment, available stored serum samples for VAP testing, and angiographic data sufficient to determine ISR status. ISR is defined as >=50% stenosis in the stent-related lumen at repeat coronary angiography. Secondary outcomes in this component include multiple-lesion ISR and multivessel ISR.

Prospective follow-up component:

Adults aged 18 years or older undergoing index PCI at participating centers will be enrolled prospectively. Eligible participants must have complete clinical data for ASCVD risk assessment, serum samples available from routine clinical blood collection, and written informed consent when required by the local ethics committee. Participants will be followed until repeat coronary angiography or ISR-related clinical events. The primary outcome is angiographic ISR, defined as >=50% stenosis in the stent-related lumen at follow-up angiography. Secondary outcomes include target lesion revascularization within 1 year and ISR-related major adverse cardiovascular events within 1 year, including cardiac death, target-vessel myocardial infarction, and target lesion revascularization.

VAP testing will assess lipid and lipoprotein subfractions, including LDL subfractions, IDL, VLDL, HDL subfractions, lipoprotein(a), and remnant lipoprotein particles. Serum samples are obtained from routine clinical blood collection and sample reuse, and no additional venipuncture is required for study participation.

Inclusion Criteria:

Retrospective cross-sectional component:

• Age >=18 years
• Prior successful implantation of second-generation drug-eluting stents
• Repeat coronary angiography available at a participating center
• Complete data available for ASCVD risk assessment
• Stored serum sample available for VAP testing
• Angiographic data sufficient to determine ISR status

Prospective component:

• Age >=18 years
• Undergoing index PCI
• Planned routine follow-up coronary angiography
• Complete data available for ASCVD risk assessment
• Serum sample available from routine clinical blood collection
• Able to provide written informed consent and any required privacy authorization

Exclusion Criteria:

• Severe hepatic dysfunction (ALT or AST >3 x ULN or Child-Pugh class C)
• Prior CABG with angioplasty performed in a non-native vessel
• In-stent restenosis occurring within 1 month after PCI
• Expected survival <1 year (prospective component)

Adults with coronary artery disease/ASCVD undergoing prior PCI with repeat coronary angiography or undergoing index PCI at participating centers, with clinical data sufficient for ASCVD risk assessment and serum samples available for VAP-based lipid and lipoprotein subfraction testing.