Prospective, observational, single-center cohort study Hypothesis Higher myocardial FAPI uptake in CTO patients predicts a greater incidence of major adverse cardiovascular events (MACE) within 12 months after PCI. FAPI PET/CT imaging is associated with plaque vulnerability features and may serve as a non-invasive marker for fibrotic activity and adverse cardiac remodeling. Inclusion Criteria * Age ≥ 18 years * Presence of at least one untreated chronic total occlusion (CTO) lesion in a major coronary artery (diameter ≥ 2.5 mm, TIMI 0 flow for ≥ 3 months) confirmed by coronary angiography or CTCA * Patient eligible for PCI and undergoing FAPI PET/CT imaging prior to intervention * Written informed consent provided Exclusion Criteria * Allergy or contraindication to antiplatelet agents (aspirin, clopidogrel, or ticagrelor) * Severe liver dysfunction (liver enzymes \>3× upper limit of normal) * Severe chronic kidney disease (eGFR \< 30 mL/min/1.73 m²) * Estimated life expectancy \< 1 year * Pregnancy or potential for pregnancy Primary Endpoint Incidence of 1-year MACE, defined as a composite of: Cardiac death, Myocardial infarction, Stroke, Urgent revascularization Secondary Endpoints * All-Cause Mortality * Death from any cause within 12 months * Quality of Life Change: Measured by Seattle Angina Questionnaire (SAQ): changes in angina frequency, physical limitation, and treatment satisfaction * Repeat PCI Events: Incidence of: In-stent restenosis (ISR): ≥50% luminal loss in previously stented segment; Target lesion revascularization (TLR): at original PCI lesion; Target vessel revascularization (TVR): other sites in same vessel; De novo lesions: new lesions not previously treated Sample Size Estimated 470 patients Follow-Up Duration 12 months post-PCI, One follow-up visit including clinical exam, SAQ questionnaire, imaging (PET/CT, echocardiography), and laboratory testing.