Inclusion Criteria:  Age≥75 years old; Treated with PCI (limited to stent implantation) ; Survivors and treated with DAPT (aspirin [100 mg once daily], cilostazol, or indobufen)combined with a P2Y12 receptor antagonist [clopidogrel (75 mg once daily) or ticagrelor (90 mg twice daily)]) at discharge;  Exclusion Criteria:  Coronary artery bypass graft (CABG) or only drug conservative treatment during hospitalization; Concurrent use of oral anticoagulants; Inability to tolerate long-term antiplatelet therapy, such as active bleeding and a bleeding tendency; Acute infectious diseases; Cognitive impairment; Declined re-examination.