Inclusion Criteria:  CAD patients with available CZT-SPECT within 3 months of measuring FFR in the left anterior descending coronary artery (Cohort 1) INOCA patients and normal controls confirmed by CZT-SPECT and angiography (Cohort 2) Stable CAD patients received PCI (Cohort 3) analyzable angiograms at the index procedure  Exclusion Criteria:  Previous coronary artery bypass grafting Chronic total occlusion patients limited image quality of coronary angiography Insufficient angiographic project for TIMI frame count Severe tortuosity of target vessel No optimal projection for reconstruction