Inclusion Criteria:
Case group (IR-CAD patients):
1. 18 years of age or older, male or female.
2. Negative results of urine or blood pregnancy test for females with childbearing potential (not post-menopausal or surgically sterile).
3. Prior history of coronary revascularization (PCI or coronary artery bypass graft \[CABG\]).
4. Receiving standard treatment for secondary prevention of AS-CAD after the last coronary revascularization.
5. Hospitalization due to rapidly-progressive myocardial ischemia:
* Typical symptoms of angina (Canadian Cardiovascular Society \[CCS\] III-IV) and non-invasive evidence of myocardial ischemia; and
* Occurred within 6 months or occurred on immunosuppressive therapy within 12 months of the last coronary revascularization.
6. Angiographic evidence of new coronary lesions (de novo stenosis or restenosis) considered to be relevant to myocardial ischemia.
7. Evidence of inflammation:
* At least one of the indexes indicating active inflammation has ever been elevated (ESR, high-sensitivity C-reactive protein \[hs-CRP\], interleukin \[IL\]-6, tumor necrosis factor \[TNF\]-α, ferritin, et al); or
* Established diagnosis of systemic autoimmune disease or systemic vasculitis; or
* Receiving immunosuppressive therapy.
Control group (AS-CAD patients):
1. ≥ 45 and \< 65 years of age (based on the age distribution of the patients currently enrolled in the IR-CAD cohort study), male or female.
2. Negative results of urine or blood pregnancy test for females with childbearing potential (not post-menopausal or surgically sterile).
3. Currently, 12±6 months after the last PCI.
4. Receiving standard treatment for secondary prevention of AS-CAD after the last PCI.
5. Coronary angiography and/or optical coherence tomography (OCT) performed during the present hospitalization.
6. No evidence of rapidly-progressive myocardial ischemia, which is defined as follows:
* Typical symptoms of angina (Canadian Cardiovascular Society \[CCS\] III-IV) and non-invasive evidence of myocardial ischemia; and
* Occurred within 6 months or occurred on immunosuppressive therapy within 12 months of the last PCI.
7. No angiographic evidence of new coronary lesions (de novo stenosis or restenosis) considered to be relevant to myocardial ischemia.
Exclusion Criteria:
Case group (IR-CAD patients):
1. Coronary restenosis due to mechanical factors (stent under-expansion, stent mal-apposition, stent rupture, et al).
2. Other moderate to severe heart diseases (congenital heart disease, valvular heart disease, myocarditis, cardiomyopathy, pericardial diseases, pulmonary hypertension, heart failure, arrhythmia, et al).
3. Active acute or chronic infection (human immunodeficiency virus \[HIV\], tuberculosis, et al).
4. Active malignancy (diagnosed within 12 months or with ongoing requirement for treatment).
5. Vital organ failure.
6. Life expectancy \< 1 year.
7. Contraindications for or intolerance to treatment for secondary prevention of AS-CAD, contrast agents, glucocorticoids, immunosuppressive agents.
8. In pregnancy or breast-feeding, or with intention to be pregnant during the study period.
9. Risk of non-compliance (history of drug addiction or alcohol abuse, et al).
10. Previous enrollment in this study.
11. Participation in another study within 30 days.
12. Involvement in the planning and conduct of this study (applying to investigators, contract research organization staffs, study site staffs, et al).
13. Any condition, which in the opinion of the investigators, would make it unsuitable for the patient to participate in this study.
Control group (AS-CAD patients):
The same as those for the case group (IR-CAD patients).
