This project aims to establish a clinical cohort and diagnostic assessment framework by conducting a national multicenter cohort registry study. Through the collection of patients' clinical characteristics, it will achieve the registration, management, follow-up, and analysis of patients with Rapid rEcurrences of Coronary Unexplained in-stent Restenosis (RECUR).

Inclusion Criteria:

1. Age ≥ 18 years;
2. Patients meeting the diagnostic criteria for Rapid rEcurrences of Coronary Unexplained in-stent Restenosis (RECUR);
3. Patients fully informed about the trial procedures who provide written informed consent.

Exclusion Criteria:

1. Patients presenting with any of the following:

   • Other severe comorbidities (e.g., malignant tumors, heart failure) with a life expectancy <12 months;

     • Known autoimmune/rheumatic diseases including systemic lupus erythematosus, Takayasu arteritis, Behçet's disease, polyarteritis nodosa, Wegener granulomatosis (granulomatosis with polyangiitis), eosinophilic arteritis, giant cell arteritis, rheumatoid arthritis, or IgG4-related disease;

       • Variant angina (Prinzmetal's angina);

         • Coronary artery dissection;

           • Thrombophilia;

             • Stent underexpansion.

2. Presence of psychiatric disorders;

3. Known inability to complete expected study follow-up for any reason;

4. Patients deemed ineligible for enrollment by the investigator.

Patients who meet the definition of Rapid rEcurrences of Coronary Unexplained in-stent Restenosis (RECUR), that is, patients who have undergone myocardial infarction or target vessel-related revascularization ≥3 times due to coronary artery stenosis in the past year after coronary stent implantation and standard coronary heart disease conventional treatment (complete revascularization and optimal medical therapy), excluding common risk factors for coronary artery restenosis and known rheumatic autoimmune diseases, systemic vasculitis, etc.

Study protocol, clinical study report can be shared.