Inclusion criteria
1. Provision of written informed consent.
2. Aged 18-70 years, male or female.
3. Currently, \> 8 but ≤ 40 weeks after index percutaneous coronary intervention (PCI) .
4. Receiving dual antiplatelet therapy (DAPT) with aspirin (Bayaspirin TM) 100 mg once daily and clopidogrel (Plavix TM) 75 mg once daily for ≥ 7 days.
5. No cardiac ischemic events or bleeding events occurred after the index PCI.
* Cardiac ischemic events include myocardial infarction, coronary revascularization, and definite or probable stent thrombosis;
* Bleeding events include major or minor bleeding according to the Platelet Inhibition and Patient Outcomes (PLATO) definition.
6. PRECISE-DAPT score \< 25 evaluated after the index PCI and before the index hospital discharge.
7. Females who are either post-menopausal \> 1 year or surgically sterile.
Exclusion criteria
1. Use of berberine within 30 days of screening.
2. Use of any fibrinolytic or antithrombotic agents, with the exception of aspirin and clopidogrel, within 30 days of screening.
3. Any indications other than coronary artery disease (e.g., atrial fibrillation, prosthetic heart valve, venous thromboembolism, ventricular thrombosis, et al) for fibrinolytic or antithrombotic treatment during the study period.
4. Planned use of berberine, as well as any fibrinolytic or antithrombotic agents, with the exception of aspirin (Bayaspirin TM) and clopidogrel (Plavix TM), during the study period.
5. Planned use of moderate or strong cytochrome P450 (CYP) 2C19 inhibitors, CYP2C19 substrates with narrow therapeutic index, or strong CYP2C19 inducers during the study period.
6. Planned coronary revascularization, including PCI and coronary artery bypass graft (CABG) during the study period.
7. Increased bleeding risk, including
* any history of intracranial, intraocular, retroperitoneal, or spinal bleeding;
* recent (within 30 days of screening) gastrointestinal (GI) bleeding;
* recent (within 30 days of screening) major trauma or major surgery;
* planned surgery or other invasive procedure during the study period;
* sustained uncontrolled hypertension (systolic blood pressure \[SBP\] \> 180 mmHg or diastolic blood pressure \[DBP\] \> 100 mmHg);
* history of hemorrhagic disorders, e.g., haemophilia, von Willebrand's disease;
* inability to discontinue non-steroidal anti-inflammatory drugs (NSAIDs) during the study period;
* platelet count less than 100,000/mm3 or hemoglobin \< 10 g/dL.
8. Contraindications for aspirin, clopidogrel, and berberine, e.g., hypersensitivity, active bleeding, bleeding diathesis, coagulation disorders, severe liver or kidney diseases, hemolytic anemia, glucose-6-phosphate dehydrogenase deficiency, et al.
9. History of intolerance to aspirin, clopidogrel, and berberine.
10. Any condition, which in the opinion of the Investigator, would make it unsuitable for the patient to participate in this study. For example, conditions which may put the patient at risk, e.g., liver or kidney dysfunction, et al; or increase the risk of non-compliance to study protocol or follow-up, e.g., history of drug addiction or alcohol abuse, et al; or influence the result of the study, e.g., active cancer, et al.
11. Patients who has previously been randomized in this study.
12. Participation in another investigational drug or device study within 30 days of screening.
13. Involvement in the planning and conduct of the study (applies to investigators, contract research organization staff, and study site staff, et al).
