Inclusion Criteria- Patients who had received long-term clopidogrel therapy (once a day for at least one month) with a minimum one-month interval between enrollment and the last cerebral ischemic or TIA event.
- Males and females aged 20 years or older who were prescribed clopidogrel for the secondary prevention of cerebral infarction or transient ischemic attack and who were willing and able to give written informed consent.
Exclusion Criteria- Malignancies
- Congenital bleeding tendency
- Atrial fibrillation
- Concomitant use of an oral anticoagulant agent
- a platelet count of < 100 x 109/L or > 450 x 109/L within 3 months of enrollment
- Modified rankin scale > 4