Intervention: Warfarin
Trial phase: Phase 2
ATC code: B01AA03
SMILES: CC(=O)CC(c1ccccc1)c1c(O)c2ccccc2oc1=O
Sex: All
Age groups: Adult | Older Adult
Healthy volunteers: No
Participants at risk: 90
Group description: Safety population : 90 (patients)

Patients allocated to warfarin receive warfarin plus aspirin 100mg until INR value exceed 1.7 followed by warfarin monotherapy with target INR value of 2.5 [2.0 - 3.0].

Warfarin: To harmonize the warfarin regimen across the sites, fixed algorithm was used in dose calculation, both loading and maintenance, and age, sex, ethnicity, race, weight, height, smoking history, presence of liver disease, indication, baseline INR, target INR and concomitant medication were considered as cofactors (http://www.warfarindosing.org/Source/InitialDose.aspx). Investigators will manage anticoagulation with warfarin per routine clinical care.
Eligibility criteria:
Inclusion Criteria: All of below

Acute ischemic stroke or TIA presumed to be cardioembolic origin (within 5 days from stroke onset) with mild severity: infarct size on DWI less than 1/3 of MCA territory, 1/2 of ACA territory, 1/2 of PCA territory, and 1/2 of one cerebellar hemisphere
Atrial fibrillation including paroxysmal atrial fibrillation: atrial fibrillation must be documented by ECG evidence (e.g., 12-lead ECG, rhythm strip, Holter, pacemaker interrogation) within 30 days before randomization. This could be obtained from a notation in the subject's record (e.g., medical chart, hospital discharge summary).
Age ≥19 years
Informed consent

Exclusion Criteria: Any of below

Chronic renal failure (GFR less than 30ml/min) or severe hepatic impairment
Significant hemorrhagic transformation (parenchymal hematoma type I or II by the ECASS definition)
Stroke mechanism of presumed small vessel occlusion: single small subcortical infarct in the perforating artery territory
Large hemispheric or cerebellar infarction; larger than 1/3 of MCA territory, 1/2 of ACA territory, 1/2 of PCA territory, and 1/2 of one cerebellar hemisphere
Mechanical valve requiring warfarin therapy
Active internal bleeding

Prior history of symptomatic intracranial bleeding

: patients with asymptomatic bleedings or microbleedings on MRI are eligible for inclusion

Major surgery or major trauma within 30 days that might be associated with increased bleeding risk
Clinically significant gastrointestinal bleeding within 6 months

Intravenous tissue plasminogen activator use or mechanical embolectomy within 48 hours plus 'significant hemorrhagic transformation as described above (exclusion criteria 2)' or 'large hemispheric infarction or cerebellar infarction as described above (exclusion criteria 4)'

: patients achieving successful reperfusion without hemorrhage nor large infarction are eligible for enrollment

Severe anemia: hemoglobin <10 g/dL
Bleeding diathesis; thrombocytopenia (<90,000/µL, prolonged PT (INR>1.7)
Sustained uncontrolled hypertension: SBP >180 mmHg or DBP >100 mmHg
Severe devastating illness, such terminal cancer, hepatic failure; therefore, the participants have a life expectancy less than 6 months.
Planned invasive procedure with potential for uncontrolled bleeding, including major surgery