Inclusion Criteria1. Patients 20 years and older with acute stroke and treated with oral apixaban within 14 days after onset.
2. Patients who are hospitalized in a period from Oct 1, 2014 to Feb 28, 2018
3. Patients with acute cerebral large vessel occlusion or stenosis (> 50%)
4. Patients with non-valvular atrial fibrillation
5. Patients who are not confirmed ICH by MRI or CT within 24 hours after r-tPA infusion.
Exclusion Criteria1. Patients who are considered to be ineligible for the study participation by the investigator.
2. Patients who are pregnant or potentially pregnant.
3. Patients who have a history of hypersensitivity to apixaban
4. Patients with hepatic disease having coagulation disorder and clinically important bleeding risk
5. Patients with renal failure (creatinine clearance < 15 mL/min) 6）Patients with Active pathological bleeding including intracranial bleeding of any type