Lead Sponsor: Columbia University

Collaborators: Bristol-Myers Squibb, National Institute of Neurological Disorders and Stroke (NINDS), Pfizer, Medical University of South Carolina, University of Cincinnati, Roche Pharma AG, University of Washington, Weill Medical College of Cornell University

Intervention / Treatment: DRUG: Aspirin, DRUG: Apixaban

Lead Sponsor: Johns Hopkins University

Collaborators: Genentech, Inc., National Institute of Neurological Disorders and Stroke (NINDS), Emissary International LLC

Intervention / Treatment: DRUG: rt-PA