Vertebrobasilar Flow Evaluation and Risk of Transient Ischemic Attack and Stroke (VERiTAS)

Inclusion Criteria: * Stroke or TIA in the vertebrobasilar territory * Conventional or CT angiographic demonstration of ≥50% stenosis or occlusion of extracranial or intracranial vertebrobasilar artery * Symptoms within 60 days of enrollment * Age 18 and above * Able to provide informed consent Exclusion Criteria: Neurologic criteria: * Major disabling stroke prohibiting the ability to return for follow-up assessment * Any neurological disease which would confound follow-up assessment Medical criteria: * Any severe co-morbidity condition with less than 12 month life expectancy * Known cardiac disease associated with cardioembolic risk specifically atrial fibrillation, prosthetic valves, endocarditis, left atrial/ventricular thrombus, cardiomyopathy with EF\<25%, cardiac myxoma * Blood dyscrasias, specifically polycythemia vera, essential thrombocytosis, sickle cell disease Disease criteria: * Non-atherosclerotic disease vertebrobasilar disease including dissection, fibromuscular dysplasia, vasculitis, radiation induced vasculopathy * Unilateral vertebral stenosis or occlusion Patient criteria: * Unable or unwilling to undergo MRI or cerebral angiography or CTA * Pregnancy concurrent participation in an interventional trial for treatment of vertebrobasilar disease. * Renal dysfunction will be exclusionary if it precludes angiography. No subjects will be excluded based upon gender, race, ethnic group, religion or socioeconomic status. Children will not be recruited as…