Prognosis of patients with symptomatic vertebral or basilar artery stenosis. The Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) Study Group.

BACKGROUND AND PURPOSE There are limited data on the prognosis of patients with angiographically proved symptomatic stenosis of the intracranial vertebral artery or basilar artery. METHODS We studied 68 patients with 50% to 99% stenosis of one of the following arteries: intracranial vertebral (n = 31), basilar (n = 28), posterior cerebral (PCA) (n = 6), or posterior inferior cerebellar (PICA) (n = 3). All patients had previous transient ischemic attack or stroke in the territory of the stenotic artery and were treated with warfarin (n = 42) or aspirin (n = 26). Follow-up was by chart review and personal or telephone interview. RESULTS During a median follow-up of 13.8 months, 15 patients (22%) had an ischemic stroke (4 fatal), 3 patients (4.5%) had a fatal myocardial infarction (MI) or sudden death, and 6 patients (9%) had a nonfatal MI. Stroke rates in any vascular territory (per 100 patient-years of follow-up) were 15.0 in patients with basilar artery stenosis, 13.7 in patients with vertebral artery stenosis, and 6.0 in patients with PCA or PICA stenosis. Stroke rates in the same territory as the stenotic artery (per 100 patient-years of follow-up) were 10.7 in patients with basilar artery stenosis, 7.8 in patients with vertebral artery stenosis, and 6.0 in patients with PCA or PICA stenosis. CONCLUSIONS Patients with symptomatic intracranial vertebral artery or basilar stenosis are at high risk of stroke, MI, or sudden death. Further studies are needed to clarify optimal therapy for these patients.