Background and Purpose: The prevalence of atherosclerotic disease of extracranial vertebral artery and associated long-term outcomes in patients with stenosis of the internal carotid artery (ICA) are not well defined.
Methods: We ascertained the rates of any stroke, vertebrobasilar stroke, and all-cause mortality over 5 years associated with various categories of extracranial vertebral artery disease based on angiographic severity (<30%, 30-69%, 70-99%, and occlusion) in patients with symptomatic ICA stenosis who participated in the North American Symptomatic Carotid Endarterectomy Trial (NASCET). We also studied the relative benefit of carotid endarterectomy in reduction of ipsilateral stroke in patients with various categories of extracranial vertebral artery disease after adjusting for age, gender, and severity of ICA stenosis.
Results: Among the 798 patients who underwent angiographic catheterization of extracranial vertebral artery, the severity of stenosis was categorized as <30% (n=342), 30-69% (n=164), 70-99% (n=70), and occlusion (n=30). Compared with those with stenosis <30%, the relative risk of any stroke was similar between those with 30-69% (relative risk (RR) 1.1, 95% confidence interval [CI] 0.9-1.3 ), 70-99% (RR 0.9, 95% CI 0.7-1.3), and occlusion (RR 1.2, 95% CI 0.8-1.9) after adjustment for age, gender, severity of ICA stenosis, and allocated treatment (endarterectomy versus medical treatment). The relative risk of vertebrobasilar stroke was two folds higher in patients with extracranial vertebral artery stenosis 70-99% compared with those with <30% stenosis (RR 2.1, 95% CI 0.8-5.2) after adjusting for potential confounders. The relative benefit of carotid endarterectomy over medical treatment was similar according to categories of extracranial vertebral artery disease: <30% (RR 0.6, 95% CI 0.3-0.9), 30-69% (RR 0.3, 95% CI 0.2-0.9), 70-99% (RR 0.6, 95% CI 0.2-2.4), and occlusion (RR 0.4, 95% CI 0.07-2.9)
Conclusions: The increased risk of vertebrobasilar stroke in patients with symptomatic ICA stenosis who have concurrent extracranial vertebral artery disease supports critical evaluation of additional endovascular treatment options in such patients.