Outcome of asymptomatic patients with carotid disease. Asymptomatic Cervical Bruit Study Group.

Asymptomatic cervical atherosclerosis carries a variable risk of vascular events. We sought to identify patients with asymptomatic cervical bruits who may be at increased risk of developing ischemic events. We conducted a prospective multicenter cohort study of neurologically asymptomatic patients presenting a cervical bruit. Patients had biannual neurologic and carotid duplex evaluation. Association between ultrasonographic findings and vascular events, adjusting for common risk factors, was evaluated. Seven hundred fifteen patients were followed on average for 3.6 years. Mean age was 65 years. At initial visit, 357 subjects had a > or = 50% stenosis. Overall, 237 events occurred in 177 patients. Annual rate of all primary vascular events in patients with > or = 50% stenosis was 11.0% versus 4.2% in those with < 50% stenosis (p < 0.001). Annual rate of stroke and vascular death was 5.5% in the > or = 50% group compared with 1.9% in the < 50% group (p < 0.001). Yearly rate of unheralded ischemic stroke was 4.2% in subjects with > or = 80% stenosis and 1.4% in those with stenosis < 80% (p < 0.001). A stroke or TIA was ipsilateral to a > or = 80% stenosis in 66% of patients. Progression of carotid stenosis particularly to more than 80% was associated both with a higher rate of ipsilateral neurologic events and overall combined vascular events. Our data suggest that severity of carotid stenosis is the main risk factor predicting occurrence of neurologic and other vascular events. Yearly rate of ipsilateral stroke with > or = 50% carotid stenosis is low (1.4%) and most are nondisabling. Progression to > or = 80% or occlusion is associated with worse outcome.