Natural history of nonoperated, significant carotid stenosis

One-hundred sixty-seven patients with 190 carotid arteries (109 asymptomatic) demonstrating 50-99% stenosis by arteriography (80), duplex scanning, or other noninvasive techniques were followed from 1-84 months (mean 24.2) for evidence of brain infarct, transient ischemic attacks, or vertebrobasilar symptoms. Thirty-nine arteries (20.5%) were symptomatic at last follow-up, including 13 (6.8%) producing ipsilateral strokes. Twenty-eight sides underwent carotid endarterectomy, 16 for symptomatic lesions at a mean interval of 14.5 months after the initial diagnostic study, with no neurologic deficit. Twenty-seven patients (16.2%) died, eight from stroke (30%), and 12 from cardiac causes (44%). In initially symptomatic sides, the incidence of any subsequent neurologic event (28.7%) or stroke/transient ischemic attack (25%) was significantly greater than in asymptomatic arteries (14.6% and 12%, respectively) (p less than .05). Carotid arteries with greater than 80% stenosis by arteriography and duplex scanning had a 46% incidence of further symptoms and 41.6% stroke/transient ischemic attack rate compared to 19.6% and 15%, respectively, in arteries with less than 80% stenosis (p less than .01). Cumulative life table analysis at 12, 24 and 36 months showed greater than 80% stenosed arteries to have stroke/transient ischemic attack free rates of 69%, 50.5%, and 21.6% compared to 91%, 83.7%, and 76% for arteries with less than 80% stenosis (p less than .05). At a mean follow-up of over two years, nonoperated carotid stenosis (greater than 50%) carries a 20.5% risk of neurologic symptoms and a 6.8% risk of stroke, 61.5% of strokes being fatal. Symptomatic carotid stenosis had a significantly greater incidence of ensuing neurologic events than asymptomatic arteries.