Late stroke after carotid endarterectomy: the role of recurrent stenosis.

Perioperative stroke after carotid endarterectomy has been well studied, although little information is available regarding later strokes. We determined the etiology of late stroke after carotid endarterectomy by examining the records of those patients in our carotid registry who had a stroke more than 30 days after surgery. Thirty-five (5.1%) of the 688 patients in our registry had a stroke more than 30 days after surgery (mean follow-up, 59.3 months; standard error, 1.8 months; range, 1 to 292 months). The cause of late stroke was established by input from consulting neurologists, CT scanning of the head, magnetic resonance imaging results, angiograms, noninvasive studies, and postmortem examinations. Eight of the 11 strokes of unknown origin were massive fatal events for which no further evaluation was undertaken. Restenosis or occlusion accounted for fewer strokes (3 of 20, 15%) in the 1- to 36-month postoperative interval than in the greater than 36-month interval (8 of 15, 53.7%) (p less than 0.02 by Fisher's Exact Test). These data support the hypothesis that the early pseudointimal hyperplastic lesion is less likely to result in stroke than is later recurrent stenosis, which is usually related to atherosclerosis.