Comparison of results of bilateral and unilateral carotid endarterectomy five years after surgery.

Consecutive patients who successfully underwent carotid endarterectomy (C) between 1970 and 1975 were followed during a 5-year period (mean follow-up 4.3 years). The patients were divided into three groups. Group I comprised 146 patients who had unilateral CE with a patent, nonstenotic contralateral carotid artery. Group II included 45 patients who underwent unilateral CE but whose contralateral internal carotid artery was found to be totally occluded. Group III consisted of 86 patients who underwent bilateral CE. There was no significant difference between the groups with respect to age, sex, neurologic status, or associated diseases, and all were maintained on antiplatelet medications for surgery. During the follow-up period a total of 22 of the 277 patients had a new hemispheric stroke; four others became comatose and died, presumably of stroke. Among the group I patients, 17 had new strokes, only six of which involved the hemisphere ipsilateral to the CE. Five later strokes occurred in group II, one ipsilateral to the CE. Four patients in group III had new strokes. The cumulative stroke rates at 5 years by the life-table method were 17.6% for group I, 16.4% for group II, and 5.6% for group III. The difference between group I and III was significant (P less than 0.05). The results suggest that patients undergoing unilateral CE should have close postoperative monitoring of the contralateral vessel.