Appropriate frequency of carotid duplex testing following carotid endarterectomy

The value of carotid duplex analysis is well proven for the diagnosis of carotid bifurcation occlusive disease, but its use in the postoperative setting is less well defined.

A series of 281 carotid endarterectomies were performed in 222 patients. A protocol of serial duplex examinations was established, with tests performed at the time of the first postoperative clinic visit and every 6 months thereafter. The goal of postoperative surveillance was to identify critical restenotic carotid lesions of greater than 80% diameter reduction and determine the incidence of subsequent carotid occlusion and neurologic events.

Critical restenoses developed in 25 (8.9%) of the arteries and occlusions occurred in 12 (4%). Restenosis occurred with greatest frequency during the first year after operation (5%), but continued to develop with a frequency of approximately 2% per year thereafter. Postoperative carotid occlusions occurred at a rate of approximately 1% per year. Known restenotic lesions progressed to occlusion over a mean duration of 11 months. Stroke was infrequent in patients with critical restenoses (4%) until the lesions progressed to occlusion (33%).

These observations suggest that a protocol of semiannual duplex testing into the late postoperative period may identify critical carotid restenotic lesions prior to the development of carotid occlusion and stroke.