Significance of plaque ulceration in symptomatic patients with high-grade carotid stenosis. North American Symptomatic Carotid Endarterectomy Trial

Abstract

Background and purpose: The importance of carotid plaque ulceration as a cause of cerebral ischemic symptoms remains uncertain. Moreover, its prominence in symptomatic patients with severe carotid stenosis is unknown.

Methods: The association between angiographically defined plaque ulceration and risk of subsequent stroke was assessed using Cox proportional hazards regression in 659 patients with severe (70% to 99%) carotid stenosis from the North American Symptomatic Carotid Endarterectomy Trial.

Results: Treatment assignment (medical versus surgical) and degree of ipsilateral stenosis were identified as having a significant influence on the results. The risk of ipsilateral stroke at 24 months for medically treated patients with ulcerated plaques increased incrementally from 26.3% to 73.2% as the degree of stenosis increased from 75% to 95%. For patients with no ulcer, the risk of stroke remained constant at 21.3% for all degrees of stenosis. The net result yielded relative risks of stroke (ulcer versus no ulcer) ranging from 1.24 (95% confidence interval, 0.61 to 2.52) to 3.43 (95% confidence interval, 1.49 to 7.88). Conversely, for surgically treated patients with antecedent presence of an ulcerated plaque, the risk of stroke increased slightly at the highest degrees of stenosis. Overall, carotid endarterectomy reduced the risk of ipsilateral stroke at 24 months by at least 50%. Similar results were obtained for risk of major ipsilateral stroke and risk of all strokes and death.

Conclusions: The presence of angiographically defined ulceration for medically treated symptomatic patients is associated with an increased risk of stroke. The risk of stroke more than doubles at higher degrees of stenosis. Carotid endarterectomy is beneficial in substantially reducing the risk of stroke, regardless of plaque ulceration and degree of severe carotid stenosis.