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Can Bruits Distinguish High-Grade from Moderate Symptomatic Carotid Stenosis?
- J. Stephane Sauve, MD;
- Kevin E. Thorpe, MMath;
- David L. Sackett, MD;
- Wayne Taylor, MA;
- Henry J. M. Barnett, MD;
- R. Brian Haynes, MD, PhD; and
- Allan J. Fox, MD
- From McMaster University, Hamilton, Ontario; the Robarts Research Institute, University of Western Ontario, London, Ontario, Canada. On behalf of the North American Symptomatic Carotid Endarterectomy Trial. Requests for Reprints: David L. Sackett, MD, Division of General Internal Medicine, Henderson General Division, Room 408, McMaster Clinic, 711 Concession Street, Hamilton, Ontario, L8V 1C3 Canada.
Abstract
Objective: To determine whether cervical bruits, alone or combined with other clinical characteristics, can distinguish high-grade (70% to 99%) carotid artery stenoses from less severe stenoses in patients with symptoms of cerebrovascular disease.
Design: Cross-sectional comparison of clinical observations with contemporaneous angiography.
Setting: The North American Symptomatic Carotid Endarterectomy Trial (NASCET), a multicenter randomized, controlled trial of carotid endarterectomy.
Patients: All patients enrolled in the NASCET from its inception in 1988 to November 1991.
Results: A focal ipsilateral carotid bruit had a sensitivity of 63% and a specificity of 61% for high-grade stenosis and, when absent, only lowered the probability for high-grade stenosis from a pretest value of 52% to a post-test probability of 40%. When combined with four other clinical characteristics (an infarction on computed tomography of the head, a carotid ultrasound scan suggesting more than 90% stenosis, a transient ischemic attack rather than a minor stroke as a qualifying event, and a retinal rather than a hemispheric qualifying event), the predicted probabilities of high-grade stenosis ranged from a low of 18% (when none of the features was present) to a high of 94% (when all the features were present).
Conclusions: Cervical bruits alone were not sufficiently predictive of high-grade symptomatic carotid stenosis to be useful in selecting patients for angiography; they were absent in over one third of patients with high-grade stenosis. When combined with other clinical variables, patients with high or low probabilities of 70% to 99% stenoses could be identified, but this prediction model still missed many individuals with high-grade stenosis, even in this training set of selected patients.
- Copyright ©2004 by the American College of Physicians
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