Do carotid bruits predict disease of the internal carotid arteries?

A carotid bruit is often thought of as a reliable sign of extracranial carotid artery disease. In addition finding a bruit may precipitate a referral to hospital. Carotid endarterectomy has now been shown to be beneficial in patients with symptomatic carotid territory ischaemia and 70-99% stenosis of the relevant carotid artery, therefore it is important that such patients are detected and referred. In this study of 331 consecutive patients referred to a specialist cerebrovascular clinic we examined the practical value of a carotid bruit mentioned by the referring practitioner. All patients underwent clinical assessment, evaluation of risk factors and Doppler duplex scanning of the carotid arteries. A bruit was stated in the referral letter of 110 (33%) patients. Moderate (30-69%) or severe (70-99%) stenosis was present in 37% of patients with, and 17% of those without a carotid bruit (P < 0.001). We found a carotid bruit was a poor predictor of such disease (positive predictive value, 37%). The false negative rate for severe disease was 43%. Normal carotid arteries were found in 32% of patients with a bruit. We therefore suggest that all patients with suspected carotid territory ischaemia should be referred for assessment whether there is a bruit present or not.