Objective: To investigate the predictive value of asymptomatic cervical bruit for detecting internal carotid artery disease in consecutive patients undergoing coronary artery bypass grafting (CABG).
Design: A prospective cohort study.
Setting: Tertiary referral university hospitals.
Patients: 153 consecutive patients (mean age 57 years) undergoing CABG, without previous history of cerebrovascular events.
Interventions: Patients underwent detailed pre-operative work-up, including coronary angiography and carotid artery duplex scanning. Internal carotid artery diameter stenosis was graded as A: normal; B: < 15%; C: 15%-50%; D: 50-80%; D+: > 80-99% and E=complete occlusion.
Results: 72 patients (47.1%) (95% CI: 39%, 55%) had no evidence of internal carotid artery stenosis; 81 (52.9%) (95% CI: 44.9%, 60.9%) had varying grades of disease, unilateral or bilateral. Cervical bruit was detected in 12/153 patients (7.8%) (95% CI: 3.5%, 12.1%) of whom all but one (0.7%) had varying grades of internal carotid artery disease; of these, 4 patients had bilateral cervical bruit (2.6%) (95% CI: 0.06%, 5.2%). The sensitivity, specificity, positive and negative predictive values and overall accuracy of cervical bruit for detection of > or = 50% internal carotid artery stenosis were 23.5%, 95.8%, 25%, 95.5% and 91.8%, respectively. The relative risk of > or = 50% stenosis ipsilateral to cervical bruit in 306 sides was 5.58 (95% CI: 2.0, 15.0) and the odds ratio 7.1 (95% CI: 2.0, 25.0).
Conclusions: Asymptomatic cervical bruit proved a highly specific clinical sign for detection of internal carotid artery stenosis, whether haemodynamically significant (> or = 50%) or otherwise, in patients undergoing myocardial revascularisation. This was matched by a high negative predictive value and overall accuracy for flow limiting atheroma (> or = 50% stenosis). Yet, steering carotid investigations on the basis of cervical bruit alone would result in > or = 80% internal carotid artery stenosis remaining undetected in 3% of overall patients, in whom cervical bruit is absent.