Predictive value of asymptomatic cervical bruit for carotid artery disease in coronary artery surgery revisited

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 ≥ 50% internal carotid artery stenosis were 23.5%, 95.8%, 25%, 95.5% and 91.8%, respectively. The relative risk of ≥ 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 (≥ 50%) or otherwise, in patients undergoing myocardial revascularisation. This was matched by a high negative predictive value and overall accuracy for flow limiting atheroma (≥ 50% stenosis). Yet, steering carotid investigations on the basis of cervical bruit alone would result in ≥ 80% internal carotid artery stenosis remaining undetected in 3% of overall patients, in whom cervical bruit is absent.