Which Doppler velocity is best for assessing suitability for carotid endarterectomy?

To evaluate which velocity, or combination of velocities, from carotid Doppler ultrasonography (DU), achieved the closest agreement with an assessment of suitability for carotid endarterectomy from intra-arterial angiograms (IAA).

We prospectively collected data from 148 consecutive patients (288 carotids), who had DU and IAA (blinded assessment) before possible carotid endarterectomy. We halved our data by randomly selecting the left or right carotid artery for each patient. We used one half to calibrate our DU results to IAA (to decide which velocity corresponded with what degree of angiographic stenosis). Using this analysis, each artery in the other half of the data was defined as suitable (80-99% stenosed) or unsuitable for carotid endarterectomy. We evaluated every individual, and combination of, velocities (strategies) to see which gave the closest agreement with IAA.

Of all 80 strategies, six resulted in better agreement than others of the same or lower complexity. Five of these strategies gave better agreement than the internal carotid artery peak systolic velocity (ICA PSV) (kappa 0.78), but the improvement was small.

Using the ICA PSV alone is adequate for assessing carotid stenosis before endarterectomy using DU, as long as the machine is calibrated to IAA. However, the addition of the ratio of the ICA PSV to the common carotid artery PSV adds only one further measurement, slightly increases the agreement with IAA, and would be reasonable to use on a daily basis.