Carotid duplex criteria for patients with contralateral occlusion

Contralateral occlusion (CLO) occurs in approximately 8% of patients undergoing intervention for carotid artery stenosis. Patients with CLO have increased stroke risk compared with patients without CLO, but standard carotid duplex ultrasonography (CDUS) criteria are not a reliable manner to screen or follow patients with CLO. Because appropriate duplex criteria for these patients are not well understood, this article defines CDUS parameters that accurately predict carotid artery stenosis at our institution.

Sixty-five patients with ipsilateral carotid stenosis and CLO were identified from our institutional database. Fifteen of sixty-five patients had arteriography, computed tomography angiography, or magnetic resonance angiography within 6 mo of CDUS. We determined accuracy of our laboratory's criteria for determining stenosis category compared with three-dimensional imaging. Receiver operating characteristic curves were used to determine optimal peak systolic velocity (PSV), end diastolic velocity (EDV), and systolic ratio (SR) cutoff values for diagnosing ≥50% stenosis in this pilot cohort. Finally, the revised criteria were prospectively applied to a validation cohort (n = 8) from the same institution.

Categorization of stenosis by standard PSV, EDV, and SR criteria saw similar accuracy trends in both pilot (46.7, 53.3, and 66.7%) and validation (25, 25, and 62.5%) cohorts. Receiver operating characteristic curve analysis in the pilot cohort identified optimized PSV, EDV, and SR cutoffs (≥250, ≥90, and ≥2.3 cm/s, respectively) for diagnosing ≥50% stenosis. In the pilot cohort, new PSV criteria increased specificity (60%-100%) with minimal decreased sensitivity (90%-80%), whereas new EDV criteria increased specificity (40%-71.4%) and maintained 100% sensitivity. New SR criteria failed to improve sensitivity or specificity above 80%. Similar trends for the new CDUS velocity criteria were observed in the validation cohort.

Increasingly stringent ultrasound parameters can provide reliable criteria for determining ≥50% carotid stenosis in patients with CLO. Further prospective validation that includes more patients with high-grade ipsilateral stenosis will help identify the role of SR in segregating high-grade versus moderate stenosis in CLO patients.