Common Carotid Artery Peak-Systolic Velocity Ratio Predicts High-Grade Common Carotid Stenosis

Abstract

Screening for common carotid artery (CCA) stenosis with duplex ultrasound (DUS) velocity criteria alone can be limited due to within-patient and between-patients hemodynamic variability. This study evaluated inter-CCA velocity ratio criteria to predict high-grade CCA stenosis. Retrospective review of consecutive patients who underwent computed tomography angiography (CTA) and DUS peak-systolic velocity (PSV) measurements of bilateral CCA, independently recorded, between 2008 and 2014. Patients with dampened CCA waveforms on DUS, readily indicating high-grade proximal stenosis, consistuted group B. The remainder without dampened waveforms constituted group A. Inter-CCA PSV ratios were calculated by dividing the higher CCA PSV to the lower one of the other side, so the ratios would always be >1. Ratios were subsequently paired with each respective unilateral CCA diameter stenosis (uDS) and differential bilateral CCA diameter stenosis (dDS). A quadratic regression model was fitted to predict uDS and dDS. Receiver operating characteristic curves were used to determine optimal ratios for ≥50% CCA stenosis. The study excluded patients with carotid artery occlusion. From 174 patients, 167 patients were included in group A and seven in group B. In group A, 31 patients had ≥50% uDS and 17 had ≥50% dDS. All stenoses ≥50% were identified on the same side with the higher PSV. Inter-CCA PSV ratio predicted ≥50% uDS (r2 = 0.57; P < .0001) and dDS (r2 = 0.75; P < .0001; Fig). In group B, all patients had ≥60% stenosis that involved the vessel origin. An increasing inter-CCA PSV ratio showed a trend toward contralateral high-grade stenosis (r2 = .54, P = .06). Receiver operating characteristic curves for ≥50% uDS showed an optimal threshold CCA ratio ≥1.96 with 93% accuracy, 75% sensitivity, and 97% specificity (area under curve, 0.857; 95% confidence interval, 0.755-0.958) and for ≥50% a dDS ratio ≥2.62 with 97% accuracy, 82% sensitivity, and 99% specificity (area under curve, 0.938; 95% confidence interval, 0.828-1.0). DUS-based CCA PSV ratio can accurately predict unilateral and differential high-grade CCA stenosis. Also, in patients with dampened waveforms, it implied contralateral severe proximal stenosis. This parameter should be further validated in prospective studies and is a promising adjunct screening tool to detect high-grade common carotid stenosis.