Should the Standard Duplex Velocities Criteria for the Diagnosis of Carotid Stenosis be Changed After Carotid Endarterectomy with Patch Closure: Results from Randomized Carotid Trial

BACKGROUND:
Duplex ultrasound velocity criteria have been used to evaluate the severity of carotid stenosis, however, these standard velocities may not be applicable to carotid restenosis after carotid endarterectomy (CEA) with patch angioplasty. The purpose of this study is to determine if patch angioplasty closure alters velocities just distal to CEA and to define the optimal velocities for detecting ≥30%, ≥50%, and ≥70% restenosis.
METHODS:
This study includes 200 CEAs randomized into 100 with PTFE ACUSEAL patch and 100 with Hemashield Finesse patch. All patients underwent immediate postoperative duplex ultrasounds, which were repeated at one month and every six months thereafter. Patients with a peak systolic velocity (PSV) of the internal carotid artery ([ICA], just distal to the patch) of ≥130 c/s underwent CTA. PSVs, end diastolic velocities (EDV), and internal carotid artery/common carotid artery (ICA/CCA) ratios were correlated to completion arteriograms/CTAs. ROC analyses were used to determine optimal velocity criteria in detecting ≥30%, ≥50%, and ≥70% restenosis.
RESULTS:
225 pairs of imagings (duplex ultrasound vs. CTA/angiogram) were available for analysis. When standard velocity criteria for non-operated arteries were applied, 37% and 10% of patients were felt to have ≥50%-<70% and ≥70%-99% restenosis versus 11.6% and 10% on CTA/angiography, respectively (p<0.001). The mean PSV for ≥30%, ≥50%, and ≥70% restenosis were 172, 250, and 389 c/s, respectively (p<0.001). An ICA PSV of ≥155c/s was optimal for ≥30% restenosis with sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy (OA) of 99%, 98%, 99%, 98%, and 98%, respectively. A PSV of ≥199 c/s was optimal for ≥50% restenosis with sensitivity, specificity, PPV, NPV, and OA of 99%, 98%, 99%, 98%, and 99%, respectively. An ICA PSV of 274 c/s was optimal for ≥70% restenosis with sensitivity, specificity, PPV, NPV, and OA of 99%, 87%, 99%, 91%, and 98%, respectively. ROC analysis showed that the PSVs were significantly better than EDVs and ICA/CCA ratios in detecting ≥30% and ≥50% restenosis (Figures 1-3).

CONCLUSIONS:
The mean PSVs of a normal ICA distal to CEA patching were higher than normal non-operated ICAs, therefore, standard duplex velocities criteria should be revised after CEA with patch closure.