Follow up on Carotid Angioplasty and Stenting: Do Ultrasound Criteria Still Apply?

OBJECTIVES:
The purpose of this study is to evaluate the efficacy of DUS in detecting the threshold for normal carotid arteries after carotid angioplasty and stenting (CAS) and to determine the need to modify the current velocity criteria.
METHODS: This is a retrospective observational study; Data from 153 carotid arteries in 149 patients treated with CAS at a single tertiary care center from December 2000 to December 2005 were reviewed. DUS velocities were taken within 24 hours after CAS and were compared to operative angiograms. The peak systolic velocities (PSV) and the ratio of internal carotid (ICA) PSV to common carotid artery (CCA) PSV were analyzed. 34 patients were excluded due to unavailability of data or due to stenting the common carotid artery alone.
RESULTS:
Data from 110 patients were included in this analysis. The mean age was 71 years. Sixty six patients were male and 44 were females. The average pre stenting PSV was 348 cm/s (+/-132) compared to 103 cm/s (+/-35) post stenting
The average stenosis by angiogram dropped from 86% (+/-9.8%) to 4.6 %
(+/-8.5).
Immediately post stenting the degree of stenosis after stenting was <20% in all patients by angiography. The PSV was higher than 125 cm/s in 20 patients (18%); higher than 150cm/s in 9 patients (8.2%) and higher than 175 cm/s in only 3 patients (2.7%). These resulted in a sensitivity of 81.6%, 91.7%, and 98.1% respectively.
The ICA/CCA ratio (carotid index) was >1.5 in 22 patients (20%) while only 6 patients (5.5%) had carotid index >2. The sensitivity of these results are 79.4% and 94.5% respectively.
CONCLUSIONS:
The standard Duplex velocity criteria for carotid arteries after CAS are not consistent with angiographic findings in 18% of the patients. To improve sensitivity for normal carotid arteries after CAS the PSV of 175 or more and an ICA/CCA PSV ratio of more than 2 should be adopted.