Abstract
OBJECTIVE: The external carotid artery (ECA) is an important collateral pathway for cerebral
blood flow. Carotid artery stenting (CAS) typically crosses the ECA, while carotid
endarterectomy (CEA) includes deliberate ECA plaque removal. The purpose of the present
study was to compare the long-term patency of the ECA following CAS and CEA as determined
by carotid duplex ultrasound.
METHODS: Duplex ultrasounds and hospital records were reviewed for consecutive patients undergoing
CAS between February 2002 and April 2008, and were compared with those undergoing
CEA in the same time period. Preoperative and postoperative ECA peak systolic velocities
were normalized to the common carotid artery (CCA) as ECA/CCA ratios. A significant
(80% or greater) ECA stenosis was defined as an ECA/CCA ratio of 4.0. A change of
ratio by more than 1 was defined as significant. Data were analyzed using Student's
t test and X2 analysis.
RESuLTS: A total of 86 CAS procedures in 83 patients were performed (81 men, mean age 69.9
years). Among them, 38.4% of patients had previous CEA, 9.6% of whom had contralateral
internal carotid artery occlusion. Sixty-seven CAS and 65 CEA patients with complete
duplex data in the same time period were included in the analyses. There was no difference
in the incidence of severe ECA stenosis on preoperative ultrasound evaluations. During
a mean follow-up of 34 months (range four to 78 months), three postprocedure ECA occlusions
were found in the CAS group. The likelihood of severe stenosis or occlusion following
CAS was 28.3%, compared with 11% following CEA (P<0.025). However, 62% of CEA patients
and 57% of CAS patients had no significant change in ECA status. Reduction in the
patient's degree of ECA stenosis was observed in 9.4% of CAS versus 26.6% of CEA patients.
Overall, immediate postoperative ratios of both groups were slightly improved, but
there was a trend of more disease progression in the CAS group during follow-up.
CONCLuSION: CAS is associated with a higher incidence of postprocedure ECA stenosis. Despite
the absence of neurological symptoms, a trend toward late disease progression of ECA
following CAS warrants long-term evaluation.