Frequency of postoperative carotid duplex surveillance and type of closure: Results from a randomized trial

Background/purpose: In several nonrandomized studies investigators have reported on the value of postoperative carotid duplex surveillance (PCDS) with mixed results; however the type of closure was not analyzed in these studies. In this study we analyze the frequency and timing of postoperative carotid duplex ultrasound scanning according to the type of closure from a randomized carotid endarterectomy (CEA) trial comparing primary closure (PC) versus patching. Patient population and methods: We randomized 399 CEAs into 135 PCs, 134 polytetra-fluoroethylene (PTFE) patch closures, and 130 vein patch closures (VPCs) with a mean follow-up of 47 months. PCDS was done at 1, 6, and 12 months and every year thereafter (a mean of 4.0 studies per artery). Kaplan-Meier analysis was used to estimate the rate of greater than or equal to 80% restenosis over time and the time frame of progression from < 50%, to 50%-79% and <greater than or equal to> 80% stenosis. Results: Restenoses of greater than or equal to 80% developed in 24 (21%) arteries with PC and nine (4%) with patching. Kaplan-Meier estimate of freedom of greater than or equal to 80% restenosis at 1, 2, 3, 4, and 5 years was 92%, 83%, 80%, 76%, and 68% for PC, respectively, and 100%, 99%, 98%, 98%, and 91% for patching, respectively, (P < .01). Of 56 arteries with 20% to 50% restenosis, two of 28 patch closures and 10 of 28 PCs progressed to 50% to < 80% restenosis (P = .02); none of the patch closures and six of 28 PCs progressed to 80% (P = .03). In PCs, the median time to progression from < 50% to 50%-79%, < 50% to greater than or equal to 80%, and 50%-79% to greater than or equal to 80% was 42, 46, and 7 months, respectively. Of the 24 arteries with greater than or equal to 80% restenosis in PC, 10 were symptomatic. Thus, assuming that symptomatic restenosis would have undergone duplex scan examinations regardless, there were 14 asymptomatic arteries (12%) that could have been detected only with PCDS (estimated cost, $139,200), and those patients would have been candidates for redo CEA. Of the 9 arteries (3 PTFE closures and 6 VPCs) with greater than or equal to 80% restenosis with patch closures, 6 asymptomatic (4 VPCs and 2 PTFE closures) arteries (3%) could have been detected with PCDS. In patients with normal duplex scan findings at the first 6 months, only four (2%) of 222 patched arteries (two asymptomatic) developed greater than or equal to 80% restenosis versus five (38%) of 13 in patients with abnormal duplex scan examination findings (P < .001). Conclusions: PCDS is beneficial in patients with PC, but is less beneficial in patients with patch closure. PCDS examinations at 6 months and at 1- to 2-year intervals for several years after PC are adequate. For patients with patching, a 6-month postoperative duplex scan examination with normal results is adequate.