Closed-cell stents present with higher velocities on duplex ultrasound compared with open-cell stents after carotid intervention: Short- and mid-term results

Background: The purpose of this study was to evaluate the effect of carotid cell design on duplex ultrasound velocity readings in the immediate postoperative period and over time. Methods: A prospective database encompassing all patients treated with carotid artery stents between 2003 and 2008 was established and analyzed for stent type (closed-cell vs. open-cell), indications, and comorbidities. Patients were followed up clinically and with duplex ultrasound immediately after surgery, and every 6 months thereafter. Peak systolic velocities (PSV), end diastolic velocities (EDV), and internal carotid artery (ICA) to common carotid artery (CCA) ratios of PSV were recorded. Results: A total of 214 interventions with 157 (73.3%) open-cell and 57 (26.7%) closed-cell types of carotid stents were performed in 205 patients. Two groups were similar regarding demographics, comorbidities, lesions characteristics, and stent length and diameter. The only difference was a significantly higher mean age (74.4 ± 10.1 vs. 70.9 ± 9.7 years; p = 0.027) and a history of myocardial infarction (34.5% vs. 15.6%; p = 0.004) in the closed-cell group versus open-cell group. Immediately after surgery PSV (115.9 ± 66.1 vs. 93.1 ± 38.7 cm/s; p = 0.003) and ICA/CCA ratio (2.08 ± 1.66 vs. 1.45 ± 0.52; p = 0.001) were significantly higher in closed-cell compared with open-cell group. This difference persisted during the follow-up period of 20.2 +/- 16.4 months; PSV (147.2 ± 108.8 vs. 110.0 ± 51.9; p = 0.003) and ICA/CCA ratio (2.61 ± 2.31 vs. 1.76 ± 0.81; p = 0.001). Patients with diabetes and calcified lesions had higher PSV and ICA/CCA ratio immediately after surgery (p > 0.05 and p < 0.05 for those with diabetes and calcified lesions, respectively) and over time. The number of readings showing significant restenosis (PSV >300 cm/s) over time were significantly higher in closed-cell 5 (8.7%) versus open-cell 1 (0.06%). EDV was not statistically different in the two groups (p > 0.05). Conclusion: Our study suggests that duplex criteria to screen for poststent restenosis may require modification according to stent-type. However, long-term effect of stent design on restenosis is still to be established.