Interprocedural Comparison of Changes in Natural Flow Velocity Patterns in the Internal Carotid Artery Following CAS or CEA

Background and purpose Different flow velocities have been reported after carotid angioplasty with stenting (CAS) than after carotid endarterectomy (CEA). We compared blood flow velocities following CAS and CEA in the International Carotid Stenting Study (ICSS; ISRCTN25337470). Materials and methods In total, 254 patients (70% male; 129 CAS and 125 CEA) were included. Mean peak systolic velocities (PSV ICA ) were assessed at baseline, 30 days, 1 and 2 years. Following both treatments, restenosis ≥50% was defined as PSV mean >125 cm s −1 . Results CAS and CEA resulted in a similar reduction in PSV ICA 1 month after treatment. Post-intervention analysis for each treatment separately revealed that PSV ICA following CAS increased significantly during follow-up (30 days to 2 years; 22.4 cm s −1 ; 95% confidence interval (CI), 14.3 to 30.5). On the contrary, PSV ICA following CEA remained relatively stable during follow-up (4.7 cm s −1 ; 95% CI, −6.5 to 15.9). When we analysed the increase in PSV ICA between both treatments after 2 years of follow-up, no significant interprocedural difference was observed. The internal carotid artery/common carotid artery (ICA/CCA) PSV ratio increased after CAS but not after CEA: 1.2 vs. 1.1 (0.04, 95% CI; −0.16 to 0.25) at 30 days; 1.5 vs. 1.1 (0.39, 95% CI; 0.13 to 0.65) at 1 year; and 1.5 vs. 1.1 (0.36; 95% CI, 0.08 to 0.63) at 2 years. The rate of apparent ipsilateral ICA restenosis >50% was higher following CAS (hazard ratio 2.35; 95% CI, 1.35 to 4.09). Conclusion Two years after carotid revascularisation, no significant interprocedural difference was observed in the increase of PSV ICA between CAS and CEA. However, the ICA/CCA ratio increased more following CAS resulting in an apparent higher rate of restenosis following CAS.