Carotid artery stenting（CAS）patients are routinely assessed for in-stent restenosis（ISR）using three-dimensional computed tomography angiography （3D-CTA）for 2 years after the procedure, because this event typically occurs in some patients within
2 years after CAS. Stented patients reaching the terminal period of the scheduled 3D-CTA are usually observed with carotid duplex ultrasonography （CDU）thereafter. The purpose of this study was to investigate the outcomes for stented patients who are beyond the 2 year follow-up period and to identify risk factors associated with late-onset ISR. Data were retrospectively collected at Shimane University Hospital. We compared the differences between the ISR-positive group and the ISR-negative group to
identify factors associated with ISR and compared the relationship between 3D-CTA and CDU with instent max intima-media hickness and stenosis rate. We could not discover significant factors to predict ISR. It was a good correlation between 3D-CTA and CDU. We also conclude that 3D-CTA could be replaced with CDU for assessment of ISR in patients who are beyond the 2 year follow-up period after CAS.