Rates of progression of carotid in-stent stenosis and clinical outcomes

Background: We previously reported the incidence of $50% and $80% carotid in-stent stenosis. In the present study, we analyzed the rate of progression of in-stent stenosis and clinical outcomes with longer follow-up. Methods: We performed a retrospective analysis of prospectively collected data for 450 patients who had undergone transfemoral carotid artery stenting with longer follow-up (mean, 70 months). The progression of in-stent stenosis was defined as stenosis advancing to a higher severity of disease (ie, from <50% to $50% and from $50% to $80%). Kaplan-Meier analysis was used to estimate the rate of progression from <50% to $50% and $50% to $80%, the overall rates of $50% and $80% in-stent stenosis, and survival at 1, 3, 5, and 10 years. Results: At a mean follow-up of 70.3 months (range, 1-222 months), 121 of 446 patients (27%) had had progression to $50% and 39 (8.7%) to $80% in-stent stenosis. Of the 406 patients whose first duplex ultrasound findings were normal or showed in-stent stenosis of <50%, 82 had had progression from normal or <50% to $50% in-stent stenosis at a mean of 51.7 months (range, 1-213 months). Of the 121 patients with $50% stenosis, 14 (11.6%) had experienced progression to $80% at a mean of 33.6 months (range, 6-89 months). Of the 82 patients with progression from <50 to $50%, 10 (12%) had experienced a neurologic event (eight transient ischemic attacks [TIAs] and two strokes). Of the 14 with progression from $50% to $80%, 2 (14.3%) had experienced a TIA, and the remaining patients were asymptomatic. Of the 39 patients with $80% in-stent stenosis, 9 (23%) had experienced a neurologic event (eight TIAs and one contralateral stroke). Overall, 13 of the 121 patients with late $50% restenosis (10.7%) had experienced a neurologic event (10 ipsilateral TIA, 2 ipsilateral stroke, and 1 contralateral stroke. Thus, 12 of 446 patients (2.7%) had experienced an ipsilateral TIA or stroke at a mean follow-up of 70 months. The rates of freedom from <50% to $50% in-stent stenosis progression were 93%, 85%, 78%, and 66% at 1, 3, 5, and 10 years. The rates of freedom from progression from $50% to $80% in-stent stenosis were 89%, 81%, and 77% at 1, 3, and 5 years, respectively. The overall rates of freedom from $50% in-stent stenosis and $80% in-stent stenosis were 86%, 77%, 71%, and 59% and 96%, 93%, 91%, and 84% at 1, 3, 5, and 10 years, respectively. Finally, the stroke survival rates were 95%, 80%, 63%, and 31% at 1, 3, 5, and 10 years, respectively. Conclusions: The rate of progression of carotid in-stent stenosis was modest, with a low incidence of stroke events. Therefore, the use of duplex ultrasound surveillance after carotid artery stenting should be selective and its benefits and utility perhaps reevaluated.