Purpose: To investigate in-stent stenosis (ISS) after carotid artery stenting (CAS) in a large series of patients over a study period of 9 years.
Methods: From January 2001 to December 2010, a total of 1738 carotid procedures for primary carotid stenosis were performed in our institution. Of the 574 patients having stent-supported angioplasty, 482 (84.2%) were enrolled in a standardized follow-up program that included duplex ultrasound scans at 1 month, 6 months, 12 months, and yearly thereafter or at any time a neurological event was present or suspected. ISS was defined as >80% stenosis as determined by duplex ultrasound (80% to 99% stenosis indicated by a PSV >250 cm/s + EDV >120 cm/s or an ICA/CCA ratio >3.2).
Results: The mean follow-up was 36.5±21.6 months (range 14-119), during which time 16 (3.3%) patients (11 men; mean age 68.7±6.7 years, range 60-81) developed >80% ISS. The mean time from primary CAS to ISS detection was 7.8±3.5 months (range 0-45). Six (37.5%) of the 16 patients were symptomatic, with transient ischemic attack (n = 2), stroke (n = 2), and amaurosis fugax (n = 2). Thirteen (81.3%) ISS patients were treated by endovascular means, while the other 3 (18.7%) had the stent removed owing to migration. The primary and assisted primary patency rates were 68.8% and 81.3%, respectively; the freedom of new neurological events during follow-up was 75%.
Conclusion: ISS >80% after CAS was not common. However, it is an ongoing process that requires frequent repeat interventions due to recurrence after primary treatment by balloon angioplasty alone. Additionally, surgery may be necessary in patients with neurological deficits and recurrent significant ISS.