Objective: A classification system developed to characterize in-stent restenosis (ISR) after coronary percutaneous transluminal angioplasty with stenting was modified and applied to describe the appearance and distribution of ISR occurring after Wingspan (Boston Scientific, Fremont, CA) intracranial percutaneous transluminal angioplasty with stenting.
Methods: A prospective, intention-to-treat, multicenter registry of Wingspan treatment for symptomatic intracranial atherosclerotic disease was maintained. Clinical and angiographic follow-up results were recorded. ISR was defined as greater than 50% stenosis within or immediately adjacent (within 5 mm) to the implanted stent(s) and greater than 20% absolute luminal loss. ISR lesions were classified by angiographic pattern, location, and severity in comparison with the original lesion treated.
Results: Imaging follow-up (3-15.5 months) was available for 127 intracranial stenotic lesions treated with Wingspan percutaneous transluminal angioplasty with stenting. Forty-one lesions (32.3%) developed either ISR (n = 36 [28.3%]) or complete stent occlusion (n = 5 [3.9%]) after treatment. When restenotic lesions were characterized using the modified classification system, 25 of 41 (61.0%) were focal lesions involving less than 50% of the length of the stented segment: three were Type IA (focal stenosis involving one end of the stent), 21 were Type IB (focal intrastent stenosis involving a segment completely contained within the stent), and one was Type IC (multiple noncontiguous focal stenoses). Eleven lesions (26.8%) demonstrated diffuse stenosis (>50% of the length of the stented segment): nine were Type II with diffuse intrastent stenosis (completely contained within the stent) and two were Type III with proliferative ISR (extending beyond the stented segment). Five stents were completely occluded at follow-up (Type IV). Of the 36 ISR lesions, 16 were less severe or no worse than the original lesion with respect to severity of stenosis or length of the segment involved; 20 lesions were more severe than the original lesion with respect to the segment length involved (n = 5), actual stenosis severity (n = 6), or both (n = 9). Nine of 10 supraclinoid internal carotid artery ISR lesions and nine of 13 middle cerebral artery ISR lesions were more severe than the original lesion.
Conclusion: Wingspan ISR typically occurs as a focal lesion. In more than half of ISR cases, the ISR lesion was more extensive than the original lesion treated in terms of lesion length or stenosis severity. Supraclinoid internal carotid artery and middle cerebral artery lesions have a propensity to develop more severe posttreatment stenosis.