Peritherapeutic intra-arterial flow changes predict long-term stent patency in patients with severe intracranial artery stenosis receiving PTAS

Background and purpose: The quantitative intra-arterial flow dynamics following percutaneous transluminal angioplasty and stenting (PTAS) for severe intracranial artery stenosis have never been investigated. We aimed to evaluate peritherapeutic intracranial artery flow dynamics following PTAS with quantitative magnetic resonance angiography (qMRA) to predict long-term stent patency.

Design: This is a prospective, single-center study.

Methods: We recruited participants with severe symptomatic stenosis from intracranial internal carotid artery (ICA) to M1 segment of middle cerebral artery (MCA) between 2018 and 2022. qMRA was performed before (preprocedural), within 24 h after (early postprocedural) and 12 months after (delayed postprocedural) PTAS, and parameters including bilateral M1 segments and basilar artery (BA) flow were recorded. The calibrated M1 ratio was calculated using contralateral M1 (cM1) and BA (cMB) flows as references. We assessed differences in qMRA parameters between subjects with and without significant 12-month in-stent restenosis (ISR).

Results: Forty-four subjects (12 with + 32 without ISR ≥ 50 %) were included. The early postprocedural M1 flow was higher than preprocedural M1 flow in subjects with (p = 0.030) and without (p = 0.031) ISR. The early postprocedural healthy-side M1 flow was lower than preprocedural healthy-side M1 flow (p = 0.014) in subjects without ISR. Both the early (p < 0.001) and delayed (p = 0.014) cM1s were greater than the preprocedural cM1. The residual stenosis grade was positively correlated with delayed postprocedural cM1 in all subjects (r² = 0.190; p = 0.003).

Conclusions: The cM1 and a distinct flow dynamic pattern on early qMRA (within 24 h after PTAS) may predict 12-month ISR.