What question did this study set out to answer?

To propose and validate a novel anatomical-functional classification for collaterals in prognosis after mechanical thrombectomy for ICA occlusion.

May 8, 2026

Abstract Number: Esoc2026a349 Novel Four-Type Classification of Circle of Willis Collaterals: Prognosis in Mt for Acute Terminal Ica Occlusion

Key Points

To propose and validate a novel anatomical-functional classification for collaterals in prognosis after mechanical thrombectomy for ICA occlusion.
Retrospective analysis of 142 patients with ICA occlusion and successful reperfusion (mTICI 3) using CTA/DSA.
Classification into four types based on collateral anatomy and function: A, B, C, and D.
Assessment of 90-day functional outcomes using mRS.
Type A showed a favorable outcome rate of 54.29%, significantly higher than Types B (10.81%) and C (7.69%) (P<0.0083).
Malignant cerebral edema and 90-day mortality were higher in Types B, C, and D compared to Type A.
Within Type A, compromised subtypes had a favorable mRS of 14.29% versus 64.29% in non-compromised patients.

Abstract

Abstract Background and aims Acute terminal internal carotid artery (ICA) occlusion has a poor prognosis despite successful mechanical thrombectomy (MT), due largely to inadequate Circle of Willis collaterals. Existing classifications fail to capture functional collateral sufficiency. We aimed to propose and validate a novel four-type anatomical-functional classification to stratify prognosis after MT. Methods In this retrospective study, 142 patients with acute terminal ICA occlusion and successful reperfusion (mTICI 3) were classified using pre-interventional CTA/DSA: Type A (patent ACoA), B (non-patent ACoA), C (absent contralateral A1), and D (absent A1 with fetal-type PCA). A compromised Type A-C subtype was defined by hypoplastic A1 (diameter 30% of ipsilateral) or ACoA providing ASITN/SIR grade ≤2 flow. The primary outcome was favorable 90-day functional outcome (mRS ≤3). Results Type A demonstrated the highest rate of favorable outcome (54.29%), significantly superior to Types B (10.81%) and C (7.69%) (all P0.0083). Type D had a numerically lower rate (11.11%). Malignant cerebral edema and 90-day mortality were significantly higher in Types B, C, and D versus Type A. Within Type A, the compromised subgroup (A-C) had significantly worse outcomes than the non-compromised (favorable mRS: 14.29% vs. 64.29%; malignant edema: 64.29% vs. 5.36%). Conclusions This four-type classification based on functional Circle of Willis integrity effectively stratifies post-MT prognosis. It identifies Type A (especially non-compromised) patients as optimal candidates, while Types B, C, D, and the compromised Type A-C subtype represent high-risk phenotypes for futile recanalization, emphasizing hemodynamic sufficiency over mere anatomical connectivity. Conflict of interest The authors report no conflicts of interest relevant to this abstract. This work was supported by a grant from the Key Scientific Research Projects of Jinhua Science and Technology Bureau (2022-3-044) and Medical Science and Technology Project of Zhejiang Province (2024XY078).

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Cite This Study

E Yajun (Fri,) studied this question.

synapsesocial.com/papers/69fd7f25bfa21ec5bbf07943 https://doi.org/https://doi.org/10.1093/esj/aakag023.1314

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