Absent leptomeningeal collateralization is associated with greatest benefit from mechanical thrombectomy in the 6-24 hour time window.

INTRODUCTION: The impact of leptomeningeal collateralization on the efficacy of mechanical thrombectomy (MT) in patients with anterior circulation large vessel occlusion (aLVO) presenting in the 6-24 h time window remains poorly elucidated. PATIENTS AND METHODS: Retrospective multicenter study of aLVO patients presenting between 6 and 24 h after stroke onset who received MT plus Best Medical Treatment (BMT) or BMT alone. Leptomeningeal collateralization was assessed using single-phase computed tomography angiography (grade 0: no filling; grade 1: filling ⩽50%; grade 2: filling >50% but <100%; grade 3: filling 100% of the occluded territory). Inverse probability of treatment weighted ordinal regression was performed to assess the association between treatment and shift of the modified Rankin Scale (mRS) score toward lower categories at 3 months. We used interaction analysis to explore differential treatment effects on functional outcomes (probabilities for each mRS subcategory at 3 months) at different collateral grades. RESULTS: Among 363 included patients, 62% received MT + BMT. Better collateralization was associated with better functional outcomes at 3 months in the BMT alone group (collateral grade 1 vs 0: acOR 5.06, 95% CI 2.33-10.99). MT + BMT was associated with higher odds of favorable functional outcome at 3 months (acOR 1.70, 95% CI 1.11-2.62) which was consistent after adjustment for collateral status (acOR 1.54, 95% CI 1.01-2.35). Regarding treatment effect modification, patients with absent collateralization had higher probabilities for a mRS of 0-4 and a lower mortality at 3 months for the MT + BMT group. DISCUSSION AND CONCLUSION: In the 6-to-24-h time window, aLVO patients with absent leptomeningeal collateralization benefit most from MT + BMT, indicating potential advantages for this group despite their poorer baseline prognosis.

Association between ischaemic stroke aetiology and leptomeningeal collateral status: a retrospective cohort study.

INTRODUCTION: There is limited understanding of the pathomechanistic relationship between leptomeningeal collateral formation and ischaemic stroke aetiology. We aimed to assess the association of leptomeningeal collateral status and ischaemic stroke aetiology, using the widely recognised "Trial of Org 10172 in Acute Stroke Treatment" (TOAST) classification categorising strokes into five distinct aetiologies. METHODS: Retrospective study of consecutively admitted adult ischaemic stroke patients at a Swiss stroke centre. Leptomeningeal collateral status was assessed on admission with single-phase CT-angiographies using a validated 4-point score. Patients were categorised into large-artery atherosclerosis (LAA), cardioembolic (CE), small-vessel disease (SVD) and cryptogenic (CG) according to the TOAST classification. We performed ordinal and binary (poor [collaterals filling ≤50% of the occluded territory] vs good [collaterals filling >50% of the occluded territory] collateralisation) logistic regression to evaluate the impact of TOAST aetiology on collateral status. RESULTS: Among 191 patients, LAA patients had better collateral status compared to non-LAA aetiology (LAA: 2 vs CE: 2 vs SVD: 3 vs CG: 2, pLAA vs non-LAA = 0.04). In weighted multivariate logistic regression, LAA and SVD independently predicted better collateral status (binary models [adjusted odds ratio; aOR]: LAA: 3.72 [1.21-11.44] and SVD: 4.19 [1.21-14.52]; ordinal models [adjusted common odds ratio; acOR]: LAA: 2.26 [95% CI: 1.23-4.15] and SVD: 1.94 [1.03-3.66]), while CE predicted worse collateral status (binary models [aOR]: CE: 0.17 [0.07-0.41]; ordinal models [acOR]: CE: 0.24 [0.11-0.51]). CONCLUSION: The aetiology of ischaemic stroke is associated with leptomeningeal collateral status on single-phase CT-angiography, with LAA and SVD predicting better and CE predicting worse collateral status.

Large ischemic core defined by visually assessed ASPECTS predicts functional outcomes comparably accurate to automated CT perfusion in the 6-24 h window.

INTRODUCTION: Automated CT perfusion (aCTP) is commonly used to select patients with anterior circulation large vessel occlusion (aLVO) for endovascular treatment (EVT). The equivalence of visually assessed Non-contrast CT Alberta Stroke Program Early CT Scores (ASPECTS) and aCTP based selection in predicting favorable functional outcomes remains uncertain. PATIENTS AND METHODS: Retrospective multicenter study of adult aLVO patients from the Swiss Stroke Registry (2014-2021) treated with EVT or best medical treatment 6-24 h after stroke onset. We assessed ASPECTS on non-contrast CT visually and ischemic core volumes on aCTP, defining ASPECTS 0-5 and aCTP CBF < 30% volumes ⩾50 mL as large ischemic cores. We used logistic regression to explore the association between CT modalities and favorable functional outcomes (modified Rankin Scale [mRS] score shift toward lower categories) at 3 months. Receiver operating characteristic (ROC) curve analysis compared the predictive accuracy of visually assessed ASPECTS and aCTP ischemic core for favorable outcomes (mRS 0-2) at 3 months. RESULTS: Of 210 patients, 11.4% had ASPECTS 0-5, and 12.9% aCTP core volumes ⩾50 mL. Within the same model, ASPECTS but not aCTP core volumes were associated with favorable outcomes (ASPECTS: acOR 1.85, 95%CI 1.27-2.70, p = 0.001). The ROC curve analyses showed comparable diagnostic accuracy in predicting favorable functional outcomes (mRS 0-2) at 3 months (ROC areas: ASPECTS 0.80 [95%CI 0.74-0.86] vs aCTP core 0.79 [95%CI 0.72-0.85]). DISCUSSION AND CONCLUSION: In patients with aLVO, visually assessed ASPECTS showed at least comparable accuracy to automatically generated CTP core volumes in predicting functional outcomes at 3 months.