Collaterals and outcomes after endovascular treatment in acute large vessel occlusion: Disparity by stroke etiologies

Background: Collateral circulation provides compensatory flow to ischemic brain regions in acute large vessel occlusion (LVO), which had been associated with better outcomes after endovascular treatment (EVT). Aims: We aimed to reveal the pre-EVT collateral status and its associations with outcomes after EVT, in patients with acute LVO with different etiologies. Methods: Based on a prospective, multicenter registry, we analyzed patients with acute, intracranial anterior-circulation LVO due to large artery atherosclerosis (LAA) and cardioembolism (CE), who underwent EVT within 24 hours. Pre-EVT leptomeningeal collateral status was classified on digital subtraction angiography by ASITN/SIR grading system. Outcomes included good 3-month functional outcome (modified Rankin Scale [mRS] 0-2), 3-month mRS distribution, successful recanalization, early neurological deterioration, symptomatic intracranial hemorrhage (sICH), and 3-month mortality. Results: Among 805 patients (median age 66 years), 450 and 355 respectively had LVO due to LAA and CE, of whom 57.8% and 56.6% (p=0.742) had good pre-EVT collaterals. In LAA patients, good collaterals were associated with lower risk of sICH (adjusted odds ratio [OR]=0.40; 95% CI 0.17-0.94; p=0.036) but not functional outcomes. In CE patients, good collaterals were associated with a higher chance of good functional outcome (adjusted OR=1.55; 95% CI 0.96-2.51; p=0.072) and lower mRS at 3 months (adjusted common OR=0.64; 95% CI 0.43-0.94; p=0.021). However, there was no significant CE/LAA and collateral status interaction on any outcome. Conclusions: The study revealed comparable pre-EVT collateral status in patients with LVO due to LAA versus CE who received EVT within 24 hours, but the pre-EVT collaterals may have different protective effects for post-EVT outcomes in these two groups of patients.