Abstract Body: Background: Hemorrhagic transformation (HT) following endovascular treatment (EVT) is influenced by multiple factors, including the leptomeningeal collateral status. This study aims to investigate the dynamic role of leptomeningeal collaterals in HT in acute ischemic stroke (AIS) patients under various recanalization conditions.
Materials and Methods: This prospective cohort study included consecutive patients with middle cerebral artery (MCA) AIS who underwent EVT at the Neurology Department of West China Hospital between January 2019 and June 2023. Preoperative leptomeningeal collaterals were evaluated using the regional leptomeningeal collateral (rLMC) score, and postoperative collaterals were assessed using the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) score. Multivariate logistic regression was employed to analyze the correlation between preoperative rLMC scores, postoperative ASITN/SIR scores, and HT. Fisher’s exact test was used to explore the impact of changes in leptomeningeal collaterals on HT.
Results: A total of 342 patients were included in this study. Multivariate analysis demonstrated that patients with good rLMC scores (>10) experienced fewer HT events compared to those with poor rLMC scores (≤10) (OR 0.46, 95% CI 0.28-0.76, P=0.002). Further subgroup analysis based on intravenous thrombolysis (IVT) showed that good leptomeningeal collaterals were significantly associated with reduced risk of HT in patients receiving bridging therapy (OR 0.12, 95% CI 0.03-0.38, P<0.001). Among 75 patients with incomplete recanalization, no significant difference was observed between those with good (＞2) and poor (≤2) postoperative ASITN/SIR scores. Analysis of collateral changes indicated that patients with consistently good pre- and post-operative collateral status had the lowest risk of HT (OR 0.19, 95% CI 0.04-0.95, P=0.043). However, no significant difference was found in HT risk among patients with improved collaterals.
Conclusion: Good preoperative leptomeningeal collateral status is associated with reduced risk of HT after EVT, particularly in those receiving bridging therapy. For patients with incomplete reperfusion, those with consistently good pre- and post-operative collaterals exhibit the lowest risk of HT, whereas improvement from poor to good collaterals does not reduce HT risk.