White matter hyperintensity burden and functional outcomes in acute ischemic stroke patients after mechanical thrombectomy: A systematic review and meta-analysis

Background: The influence of white matter hyperintensity (WMH) on clinical outcomes in acute ischemic stroke (AIS) patients treated with mechanical thrombectomy (MT) remains controversial. We performed a systematic review and meta-analysis to examine whether WMH burden is associated with clinical outcomes in AIS patients after MT. Methods: PubMed, Embase, and Web of Science were searched from inception to Sep 03, 2023. The registration number for PROSPERO is CRD42022340568. Studies reporting an association between the burden of WMH in AIS patients and clinical outcomes after MT were included in the meta-analysis. A random-effects model was used for meta-analysis. The quality of the included studies was assessed using the Newcastle-Ottawa Scale. Additionally, the presence of imprecise-study effects was evaluated using Egger's test and funnel plot. Results: Fifteen studies with 3,456 patients were enrolled in this meta-analysis. Among AIS patients who underwent MT, moderate/severe WMH had higher odds of 90-day unfavorable functional outcomes (odds ratio [OR] 2.72, 95% confidence interval [CI] 2.14-3.44; I2 = 0.0%; 95% CI 0.0%-42.7%), 90-day mortality (OR 1.94, 95% CI 1.45-2.60; I2 = 19.5%; 95% CI 0.0%-65.2%) and futile recanalization (OR 2.99, 95% CI 1.42-6.28; I2 = 69.7%; 95% CI 0.0%-91.0%) compared with none/mild WMH. However, the two groups had no significant difference in successful recanalization, symptomatic hemorrhagic transformation, and hemorrhagic transformation. A subset analysis of patients from 3 articles showed that WMH volume was not significantly associated with these outcomes. A notable limitation is that this meta-analysis lacks direct adjustment for imbalances in important baseline covariates. Conclusions: Patients with moderate/severe WMH on baseline imaging are associated with substantially increased odds of 90-day unfavorable outcomes, futile recanalization, and 90-day mortality after MT. This association suggests that moderate/severe WMH may contribute to the prediction of clinical outcomes in AIS patients after MT.