Risk of Hemorrhagic Transformation and Its Subtypes After Endovascular Therapy vs Medical Management in Large Core Ischemic Stroke: A Systematic Review and Meta Analysis of Randomized Clinical Trials.

BACKGROUND: Endovascular therapy (EVT) improves outcomes in selected patients with large-core acute ischemic stroke (AIS), but concerns remain regarding hemorrhagic transformation (HT). We evaluated the risk of intracranial hemorrhage (ICH) and its subtypes following EVT versus medical management (MM). METHODS: PubMed, Embase, and Scopus were searched through February 2026. Randomized clinical trials (RCTs) enrolling adults with large-core AIS (ASPECTS ≤5 or ischemic core volume ≥70 mL) were included. Risk ratios (RRs) were pooled using random-effects models. RESULTS: Six RCTs (n=1,887) and five post hoc publications from same trials were included. EVT increased the risk of any ICH compared with MM (RR=1.80, 95% CI: 1.40-2.30; P<0.001). Risks of HI2 (RR=2.23), PH1 (RR=2.42), and subarachnoid hemorrhage (RR=2.21) were significantly higher, whereas PH2 and intraventricular hemorrhage were not. Symptomatic ICH occurred more frequently after EVT (5.0% vs. 3.1%; P=0.02), but this finding was not robust to sensitivity analyses. In ASPECTS 0-2 neither any ICH nor symptomatic ICH was significantly increased; however, limited sample size and influential studies precluded excluding clinically meaningful risk. CONCLUSION: EVT increased radiographic hemorrhage, primarily HI2 and PH1, without a significant increase in PH2. The modest increase in symptomatic ICH was sensitive to the contributing trial and definition.