OBJECTIVE: Aneurysmal subarachnoid hemorrhage (aSAH) is an acute cerebrovascular event that leads to devastating consequences. Early brain infarction (EBI) develops very early, within the first 72 hours after bleeding, and may have a significant impact on long-term outcomes. The incidence andimpact of EBI in the prognosis of aSAH remain uncertain. We performed a systematic review and meta-analysis to evaluatethe incidence of EBI in patients with aSAH and determine its effect on mortality and functional outcomes. METHODS: We performed a systematic review and meta-analysis. Inclusion criteria were 1) studies that evaluated aSAH within 72 hours after bleeding; 2) performed a brain imaging study up to 72 hours of hemorrhage; 3) used computed tomography or magnetic resonance imaging; and 4) included a description of the findings of the brain imaging study (whether or not an infarct was present). RESULTS: Ten studies that met the criteria were included. The incidence of EBI was 17%. The risk ratio for 3-month mortality was 2.18 (95% confidence interval 1.48-3.30). The overall risk ratio for poor outcome was 2.26 (95% confidence interval 1.75-2.93). CONCLUSIONS: EBI plays an important role in the outcome of patients with aSAH. Its significant impact couldrepresent a new therapeutic frontier for improving outcomesof these patients.2026-12-31