Thrombectomy improves functional outcome in large core stroke partly by preventing severe cerebral edema: a real-world mediation analysis.

EVT was associated with lower odds of mass effect due to severe cerebral edema in large infarct core stroke.

• Prospective observational cohort of 202 patients (EVT 119; medical management 83) with anterior circulation LVO, NIHSS ≥6, ASPECTS ≤5, within 24 h of onset.
• Mass effect (midline shift ≥5 mm within 72 h) occurred in 31.1% with EVT vs 51.8% with medical management.
• IPTW-adjusted OR 0.28 (95% CI, 0.12-0.67) with doubly robust adjustment.

EVT was associated with higher odds of favorable functional outcome (mRS 0-3 at 90 days).

• IPTW-adjusted OR 2.32 (95% CI, 1.01-5.31).
• Favorable outcome was the secondary outcome, assessed at 90 days.
• Estimated using IPTW with doubly robust adjustment.

EVT was associated with lower 90-day mortality without an excess of symptomatic intracranial hemorrhage.

• Mortality aOR 0.45 (95% CI, 0.21-0.97).
• sICH defined by SITS-MOST criteria; no excess sICH was found with EVT.
• Safety outcomes were death at 90 days and sICH.

Mass effect independently predicted poor functional outcome.

• aOR for mRS 4-6 was 7.7 (95% CI, 3.01-19.69).
• Supports mass effect as a clinically relevant mediator of outcome.

About 29.5% of the association between EVT and favorable outcome was statistically mediated by attenuation of mass effect.

• Mediation analysis assessed whether ME contributed to the EVT-favorable outcome association.
• Authors summarize this as approximately one-third of EVT's functional benefit mediated by attenuation of severe cerebral edema.

Lower baseline ASPECTS and higher admission glucose independently predicted mass effect, yielding a model with good discrimination.

• Optimism-corrected AUC was 0.82.
• Both are admission variables available at the bedside.
• Authors suggest use for risk stratification to guide intensified monitoring and edema-targeted management.