Abstract Number: Esoc2026a580 Cerebral Small Vessel Disease and Unfavorable Functional Outcome Despite Successful Recanalization: Mediation by Contrast Extravasation and Intracranial Hemorrhage

Abstract Background and aims Cerebral small vessel disease (CSVD) is common in patients undergoing endovascular thrombectomy (EVT) and is associated with unfavorable functional outcomes and increased risks of contrast extravasation and intracranial hemorrhage (ICH). We investigated whether contrast extravasation and ICH mediate the association between CSVD burden and unfavorable outcome after EVT. Methods We retrospectively enrolled patients with anterior circulation large-vessel occlusion who achieved successful recanalization (modified Thrombolysis in Cerebral Infarction ≥2b) between January 2020 and December 2024. CSVD burden was assessed on 3.0-T magnetic resonance imaging and categorized as none-to-mild (score 0–2) or moderate-to-severe (score 3–4). Contrast extravasation and ICH were evaluated on post-EVT dual-energy computed tomography. Mediation analysis quantified indirect effects on unfavorable 90-day outcome (modified Rankin Scale 3–6). Results Among 243 patients (median age, 65 years; 73.3% male), 101 (41.6%) had moderate-to-severe CSVD. Unfavorable outcomes at 90 days were more frequent in patients with moderate-to-severe CSVD than in those with none-to-mild CSVD (58.4% vs 35.9%; adjusted odds ratio OR, 2.02; 95% CI, 1.09–3.74). Contrast extravasation and ICH were more prevalent with higher CSVD burden. The total indirect effect through contrast extravasation and ICH was significant (adjusted OR, 1.06; 95% CI, 1.02–1.12), accounting for 30% of the total effect. Contrast extravasation was the dominant mediator (21%) and fully mediated the association between CSVD burden and ICH. Conclusions Moderate-to-severe CSVD is independently associated with unfavorable outcomes after successful EVT, partially mediated by postprocedural contrast extravasation and ICH, with contrast extravasation as the primary pathway. Conflict of interest Min Zhao: nothing to disclose