Abstract TP290: Final Infarct Volume as a Surrogate Endpoint in Anterior-Circulation ICAS-LVO Stroke – Secondary Analysis of the RESCUE-ICAS Registry

Introduction: Final infarct volume (FIV) on 24-hour MRI is a well-established imaging biomarker linked to functional recovery after ischemic stroke, 1-3 yet its prognostic value in ICAS-LVO remains poorly explored. The impact of adjunct intracranial stenting on both infarct size and infarct progression also remains unclear in this population. This study aimed to examine the association between FIV and clinical outcome, evaluate the effect of adjunct stenting on FIV and infarct progression, and assess the relationship between infarct progression and functional independence. Methods: We conducted a secondary analysis of the RESCUE-ICAS registry, 4 only patients with anterior circulation LVO with MRI after thrombectomy were included. Final infarct volume (FIV) was measured on diffusion-weighted MRI performed 24-36 hours post thrombectomy. Infarct progression was defined as the difference between baseline CTP infarct volume (CBF <30%) on presentation and 24–36-hour FIV. The primary outcome was 90-day functional independence (mRS 0–2). Secondary outcomes included the effect of adjunct stenting on FIV and infarct progression. Associations were analyzed using multivariable logistic regression and inverse probability of treatment weighting (IPTW). Results: Of the 417 patients included in the RESCUE-ICAS registry, 203 had anterior circulation ICAS-LVO and underwent MRI 24–36 hours post-thrombectomy. Among these, 80 patients (39%) received adjunct stenting. FIV was independently associated with 90-day functional independence (adjusted OR per 10 mL increase: 0.8; 95% CI: 0.68–0.94; p = 0.007). Adjunct stenting was associated with smaller FIV (IPTW-adjusted mean difference: –25.07 mL; 95% CI: –40.36 to –9.78; p = 0.001). In 108 patients with baseline CTP data and FIV data, infarct progression was not significantly different between stented and non-stented groups (Δ –9.53 mL; 95% CI: –37.9 to 18.8; p = 0.506), but progression <44.5 mL was strongly associated with favorable outcome. Conclusion: Among ICAS-LVO patients, 24-36-hour FIV is a strong predictor of functional outcome. Adjunct stenting is associated with smaller FIV. Lower infarct progression was also associated with favorable outcome. These findings highlight FIV as a reliable imaging biomarker and potential surrogate endpoint in future trials.