Abstract 508: Impact of Reperfusion on Thrombectomy Outcomes in Patients with Pre‐Stroke Disability

Purpose Mechanical thrombectomy (MT) is often performed outside standard eligibility criteria. While patients with varying levels of pre‐stroke disability are offered MT in clinical practice, the clinical benefit in this population remains underexplored. Methods We conducted a retrospective multicenter cohort study across four U.S. comprehensive stroke centers, including patients who underwent MT for anterior circulation large vessel occlusion in Internal Carotid Artery (ICA), and M1/M2 segments of Middle Cerebral Artery (MCA) with varying baseline functional status. The primary analysis had two prespecified components: 1) evaluating the shift in 90‐day mRS distribution by reperfusion status within each baseline mRS stratum, using ordinal logistic regression adjusted for age, NIHSS, ASPECTS, and occlusion site; 2) testing for reperfusion × baseline mRS interaction and estimating within‐stratum associations (mRS 0‐4). Secondary analyses assessed discharge mRS, the effect of first‐pass effect (FPE), and outcomes stratified by disability etiology (neurological vs. non‐neurological). Rates of good 90‐day outcome were examined across baseline mRS strata and within specific etiological subgroups. Good outcome was defined relative to baseline: mRS 0‐2 for patients with baseline mRS 0‐2, and functional stability or improvement for those with baseline mRS 3‐4. Results Of 4,840 patients, 1,457 (30.1%) had pre‐stroke disability (mRS 1‐4), with substantial variability in treatment rates of patients with disability across centers. In adjusted analyses, higher reperfusion was associated with significantly lower odds of worse 90‐day mRS in patients with baseline mRS 0‐3, with a consistent direction of benefit in those with baseline mRS 4 (Figure 1A). No significant interaction between reperfusion and baseline mRS was observed (p=0.12). The rates of good outcome at 90‐days according to final reperfusion status (eTICI2b‐3 vs eTICI0‐2a) is illustrated in Figure 1B. Higher reperfusion grades also predicted lower discharge mRS across all disability strata, and first‐pass effect (FPE) conferred systematic benefit at 90 days regardless of baseline mRS. Outcomes were comparable between neurological and non‐neurological disability etiologies, and across specific disability subcategories, which showed relatively similar rates of good outcome at 90 days (Figure 1C). Conclusions In this large multicenter cohort, reperfusion was associated with functional improvement across varying levels of baseline disability, without significant modification by disability etiology. These findings support MT in patients with pre‐stroke disability, though individualized selection remains essential. Further studies are warranted. image