Abstract TP314: Reactive Leukocytosis Following Endovascular Thrombectomy for Large Vessel Occlusion Stroke: Incidence, Predictors, and Impact on Functional Outcomes

Background: Post-stroke systemic inflammation has been proposed as a negative predictor for functional recovery, and anti-inflammatory agents have been explored as potential neuroprotective agents after stroke reperfusion treatments. Yet the incidence and impact of post-stroke inflammation on outcomes after endovascular thrombectomy (EVT) for large vessel occlusion (LVO) stroke are unclear. Methods: A retrospective analysis of LVO stroke patients treated with EVT from 2016 to 2024 was conducted. White blood cell (WBC) counts before and after EVT were collected, and those with post-EVT reactive leukocytosis (PERL) were compared to those without significant WBC elevations. Patients with missing data were excluded. The primary outcome was a 90-day modified Rankin scale (mRS). Patient demographics, time from last known well, stroke severity, infarct burden, comorbidities, and hemorrhagic transformation were also captured. Results: 421 patients were included; mean age was 67.3 years; 51% were male; 123 (29.2%) experienced PERL. PERL patients had lower rates of smoking (35.2% vs. 47.1%, p=0.019), higher rates of antiplatelet use (39.8% vs. 28.9%, p=0.028), and lower pre-EVT WBC counts (mean 8.1 vs. 9.6 thousand cells per microliter, p<0.001). Pre-EVT infarct burden, collateral status, site of occlusion, NIH stroke scale, and time from last known well to arteriotomy were not associated with PERL incidence, nor were TICI score, number of EVT passes, or first-pass EVT technique (all p>0.05). PERL was associated with higher rates of hemorrhagic transformation (23.6% vs. 15.4%, p=0.047), larger shifts towards worse mRS (median 3 vs. 2, p<0.001), lower rates of functional independence (39.0% vs. 53.0%, p=0.009), and higher rates of bedridden state or death (26.0% vs. 14.1%, p=0.003). After multivariable adjustments, including hemorrhagic transformation, PERL remained significantly associated with higher odds of worse mRS (common OR 2.46 [95%CI 1.60-3.80], p<0.001), lower odds of functional independence (OR 0.45 [95%CI 0.24-0.84], p=0.013), and higher odds of bedridden state or death (OR 2.78 [95%CI 1.26-6.26], p=0.012). Conclusion: PERL is a common post-EVT phenomenon among LVO stroke patients, is largely unassociated with stroke or procedural characteristics, and is significantly associated with worse post-EVT outcomes independent of hemorrhagic transformation. These findings support future investigations targeting post-EVT inflammation to improve neurological outcomes.