ABSTRACT NUMBER: ESOC2026A1274 GFAP TRAJECTORIES CAN PREDICT HEMORRHAGIC TRANSFORMATION AND EARLY NEUROLOGICAL DETERIORATION IN LARGE VESSEL OCCLUSION STROKE

Abstract Background and aims Glial fibrillary acidic protein (GFAP), a promising stroke biomarker, remains understudied in large-vessel occlusion (LVO) stroke. We assessed whether GFAP trajectories predict post-reperfusion outcomes. Methods Plasma GFAP levels were measured using the iSTAT Alinity system at T1=hospital arrival, T2=post-reperfusion, and T3=24h. Outcomes included hemorrhagic transformation (HT) as per Heidelberg criteria, and early neurological deterioration (END) defined as a 24h-NIHSS increase ≥4, ICU transfer, palliation and/or mortality ≤72 hours. GFAP values were log-transformed. Regression analyses were adjusted for age, thrombolysis and recanalization (TICI 2b-3). Sensitivity analyses explored a 213 pg/mL cutoff based on commercial point-of-care assays. Results Eighty participants were included; 42 received thrombolysis, 55 underwent thrombectomy (47 recanalized), 34 received both. HT occurred in 28(35.0%), moderate–severe HT (Heidelberg ≥1c) in 11(13.8%), and END in 20(25.0%). Median(IQR) GFAP increased from 51(29-80) (T1) to 84(44-129) (T2) to 686(154-2309) (T3). Log-fold GFAP increases from T2–T3 predicted HT (aOR 2.95 95%CI (1.69–6.22), p=0.0009) and END (aOR 1.98(1.20–3.60), p=0.0127). T1–T3 change showed good discrimination for HT (AUC 0.85(0.75–0.93). Among recanalized participants, T2-T3 increase predicted END (OR 3.9(1.63–16.16), p=0.014) compared to non-recanalized participants (OR 1.12(0.56–2.26), p=0.73). T1-T2 GFAP rise >213 pg/mL indicated moderate–severe HT [specificity 0.94(0.83–0.99); LR+ 5.82(1.51–22.35)], while T3 GFAP ≤213 pg/mL excluded HT [sensitivity 0.96(0.80–1.00); LR– 0.08(0.01–0.58]. Conclusions GFAP trajectories may support HT and END risk stratification in LVO stroke. Conflict of interest Timothé Langlois-Thérien: nothing to disclose; Catherine Brassard: nothing to disclose; Ralph Robert Nuhay: nothing to disclose; Julien Frédérick Paul: nothing to disclose; David Chiasson-Ricard: nothing to disclose; Sarah-Emilie Godin: nothing to disclose; Dr Laura Gioia: : I declare having current funding from the Heart and Stroke foundation of Canada.