ABSTRACT NUMBER: ESOC2026A2417 POSTPROCEDURAL GFAP PREDICTS CLINICALLY RELEVANT HEMORRHAGIC TRANSFORMATION AFTER ENDOVASCULAR THROMBECTOMY

Abstract Background and aims Hemorrhagic transformation (HT) remains a major concern after endovascular therapy (EVT) for large-vessel occlusion stroke (LVO-AIS), and reliable predictors of HT are lacking. Glial fibrillary acidic protein (GFAP), a marker of astroglial injury, may reflect tissue vulnerability to reperfusion-related hemorrhage. We aimed to assess the predictive value of post-EVT plasma GFAP for HT. Methods Prospective single-centre study including two temporally distinct cohorts of anterior-circulation-LVO-AIS patients successfully recanalized after EVT with/without IVT (mTICI≥2B): derivation cohort (cohort-1, n=78) and evaluation cohort (cohort-2, n=110). Plasma GFAP was sampled immediately after EVT and measured using Simoa® in cohort-1 and Lumipulse® in cohort-2. The primary outcome was relevant HT, defined as parenchymal hematoma on 24-hour CT. ROC analyses compared the predictive performance of GFAP with clinical and imaging variables and across cohorts. Results Cohort-1 (50% female; mean age 72.8 years) and cohort-2 (57% female; mean age 74.5 years) had 16% and 9.1% HT, respectively. HT-patients presented approximately 6-fold higher GFAP mean concentration across cohorts. Baseline ASPECTS was the only significant predictor of HT (0.74<AUC<0.790). GFAP consistently showed excellent discriminatory performance (AUC 0.846 and 0.836) in both cohorts. In cohort-2, GFAP >3500pg/mL identified 20% of HT with 100% specificity, while <61.4pg/mL excluded HT with 100% specificity in 23% of patients. Conclusions In successfully recanalized LVO-AIS, post-EVT GFAP consistently predicted relevant HT across two independent cohorts. Early and rapid clinical-grade testing may enable more individualized post-EVT monitoring, especially in neurocritical patients with limited neurological assessment. Conflict of interest All authors: nothing to disclose