CT perfusion ischemic core predicts PH-2 hemorrhagic transformation following intravenous alteplase bridging treatment prior to endovascular thrombectomy

Background: Intravenous thrombolysis (IVT) administered as a bridging therapy prior to endovascular thrombectomy (EVT) for acute ischemic stroke may increase the risk of hemorrhagic-transformation (HT). CT-perfusion (CTP) imaging enables quantitative assessment of ischemic core and penumbral tissue and may support individualized hemorrhagic risk stratification. Objectives: To assess whether baseline CTP-defined ischemic core parameters are associated with parenchymal-hematoma type 2 (PH-2) following bridging IVT before EVT. Design: Observational-cohort-study. Data sources and methods: Consecutive patients with large-vessel occlusion treated within 4 h of symptom onset at two tertiary stroke centers between 2017 and 2023 were analyzed. All patients underwent baseline CTP imaging. Outcomes were compared between patients treated with IVT plus EVT and those treated with direct-EVT. HT was assessed on 24-h follow-up noncontrast-CT using ECASS-2 criteria. Multivariable logistic regression was performed to identify independent predictors of PH-2. Results: Among 398 patients (50.6% male), 180 received IVT + EVT (mean age 70.2 ± 15.0 years) and 218 underwent direct-EVT (69.5 ± 14.5 years). Baseline characteristics, workflow times, thrombectomy passes, and reperfusion rates were comparable. PH-2 was associated with higher mortality (43.8% vs 11.7%, p < 0.001) and worse 90-day functional outcome (median modified Rankin Score 4 (2–6) vs 3 (1–4), p = 0.002). Bridging-IVT was associated with higher PH-2 rates compared with direct EVT (6.1% vs 2.0%, p = 0.036), without increased symptomatic intracranial-hemorrhage. In sensitivity analyses, bridging-IVT was associated with higher PH-2 rates only in patients with any ischemic core (7.8% vs 1.5%, p = 0.014), core volume >10 mL (8.8% vs 0.8%, p = 0.004), and >20 mL (8.7% vs 1.3%, p = 0.03). Penumbral volume was not associated with PH-2. In multivariable analysis, any ischemic core (odds ratio (OR) 12.67, p = 0.02) and core volume >10 mL (OR 11.12, p = 0.034) independently predicted PH-2. Conclusion: Baseline CTP-defined ischemic core volume is strongly associated with severe HT following bridging intravenous alteplase prior to EVT and may inform individualized risk–benefit assessment of bridging therapy.