Abstract 415: Pre‐Treatment Hemorrhagic Infarct Is Associated with Worse Outcome After Mechanical Thrombectomy: A Multicenter Bayesian Analysis

Introduction/Purpose Hemorrhagic infarction (HI), defined as petechial bleeding within infarcted tissue, is often considered benign. However, its clinical significance before mechanical thrombectomy (MT) remains unclear. We sought to evaluate whether HI detected on sensitive pre‐treatment MRI is associated with 90‐day functional dependence, post‐MT parenchymal hematoma (PH), and symptomatic intracerebral hemorrhage (SICH). Materials/Methods We conducted a retrospective multicenter, multinational study of consecutive patients with anterior circulation large vessel occlusion who underwent MT and had pre‐treatment T2*‐weighted MRI. HI was classified as type I or II according to ECASS III criteria, blinded to other data. Outcomes included functional dependence or death at 90 days (modified Rankin scale, mRS 3‐6), ipsilateral PH, and SICH during the acute hospitalization according to ECASS III. Multivariable Bayesian reporting posterior odds ratios (OR), 95% credible intervals (CrI), and posterior probability that OR>1and frequentist logistic regression models reporting adjusted odds ratios (aOR), 95% confidence intervals (CI), and p‐values were used to assess associations, adjusting for clinical and procedural covariates. Results Among 479 patients, the median age was 72 years (IQR: 59‐80), 46% were female, 50% received intravenous thrombolysis, and 83% achieved mTICI 2b‐3 successful reperfusion. Pre‐treatment HI was present in 5.2% (Type I: 2.7%, II: 2.5%). Functional dependence or death at 90 days was observed in 52%, PH in 9.4%, and SICH in 3.1%. Accounting for age, sex, baseline mRS, vascular risk factors, NIHSS, intravenous thrombolysis, infarct volume, time from onset, and successful reperfusion (mTICI 2b‐3), pre‐treatment HI was independently associated with functional dependence or death (Bayesian OR=6.66, 95%CrI=2.15‐24.28, PrOR>1=1.00; frequentist aOR=5.95, 95%CI=1.91‐18.52, p=0.002, Table ). Pre‐MT HI was also independently associated with the development of ipsilateral PH (Bayesian OR=2.76, 95%CrI=0.73‐9.26, PrOR>1=0.94; frequentist aOR=2.84, 95%CI=0.84‐9.58, p=0.091) and SICH (Bayesian OR=5.59, 95%CrI=0.63‐34.92, PrOR>1=0.95; frequentist aOR=6.02, 95%CI=1.00‐36.11, p=0.049). Results were consistent across other sensitivity analyses using Hüber‐White standard errors and Firth regression. Conclusion HI on pre‐treatment MRI is associated with worse long‐term functional outcomes and increased risk of more significant hemorrhagic transformation after thrombectomy. While not a contraindication to MT, HI may serve as a prognostic marker of reperfusion vulnerability and warrants further study as a potential target for neuroprotective strategies to prevent reperfusion injury. image