Pre-treatment hemorrhagic infarct on MRI is associated with poor outcome after mechanical thrombectomy for stroke: a multicenter Bayesian analysis

Abstract

Background: Hemorrhagic infarction (HI), defined as petechial bleeding within infarcted tissue, is often considered benign. However, its prognostic significance before mechanical thrombectomy (MT) remains unclear. Objective: To evaluate whether HI detected on pre-treatment MRI is associated with 90-day functional dependence, post-MT parenchymal hematoma (PH), and symptomatic intracerebral hemorrhage (SICH). Methods: We conducted a retrospective multicenter study including 479 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. Outcomes included functional dependence at 90 days (mRS 3–6), ipsilateral PH, and SICH. Multivariable logistic regression, Firth regression, and Bayesian models were used to assess associations, adjusting for clinical and procedural covariates. Results: Among 479 patients (median age 72.0 years [IQR: 59.0–80.0], 46.1% female), pre-treatment HI was present in 5.2%. Functional dependence (mRS 3–6) occurred in 51.6%, PH in 9.4%, and SICH in 3.1%. Patients with HI had higher NIHSS (median 17 vs. 16) and larger infarct volumes. HI was independently associated with functional dependence (Bayesian OR=6.09, 95% CrI: 2.07–20.29). HI showed high posterior probabilities of association with PH (OR=2.38, 95% CrI: 0.61–7.70; Pr[OR>1]=0.91) and SICH (OR=4.40, 95% CrI: 0.55–24.06; Pr[OR>1]=0.93). Results were consistent across models using Firth regression and robust standard errors. Conclusion: HI on pre-treatment MRI is associated with worse functional outcomes and increased risk of hemorrhagic complications after thrombectomy. Although not a contraindication to treatment, HI may serve as a prognostic marker of reperfusion vulnerability and warrants further study as a target for neuroprotective strategies.