Abstract Number: Esoc2026a960 Isolated Anterior Cerebral Artery Infarction Is Associated With Higher Haemorrhagic Transformation but Comparable Functional Outcomes to Middle Cerebral Artery Infarction

Abstract Background and aims Haemorrhagic transformation (HT) is a common complication of acute ischaemic stroke, yet territory-specific characteristics remain unclear. We compared HT frequency and clinical impact between isolated anterior cerebral artery (ACA) and isolated middle cerebral artery (MCA) infarctions. Methods We analysed registry patients admitted June 2020−February 2025 with acute unilateral isolated ACA or MCA infarction. Neurological severity was assessed using the National Institutes of Health Stroke Scale (NIHSS). HT was evaluated on follow-up neuroimaging during hospitalisation using European Cooperative Acute Stroke Study criteria. Favourable functional outcome was defined as 90-day modified Rankin Scale (mRS) 0–2 or no worsening from admission. Multivariable logistic regression analysis was performed. Results Of 334 patients (17 ACA, 317 MCA), HT was more frequent in the ACA group (41.2% vs 20.2%, p = 0.046, Figure 1). HT in the ACA group was exclusively haemorrhagic infarction, whereas the MCA group included parenchymal haematoma. Vessel occlusion and recanalisation rates were similar between groups. Despite higher HT rates in the ACA group, favourable functional outcomes were comparable between groups. Multivariable analysis identified isolated ACA infarction (odds ratio OR, 4.614; 95% confidence interval CI, 1.516–14.047; p = 0.007) and admission NIHSS score (OR, 1.111; 95% CI, 1.066–1.158; p 0.001) as independent HT predictors. Conclusions Isolated ACA infarction is associated with frequent HT, which is limited to haemorrhagic infarction without parenchymal haematoma. Consequently, favourable functional outcomes are comparable between the groups. These findings suggest that the pathophysiology and clinical relevance of HT differ between ACA and MCA infarctions. Conflict of interest Momoyo Ibukuro: nothing to disclose. Kenichi Sakuta: nothing to disclose. Motohiro Okumura: nothing to disclose. Hiroyuki Kida: nothing to disclose. Yuri Shojima: nothing to disclose. Teppei Komatsu: nothing to disclose. Hidetaka Mitsumura: nothing to disclose. Kenichiro Sakai: nothing to disclose. Yasuyuki Iguchi: nothing to disclose. Figure 1 - belongs to Results