Abstract Number: Esoc2026a941 Mechanisms of End in Minor Stroke With Large Vessel Occlusion Based on Cerebrovascular Reactivity Mapping Using Resting-State Bold Fmri

Abstract Background and aims The underlying pathophysiology of early neurological deterioration (END) in minor stroke patients with large vessel occlusion (LVO) or severe stenosis is incompletely understood. This study aimed to investigate the hemodynamic mechanisms of END using relative cerebrovascular reactivity (rCVR) derived from resting-state BOLD fMRI. Methods This single-center prospective study included acute ischemic stroke patients between 2024 and 2025, presenting within 24 hours from last known well, with a baseline NIHSS≤5 and anterior circulation LVO or severe stenosis. END was defined as an increase of ≥4 points in the total NIHSS score or ≥2 points in any single item within 72 hours without evidence of parenchymal hemorrhage. Three rCVR metrics were calculated from resting-state BOLD fMRI acquired before END: rCVRMCA, the ratio of CVR between the ipsilateral and contralateral middle cerebral artery territories; rCVRhemisphere, the comparison of CVR between the affected hemisphere and the contralateral hemisphere; and rCVRaffected region, the CVR of the affected vascular territory relative to the corresponding region on the opposite side. Results Sixty-seven patients were included, and END occurred in 14.9% (10/67). Patients who experienced END showed a significantly lower rCVRMCA (0.25 vs. 0.84), rCVRhemisphere (0.69 vs. 0.86), and rCVRaffected region (0.31 vs. 0.85), compared with those without END (all p0.001). Receiver operating characteristic analysis demonstrated that rCVRMCA had the highest predictive performance for END (AUC = 0.93). Conclusions In patients with mild symptoms due to anterior circulation LVO or severe stenosis, END was associated with impaired rCVR, suggesting reduced hemodynamic reserve. These findings require further confirmation in larger cohorts. Conflict of interest Zhijiao He, Lan Hong, Xinru Wang, Siyuan Li, Anqi Zhang, Nan Cao, Cuiling Qin, Xin Cheng: nothing to disclose Figure 1 - belongs to Methods Figure 2 - belongs to Results