ABSTRACT NUMBER: ESOC2026A499 VASOSPASMS TREATED WITH INTRA-ARTERIAL NIMODIPINE DURING ENDOVASCULAR ANEURYSM TREATMENT AND DELAYED CEREBRAL ISCHEMIA IN ANEURYSMAL SUBARACHNOID HEMORRHAGE

Abstract Background and aims Delayed cerebral ischemia (DCI) occurs in approximately 30% of patients with aneurysmal subarachnoid hemorrhage (aSAH) and contributes substantially to poor outcome. Although cerebral vasospasm is associated with DCI, its clinical relevance remains unclear. We assessed the association between vasospasm treated with intra-arterial nimodipine during endovascular aneurysm treatment and subsequent DCI in aSAH patients, and explored potential sex differences in this association. Methods Consecutive aSAH patients aged ≥18 years undergoing endovascular treatment of a ruptured aneurysm at the UMC Utrecht between January 2018 and July 2025 were retrospectively identified. Periprocedural administration of intra-arterial nimodipine was recorded and DCI was defined clinically according to established criteria. Multivariable logistic regression analysis was performed to assess the association with DCI, adjusting for age, treatment type, modified Fisher scale, modified World Federation of Neurosurgical Societies grade, hypertension, smoking, and time from ictus to treatment. Results Among 333 aSAH patients (74.2% women), 132 received periprocedural nimodipine, of whom 27 developed DCI, compared with 63 patients not receiving periprocedural nimodipine. In univariable analysis, periprocedural vasospasm treated with nimodipine was associated with DCI (odds ratio (OR) 0.56; 95% confidence interval (CI) 0.34 – 0.94). After multivariable adjustment, this association was attenuated and reached only borderline statistical significance (OR 0.57; 95%CI 0.33 – 1.00). No evidence of effect modification by sex was observed (interaction p=0.69). Conclusions Periprocedural vasospasm treated with intra-arterial nimodipine was borderline associated with a reduced DCI risk in aSAH patients, with no evidence of sex-specific effects. Prospective studies are needed to further evaluate the potential protective effect of periprocedural nimodipine. Conflict of interest Maaike J.A. van Eldik: nothing to disclose. Joost J. G. W. Haring: nothing to disclose. Jolijn van de Putte: nothing to disclose. Mervyn D.I. Vergouwen: nothing to disclose. Irene C. van der Schaaf: nothing to disclose. Ynte M. Ruigrok: nothing to disclose.