Abstract 251: Development of Medically‐Refractory Vasospasm in Aneurysmal Subarachnoid Hemorrhage

Introduction Cerebral vasospasm is a significant contributor to delayed cerebral ischemia and poor clinical outcomes following aneurysmal subarachnoid hemorrhage (aSAH). Despite medical interventions to treat vasospasm, a subset of patients will experience persistent vasospasm that often requires endovascular treatment with percutaneous transluminal angioplasty or intra‐arterial calcium channel blocker infusion. However, the risk factors and clinical outcomes of medically‐refractory vasospasm remain unclear. Recognizing clinical or laboratory predictors of refractory vasospasm may allow for earlier risk stratification and treatment. In this study, we aimed to identify predictors of refractory vasospasm requiring endovascular treatment and assess its impact on functional outcomes at discharge. Methods This study employed a prospectively‐maintained database of patients admitted to a high‐volume aSAH center (August 2003 ‐ March 2024). The diagnosis of vasospasm was determined using transcranial Doppler or CT angiography reports. Clinical and neuroimaging variables were compared in univariate tests between patients with and without medically‐refractory vasospasm. In addition to age and sex, variables with significant differences (p < 0.1) in univariate tests were entered into a multivariable regression model to determine predictors of medically‐refractory vasospasm. To determine the relationship between medically‐refractory vasospasm and poor discharge functional status (modified Rankin Scale mRS scores ≥ 3), a separate multivariable regression model adjusted for age, sex, Hunt 61% vs. 45%, p = 0.04). In the multivariable regression model, hyponatremia (OR 2.18, 95% CI 1.15‐4.12, p = 0.02) and Hunt & Hess scores (OR 1.32, 95% CI 1.01‐1.72, p = 0.04) were significantly associated with medically‐refractory vasospasm. Among aSAH patients with vasospasm, poor discharge outcomes occurred in 95 (49%) patients, with more medically‐refractory vasospasm patients experiencing worsened functional outcomes compared to those with medically‐responsive vasospasm (44% vs. 30%, p = 0.05). After multivariable adjustment, medically‐refractory vasospasm was not significantly associated with poor functional outcome at discharge (OR 1.55, 95% CI 0.73‐3.30, p = 0.26). Conclusion In this study of aSAH patients, higher Hunt & Hess scores and hyponatremia were independent predictors of vasospasm that required endovascular intervention. However, endovascular vasospasm treatment was not significantly associated with poor functional outcomes at discharge. These findings support the safety of endovascular therapy, with outcomes comparable to those of patients who did not require procedural intervention for vasospasm. Furthermore, these results underscore the utility of clinical severity scores as valuable risk stratification tools in aSAH. Further study is warranted to determine whether aggressive hyponatremia management can reduce the incidence of medically‐refractory vasospasm.