Feasibility and Outcomes of Clazosentan in Ruptured Vertebrobasilar Dissecting Aneurysms: A Retrospective Cohort Study

Background and Aims Subarachnoid hemorrhage (SAH) caused by ruptured vertebrobasilar dissecting aneurysms (VBDAs) is associated with high morbidity and mortality rates. Although clazosentan is effective in preventing cerebral vasospasm after SAH due to saccular aneurysms, its efficacy and safety have not yet been established in patients with ruptured VBDAs. We aimed to evaluate the efficacy and safety of clazosentan in patients with SAH due to ruptured VBDAs. Methods We conducted a retrospective cohort study of patients treated for SAH due to ruptured VBDAs at a single institution between January 2017 and March 2025. The patients were divided into the clazosentan ( n = 10) and control ( n = 28) groups. The baseline characteristics and clinical outcomes were compared between the groups. Results A total of 38 patients were included in the study. The severity of SAH did not differ significantly between the two groups (World Federation of Neurosurgical Societies grades IV–V: 60.0% vs. 64.3%, p > 0.99). No significant differences in the incidences of symptomatic vasospasm (10.0% vs. 14.3%, p > 0.99) or delayed cerebral ischemia (10.0% vs. 10.7%, p > 0.99) were observed between the clazosentan and control groups. Pulmonary edema occurred more frequently in the clazosentan group than in the control group (30.0% vs. 10.7%, p = 0.31). However, unfavorable outcomes at discharge were comparable between the clazosentan and control groups (40.0% vs. 60.7%, p = 0.29). Conclusion Clazosentan use in patients with SAH due to VBDAs appeared to be feasible and generally well tolerated without apparent excess harm. Larger prospective studies with adequate sample size are warranted to clarify the effect on clinical outcomes.