Abstract Body: Introduction: Antiplatelet therapy (APT) is increasingly common in the treatment of aneurysmal subarachnoid hemorrhage (aSAH) with the growth of endovascular therapy, raising concerns about ventriculostomy-related hemorrhage (VRH). This study aimed to evaluate whether platelet transfusion or ventriculostomy timing relative to APT initiation reduces VRH risk.

Methods: We conducted a retrospective review of a prospectively collected cohort of aSAH patients treated at a single academic center between 2016 and 2023. The study focused on those who underwent ventriculostomy and received APT. Patients on anticoagulation were excluded. The cohort was then split into three groups: 1) APT at ventriculostomy without platelet transfusion, 2) APT at ventriculostomy with platelet transfusion, and 3) APT initiated post-ventriculostomy. Univariate and multivariate analyses assessed the incidence of tract hemorrhage, symptomatic tract hemorrhage, and poor neurologic outcomes defined as modified Rankin scale (mRS) ≥3 at three months.

Results: Among 404 identified aSAH cases, 129 patients were on APT during or after ventriculostomy. The mean age was 59.5 years (SD=13.9), with 38.8% male, and 74.4% white. Comparison between patients who received APT without platelet transfusion (n = 24) and those who received APT with platelet transfusion (n = 34) showed no significant association with reduced rates of VRH or symptomatic VRH on univariate (37.5% vs. 29.4%; P=0.52 and 4.2% vs. 5.9%; P=0.77, respectively) or multivariate analysis (OR 0.79, 95%CI [0.24, 2.61]; P=0.7 and OR 1.92, 95%CI [0.14, 52.3]; P=0.6). Similarly, when compared to those already on APT, initiating APT post-ventriculostomy did not significantly alter VRH or symptomatic VRH rates on univariate (37.5% vs. 25.4%; P=0.26 and 4.2% vs. 1.4%; P=0.42, respectively) or multivariate analysis (OR 0.74, 95%CI [0.42, 1.31]; P=0.3 and OR 0.28, 95%CI [0.01, 7.99]; P=0.4). No differences in neurologic outcomes were observed at 3-month follow-up in either analysis.

Conclusion: Our study did not identify benefits conferred from platelet transfusion in VRH or outcomes regarding ventriculostomy placement in aSAH patients on APT. Additionally, the timing of APT initiation relative to ventriculostomy did not significantly affect VRH rates. With the increasing use of endovascular therapies, ventriculostomy placement under APT is increasingly common, and further research is needed to identify effective strategies for minimizing VRH risk.