Venous thromboembolism in aneurysmal subarachnoid hemorrhage: Risk factors and timing of chemoprophylaxis

Introduction: Venous thromboembolism (VTE) is a significant contributor to morbidity and mortality among patients recovering from aneurysmal subarachnoid hemorrhage (aSAH). Prophylactic heparin reduces the risk of VTE, but the optimal timing for its initiation among aSAH patients remains unclear. Objective: To conduct a retrospective study assessing risk factors for VTE and optimal timing of chemoprophylaxis in patients treated for aSAH. Methods: From 2016-2020, 194 adult patients were treated for aSAH at our institution. Patient demographics, clinical diagnoses, complications, pharmacologic interventions, and outcomes were recorded. Risk factors for symptomatic VTE (sVTE) were analyzed via Chi-squared, univariate, and multivariate regression. Results: In total 33 patients presented with sVTE (25 DVT, 14 PE). Patients with sVTE had longer hospital stays (p < 0.01) and worse outcomes at one-month (p < 0.01) and three-month follow-up (p = 0.02). Univariate predictors of sVTE included male sex (p = 0.03), Hunt Hess score (p = 0.01), Glasgow Coma scale (p = 0.02), intracranial hemorrhage (p = 0.03), hydrocephalus requiring external ventricular drain (EVD) placement (p < 0.01), and mechanical ventilation (p < 0.01). Only hydrocephalus requiring EVD (p = 0.01) and ventilator use (p = 0.02) remained significant upon multivariate analysis. Patients with delayed heparin introduction were significantly more likely to sustain sVTE on univariate analysis (p = 0.02) with a trend-level significance on multivariate analysis (p = 0.07). Conclusions: Patients with aSAH are more likely to develop sVTE following use of perioperative EVD or mechanical ventilation. sVTE leads to longer hospital stays and worse outcomes among patients treated for aSAH. Delayed heparin initiation increases the risk of sVTE. Our results may help guide surgical decision-making during recovery from aSAH and improve VTE-related postoperative outcomes.