Early prophylactic heparin use is associated with reduced mortality in patients with non-traumatic subarachnoid hemorrhage

Background Heparin may mitigate secondary brain injury in subarachnoid hemorrhage (SAH), but its effect on survival in non-traumatic SAH (NSAH) remains uncertain. This study aimed to investigate the association between early prophylactic heparin use (within 72 h of admission) and mortality outcomes in patients with NSAH. Methods We performed a retrospective cohort study using the Medical Information Mart for Intensive Care (MIMIC) and the eICU Collaborative Research Database (eICU-CRD). Patients were stratified by early heparin use. Cox models, Kaplan–Meier (KM) curves, subgroup analyses, and comprehensive propensity score–based sensitivity analyses were applied to assess the robustness of the observed associations. The primary outcome was in-hospital mortality; 28-, 90-, 180-, and 365-day mortality were secondary outcomes. Findings were validated using the eICU-CRD cohort. Results In the MIMIC-IV cohort, early heparin use was associated with lower in-hospital mortality (HR 0.62, 95% CI 0.39–0.97, p = 0.037), which was confirmed in the eICU-CRD cohort (HR 0.47, 95% CI 0.22–1.00, p = 0.049). Consistent reductions were also observed for 28-day (HR 0.57, p = 0.009), 90-day (HR 0.62, p = 0.010), 180-day (HR 0.63, p = 0.009), and 365-day mortality (HR 0.61, p = 0.004) in the MIMIC-IV cohort. Subgroup analyses and KM curves further supported these findings. Propensity score-based sensitivity analyses further validated the robustness of these findings in both cohorts. Conclusion Early prophylactic heparin was associated with lower risk-adjusted short- and long-term mortality in NSAH.