Antithrombotic states and outcomes in patients with angiographically negative subarachnoid hemorrhage.

Background: Antithrombotic states are encountered frequently, either because of medical therapy or by preexistent pathological states, and may affect the severity of hemorrhagic strokes such as angiographically negative subarachnoid hemorrhages.
Objective: To determine the effects of antithrombotic states on the outcomes of patients with angiographically negative subarachnoid hemorrhage by examining data pooled from 2 institutions.
Methods: This is a retrospective review of patients who experienced angiographically negative subarachnoid hemorrhage at 2 institutions over the past 5 years. The patients were grouped into those with and those without an antithrombotic state at time of hemorrhage and were stratified according to presentation, clinical grades, outcomes, need for cerebrospinal fluid diversion, and development of vasospasm. Computed tomography of the head was assessed for bleed pattern and modified Fisher grade. Patients were excluded if a causative lesion was subsequently discovered.
Results: There is a statistically significant association between antithrombotic states and poorer presentation, higher Hunt and Hess score, increased amount of subarachnoid hemorrhage, higher modified Fisher grade, increased incidence of vasospasm, hydrocephalus, and poor outcomes as assessed by modified Rankin scale (P < .001). Patients with an antithrombotic state experience worse outcomes even with adjustment for the amount of hemorrhage as assessed by modified Fisher grade (P < .001).
Conclusion: Patients in an antithrombotic state presenting with angiographically negative subarachnoid hemorrhage present with inferior clinical scores, diffuse hemorrhage patterns, and worse modified Fisher grades and have worse outcomes.