Antithrombotic Treatment, Prehospital Blood Pressure, and Outcomes in Spontaneous Intracerebral Hemorrhage.

Background In acute intracerebral hemorrhage, both elevated blood pressure (BP) and antithrombotic treatment are associated with poor outcome. Our aim was to explore interactions between antithrombotic treatment and prehospital BP. Methods and Results This observational, retrospective study included adult patients with spontaneous intracerebral hemorrhage diagnosed by computed tomography within 24 hours, admitted to a primary stroke center during 2012 to 2019. The first recorded prehospital/ambulance systolic and diastolic BP were analyzed per 5 mm Hg increment. Clinical outcomes were in-hospital mortality, shift on the modified Rankin Scale at discharge, and mortality at 90 days. Radiological outcomes were initial hematoma volume and hematoma expansion. Antithrombotic (antiplatelet and/or anticoagulant) treatment was analyzed both together and separately. Modification of associations between prehospital BP and outcomes by antithrombotic treatment was explored by multivariable regression with interaction terms. The study included 200 women and 220 men, median age 76 (interquartile range, 68-85) years. Antithrombotic drugs were used by 252 of 420 (60%) patients. Compared with patients without, patients with antithrombotic treatment had significantly stronger associations between high prehospital systolic BP and in-hospital mortality (odds ratio [OR], 1.14 versus 0.99, P for interaction 0.021), shift on the modified Rankin Scale (common OR, 1.08 versus 0.96, P for interaction 0.001), and hematoma volume (coef. 0.03 versus -0.03, P for interaction 0.011). Conclusions In patients with acute, spontaneous intracerebral hemorrhage, antithrombotic treatment modifies effects of prehospital BP. Compared with patients without, patients with antithrombotic treatment have poorer outcomes with higher prehospital BP. These findings may have implications for future studies on early BP lowering in intracerebral hemorrhage.