Preceding Antithrombotic Treatment is Associated With Acute Ischemic Stroke Severity and Functional Outcome at 90 Days Among Patients With Atrial Fibrillation

Background: Antithrombotic therapies are known to prevent ischemic stroke (IS) for patients with atrial fibrillation (AF), but are often underused in clinical practice. The aim of present study was to investigate the prevalence of patients with acute IS with known history of AF who were not receiving antithrombotic treatment before stroke and to evaluate the association of preceding antithrombotic treatment with stroke severity and outcomes at 90 days after admission. Materials and Methods: This was a retrospective, multi-center, observational study of 748 patients with acute IS and known history of AF admitted to 6 participating hospitals between March 2016 and October 2017. The primary outcome was stroke severity at admission as assessed using National Institutes of Health Stroke Scale (NIHSS) score. The secondary outcome was functional outcome at 90 days after admission as measured by modified Rankin Scale (mRS) score. Results: A total of 748 patients, 54 (7.2%) were receiving therapeutic warfarin (international normalized ratio [INR] >= 2) and 100 (13.4%) had subtherapeutic warfarin anticoagulation (INR < 2), 340 (45.5%) were receiving antiplatelet treatment, and 254 (34.0%) were not receiving any antithrombotic treatment prior to stroke. Compared with no antithrombotic treatment, therapeutic warfarin (OR: 0.64; 95% CI: 0.52-0.82; P = .022), and antiplatelet therapy only (OR: 0.89; 95% CI: 0.76-0.96; P = .041) were associated with lower odds ratio of moderate or severe stroke (NIHSS >= 16). Patients receiving preceding therapeutic warfarin (OR: 1.32; 95% CI: 1.22-3.57; P = .025), antiplatelet therapy only (OR: 1.13; 95% CI: 1.07-2.59; P = .043), and subtherapeutic warfarin with INR 1.5 to 1.99 (OR: 1.15; 95% CI: 1.10-2.66; P = .042) had higher odds ratio of better functional outcome (mRS <= 2) at 90 days. Conclusions: Among patients with AF who had experienced an acute IS, inadequate therapeutic warfarin preceding the stroke was very prevalent in China. Therapeutic warfarin was associated with less severe stroke and better functional outcome at 90 days.