Association between antithrombotic therapy after stroke in patients with atrial fibrillation and the risk of net clinical outcome: an observational cohort study

Abstract

Background and Objectives Data on the optimal use of antithrombotic drugs and associated clinical outcomes in patients with atrial fibrillation (AF) and acute ischemic stroke (IS) are limited. We investigated the prescription patterns of antithrombotics in community practice and long-term clinical prognosis according to early poststroke antithrombotic therapy in patients with AF and acute IS. Methods Patients with AF who were admitted for acute IS at a single tertiary hospital in 2010-2020 were retrospectively reviewed. Clinical profiles including the etiology of stroke and prescription patterns of antithrombotics were identified. The net clinical outcome (NCO) – the composite of recurrent stroke, any bleeding, hospitalization or emergency department (ED) visits for cardiovascular (CV) events, and death – were compared according to the antithrombotic therapy at the first outpatient clinic visit [oral anticoagulation (OAC) alone vs. antiplatelet (APT) alone vs. OAC/APT(s)] following discharge. Results A total of 918 patients with AF and acute IS (mean age, 72.6 years; male, 59.3%; mean CHA₂DS₂-VASc score 3.3) were analyzed. One-third (33.9%, n = 310) of patients were simultaneously diagnosed with AF and IS. The most common etiology of IS was cardioembolism (71.2%), followed by undetermined etiology (19.8%) and large artery atherosclerosis (6.0%). OAC, APT(s), and concomitant OAC and APT(s) were prescribed in 33.4%, 11.1%, and 53.4% of patients during admission which changed to 67.0%, 9.1%, and 21.7% at the first outpatient clinic, and were mostly continued up to one year after IS. Non-prescription of OAC was observed in 11.3% of poststroke patients with AF. During a median follow-up of 2.1 years, the overall incidence rate of NCO per 100 patient-year (PY) was 20.14. APT(s) monotherapy presented the highest cumulative risk of NCO [adjusted hazard ratio (HR) 1.47, 95% confidence interval (CI) 1.08-2.00, p = 0.015; with reference to OAC monotherapy] mainly driven by the highest rates of recurrent stroke and any bleeding. OAC/APT(s) combination therapy was associated with a 1.62-fold significantly higher risk of recurrent stroke (p = 0.040) and marginally higher risk of any bleeding than OAC monotherapy. Conclusion Approximately one-third of acute IS in AF have a distinctive mechanism from cardioembolism. Although APT was frequently prescribed in poststroke patients with AF, no additive clinical benefit was observed. Adherence to OAC treatment is essential to prevent further cardiovascular adverse events in patients with AF and IS.