Antithrombotic therapy after acute ischemic stroke in patients with atrial fibrillation

Background and purpose — For patients with atrial fibrillation and ischemic stroke (IS), current guidelines recommend oral anticoagulation (OAC) alone for secondary prevention of IS. In a large prospective cohort of patients with acute IS and atrial fibrillation, we determine the association between antithrombotic regimen on discharge and risk of major vascular events.

Methods — Prospective cohort of consecutive patients included in the Ontario Stroke Registry. Multivariable Cox proportional hazard models were used to determine the association between antithrombotic regimen on discharge and time to death or admission for recurrent IS, myocardial infarction, or major bleeding.

Results —Two thousand one hundred sixty-two patients were hospitalized atrial fibrillation and acute IS. At discharge, 8.0% were prescribed no antithrombotic therapy, 21.6% antiplatelet therapy alone, 39.3% OAC (warfarin) alone, and 31.1% combination OAC and antiplatelet therapy. Compared with OAC alone (hazard ratio [HR], 1.0), no antithrombotic therapy (HR, 1.51; 95% confidence interval, 1.23-1.86) and antiplatelet therapy (HR, 1.31; 95% confidence interval, 1.14-1.50) were associated with an increased risk of the primary composite outcome, whereas combination OAC and antiplatelet therapy was associated with a trend toward a reduced risk (HR, 0.91; 95% confidence interval, 0.80-1.04 overall and HR, 0.79; 95% confidence interval, 0.61-1.02 in those with coronary heart disease). Results were consistent in those with severe stroke: HR 1.58 (95% CI, 1.21-2.06), 1.34 (95% CI, 1.09-1.63), and 0.91 (95% CI, 0.74-1.11), respectively.

Conclusions — Contrary to current guidelines, 30% of patients with atrial fibrillation and recent IS are not prescribed any OAC therapy on discharge, whereas a further 30% are prescribed combination OAC and antiplatelet therapy. Combination OAC and antiplatelet therapy in patients at high cardiovascular risk requires evaluation in clinical trials, particularly with the newer OACs, given their more favorable risk-benefit ratio compared with warfarin.