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.

Association of atrial fibrillation with mortality and disability after ischemic stroke.

OBJECTIVE: We determined whether patient characteristics (age, sex, comorbidities), stroke severity, and quality of care explained a proportion of the association between atrial fibrillation (AF) and increased disability and mortality in patients with acute ischemic stroke. METHODS: The study included a prospective cohort of consecutive patients admitted with acute ischemic stroke included in the Registry of the Canadian Stroke Network (July 1, 2003 to March 31, 2008). Multivariable logistic regression analyses were used to determine the magnitude of association between AF and modified Rankin score 4-5 at discharge, 30-day mortality, and 1-year mortality. RESULTS: There were 10,528 patients admitted with acute ischemic stroke. AF was associated with an increased risk of severe disability and mortality, but the magnitude of association was substantially attenuated in the full multivariable models: modified Rankin score 4-5 at discharge (univariate odds ratio [OR] 1.74, 95% confidence interval [CI] 1.57-1.93; multivariable OR 1.19, 95% CI 1.03-1.36), 30-day mortality (univariate OR 2.52, 95% CI 2.25-2.84; multivariable OR 1.36, 95% CI 1.17-1.58), and 1-year mortality (univariate OR 2.41, 95% CI 2.19-2.66; multivariable OR 1.25, 95% CI 1.10-1.42). Older age and increased stroke severity explained most of the association between AF and poor stroke outcomes. We found no association between AF and poor stroke outcomes in patients receiving therapeutic preadmission oral anticoagulant therapy. CONCLUSIONS: Older age and increased stroke severity explain most of the association between AF and poorer outcomes after acute ischemic stroke. Nonuse of oral anticoagulant therapy represents the most important modifiable care gap to mitigate the association between AF and poor outcomes after ischemic stroke.