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.