Antiplatelet therapy for stable coronary artery disease in atrial fibrillation patients taking an oral anticoagulant: a nationwide cohort study.

Background: The optimal long-term antithrombotic treatment of patients with coexisting atrial fibrillation and stable coronary artery disease is unresolved, and commonly, a single antiplatelet agent is added to oral anticoagulation. We investigated the effectiveness and safety of adding antiplatelet therapy to vitamin K antagonist (VKA) in atrial fibrillation patents with stable coronary artery disease.
Methods and Results: Atrial fibrillation patients with stable coronary artery disease (defined as 12 months from an acute coronary event) between 2002 and 2011 were identified. The subsequent risk of cardiovascular events and serious bleeding events (those that required hospitalization) was examined with adjusted Cox regression models according to ongoing antithrombotic therapy. A total of 8700 patients were included (mean age, 74.2 years; 38% women). During a mean follow-up of 3.3 years, crude incidence rates were 7.2, 3.8, and 4.0 events per 100 person-years for myocardial infarction/coronary death, thromboembolism, and serious bleeding, respectively. Relative to VKA monotherapy, the risk of myocardial infarction/coronary death was similar for VKA plus aspirin (hazard ratio, 1.12 [95% confidence interval, 0.94-1.34]) and VKA plus clopidogrel (hazard ratio, 1.53 [95% confidence interval, 0.93-2.52]). The risk of thromboembolism was comparable in all regimens that included VKA, whereas the risk of bleeding increased when aspirin (hazard ratio, 1.50 [95% confidence interval, 1.23-1.82]) or clopidogrel (hazard ratio, 1.84 [95% confidence interval, 1.11-3.06]) was added to VKA.
Conclusions: In atrial fibrillation patients with stable coronary artery disease, the addition of antiplatelet therapy to VKA therapy is not associated with a reduction in risk of recurrent coronary events or thromboembolism, whereas risk of bleeding is increased significantly. The common practice of adding antiplatelet therapy to oral VKA anticoagulation in patients with atrial fibrillation and stable coronary artery disease warrants reassessment.