Patients With Atrial Fibrillation Who Are Not on Anticoagulant Treatment Due to Increased Bleeding Risk Are Common and Have a High Risk of Stroke.

Objectives: This study sought to determine how many patients with atrial fibrillation (AF) are not treated with oral anticoagulants (OAC) due to a high risk of bleeding and to characterize their risk of ischemic stroke in a real-world setting.

Background: AF is associated with a 5-fold increased risk of ischemic stroke. OAC reduce the risk of stroke in patients with AF who do not have an increased bleeding risk, but no comparably effective treatment exists for patients with contraindications to OAC.

Methods: We analyzed administrative claims data from individuals with commercial and Medicare supplemental health insurance in the United States. We selected patients with AF and a documented contraindication to OAC who were not treated with OAC. The primary endpoint was the occurrence of ischemic stroke, as calculated per patient year.

Results: We identified 1,300,643 patients with AF claims, of which 43,248 had a contraindication event and remained OAC naive for at least 1 year or died in hospital. More than 80% of the patients had a CHADS-VASc score of >1. The incidence of ischemic stroke was 4.1% in the overall OAC naive cohort and was more common with increasing CHADS/CHADS-VASc score. Hemorrhagic stroke occurred in 3.6%. For patients with previous intracranial bleeding, the incidences of ischemic and hemorrhagic stroke were 12.2% and 20.3%, respectively.

Conclusions: Patients with AF who are not treated with OAC due to increased bleeding risk are common. These patients are at considerable risk of both ischemic and hemorrhagic events. A novel approach to stroke prophylaxis in this population is needed.