Bleeding During Anticoagulation for Atrial Fibrillation and Subsequent Malignancy

Bleeding during anticoagulation for atrial fibrillation might be the first sign of occult cancer (J Am Heart Assoc 2020; 9:e016836). In a new study, researchers identified 120,000 older patients (age, ≥66; median age, 77) in Ontario who received vitamin K antagonists (e.g., warfarin) or direct-acting oral anticoagulants (DOACs) for atrial fibrillation between 2008 and 2022. A total of 69% of patients received DOACs; use of P2Y12 inhibitors (e.g., clopidogrel), but not aspirin, was recorded.

Bleeding occurred in 22% of patients during the 2 years after starting anticoagulation, with higher risk in those who received vitamin K antagonists than in those who received DOACs. Malignancies were diagnosed in ≈5% of patients, and bleeding was associated with a greater likelihood of cancer diagnosis, especially for cancers concordant with sites of bleeding (i.e., colorectal, genitourinary, and respiratory). For instance, diagnosis of gastrointestinal cancer was 15 times more likely after gastrointestinal bleeding compared with diagnosis with no gastrointestinal bleeding.