Risk of Myocardial Infarction in Anticoagulated Patients with Atrial Fibrillation

Background: Evidence is conflicting as to the efficacy of direct oral anticoagulation (DOAC) and vitamin K antagonist (VKA) for prevention of myocardial infarction (MI). Objectives: This study aimed to investigate the risk of MI associated with the use of apixaban, dabigatran, rivaroxaban, and VKA in patients with atrial fibrillation. Methods: Patients with atrial fibrillation were identified using Danish health care registers and stratified by initial oral anticoagulant treatment. Standardized absolute 1-year risks were estimated based on Cox regression for hazard rates of MI hospitalizations and mortality. Reported were absolute risks separately for the oral anticoagulation treatments and standardized to the characteristics of the study population. Results: Of the 31,739 patients included (median age, 74 years; 47% females), the standardized 1-year risk of MI for VKA was 1.6% (95% confidence interval [CI]: 1.3 to 1.8), apixaban was 1.2% (95% CI: 0.9 to 1.4), dabigatran was 1.2% (95% CI: 1.0 to 1.5), and rivaroxaban was 1.1% (95% CI: 0.8 to 1.3). No significant risk differences were observed in the standardized 1-year risks of MI among the DOACs: dabigatran versus apixaban (0.04%; 95% CI: −0.3 to 0.4), rivaroxaban versus apixaban (0.1%; 95% CI: −0.4 to 0.3), and rivaroxaban versus dabigatran (−0.1%; 95% CI: −0.5 to 0.2). The risk differences for DOACs versus VKA were all significant: −0.4% (95% CI: −0.7 to −0.1) for apixaban, −0.4% (95% CI: −0.7 to −0.03) for dabigatran, and −0.5% (95% CI: −0.8 to −0.2) for rivaroxaban. Conclusions: No significant risk differences of MI were found in the direct comparisons of DOACs, and DOACs were all associated with a significant risk reduction of MI compared with VKA.