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MI Risk in Anticoagulated AF Patients
Study Questions:
What is the risk of myocardial infarction (MI) associated with the use of apixaban, dabigatran, rivaroxaban, and vitamin K antagonist (VKA) in patients with atrial fibrillation (AF)?
Methods:
The investigators identified patients with AF using Danish health care registers and stratified them 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. Crude nonadjusted MI-free survival probabilities after 1 year on oral anticoagulation therapy were computed with the Kaplan-Meier method and supplied by crude hazard rates obtained with simple Cox regression (oral anticoagulation therapy as the only variable) for the hazard rate of the combined endpoint of MI or all-cause death.
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], 1.3-1.8), apixaban was 1.2% (95% CI, 0.9-1.4), dabigatran was 1.2% (95% CI, 1.0-1.5), and rivaroxaban was 1.1% (95% CI, 0.8-1.3). No significant risk differences were observed in the standardized 1-year risks of MI among the direct oral anticoagulants (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:
The authors concluded that 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.
Perspective:
This study reports no significant differences in the direct comparisons of the DOACs apixaban, dabigatran, and rivaroxaban in the risk of MI for patients with AF. Furthermore, all the DOACs were associated with a significant risk reduction of MI compared with VKA, and the results were consistent for patients with and without prior ischemic heart disease and concomitant antiplatelet therapy. These registry data should be considered preliminary; direct comparative studies of the DOACs with and without concurrent antiplatelet therapy are needed to determine the optimum antithrombotic strategy for patients with AF who are at elevated risk of MI.
Keywords: Acute Coronary Syndrome, Arrhythmias, Cardiac, Anticoagulants, Atrial Fibrillation, Geriatrics, Myocardial Infarction, Risk Reduction Behavior, Secondary Prevention, Vitamin K
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