Atrial Fibrillation and Acute Myocardial Infarction: Antithrombotic Therapy and Outcomes

Study Questions:

How does atrial fibrillation (AF) affect outcomes after an acute myocardial infarction (MI)?


The data for this study were extracted from a national myocardial infarction registry that included 69,255 patients (mean age 65 years). In-hospital outcomes were compared between patients with and without AF during the 2 weeks before the MI.


AF was present within the 2 weeks before MI in 4,947 patients (7.1%). Compared to patients without AF, patients with AF had higher in-hospital rates of death (9.9% vs. 4.2%), stroke (1.3% vs. 0.7%), and major bleeding (14.6 vs. 9.9%). Compared to patients without AF, patients with AF more often were discharged on warfarin (41% vs. 6.1%) and less often discharged on aspirin (95% vs. 97.7%) or clopidogrel (63.5% vs. 82.7%). Only 43.5% of patients with a CHADS2 score >1 were discharged on warfarin. The combination of aspirin, clopidogrel, and warfarin was used in 14.6% of patients.


Recent AF is associated with worse outcomes in patients with MI. Less than 50% of patients with AF and ≥2 risk factors for stroke receive warfarin at the time of hospital discharge.


Prior studies have demonstrated that new-onset AF after an MI has an adverse effect on outcomes, and this study demonstrates that AF in the 2 weeks before MI also is associated with worse outcomes. The underutilization of warfarin could be partly due to the fear of bleeding when used in combination with aspirin/clopidogrel. However, multiple studies have shown that warfarin is underutilized in patients with AF even when there is not an indication for antiplatelet therapy.

Clinical Topics: Anticoagulation Management

Keywords: Myocardial Infarction, Denervation, Warfarin, Risk Factors, Blood Coagulation, Renal Artery, Cardiology, Cardiovascular Diseases, Hemorrhage

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