Antithrombotic Therapy and First MI in AF Patients

Study Questions:

What is the incidence of first time myocardial infarction (MI) in patients with atrial fibrillation (AF) according to antithrombotic treatment and the risk of stroke and bleeding?

Methods:

The investigators identified subjects with first-time AF diagnosed from 1997 to 2012 without prior history of coronary artery disease using Danish nationwide administrative registries. Subjects were divided into time-varying exposure groups according to antithrombotic treatment. The relative risks of outcomes were estimated by Poisson regression models.

Results:

A total of 71,959 patients (median age 75 years, female 47%). At baseline, 37,539 (52%) patients were treated with vitamin K antagonist (VKA) monotherapy—25,458 (35%) with acetylsalicylic acid (ASA) monotherapy, and 8,962 (13%) with dual therapy (VKA plus ASA). The incidence of MI was 2,275 (3%). Relative to VKA, the associated risk of MI was significantly higher for ASA (incidence rate ratio [IRR], 1.54; 95% confidence interval [CI], 1.40-1.68) and dual therapy (IRR, 1.22; 95% CI, 1.06-1.40). The bleeding risk was significantly higher for dual therapy (IRR, 1.93; 95% CI, 1.81-2.07). The risk of stroke relative to VKA was significantly higher for both ASA (IRR, 2.00; 95% CI, 1.88-2.12), and dual therapy (IRR, 1.30; 95% CI, 1.18-1.43).

Conclusions:

The authors concluded that VKA monotherapy in patients with AF was associated with a lower risk of first-time MI and stroke compared with ASA monotherapy.

Perspective:

This study reports that as primary prophylaxis of MI, VKA monotherapy was associated with a lower risk compared with ASA monotherapy. Furthermore, combination therapy was not associated with better prevention, but the bleeding risk was increased. Since anticoagulants that inhibit thrombin or factor Xa are increasingly used in patients with AF, additional studies are indicated in prevention of coronary atherothrombotic events in high-risk patients with AF treated with nonvitamin K oral anticoagulants compared with VKA.

Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Dyslipidemia, Prevention, Anticoagulation Management and Atrial Fibrillation, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Lipid Metabolism, Novel Agents

Keywords: Anticoagulants, Arrhythmias, Cardiac, Aspirin, Atrial Fibrillation, Coronary Artery Disease, Fibrinolytic Agents, Hemorrhage, Myocardial Infarction, Primary Prevention, Risk, Stroke, Thrombin, Vitamin K


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