Study Questions: How does obesity affect prognosis in patients with atrial fibrillation (AF) treated with oral anticoagulants?

Methods: This was a post hoc analysis of a clinical trial in which patients with AF were randomly assigned to treatment with apixaban or warfarin. The subjects of this study were 17,913 patients in whom measurements of body mass index (BMI) and waist circumference (WC) were available. Outcomes were stroke or systemic embolism, all-cause mortality, and a composite of stroke/embolism, myocardial infarction, or all-cause mortality.

Results: Approximately 37% of patients were overweight (BMI 25-30 kg/m2) and 40% were obese (BMI ≥30 kg/m2). A BMI in the overweight or obese range was independently associated with approximately a 35% lower risk of all-cause mortality and a 26-32% lower risk of the composite endpoint. In women, high WC was independently associated with a 27-31% lower risk of stroke/embolism, all-cause mortality, and the composite endpoint.

Conclusions: In patients with AF who are anticoagulated with warfarin or apixaban, being overweight or obese is associated with a lower risk of adverse outcomes, including mortality.

Perspective: Obesity is an independent predictor of new-onset AF and recurrent AF during antiarrhythmic drug treatment or after catheter ablation. Yet this and prior studies suggest that in patients with AF, adverse outcomes such as mortality are less likely in patients who are overweight or obese. This relationship between obesity and improved prognosis also has been reported in patients with hypertension, coronary artery disease, and heart failure. Because there is no clear-cut explanation for this counter-intuitive relationship, the term ‘obesity paradox’ is very appropriate.

Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Prevention, Anticoagulation Management and Atrial Fibrillation, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias

Keywords: Anti-Arrhythmia Agents, Arrhythmias, Cardiac, Atrial Fibrillation, Anticoagulants, Body Mass Index, Embolism, Myocardial Infarction, Obesity, Overweight, Primary Prevention, Risk, Stroke, Waist Circumference, Warfarin