Introduction and Objectives. Previous studies have described an inverse relationship between obesity and adverse events in a variety of conditions. Our aim was to investigate the relationship between obesity and prognosis in patients with atrial fibrillation.

Methods. We studied 746 patients who were prospectively included, between January and April 2008, in the AFBAR (Atrial Fibrillation in BARbanza area) registry. Patients were categorized into 3 body mass index groups using baseline measurements: normal (< 25 kg/m2), overweight (25-30 kg/m2), and obese (≥30 kg/m2). Survival free from the composite endpoint hospitalization for cardiovascular causes or all-cause mortality was compared across the 3 body mass index groups. A multivariable Cox proportional hazard regression was also performed to determine the independent effect of obesity as well as overweight, with respect to normal body mass index as a reference category, regarding the study endpoint. Median follow-up time was 36 (28-36) months. 

Results. 49.3% were obese and 38.2% had overweight. The composite endpoint rate was 70.9%, 67.5%, and 57.6% for obese, overweight, and normal weight patients, respectively (log rank test; p=0.02). An inverse association of obesity with a favorable prognosis persisted even after multivariable adjustment: hazard ratio 0.668; confidence interval 95% 0.449-0.995; p=0.047. Hazard ratio of overweight, however, was 0.741; 95% confidence interval: 0.500-1.098; p=0.096.  

Conclusions. Obesity, defined as a body mass index ≥ 30 kg/m2, is associated with better prognosis in a community-based cohort of patients with atrial fibrillation.