Obesity and outcomes among patients with established atrial fibrillation.

Atrial fibrillation (AF) and obesity have reached epidemic proportions. The impact of obesity on clinical outcomes in patients with established AF is unknown. We analyzed 2,492 patients in the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) study. Body mass index (BMI) was evaluated as a categorical variable (normal 18.5 to <25 kg/m(2), overweight 25 to <30 kg/m(2), obese >or=30 kg/m(2)). Rate of death from any cause was higher in the normal BMI group (5.8 per 100 patient-years) than in the overweight and obese groups (3.9 and 3.7, respectively). Cardiovascular death rate was highest in the normal BMI group (3.1 per 100 patient-years), lowest in the overweight group (1.5 per 100 patient-years), and intermediate in the obese group (2.1 per 100 patient-years). After adjustment for baseline factors, differences in risk of death from any cause were no longer significant. However, overweight remained associated with a lower risk of cardiovascular death (hazard ratio 0.47, p = 0.002). Obese patients were more likely to have an uncontrolled heart rate at rest, but rhythm-control strategy success was similar across BMI categories. In each BMI category, risk of death from any cause was similar for patients randomized to a rhythm- or rate-control strategy. In conclusion, in patients with established AF, overweight and obesity do not adversely affect overall survival. Obesity does not appear to affect the relative benefit of a rate- or rhythm-control strategy.