Relation of obesity to recurrence rate and burden of atrial fibrillation.

Obesity is associated with new-onset atrial fibrillation (AF). However, the effect of obesity on AF recurrence or burden has not been studied. The aim of this study was to investigate the relation between AF recurrence, AF burden, and body mass index (BMI). A limited-access data set from the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) trial provided by the National Heart, Lung, and Blood Institute was used. Statistical analysis was done with a generalized linear mixed model. In 2,518 patients who had BMIs recorded, higher BMI was associated with a higher number of cardioversions (odds ratio [OR] 1.017, 95% confidence interval [CI] 1.005 to 1.029 for a BMI increase of 1 kg/m(2); OR 1.088, 95% CI 1.024 to 1.155 for a BMI increase of 5 kg/m(2); OR 1.183, 95% CI 1.049 to 1.334 for a BMI increase of 10 kg/m(2); p = 0.006 for each). Increased BMI was also associated with a higher likelihood of being in AF on follow-up (OR 1.020, 95% CI 1.002 to 1.038 per 1 kg/m(2) increased BMI, p = 0.0283; OR 1.104, 95% CI 1.011 to 1.205 per 5 kg/m(2) increased BMI, p = 0.0283; OR 1.218, 95% CI 1.021 to 1.452 per 10 kg/m(2) increased BMI, p = 0.0283). In a multivariate analysis, left atrial size but not BMI was an independent predictor of AF recurrence and AF burden. Because left atrial size was correlated with BMI, the effect of BMI on AF can be likely explained by greater left atrial size in subjects with higher BMIs. In conclusion, obesity is associated with a higher incidence of recurrence of AF and greater AF burden.