Abstract 9227: Higher Body Mass Index is Linked to Greater Atrial Fibrillation Burden.
Background: High body mass index (BMI) is associated with higher incidence of atrial fibrillation (AF). Effect of obesity on AF recurrence or burden has not been studied.
Methods: We used limited access dataset from the AFFIRM trial, provided by National Heart, Lung, and Blood Institute. Number of cardioversions, both electrical and pharmacological, was used as a surrogate measure of AF recurrence, and number of follow-up visits when patients were in AF as a surrogate measure of AF burden. Statistical analysis was done with generalized linear mixed model (SAS). Different confounding variables were also checked for association with AF recurrence rate or AF burden and variables found to be significantly associated with the outcomes were then put in a multivariable model. P<0.05 considered statistically significant.
Results: From 4060 patients enrolled in the trial, 1542 did not have baseline BMI information and were excluded. From remaining 2518 patients, 1255 were in rate control arm and 1263 were in rhythm control arm. In 2518 patients who had BMI recorded, higher BMI was associated with a higher number of cardioversions; odds ratio (OR) = 1.017 [1.005–1.029] for BMI increase of 1 unit, OR = 1.088 [1.024–1.155] for BMI increases of 5 units and 1.183 [1.049–1.334] for BMI increases of 10 units, p = 0.006 for each. Obese (BMI≥30 kg/m2) in reference to normal weight (BMI 18.5–24.9 kg/m2) had OR of having cardioversion was 1.268 (p = 0.0194) and 1.291 (p = 0.0173) in total population and rhythm control arm respectively. Increased BMI was also associated with higher likelihood of being in AF on follow-up visits; OR = 1.020 [1.002–1.038] per 1 unit of BMI increase, 1.104 [1.011–1.205] per 5 units of BMI increase, and 1.218 [1.021–1.452] per 10 units of BMI increase, p = 0.0283 for each. In a multivariate analysis, age, left atrial size and not BMI was an independent predictor of AF recurrence and AF burden. Because left atrial size correlated with BMI significantly (r=0.14, p<0.0001), the effect of BMI on AF can be likely explained by greater left atrial size in individuals with higher BMI.
Conclusions: Obesity is associated with a higher recurrence of AF and greater AF burden that mediated by greater left atrial size.
- © 2010 by American Heart Association, Inc.