Body mass index and the risk of new-onset atrial fibrillation in middle-aged adults

Background Increased body mass index (BMI) and obesity are associated with increased risk of new-onset atrial fibrillation (AF) among middle-aged adults. Objectives The objective of the study is to investigate the association between BMI and the risk for new-onset AF among middle-aged adults. Methods We investigated 18,290 men and women who were annually screened in a tertiary medical center. Participants were divided at baseline into 3 groups: normal weight (BMI ≥18 and <25 kg/m², n = 7,692), overweight (BMI ≥25 and <30 kg/m², n = 8,032), and obese (BMI ≥30 kg/m², n = 2,566). The primary end point was new-onset AF during follow-up. Results Mean age of study population was 49 ± 11 years, and 73% were men. A total of 288 incident events (1.6%) occurred during 6 ± 4 years. Kaplan-Meier survival analysis showed that the cumulative probability of AF at 6 years was highest among obese participants, intermediate among overweight participants, and lowest among participants with normal weight (2.1%, 1.7%, and 0.8% respectively, P <.001). Multivariable Cox regression analysis showed that overweight and obesity were independently associated with increased AF risk (hazard ratio 1.54 P =.004 and 2.41 P <.001, respectively). Assessment of BMI change as a time-dependent covariate in the multivariable model showed that each 1 kg/m² reduction in BMI during follow-up was associated with a significant 7% reduction in the risk for the occurrence of a first AF event (hazard ratio 0.93, 95% CI 0.88-0.99, P =.019). Consistently, similar analysis showed that each 5-kg weight loss during follow-up was independently associated with a significant 12% reduced risk of new-onset AF (95% CI 0.81-0.98, P =.02). Conclusions Our findings suggest that overweight and obesity are associated with increased AF risk, whereas weight reduction is independently associated with reduced risk of de novo AF.