Association of predicted body composition with occurrence of atrial fibrillation.

Background: Body mass index (BMI) is insufficient evidence as a risk factor for numerous health disorders. Body composition may be more appropriate for confirming the association with cardiovascular diseases, including atrial fibrillation (AF). This study aimed to examine the association between body composition and the occurrence of AF. Methods: A total of 2,673,108 participants (48.6% women) without AF at baseline from the Korean national health insurance data were included. Body composition including appendicular skeletal muscle mass, body fat mass, and lean body mass were indirectly measured through validated anthropometric prediction equations. The diagnosis of AF and comorbidities were defined. Results: With a median of 9.5 (interquartile range 9.2-10.1) years' follow-up, 25,841 (0.96%) cases of incident AF were included. In multivariable analysis, higher appendicular skeletal muscle was related to low risk of AF [hazard ratio (HR) 0.829, 95% confidence interval (CI) 0.753-0.912 for men (fifth quintile) and HR 0.888, 95% CI 0.792-0.995 for women (fifth quintile)]. In contrast, a higher body fat mass [HR 1.345, 95% CI 1.221-1.483 for men (fifth quintile) and HR 1.420, 95% CI 1.274-1.591 for women (fifth quintile)] and lean body mass [HR 2.241, 95% CI 2.182-2.303 for men (fifth quintile) and HR 1.516, 95% CI 1.368-1.667 for women (fifth quintile)] were associated with the occurrence of AF. Conclusions: In this study, body composition parameters were associated with the occurrence of AF. It should be noted that when appendicular skeletal muscle mass decreases and body fat mass and lean body mass increase, the risk of AF may be increased in general population except underweighted BMI group.