Big men and atrial fibrillation: effects of body size and weight gain on risk of atrial fibrillation in men

Obesity is a recognized risk factor for atrial fibrillation (AF), partly because of the association between body mass index (BMI) and atrial volume. We aimed to determine whether other factors relating to body size were related to AF. Data were derived from a random population sample of 6903 men (mean age 51.5 years) who underwent a single midlife evaluation as part of the multifactor Swedish Primary Prevention Study. A total of 1253 men (18.2%) had a subsequent hospital discharge diagnosis (principal or secondary) of AF during a maximum follow-up of 34.3 years. Body surface area (BSA) at age 20 (calculated from recalled weight and measured height) was strongly related to subsequent AF (P < 0.0001), as were midlife BMI and weight gain from age 20 to midlife (P < 0.0001). In a Cox regression model which adjusted for midlife BMI, weight gain and other risk factors, hazard ratios (HR) [95% confidence intervals (CI)] for AF for the second, third, and fourth quartile of BSA at age 20, compared with the lowest quartile, were 1.47 (95% CI, 1.22-1.76), 1.66 (95% CI, 1.38-2.00), and 2.22 (95% CI, 1.82-2.70) (P for trend < 0.0001). Large body size in youth, in an era when obesity was rare, as well as weight gain from age 20 to midlife, were both independently related to the development of AF. Given the current trends not only for obesity but also for height, a substantial increase in the incidence of AF is likely.