Body size and risk of atrial fibrillation: a cohort study of 1.1 million young men

Abstract Background Whilst tall stature has been related to lower risk of vascular disease, it has been proposed as a risk factor for atrial fibrillation. Little is known about other anthropometric measures and their joint effects on risk of atrial fibrillation. Objectives We aim to investigate associations and potential joint effects of height, weight, body surface area ( BSA ) and body mass index ( BMI ) with risk of atrial fibrillation. Methods In a cohort covering 1 153 151 18‐year‐old men participating in the Swedish military conscription (1972–1995), Cox regression was used to investigate associations of height, weight, BSA and BMI with risk of atrial fibrillation. Results During a median of 26.3 years of follow‐up, higher height was associated with higher risk of atrial fibrillation (hazard ratio [ HR ] 2.80; 95% CI 2.63–2.98; for 5th vs. 1st quintile) and so was larger BSA ( HR 3.05; 95% CI 2.82–3.28; for 5th vs. 1st quintile). Higher weight and BMI were to a lesser extent associated with risk of atrial fibrillation ( BMI : 1.42; 95% CI 1.33–1.52, for 5th vs. 1st quintile). We found a multiplicative joint effect of height and weight. Adjusting for muscle strength, exercise capacity and diseases related to atrial fibrillation attenuated these measures. Conclusions Higher height and weight are strongly associated with higher risk of atrial fibrillation. These associations are multiplicative and independent of each other and are summarized in a strong association of body surface area with risk of atrial fibrillation. The mechanisms remain unknown but may involve increased atrial volume load with larger body size.