Size matters- weight gain predicts AF

Data derived from the Primary Prevention Study, which began in 1970 in Sweden, shed some light on the separate influences of body size and weight in youth and weight gain during adulthood on the risk of future atrial fibrillation (AF).

The population included in this study were all men, born in Göteborg between 1915 and 1925. Of these men, 7,495 underwent a medical examination to identify and treat cardiovascular risk factors in the early 1970s. These factors included smoking history, physical activity during leisure time, diabetes, treatment for hypertension, and alcohol problems. The men were also asked for their recalled weight at age 20, which was used to calculate body surface area (BSA) and body mass index (BMI). The men were subsequently followed up until 31^st December, 2004. The study population described here consisted of 6,903 men.

Results

During a maximum of 34.3 years of follow-up, 1,253 men were discharged from hospital with a diagnosis of AF. The risk of developing AF increased with increasing midlife BMI, midlife height, body surface area at age 20, and weight change from age 20 to midlife (p<0.0001 for trend for all variables). After multivariable adjustment, the risk of AF in obese men versus men with low-normal BMI remained elevated (hazard ratio 1.56. 95% CI 1.20-2.02), with an estimated 4% increase in risk for every 1 kg/m2 increase in BMI. Height was also associated with risk of AF.

The risk for AF was raised in the second, third and fourth quartiles of BSA at age 20, compared with the lowest, and for increase in weight from age 20 to midlife compared with stable weight. The risk was graded: to be in the highest quartile of body height or BSA was associated with an approximate doubling of risk compared to the lowest quartile.

There is a biologically plausible explanation for these findings since body size and left atrial size tend to be linked. Left atrial size has previously been shown to be independently associated with incidence of AF.

Reference

Rosengren A, Hauptman PJ, Lappas G, Olsson L, Wilhelmsen L, Swedberg K. Big men and atrial fibrillation: effects of body size and weight gain on risk of atrial fibrillation in men. Eur Heart J 2009; 30: 1113-20.