COLORADO SPRINGS — Large body size in youth is associated with increased risk of atrial fibrillation in later life in men, Dr. Annika Rosengren said at a conference sponsored by the American Heart Association.
“If you were tall, or had a lot of muscles … you had more risk of atrial fibrillation. And you could add to this risk further by putting on weight after age 20,” said Dr. Rosengren, professor of medicine at Sahlgrenska University Hospital, Goteborg, Sweden.
The implication of this finding from a large Swedish longitudinal study is that the already-high prevalence of atrial fibrillation (AF) in western societies will keep climbing, and the increase won't simply be due to the aging of the population, inadequately controlled hypertension, and worsening obesity epidemic, all well-recognized contributors to AF.
“Each successive generation is bigger in youth. People are not only growing fatter with each succeeding cohort being born, they're also getting taller and larger, independent of obesity. So expect more atrial fibrillation,” she said in an interview.
Dr. Rosengren reported on 6,903 Swedish men who were a mean of 52 years old in the early 1970s when they enrolled in the Swedish Primary Prevention Study. They were followed until 2004, for a maximum of 34 years. During follow-up, 18% of the men were diagnosed with AF.
The participants' body surface area at age 20 was strongly related to risk of AF, based on a Cox regression analysis adjusted for midlife body mass index and other potential confounders. They turned 20 during 1935–1945, when “obesity was virtually non- existent in Sweden,” she noted.
In the adjusted regression analysis, men in the second quartile of body surface area at age 20 had a 42% greater risk of later developing AF as did men in the lowest quartile. Men in the third quartile had a 58% increase in risk, and those in the top quartile for body surface had a 200% greater risk. Body weight at age 20 showed a virtually identical association with subsequent AF.
“If you're big … there's a high likelihood of having large atria [which] are more prone to develop atrial fibrillation,” she said.
Weight gain between age 20 and midlife was also independently tied to higher AF risk. A 5%–15% weight gain was associated with a 13% greater rate of AF, compared with no weight gain. A 16%–35% gain was associated with a 33% increase in AF rate, and a gain of more than 35% was linked to a 61% increase in risk.