By Lisa Rapaport
(Reuters Health) – Both men and women who are overweight or
obese may be more likely to develop an irregular heart rhythm
condition known as atrial fibrillation than their counterparts
who maintain a healthy weight, a recent study suggests.
In atrial fibrillation, the upper chambers of the heart, or
atria, quiver instead of beating to move blood effectively.
While the condition has long been linked to obesity, the current
study offers fresh evidence of how gender may impact the risk of
atrial fibrillation associated with excess weight.
Extremely obese men, for example, were more than four times
more likely to develop atrial fibrillation than men who
maintained a healthy weight, the study found. By contrast,
extremely obese women had almost twice the risk of developing
atrial fibrillation as women at a healthy weight.
“Not only does being overweight/obese change the structure
of the heart, making it more susceptible to AF development, but
other risk factors for AF are more likely to exist in overweight
and obese individuals, such as high blood pressure,” said lead
study author Jocasta Ball of the Baker Heart and Diabetes
Institute in Melbourne, Australia.
“For patients, recognizing that being overweight or obese
increases the risk of future AF development and that even small
reductions in BMI can reduce this risk should trigger an attempt
at weight loss,” Ball said by email.
Atrial fibrillation is the most common heart rhythm
disorder, affecting approximately 2 to 3 percent of the world’s
population, researchers note in the Journal of the American
For the current study, researchers examined survey data from
24,799 adults in Norway who were followed for an average of
about 16 years to see how their weight impacted their chance of
developing atrial fibrillation.
Atrial fibrillation most often develops after age 50. At the
start of the study, participants were typically in their mid- to
late- 30s. Most of them also started out at a healthy weight
based on their body mass index (BMI) – a ratio of weight to
During the study period, 811 men and 918 women developed
Even when people weren’t seriously overweight, a higher BMI
was still tied with a higher risk for atrial fibrillation. For
example, compared to a BMI of 23, which falls within a healthy
weight range, men with a BMI of 25, which is slightly
overweight, were 14 percent more likely to develop atrial
When men had a BMI of 18, which is underweight, they were 25
percent less likely to develop atrial fibrillation than men with
a BMI of 23. Men with a BMI of 20, meanwhile, were 14 percent
less likely to develop atrial fibrillation than men with a BMI
For women, the pattern was similar at lower weights but as
with heavier individuals, the association between obesity and
atrial fibrillation wasn’t as strong as it was with men.
Women with a BMI of 18 were 18 percent less likely to
develop atrial fibrillation than women with a BMI of 23, and
women with a BMI of 20 had an 11 percent lower risk.
The study wasn’t a controlled experiment designed to prove
whether or how obesity causes atrial fibrillation. Researchers
also lacked data on changes over time in medical conditions or
medication use that might independently influence the risk of
Still, the study adds to the evidence linking excess weight
to a higher risk of atrial fibrillation, said Dr. Gregg Fonarow,
a cardiology researcher at the University of California Los
Angeles who wasn’t involved in the study.
“While the study finds the relationship was stronger in men,
both men and women who were overweight or obese according to
their body mass index were at increased risk for atrial
fibrillation,” Fonarow said by email.
Losing even a little weight may help lower the risk, said
Dr. Prash Sanders, a researcher at the University of Adelaide in
Australia who wasn’t involved in the study.
“While even small amounts of weight loss can make a
difference, we see an even greater magnitude in reduction of
risk if more weight loss is achieved,” Sanders said by email.
“Importantly, research has demonstrated that the structural and
electrical changes we see in overweight and obese individuals
are reversible with weight loss.”
SOURCE: http://bit.ly/2IgKDlI Journal of the American Heart
Association, online April 19, 2018.