Nov. 23, 2004 -- If you're obese and find your heart racing and fluttering from time to time, don't chalk it up to a bad case of nerves. A new study shows that those who are obese are 50% more likely to have a potentially deadly heart rhythm disorder called atrial fibrillation (AF).
The chaotic heartbeat noted during atrial fibrillation typically results when the upper heart chambers contract in a very disorganized fashion. Symptoms can stop or start suddenly. It is the most common heart rhythm abnormality, and is seen frequently as we age, in diabetes patients, and in people with heart disease. Because of the ineffective pumping of the heart, blood pools within the chambers, which can lead to stroke.
Many of the conditions associated with the irregular heartbeat are seen in overweight and obese individuals. However, it is unclear whether excess weight is a risk factor for the heartbeat abnormality. The researchers say that excess weight has been shown to produce an enlargement in the heart chambers as well as changes in the electrical stability of the heart that causes the heart to beat.
Researchers reporting in the Nov. 24 issue of the Journal of the American Medical Association analyzed data from the Framingham Heart Study to determine whether a person's weight determined by body mass index (BMI) played a role in the development of AF.
More than 5,000 people, about age 57, were grouped into three BMI categories: normal (less than 25), overweight (25-30), or obese (greater than 30). BMI is an indirect measure of body fat that uses height and weight to calculate this measure.
By the end of the follow-up period, 292 men and 234 women developed AF.
The researchers found that obese men had a 52% increased risk for AF. The risk for obese women was 46% greater than those with a normal BMI.
Thomas J. Wang, MD, and researchers also noted that the size of the left heart chamber was significantly greater in obese men than in men with a normal BMI. Obese women exhibited a typical result, when compared with other females in the study.
"Our analyses suggest that the excess risk of AF associated with obesity may be attributable to difference in left atrial size between lean and obese individuals," Wang and co-authors wrote in the journal report.
In an accompanying editorial, James Coromilas, MD, of Columbia University Medical Center, says the obesity epidemic makes Wang's study of timely importance.
"Obesity now needs to be considered a risk factor for the development of AF. Although the increase risk for the development of AF with increased BMI is modest, the public health implications are substantive," he writes.