Obesity increases the odds of developing atrial fibrillation by 49 percent and the risk rises as body mass index (BMI) climbs, the results of a “meta-analysis” of published studies indicate.

Atrial fibrillation - the rapid and uncoordinated beating of the upper chambers of the heart - is a fairly common disorder that has been linked to an increased risk of blood clots, stroke, and early death, if not controlled.

To investigate ties between obesity and atrial fibrillation, Dr. Franz H. Messerli, from St. Luke’s-Roosevelt Hospital in New York, and colleagues analyzed data from 16 relevant studies involving 123,249 individuals.

Five studies were population-based and included 78,602 adults from the US and Europe and 11 were post-heart surgery studies of 44,647 patients.

Analysis of the population-based studies showed that obese individuals have a 49 percent higher relative risk of developing atrial fibrillation than their non-obese counterparts. Moreover, the risk of the arrhythmia was directly related to BMI. This association was seen in both men and women.

However, obesity does not seem to increase the risk of atrial fibrillation in individuals who have undergone heart surgery, Messerli and colleagues note in a report in the American Heart Journal. In the post-cardiac surgery studies, obese patients were no more (or less) likely than non-obese patients to develop atrial fibrillation.

Exactly how obesity promotes atrial fibrillation remains to be determined, the investigators say.

SOURCE: American Heart Journal, February 2008.