Obesity could increase a person’s risk for atrial fibrillation

New research indicates that being obese could increase a person’s risk for atrial fibrillation, the most common irregular heart rhythm, by 50 percent, according to work published in the November 24 issue of JAMA.

The prevalence of atrial fibrillation (AF) is expected to increase several-fold in the coming decades, according to background information in the article. Because the onset of AF is associated with considerable illness and a higher risk of death despite various therapies, the identification of potentially modifiable risk factors for AF is important. While obesity has been associated with other heart problems, it has been unclear whether it is a risk factor for AF.

Thomas J. Wang, M.D., of the Framingham Heart Study, Framingham, Mass., and colleagues examined long-term followup data from the Framingham Heart Study to determine if there was an association between body mass index (BMI, a person’s weight in kilograms divided by height in meters squared) and the risk of developing AF. The study group included 5,282 participants (average age, 57 years; 2,898 women) without baseline AF. The researchers examined risk for three categories of BMI: normal, defined as less than 25.0; overweight, 25.0 to less than 30.0; and obese, greater than 30.0. A 5’4” woman would have a BMI of 30 if she weighed 174 lbs.; a 6’00” man would have a BMI of 30 if he weighed 221 lbs.

During an average follow-up of 13.7 years, 526 participants (234 women) developed AF. Age-adjusted incidence rates for AF increased across the 3 BMI categories in men and women. In multivariable models adjusted for cardiovascular risk factors and interim heart attack or heart failure, a 4 percent increase in AF risk per 1-unit increase in BMI was observed in men. Obese men had a 52 percent increased risk for AF; obese women, 46 percent increased risk, compared with individuals with normal BMI. The researchers found that the increased risk for AF may be mostly attributable to an associated dilation of the left atrial (upper chamber of the heart).

“… the implication of these results for the population burden of AF may be substantial, because obesity is highly prevalent and potentially modifiable. Thus, even a small decrease in the prevalence of obesity could lead to a large reduction in the incidence of AF,” the authors write.

“Because management of AF remains a difficult clinical challenge, the identification of potentially modifiable risk factors may have important public health implications. Although our study was observational, it raises the intriguing possibility that weight reduction may decrease the risk of AF,” the researchers write.