Heavier individuals who suffer an initial episode of atrial fibrillation (AF) are at increased risk of permanent AF if they are obese, according to researchers. Development of permanent AF is not associated with diabetes, hypertension, and blood pressure (BP).

Investigators studied 1,385 patients (mean age 69 years) whose initial AF terminated within six months and who had at least six months of follow-up. They defined permanent AF as AF present on two separate occasions 6-36 months apart without any sinus rhythm between the two occasions.

The five-year cumulative incidence of permanent AF was 24%, Evan L. Thacker, PhD, of the Cardiovascular Health Research Unit at the University of Washington in Seattle, and colleagues reported online ahead of print in the Journal of General Internal Medicine. Compared with patients with a normal body mass index (BMI), defined as 18.5-24.9 kg/m2, those with a BMI of 25.0-29.9 (overweight), 30.0-34.9 (obese), 35.0-39.9, and 40.0 or higher had a 26%, 35%, 50%, and 79%  increased risk of permanent AF, after adjusting for age, gender, diabetes, hypertension, BP, coronary heart disease, valvular heart disease, heart failure, and prior stroke.

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Dr. Thacker and his team noted that AF progression is associated with greater morbidity and mortality. “Understanding the risk factors for permanent AF could help identify people who would benefit most from interventions,” the authors wrote.

The investigators had hypothesized that diabetes, hypertension, and BP would be associated with increased risk of permanent AF because these factors were associated with a greater risk of new-onset AF in previous studies.