Waist size may better predict AFib risk in men Sarah Amandolare, American Heart Association News April 15, 2021 FacebookTwitterEmail Body mass index may be more helpful in predicting the risk of a common type of irregular heartbeat in women, while waist size may better predict that risk in men, new research suggests. The link between obesity and atrial fibrillation, or AFib – when the heart beats irregularly and often too fast – is well established. But researchers wanted to understand the extent to which body fat distribution might predict AFib risk among men and women. The researchers analyzed BMI, waist circumference and electrocardiogram data gathered between 2008 and 2013 from more than 2 million older adults in the U.S. and United Kingdom who didn't have cardiovascular conditions, including heart failure and stroke. The study's lead author, Dr. Michiel Poorthuis of University Medical Center Utrecht in the Netherlands, described it as "probably the largest study of its kind to date."