A recent study suggests that the risk of developing an irregular heart rhythm increases as people age and become overweight or obese, spiking after age 50 for men and age 60 for women. Researchers examined data on almost 80,000 people, ages 24 to 97, in four European studies. When they joined the studies, none of the participants had atrial fibrillation. After following half of the participants for at least 13 years, and some of them for nearly 28 years, researchers found that 4.4% of the women and 6.4% of the men had developed atrial fibrillation. Researchers report in Circulation journal that when they compared to people who didn’t develop atrial fibrillation, those who did had a tripled risk of dying during the study period. The study author Dr. Christina Magnussen of the University Heart Center Hamburg in Germany, said that excess weight explained most of the increased risk with atrial fibrillation. Magnussen noted by email that for each additional 10 pounds, the atrial fibrillation rate increases by 31% in men and by 18% in women. In atrial fibrillation, the heart quiver instead of beating to move blood effectively. Few people developed atrial fibrillation before age 50, the study found. By age 90, one in four men and women had the condition. High cholesterol didn’t appear to increase the risk of atrial fibrillation.