Drinking two liters or more per week of artificially sweetened beverages — the equivalent of a medium-sized fast-food diet soda a day — raised the risk of an irregular heartbeat called atrial fibrillation by 20% when compared to people who drank none, a new study found.

Known as A-fib, atrial fibrillation is an irregular heartbeat often described by many people who have it as a “quiver,” “flutter” or “flip-flop” of the heart in the chest.

Drinking a similar number of added-sugar beverages raised the risk of the condition by 10%, while drinking about four ounces of pure, unsweetened juices, such as orange or vegetable juice, was associated with an 8% lower risk of atrial fibrillation, the study found.

“This is the first study to report an association between no- and low-calorie sweeteners and also sugar-sweetened beverages and increased risk of atrial fibrillation,” said Penny Kris-Etherton, a professor emeritus of nutritional sciences at the Pennsylvania State University, in a statement. She was not involved in the new study.

While the study could only show an association between sweetened drinks and A-fib, the relationship remained after accounting for any genetic susceptibility to the condition. A 2017 study found people with European ancestry had about a 22% risk of inheriting the condition.