After revealing that it’s working on technology to detect sleep apnea, Fitbit now tells TIME that it is looking at ways to identify atrial fibrillation.

“When we start to look at our PurePulse [heart rate monitor] data that we get from all of these users, we began to see irregularities in heart rhythms,” says Subramaniam Venkatraman, Fitbit’s director of research. “From our knowledge of physiology, [that] suggests an indicator of atrial fibrillation.”