Smartwatches have gotten pretty good at detecting atrial fibrillation, the world’s most common heart rhythm disorder, affecting nearly 38 million people worldwide. But many people ignore the warning and assume that if they’re fine, it’s probably no big deal. New research presented at EHRA 2026 in Paris suggests this is a mistake worth reconsidering.
The study is a post hoc analysis of two large Swedish screening programs, STROKESTOP and STROKESTOP II, in which adults aged 75 to 76 years were screened for atrial fibrillation using an ECG. Researchers followed participants for several years to find out who went on to develop heart failure.
The numbers are hard to ignore. In STROKESTOP, about 23% of people whose atrial fibrillation was detected through screening later developed heart failure. STROKESTOP II achieved a similar value of around 20%.
What does this have to do with your smartwatch?
If you’ve ever watched an Apple Watch keynote video, you know that Apple loves to show how its smartwatch helps people avoid heart attacks thanks to its atrial fibrillation (AF) detection feature.
Apple Watch isn’t the only smartwatch to do this. Most modern smartwatches can quietly detect atrial fibrillation in people who feel perfectly well and have no obvious symptoms. This research shows that asymptomatic does not mean harmless.
People with screen-detected atrial fibrillation had about three times the risk of heart failure compared to people without atrial fibrillation.
Why should you act quickly?
In both studies, heart failure occurred within six months of detection of atrial fibrillation. That’s a short window of time, and it makes a case for considering a smartwatch alarm as a reason to see a doctor sooner rather than later.
Doctor Gina Sado from Danderyd Hospital in Stockholm, who led the research, noted that atrial fibrillation and heart failure accelerate each other and that early detection of both conditions gives patients the best chance of effectively treating both conditions.
So if your smartwatch gives you an AF alert, it’s probably a good idea to consult your doctor. In the worst case scenario, everything is fine and you pay for an examination. In most cases, however, a frightening health condition can be prevented.
