A huge study suggests the Apple Watch can detect a worrisome irregular heartbeat – but experts say more work is needed to tell if using wearable technology to screen for heart problems really helps.

More than 419,000 Apple Watch users signed up for the study, which was funded by Apple and the largest ever to explore screening seemingly healthy people for atrial fibrillation (A-fib), a condition that if untreated eventually can trigger strokes. People who received an alert were supposed to consult a study doctor via telemedicine and then wear an EKG patch measuring cardiac activity for the next week. Some skipped the virtual check-up to consult their own doctors. Overall, about 57% sought medical attention.

“This study we believe provides very encouraging evidence that a device, the Apple Watch, can be used to detect a-fib and to point out to people when additional monitoring or testing may be needed,” said Dr. Lloyd Minor, Stanford’s dean of medicine.

A huge study suggests the Apple Watch can detect a worrisome irregular heartbeat – but experts say more work is needed to tell if using wearable technology to screen for heart problems really helps.

More than 419,000 Apple Watch users signed up for the study, which was funded by Apple and the largest ever to explore screening seemingly healthy people for atrial fibrillation (A-fib), a condition that if untreated eventually can trigger strokes. People who received an alert were supposed to consult a study doctor via telemedicine and then wear an EKG patch measuring cardiac activity for the next week. Some skipped the virtual check-up to consult their own doctors. Overall, about 57% sought medical attention.

“This study we believe provides very encouraging evidence that a device, the Apple Watch, can be used to detect a-fib and to point out to people when additional monitoring or testing may be needed,” said Dr. Lloyd Minor, Stanford’s dean of medicine.