According to a post from ABC News, researchers from Stanford University have confirmed that Apple watches can detect atrial fibrillation, an irregular and dangerous heart rhythm that can potentially lead to a stroke.

An Apple Watch owner, Ed Dentel was informed by his watch that he had an irregular heartbeat. Dentel did, in fact, have an irregular heartbeat and the finding potentially saved his life.

Atrial Fibrillation, in-depth, is the most common abnormal heart rhythm and it affects approximately six million people in the United States. Usually, those who suffer from atrial fibrillation have no symptoms.

The first sign is sometimes a stroke.

This is due to blood pooling into the upper chambers of the heart causing a clot to form. If the clot dislodges from the heart, it goes to the brain, causing a stroke.

Up to 20 percent of strokes are due to atrial fibrillation.

The study on the watch involved an app on the Apple Watch that uses the watch’s light sensors to monitor heart rates over the span of eight months. When the app detects five irregularities in a row, an alarm goes off, telling the patients to contact a doctor through the app. Those who did were sent a patch to wear for a week to record their heart’s electric activity. This confirmed if atrial fibrillation was present or not.

There were only a .5 percent of people who set off the alarm so researchers figured that anyone who received an alarm were 84 percent likely to have atrial fibrillation.

Apple has sold over eight million watches in the span of three months according to the International Data Corporation.

The starting price for an Apple Watch is $279, but cardiologists are concerned that the Watch would have limited appeal for clinical use.

For them, more research is needed to be able to rely entirely on the watches for detection of atrial fibrillation.