In a first, a US doctor has saved a person's life by using Apple Watch Series 4 on his wrist to detect atrial fibrillation at a restaurant.

Atrial fibrillation, a deadly and often undiagnosed condition, can lead to strokes. The condition often remains hidden because many people do not experience symptoms. The irregular rhythm notification feature on Apple Watch can check heart rhythms and send a notification if an irregular heart rhythm that appears to be atrial fibrillation (AFib) is identified. "As a physician, it's much faster to put my #applewatch4 on someone else's wrist to detect disease (A. fib) than finding a ECG machine at a public restaurant! (Indeed, a true #mhealth guardian)," tweeted Tommy Korn MD, and ophthalmologist from San Diego, California.

In the replies to his tweet, Korn said that the person diagnosed with A-fib was later doing fine. Apple Watch Series 4 is now helping users in the US, Europe and Hong Kong take an electrocardiogram (ECG) right from their wrist, capturing heart rhythm in a moment when they experience symptoms like a rapid or skipped heart beat and helping to provide critical data to physicians. The key health feature on Apple Watch is yet to arrive in India.