Apple released watchOS 5.1.2 yesterday, and with it was the much-anticipated ECG app. While most were excited to try it out and saw a normal sinus rhythm, some weren’t so lucky. A new report from one user describes how his surprising ECG results may have saved his life.

As users are getting their Apple Watches updated, one user on Reddit found an unexpected result after taking their ECG: it came back with A-fib (atrial fibrillation). Naturally, as Apple even states themselves, the Apple Watch can return false-positives at times. So he tried “again and again and again”, and it still returned A-fib.

The user then proceeded to put it on his wife, and to his surprise, it returned normal results, multiple times. He even put it on his other wrist just to make sure. It still returned A-fib for him.

He then headed to a walk-in clinic, and told them that his Apple Watch was showing him that he had A-fib. Surprised, he bypassed the entire queue at the clinic, which had a full parking lot.

He was taken to the back and got hooked up to do another ECG. Again, it returns A-fib. The doctor comes in and told him, “This probably saved you. I read about this last night and thought we would see an upswing this week. I didn’t expect it first thing this morning.”

The story cuts there, but the user says he is headed to a cardiologist to get checked out.

Apple Watch has been credited by tons of people over the years for saving their lives, and the new ECG app is now capable of monitoring for atrial fibrillation or A-fib, for short.. Whether it be for low/high heart rate notifications, or emergency SOS, the Apple Watch and other fitness trackers have been not only improving users lives, but also saving them.