Before Apple announced the Apple Watch's ability to perform echocardiograms on the go last year, it was working with Stanford University to study the technology. The Apple Heart Study enrolled 400,000 people.

According to study results, presented Saturday, 2,000 of those participants received a notification about an irregular heart rhythm, which can be a sign of a larger problem, like atrial fibrillation. The sooner warning signs can be spotted, the sooner people can seek help.

"Many participants sought medical advice following their irregular rhythm notification, using the information to have more meaningful conversations with their doctors," Apple said in a press release.

Fifty-seven percent of participants who received an irregular pulse notification went to the doctor.

"The results of the Apple Heart Study highlight the potential role that innovative digital technology can play in creating more predictive and preventive health care," said Lloyd Minor, dean of the Stanford School of Medicine. "Atrial fibrillation is just the beginning, as this study opens the door to further research into wearable technologies and how they might be used to prevent disease before it strikes — a key goal of precision health."

In November, the ECG sensor gained support in WatchOS version 5.1.2.