A man in US has claimed an Apple Watch app notification saved his life after it detected signs of a life-threatening blood clot in his lungs and alerted him to get medical attention.

New York resident James Green, 28, got an alert from the HeartWatch app, which monitors a person's heart rate constantly throughout the day and notifies users when their resting heart rate rises above or dips below a certain threshold, the Telegraph reported. "Never thought a stupid lil wrist computer I bought two years ago would save my life. Saw my heart rate go up, ended up being a pulmonary embolism (a blood clot in the lungs)," Green said in a tweet.The app notified him that his heart rate was continuously above his usual heart rate of 54 beats per minute.

"That along with other symptoms I was having was enough data I needed to act on it, and realise it wasn't a panic attack (since I have severe generalised anxiety), that it was something more," Green said.Later, a CT scan in the hospital showed that Green suffered a blood clot in his lungs. His doctor said the clot could have been fatal if Green had waited longer to get medical attention.Because some fitness trackers and smartwatches include heart rate monitors, the devices can potentially alert people to certain health problems that cause changes in heart rate. However, it's important to note that many of these devices are not approved. So they cannot be used to diagnose cardiovascular conditions, experts suggest.