How an Apple watch saved this man from a life-threatening blood clot

Your health tracker may not always be perfect—but for 28-year-old James Green of Brooklyn, New York, receiving a simple alert from his Apple Watch saved his life.

Green tweeted on Friday that HeartWatch, one of the Apple Watch’s health sensors, measured his heart rate at consistently above his resting rate of 54, even though he was just sitting at his desk. Turns out those spikes were signaling a pulmonary embolism, his doctors told him after he made his way to the hospital, where they performed CT scans to reach their diagnosis, The Telegraph reports.

A pulmonary embolism occurs when a clot deep in your vein, most commonly in your leg, travels to your lungs from its original spot, blocking some or even all of your blood supply, according to the American Heart Association. This can prevent vital organs from getting the oxygen and blood they need to properly function, which can be fatal.

Green, a self-proclaimed “serial health tracker,” has experienced a pulmonary embolism before, meaning he had all the more reason to pay attention to what his heart is doing. While he suffers from generalized anxiety disorder, he told The Telegraph he was experiencing other symptoms during the time he received the heart rate alert, which pushed him to believe that he wasn’t experiencing a panic attack, but rather “something more.”

HeartWatch monitors your heart rate data across four views: Waking, Regular, Workout, and Sleeping. Each view is isolated so you can learn to notice unusual changes in how your heart is beating, according to the app’s official page.

After Green’s diagnosis, his doctors performed a couple of ultrasounds and prescribed him blood thinners, which interfere with the proteins in your body responsible for blood clots, working to minimize the damage.

Green isn’t the only one that owes his life to a health tracker, either. Just last April, a woman’s FitBit also measured a constant spike in her heart rate. She, too, was diagnosed with a pulmonary embolism.

If you don’t feel that monitoring your heart rate is completely necessary, being aware of any risk factors is still important. Read up on top six signs you may have a blood clot, so you can act just as quickly as Green did if any symptoms pop up.