Patricia Lauder (73) from Connecticut, USA, had been feeling unwell for a number of days and the heart rate monitor on her fitness device was showing her resting heart rate gradually rising.
While awaiting diagnostic tests to see if she was suffering from pneumonia, the pensioner became concerned when the device showed a resting heart rate of 140 beats per minute and she immediately called an ambulance.
Scans later revealed that the pensioner had two large blood clots in her lungs which were obstructing the blood flow around her body.
Speaking to CNN, Lauder said: “When I got to the hospital, they did a series of tests and found that I had blood clots in both lungs.
“My heart had enlarged to about 65pc beyond its normal capacity.”
Responding quickly, doctors at UConn Health Calhoun Cardiology Center dissolved the clots by injecting medication through a catheter. Within 24 hours, Lauder’s heart and lung function had returned to normal.
“I had the procedure on Friday, removed the catheter on Saturday and was home Monday evening,” she said.
Speaking to CNN, Lauder’s physician Dr JuYong Lee, director of vascular and endovascular medicine, said the device helped alert doctors to the immediate risk posed to Lauder.
“I think the Fitbit actually helped her decide whether or not this was a serious condition at that time,” Lee said.
“This condition is very critical and she may have actually died if she had not sought medical attention.”