Doctors at an emergency room in New Jersey used data from a patient's Fitbit activity tracker -- which they happened to notice on his wrist -- to determine his course of treatment.

When the 42-year-old patient showed up in the ER at Our Lady of Lourdes Medical Center in Camden, New Jersey, he had already had a seizure and he had atrial fibrillation. Doctors had to decide whether or not to use an electric shock to reset the patient's heart rhythm. But the doctors were missing a key piece of information they use to make that determination -- the timing of the onset of the atrial fibrillation.

"Because the patient was asymptomatic during his current atrial fibrillation event, it was not possible to assign an onset time for his arrhythmia," doctors wrote in the case study, published in the Annals of Emergency Medicine. "During the patient’s examination, it was noted that he was wearing a wrist activity tracker (Fitbit Charge HR, Fitbit, San Francisco, CA), which was synchronized with an application on the patient’s smartphone, recording his pulse rate as part of a fitness program. The application was accessed on the patient’s smartphone and revealed a baseline pulse rate between 70 and 80 beats/min, with an immediate persistent increase to a range of 140 to 160 bpm at the approximate time of the patient’s seizure. ... Once the patient’s onset time for his atrial fibrillation was established as three hours before ED presentation, he was considered a candidate for rhythm conversion."

The procedure was successful and the patient was discharged, but the doctors thought the use of the Fitbit in an emergency response situation was worth writing up, especially because it's extensible to other scenarios.

"Any number of symptomatic conditions can resolve before an encounter with a medical provider," they wrote. "Syncope, palpitations, dizziness, and even chest pain are all frequently self-limited complaints, leaving the clinician with only the history of the present illness on which to formulate a diagnosis. In many instances, knowledge of the patient’s pulse rate at the event could help in establishing a firmer diagnosis. Dizziness associated with a pulse rate of 180 beats/min would be approached much differently than the same complaint with a pulse rate of 30 beats/min."

A number of hospitals have deployed Fitbits for a range of applications in research projects and even in clinical practice. Nor is this the first time a heart-reate tracking consumer wearable has proved fortuitous in a patient's care: Back in September, a Massachusetts teenager's Apple Watch registered a surprisingly high heart rate which turned out to be rhabdomyolysis, a potentially fatal muscle syndrome that might have led to kidney failure if it hadn't been caught.

Nonetheless, consumer activity trackers' main use is still in the realms of weight loss, athletics, and workplace wellness, and the clinical accuracy of the non-FDA-cleared devices has even been questioned in recent lawsuits.

"To date, activity trackers have been used medically only to encourage or monitor patient activity, particularly in conjunction with weight loss programs," Our Lady of Lourdes doctors wrote in the case report. "To our knowledge, this is the first report to use the information in an activity tracker -- smartphone system to assist in specific medical decision making. The increased use of these devices has the potential to provide clinicians with objective clinical information before the actual patient encounter."

In other Fitbit news, the company announced today that its Fitbit Surge tracker will play a big role in NBC's new fitness series "Strong". The last time an NBC show incorporated wearable technology it was the Bodymedia device (now discontinued after its acquisition by Jawbone) on "The Biggest Loser".