Fitbit algorithm catches 98% of irregular heartbeat episodes, US study finds

Fitbit is seeking approval from the US Food and Drug Administration (FDA) for a special algorithm to be widely deployed after a study of nearly half a million participants showed that the wearable fitness tracker, along with an ECG monitor, could detect undiagnosed heart rhythm irregularities in 98% of wearers.

Conducted by researchers from Massachusetts General Hospital (MGH), the novel Fitbit algorithm tracked the a pulse rate of 455,000 volunteers during periods of inactivity, and possible atrial fibrillation was noted after at least 30 minutes of irregular heart rhythms.

Atrial fibrillation or irregular intervals between heart beats can be an early sign of cardiovascular disease. According to the American Heart Association, while serious episodes of atrial fibrillation can manifest in symptoms similar to that of a heart attack, shorter episodes can be asymptomatic.

In the study, when possible atrial fibrillation was detected the subject completed a telehealth consultation with a doctor and then received an electrocardiogram (ECG) patch to wear for one week alongside the fitness tracker. In the week that followed, the new algorithm effectively picked up nearly all of the atrial fibrillation episodes detected by the ECG patch.

Steven Lubitz, a researcher from MGH working on the project, commented: “These results show that wearables have the ability to identify undiagnosed atrial fibrillation with high reliability. Since so many consumers use wearables, it is possible that algorithms such as the one we studied could be applied widely to help identify undiagnosed atrial fibrillation, allowing patients to obtain care before devastating complications such as a disabling stroke may occur.

“Most of the episodes of undiagnosed atrial fibrillation detected occurred during sleep, and we suspect that these episodes were asymptomatic. Since the algorithm is most active when wearers are physically inactive, the wearable should be worn during sleep for the greatest benefits.”

This isn’t the first time that fitness wearables have been shown to have potentially life-saving benefits. In 2019, Stanford University carried out a large study which demonstrated the potential for Apple Watches to detect instances of atrial fibrillation. According to a press release from the American Heart Association, FitBit’s study slightly improves on Apple’s results.

In Apple’s study, which featured 400,000 participants, only about 0.5% of participants received an notification of atrial fibrillation, but it ultimately delivered a similarly high positive predictive value of 84%. However, the percentage of people who received a later diagnosis confirmed with an ECG patch were about the same between the two trials, at around 33%.

Lubitz says that with Fitbit’s heart-rate sensor software and the wearable ECG monitor patch working together, the technology could potentially help enable expansive mass screening for previously invisible cases of atrial fibrillation, however there was also a high rate of false positives seen in the trial and these incorrect alerts could drive up personal anxiety and send in more people for otherwise unneeded doctor’s visits.

Courtesy of Fitbit

It is thought that fitness trackers like Fitbit could be used as part of a solution to catch the first signs of heart conditions in the future.

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