Apple's Heart Study Shows Positive Results in Detecting A-Fib

Samara Rosenfeld
MARCH 19, 2019
apple heart study
Photo and thumbnail have been modified. Courtesy of Apple.

The results of an observational study conducted by researchers at Apple and Stanford Medicine determined that wearable technology can safely identify heart rate irregularities that subsequent testing confirmed to be atrial fibrillation (A-fib).

More than 400,000 participants that had an Apple Watch series 1, 2, or 3 and an iPhone were enrolled in the study — the Apple Watch series 4 which features a built-in electrocardiogram (ECG) was not part of the study.

The Apple Heart Study application would intermittently check the heart-rate pulse sensor for measurements of an irregular pulse. If an irregular pulse was detected, the participant received a notification and was asked to schedule a telemedicine consultation with a doctor working on the study.  The participant was then sent ambulatory ECG patches, which recorded the electrical rhythm of their heart for up to a week.

The pulse detection algorithm had a 71 percent positive predictive value and 84 percent of the time, participants who received irregular pulse notifications were found to be in A-fib at the time of the notification.

The study launched in 2017 to determine whether a mobile app that uses data from a heart-rate pulse sensor on the Apple Watch can identify A-fib, a condition that often remains hidden because many people don’t experience symptoms.

While these results can be viewed as optimistic for some, many doctors have expressed reasons to be wary about the findings.

Of the 419,000 participants, about 0.5 percent received a notification about an irregular heartbeat. But not all of those who were notified followed the protocol to contact the researchers to ask for an ECG patch to confirm the diagnosis. Only about 450 out of more than 2,000 participants that got a notification saying they might have A-fib followed protocol — roughly one in five.

A-fib was confirmed in 34 percent of cases for the people who received and wore the patches.

Other doctors said that it is important to remember that this was just an observational study, not a randomized control trial, and that the findings of the study were only preliminary and not published in a scientific journal.

Still, this study could serve as a step in the right direction for better wearable health monitors and virtual trials.

“The performance and accuracy we observed in this study provides important information as we seek to understand the potential impact of wearable technology on the health system,” said Marco Perez, M.D., associate professor of cardiovascular medicine. “Further research will help people make more informed health decisions.”

A study is currently underway between Apple and Johnson & Johnson to see how the Apple Watch can help improve A-fib outcomes, including stroke prevention. 

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