Apple presents smartwatch results from 400,000-strong heart study

Of the at least 2,000 people who received an irregular heartbeat notification, only 34% were later confirmed to have atrial fibrillation with a wearable ECG patch. (Apple)

After canvassing more than 400,000 people across all 50 states in just eight months, Apple has finished a virtual investigation of its smartwatch’s ability to alert users to irregular heart rhythms possibly linked to atrial fibrillation. It was one of the largest studies of its kind.

The Apple Heart Study—first launched in November 2017 in collaboration with Stanford Medicine—focuses on the earlier generations of the Apple Watch, which lack the latest version’s onboard ECG that was cleared by the FDA last fall. Instead, the smartwatches check a user’s pulse rate in the background for an arrhythmia.

Only 0.5% of participants of the Apple Heart Study received an irregular heartbeat notification. This amounted to at least 2,000 people, who were then connected with a doctor via a telehealth consultation and given an ECG chest patch for further monitoring over the course of a week.

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But of those, only 34% were later confirmed to have atrial fibrillation with the wearable patch—while 57% had gone on to seek medical attention.

Among participants wearing both an Apple Watch and the ECG chest patch, positive readings of irregular heartbeats coincided 84% of the time. All told, the smartwatch’s algorithms were found to have a 71% positive predictive value, according to Apple and Stanford.

RELATED: The Apple Watch’s ECG features are live

While the overall percentage of hits in the study was low, the remaining potential for false alarms urges caution about relying on the Apple Watch as a hard diagnostic—although the sporadic nature of atrial fibrillation could allow it to evade detection in subsequent ECG patch monitoring.

Co-principal investigator Mintu Turakhia described the virtual assessment of the smartwatch as a “strong foundation upon which future research can be conducted to explore the health implications of wearable technology.”

“The study’s findings have the potential to help patients and clinicians understand how devices like the Apple Watch can play a role in detecting conditions such as atrial fibrillation, a deadly and often undiagnosed disease,” said Turakhia, an associate professor of cardiovascular medicine at Stanford University.

The preliminary results of the study were showcased at the annual meeting of the American College of Cardiology annual scientific session and expo in New Orleans.

RELATED: Apple, J&J to put the Apple Watch’s ECG through large-scale clinical testing

Going forward, Apple is planning to launch a study this year with Johnson & Johnson to test its latest, ECG-equipped Apple Watch. The multiyear project will not only evaluate the device’s ability to catch atrial fibrillation, but also improve cardiovascular outcomes and prevent strokes.

The smartwatch will be paired with a patient engagement and medication adherence app developed by J&J, and tested in a controlled, randomized study of participants age 65 and older. According to the Big Pharma, 33 million people worldwide have atrial fibrillation, which is ultimately responsible for about 130,000 deaths and 750,000 hospitalizations each year.

“The results of the Apple Heart Study highlight the potential role that innovative digital technology can play in creating more predictive and preventive health care,” said Lloyd Minor, dean of the Stanford School of Medicine.

“Atrial fibrillation is just the beginning, as this study opens the door to further research into wearable technologies and how they might be used to prevent disease before it strikes—a key goal of precision health,” Minor added.

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