Apple Watch May be Able to Detect Atrial Fibrillation

Razi Berry

A preliminary report from Stanford University School of Medicine shows promise of wearable technology being used to detect atrial fibrillation.1 The research was part of the Apple Heart Study, an unprecedented virtual study including over 400,000 enrolled individuals. The study concluded that wearable technology is able to safely identify heart rate irregularities, including atrial fibrillation, a leading cause of stroke in the U.S.

Apple Heart Study

The study was launched with sponsorship by Apple Inc. in November 2017 to determine whether a mobile app that uses data from a heart-rate pulse sensor on the Apple Watch can identify atrial fibrillation. The condition often remains hidden because many people don’t experience symptoms.

Key findings from the study include the following:

  • Overall, only 0.5 percent of participants received irregular pulse notifications, an important finding given concerns about potential over-notification.
  • Comparisons between irregular pulse-detection on Apple Watch and simultaneous electrocardiography patch recordings showed the pulse detection algorithm (indicating a positive tachogram reading) has a 71 percent positive predictive value. Eighty-four percent of the time, participants who received irregular pulse notifications were found to be in atrial fibrillation at the time of the notification.
  • One-third (34 percent) of the participants who received irregular pulse notifications and followed up by using an ECG patch over a week later were found to have atrial fibrillation. Since atrial fibrillation is an intermittent condition, it’s not surprising for it to go undetected in subsequent ECG patch monitoring.
  • Fifty-seven percent of those who received irregular pulse notifications sought medical attention.

Results of the Apple Heart Study

“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, MD, 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.”

All about the Apple Heart Study

For the study, each participant was required to have an Apple Watch (series 1, 2 or 3) and an iPhone. The most recent Apple Watch, which features a built-in ECG, wasn’t part of the study, as it was released after the study’s launch. The Apple Heart Study app intermittently checked 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 involved in the study through American Well. Participants were then sent ambulatory ECG patches through BioTelemetry, which recorded the electrical rhythm of their hearts for up to a week.

The Stanford principal investigators were Mintu Turakhia, MD, associate professor of cardiovascular medicine, and Marco Perez, MD, associate professor of cardiovascular medicine, and the study chair was Kenneth Mahaffey, MD, professor of cardiovascular medicine.

“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. “The virtual design of this study also provides a strong foundation upon which future research can be conducted to explore the health implications of wearable technology.”

Performance and accuracy provides important information

“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 Perez. “Further research will help people make more informed health decisions.”

From Stanford University School of Medicine


Razi Berry is the founder and publisher of  the journal Naturopathic Doctor News & Review  that has been in print since 2005 and the premier consumer-faced website of naturopathic medicine, NaturalPath.  She is the host of The Natural Cancer Prevention Summit and The Heart Revolution-Heal, Empower and Follow Your Heart, and the popular 10 week Sugar Free Summer program. From a near death experience as a young girl that healed her failing heart, to later overcoming infertility, chronic fatigue syndrome, and fibromyalgia through naturopathic medicine, Razi has lived the mind/body healing paradigm. Her projects uniquely capture the tradition and philosophy of naturopathy: The healing power of nature, the vital life force in every living thing and the undeniable role that science and mind/body medicine have in creating health and overcoming dis-ease. Follow Razi on Facebook at Razi Berry and join us at  Love is Medicine  to explore the convergence of love and health.

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