A virtual study of more than 400,000 participants has revealed that the Apple Watch could detect atrial fibrillation (AFib), a leading cause of stroke and hospitalization in the U.S.
Researchers from the Stanford University School of Medicine presented the study’s findings at the American College of Cardiology conference in New Orleans this past weekend. The Apple Heart Study, funded by Apple, set out to explore if a mobile app that uses data from a heart-rate pulse sensor on the Apple Watch can identify atrial fibrillation—a quivering or irregular heartbeat that can lead to blood clots, stroke, heart failure and other heart-related complications.
At least 2.7 million Americans are living with AFib, according to the American Heart Association, yet the condition often remains hidden because many people don’t experience symptoms, according to researchers.
The study had multiple key findings, including:
- 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.
- Overall, just 0.5 percent of participants received irregular pulse notifications, an important finding given concerns about potential over-notification, the researchers stated.
- Comparisons between irregular pulse-detection on Apple Watch and simultaneous electrocardiography (ECG) patch recordings showed the pulse detection algorithm (indicating a positive tachogram reading) has a 71 percent positive predictive value.
- 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, according to the researchers.
- Fifty-seven percent of those who received irregular pulse notifications sought medical attention.
“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, M.D., 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.”
For the study, each participant was required to have an Apple Watch (series 1, 2 or 3) and an iPhone. 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 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,” added Mintu Turakhia, M.D., associate professor of cardiovascular medicine at Stanford and one of the study’s principal investigators. “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.”
In September, Apple announced its latest version of the Apple Watch, its Series 4 product, inclusive of an electrocardiogram function as well as fall detection capabilities. Some major healthcare insurers, such as Aetna and UnitedHealthcare, already offer the Apple Watch to its employees as part of a wellness program. This watch was not part of the Stanford study, however, since it was released after its launch.
In a March 16 press release touting the results of the study, Apple officials said, “Stanford Medicine today reported results of the Apple Heart Study, the largest study ever of its kind, which enrolled over 400,000 participants from all 50 states in a span of only eight months. Apple and Stanford created the study to evaluate Apple Watch’s irregular rhythm notification, which occasionally checks the heart's rhythm in the background and sends a notification if an irregular heart rhythm appears to be suggestive of atrial fibrillation. As part of the study, if an irregular heart rhythm was identified, participants received a notification on their Apple Watch and iPhone, a telehealth consultation with a doctor and an electrocardiogram patch for additional monitoring.”
Marco Perez, M.D., associate professor of cardiovascular medicine at Stanford, and another of the study’s key investigators, added, ““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. Further research will help people make more informed health decisions.”