Researchers at Stanford University say that wearable technology, such as the Apple Watch, could serve as precursor warnings to standardized testing for atrial fibrillation.

Their assertion stems from the findings of the Apple Heart Study, a virtual evaluation of more than 400,000 participants, which reported that wearable technology was able to safely identify irregular heart rates that were later confirmed to be atrial fibrillation. Such results could pave the way for earlier intervention for stroke prevention and hospitalization.

“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,” Mintu Turakhia, M.D., associate professor of cardiovascular medicine and one of the principal investigators in the study, said in a statement. “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.”

Atrial fibrillation is responsible for 130,000 deaths and 750,000 hospitalizations, according to the Centers for Disease Control and Prevention, which estimates that between 2.7 million and 6.1 percent suffer from the condition, and that 700,000 more may not be diagnosed.

Conducted with sponsorship by Apple, the study questioned whether a mobile app could use data from a heart-rate pulse sensor on the Apple Watch to identify the heart condition, which often goes unnoticed due to a lack of symptoms among many people.

Participants were required to have an iPhone and wear a series 1-3 Apple Watch with the Apple Heart Study app, which intermittently checked the heart-rate pulse sensor for measurements of an irregular pulse. Those who received a notification of such a pulse were told to schedule a telemedicine consultation with a doctor involved in the study through American Well. Each was then provided an ambulatory ECG patch through BioTelemetry to record the electrical rhythm of their heart for up to a week.

Of the 400,000 who took part in the examination, only 0.5 percent received notifications indicating an irregular pulse. The finding was viewed by the researchers as a significant factor, in that it relieved worries about the potential for over-notification.

Comparing irregular pulse-detection on the Apple Watch to simultaneous electrocardiography patch recordings, the authors found that the watch’s pulse detection algorithm for detecting a positive tachogram reading had a 71 percent positive predictive value, and participants 84 percent of the time experienced atrial fibrillation at the time they received their notification.

One-third of those who received these messages were diagnosed with the ECG patch a week later, a result which echoes how the intermittent nature of the condition makes it simple for it to go undetected in subsequent ECG patch monitoring.

Fifty-seven percent of all who received an irregular pulse notification sought medical attention, an action that the authors hope will increase by conducting further research, which will validate the benefits of this form of technology.

“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,” Marco Perez, M.D., associate professor of cardiovascular medicine and another principal investigator, said in a statement. “Further research will help people make more informed health decisions.”

The study was funded by Apple and conducted by researchers from the Lankenau Heart Institute, Jefferson Medical College, the University of Colorado School of Medicine, Cooper Medical School of Rowan University, StopAfib.org, the American Foundation for Women’s Health, and Duke University.

Turakhia did not respond for comment.