The condition, which is characterized by an irregular heartbeat, often remains hidden because many people don't experience symptoms. Atrial fibrillation can increase the risk of stroke and heart failure.
According to Stanford, the study involved 400,000 participants, making it the the largest screening program for atrial fibrillation ever conducted. A paper has also been published in the American Heart Journal describing the unique design of the clinical trial.
Enrollment began in late 2017 and closed in August. Although some participants were informed in September that their participation in the study was complete, Stanford says it will continue to collect and collate data until early next year, which is consistent with Apple's original announcement.
"We hope this study will help us better understand how wearable technologies can inform precision health," said Lloyd Minor, MD, dean of the School of Medicine. "These new tools, which have the potential to predict, prevent and manage disease, are finally within our reach."The FDA cleared two Apple Watch medical apps in September. One app uses data from the Apple Watch Series 4 to take an ECG by touching the button on the side of the device. The second app uses data from an optical sensor available on the Apple Watch Series 1 and later to analyze pulse data and identify irregular heart rhythms indicating atrial fibrillation. The Apple-Stanford Heart Study used the second app.
Each year in the United States alone, atrial fibrillation results in 130,000 deaths and 750,000 hospitalizations, according to the Centers for Disease Control and Prevention. The CDC estimates that the condition affects between 2.7 million and 6.1 million people. In addition, another 700,000 people may have undiagnosed atrial fibrillation.