ACC: Massive Chinese smartwatch study screens millions for signs of afib

A truly massive screening study in China spanning more than 2.8 million participants found consumer smartwatches could help accurately detect the signs of an abnormal heart rhythm in the background of everyday life. 

Using Huawei devices equipped with photoplethysmography sensors—the same light-based readers found on the undersides of Apple Watches, Fitbits and more—researchers found that a free downloadable app could track a person’s pulse and issue and alert when it falls out of sync. That’s one of the hallmarks of atrial fibrillation, the most common arrhythmia, which, if left untreated, can raise a person’s risk of stroke and heart failure.

At the same time, the app was used to screen a smaller number of users (about 960,000) for signs of sleep apnea. It found that people who had the condition were 1.5 times more likely to also have afib compared to those who did not, suggesting tools for detecting the two conditions could work together. Previous studies have suggested that about half of people with afib also have sleep apnea, the researchers said.

“Digital technologies make it possible to increase general awareness about afib and its risk factors as well as to improve prevention of afib and its complications,” the study’s lead author, Yutao Guo, M.D., a professor of internal medicine at Chinese PLA General Hospital in Beijing, said in a statement.

“With the global surge of wearable technology for afib screening, especially in the challenging setting of the COVID-19 pandemic, the present study provides a possible solution to help people identify possible signs of afib and get diagnosed and treated earlier,” said Guo, who presented the results at the annual meeting of the American College of Cardiology.

In the four-year-long study, 93.8% of people who received a smartwatch alert for possible afib and completed the follow-up process went on to get a confirmation from standard diagnostic tools such as an electrocardiogram and 24-hour monitoring with Holter heart recorders. 

The project, funded by the National Natural Science Foundation of China, saw nearly 3.5 million people download the screening app, with more than 2.8 million providing heart rhythm data for the final analysis. About 12,000, or 0.4%, of participants received a notification for suspected afib.

While some participants refused a follow-up meeting—including younger people without other symptoms—about 5,000 effectively completed telehealth appointments and had their results confirmed.

“Future studies will be needed to move toward using ‘smart’ technology to help manage afib and the risk factors that increase afib susceptibility, as well as to evaluate attitudes and concerns related to this digital health tool,” Guo said.

Companies such as Fitbit have also shown they can detect afib with a wrist-worn wearable—and that consumer devices can quickly be used to scale up large screening studies.

The company signed up more than 455,000 Fitbit users in less than five months and showed similar rates of alerts, with about 1% receiving a notification of afib’s previously invisible symptoms.

And, in addition to the light-based PPG sensors, Apple has been testing out its smartwatch’s built-in ECG. The Apple Heart Study, which began in 2017 and enrolled more than 400,000 participants, found that about 84% had their results confirmed in a follow-up clinical consultation. 

Later analyses of the study’s data will assess whether the Apple Watch could also be used to identify arrhythmias other than afib, such as tachycardia rhythms where the heart beats too quickly.