Heartbeat-tracking technology embedded in wearable devices such as the Apple Watch and Fitbit are "feats of technology," but health experts say the data they produce isn't always useful and may lead to unnecessary diagnoses and treatments, Darius Tahir reports for Kaiser Health News.

Telehealth primer: Wearables

The rise of heartbeat-tracking technology

In recent years, tech companies such as Apple and the Google-owned Fitbit have begun selling wearable devices that can track a user's heartbeat and alert them when it's out of sync.

The outlook for wearable devices in the CV service line

According to Tahir, these devices use different methods to monitor heart rhythm. For example, some use sophisticated optical sensors to monitor blood volume changes below the skin. Other devices have miniature electrocardiograms (EKGs), which record the heart's electrical activity.

Both methods can detect irregular heartbeats, potentially as well as atrial fibrillation (A-fib). A-fib is a condition in which the heart's upper chamber beats erratically, and blood flows less efficiently to the heart's lower chamber. It affects around 2.7 million Americans and can increase the risk of heart failure and stroke.

Since their release, these wearable devices have grown significantly in popularity. According to data from Counterpoint Research, the Apple Watch, which has had an EKG function since 2018, last summer reached 100 million users worldwide. In addition, Fitbit likely has tens of millions of users, although the heartbeat tracking function is not yet available in all its devices.

James Park, Fitbit's co-founder, said the A-fib function in the company's fitness-tracking bands is one of several features that are "making users effortlessly in control of health and wellness." Once users are informed of an irregularity, they can follow up with a doctor for a potential diagnosis and treatment.

How useful will this technology be?

According to Tahir, these devices are a "technical achievement," but some health experts say the information they produce isn't always useful for making an actual diagnosis, particularly since A-fib is a broad condition and patients can have different symptoms.

"The technology has outpaced us," said Rod Passman, a cardiologist at Northwestern University who is assisting with a study on the Apple Watch's ability to screen for A-fib. "Industry came out with these things because they could. Now we're playing catch-up and trying to figure out what to do with this information."

Incorporating wearables data into clinical practice

Getting an A-fib diagnosis can also be "quite the odyssey," said Ethan Weiss, a cardiologist at the University of California, San Francisco. Data from wearable devices alone cannot be used to make a diagnosis, so medical-grade diagnostic devices, such as a patch or a bulky monitor, are needed to get more accurate heartbeat rhythms. Patients may have to wear these devices over an extended period of time, which can lead to more time and money spent on follow up visits, as well as anxiety.

And even with a diagnosis, it is not clear what treatment would be best for these patients, Tahir writes. Although A-fib is typically treated with anticoagulants, this may result in unnecessary side effects for patients who are otherwise healthy.

The patients who would most benefit from A-fib monitoring are the least likely to use these wearable devices. According to Aaron Carroll, a professor of pediatrics at the Indiana University School of Medicine, people who buy wearable devices "will most likely be younger, healthier, wealthier and more plugged into the health care system—and less likely to remain undiagnosed."

However, other health experts have argued that these devices can be beneficial for both physicians and researchers. In particular, Christopher Worsham, a critical care physician at Massachusetts General Hospital and Harvard Medical School, and Anupam Jena, an internist at Massachusetts General Hospital and an associate professor of health care policy at Harvard Medical School, noted that data from wearable devices could be aggregated across watch users, linked to clinical information, and analyzed to better understand how often abnormalities of the heart are the root cause of patient morbidity and mortality.

Ultimately, more companies will likely follow in the steps of Apple and Fitbit and release their own wearable devices, Tahir writes. Many companies are also looking to passively track other conditions, such as blood oxygen levels and high blood pressure.

"Everyone wants to add higher- and higher-caliber medical grade sensors" to their wearable devices, said Justin Klein, managing partner of the venture capital firm Vensana Capital. And this is likely "going to drive patients to clinics to get these diagnoses confirmed." (Tahir, Kaiser Health News, 4/20)