Wearable electronic devices, such as smart watches and fitness trackers, could potentially interfere with cardiac devices and negatively impact patients, according to a new study published in Heart Rhythm. However, the researchers note that further study is needed before these devices can be labeled an actual risk.

Study details and key findings

Currently, most implantable heart devices already warn patients about potential interference from electronic devices, such as cell phones, due to magnetic fields. According to FDA, patients are recommended to keep electronic devices at least six inches away from implanted medical devices.

However, wearable electronic devices, such as fitness trackers, have not yet been comprehensively evaluated to ensure their safety with cardiac devices.

Certain fitness trackers, including smart watches, smart rings, and smart scales, emit an electric current through a technology called bioimpedance sensing. Through this technology, a small, imperceptible electrical current is sent through the body, and a response is measured through a sensor, which allows the device to measure a person's breathing rate, level of stress, skeletal muscle mass, and other vital signs.

For the study, researchers tested how three cardiac resynchronization therapy (CRT) devices from different manufacturers functioned while an electrical current was applied to it through bioimpedance sensing.

Overall, they found that the bioimpedance sensing that comes from a smart watch or other fitness tracker could generate electrical interference that exceeds FDA's maximum allowable values and interfere with proper cardiac implantable electronic devices' (CIED) functioning.

"When we attached these CRT devices to a bioimpedance device, they did not behave as they should," said Benjamin Sanchez Terrones, an assistant professor of electrical and computer engineering at the University of Utah and the study's senior author. "In addition, we found that the level of interference generated by the electrical current exceeded the maximum set by the FDA, so, essentially, the CRTs were confused."

Commentary

Although the findings suggest that there is potential for interference from wearable devices, other health experts have pointed out that the study was based on a simulated model and electric current – not real people.

"It's not known if these findings translate to an actual human body," said Jim Liu, a cardiologist at the Ohio State University Wexner Medical Center. "More research would be needed before knowing if this is actually a real concern."

For their part, the researchers acknowledged that the findings "do not convey immediate or clear risk" to patients who use the trackers, but said it is important to be aware of the potential dangers from different levels of electrical interference, including interruptions to pacemakers or unnecessary shocks to the heart.

"Our findings call for future clinical studies examining patients with CIEDs and wearables," Sanchez Terrones said. "… We need to test across a broader cohort of devices and in patients with these devices. Collaborative investigation between researchers and industry would be helpful for keeping patients safe."

As wearable devices become more commonplace, more research will be needed to ensure that they are safe for patients to use, particularly across different brands and functions.

"It is challenging to single out any one brand or device in particular," said Nancy Mitchell, an RN and medical writer. "The charges emitted depend heavily on the individual's biometrics. So, one device may cause complications for certain patients and not anything significant for others."

John Higgins, a professor of cardiovascular medicine at UTHealth Houston's McGovern Medical School, also noted that technology may need to change in the future to prevent any potential interference from either wearable or cardiac devices.

"Some alternative technology to a magnet/magnetic field in these wearables may need to be developed, or a stronger barrier/forcefield in the AICD/PPM [automatic implantable cardioverter defibrillator/permanent pacemaker] shield to block this interference may need to be developed," he said. (Lowry, Medscape, 2/23; Sankaran, The Independent, 2/23; Banfield-Nwachi, The Guardian, 2/22; Hicks, Healthline, 2/21)