Some wearable fitness trackers may interfere with pacemakers, study suggests

Some wearable gadgers like fitness trackers may potentially interfere with the functioning of pacemakers and other implanted heart electronic devices.

Research published in the journal Heart Rhythm warned that despite their proven benefits, some fitness trackers could pose “serious risks” for people with cardiac implantable electronic devices (CIEDs) like pacemakers, implantable cardioverter defibrillators and cardiac resynchronisation therapy (CRT) devices.

The functioning of CRT devices from three leading manufacturers were assessed by researchers, including those from the University of Utah, who applied a very small and imperceptible current of electricity into the body.

In this process, called bioimpedance, electrical current flows through the body and its response to the flows is measured by a sensor.


This is done to determine the person’s body composition, level of stress or vital signs like breathing rate.

“Bioimpedance sensing generated an electrical interference that exceeded Food and Drug Administration (FDA)-accepted guidelines and interfered with proper CIED functioning,” study co-author Benjamin Sanchez Terrone said in a statement.

While the findings “do not convey an immediate or clear risk” to patients wearing the trackers, the different levels emitted may result in pacing interruptions or unnecessary shocks to the heart, scientists said.

The study results, they said, “call for future clinical studies examining patients with CIEDs and wearables”.

A growing number of studies are attempting to study the ways in which general electrical appliances, including smart phones, interact with CIEDs.

Most implantable heart devices already warn patients about the likelihood of interference with electronics due to magnetic fields.

Citing an example, researchers said pacemakers come with a warning against carrying a mobile phone in a breast pocket.

The FDA warns that certain cell phones and smart watches that include high-field strength magnets may cause some implanted medical devices to switch to “magnet mode” and suspend normal operations until the magnet is moved away.

The US federal agency recommends patients keep consumer electronic devices that may create magnetic interference, such as cell phones and smart watches, at least six inches away from implanted medical devices.

But until the latest study, researchers said an objective evaluation for ensuring safety of wearable health tech like fitness trackers has not kept pace with the exciting new gadgets.

“Our research is the first to study devices that employ bioimpedance-sensing technology as well as discover potential interference problems with CIEDs such as CRT devices,” Dr Terrone 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,” he said.