The technology within wearable devices like Fitbits could interfere with cardiac implantable electronic devices (CIEDs), such as defibrillators and pacemakers, putting the health of individuals with those medical devices at risk, a study released Wednesday suggests.
Using computer simulations, researchers at the University of Utah looked at how a sensing technology within some wearable devices called bioimpedance—which emits a small, imperceptible electric current to measure a person’s skeletal muscle mass, fat mass or level of stress—can impact people’s cardiac devices.
When researchers tested a set of cardiac resynchronization therapy devices, which include certain types of pacemakers and are used to monitor and control heart rhythm, they found that slight electrical currents from wearable gadgets can sometimes confuse cardiac implants, causing them to operate incorrectly.
In the case of implantable cardioverter defibrillators, which can both act as pacemakers and shock the heart to restore a regular rhythm, gadgets with bioimpedance could trick implanted devices into unnecessarily and painfully shocking patients, the study found.
This study, published in the journal Heart Rhythm, was the first to look at potential problems associated with wearable device’s bioimpedance, and more studies are needed in order to better understand the effects on patients, researchers said.
“We have patients who depend on pacemakers to live,” said Benjamin Steinberg, a cardiac electrophysiologist who co-authored the study. “If the pacemaker gets confused by interference, it could stop working during the duration that it is confused. If that interference is for a prolonged time, the patient could pass out or worse.”
Implantable cardiac devices—which are common for individuals who need help controlling their heart rhythm—often come with warnings about potential interference from electronics because of magnetic fields. For example the Cleveland Clinic warns against carrying a phone in a pocket near a pacemaker. In 2021, a study recommended that patients with pacemakers and defibrillators keep any electronic devices that “may create magnetic interference” at least six inches away from implanted medical devices. The concern, according to researchers who published the study, is that implantable devices have a feature called “magnet mode” that can be activated from stronger magnets, like the ones found in newer iPhones. The study came after the Food and Drug Administration did its own testing, confirming that the magnetic field of some devices is “strong enough to turn on the magnetic safety mode of the medical devices in question.” The FDA also said the risk to patients was low. Earlier in 2021, Apple issued the same guidance for users with implantable cardiac devices.