A study published in Heart Rhythm journal suggests that wearable fitness and wellness trackers may affect some implanted cardiac devices, such as pacemakers.

Researchers discovered that the electrical current used in wearable smart devices during "bioimpedance sensing" interfered with the proper operation of some implanted cardiac implantable electronic devices (CIEDs) such as pacemakers, implantable cardioverter defibrillators (ICDs), and cardiac resynchronization therapy (CRT) devices. These devices include smartwatches, smart rings, and smart scales used to monitor fitness-related activities. They claimed this was the first study to examine devices using bioimpedance-sensing technology and identify potential interference issues with CIEDs like CRT devices.

With bioimpedance sensing technology, it is possible to quantify a persons body composition, including their degree of body fat, muscle mass, stress level, and respiration rate. Wearable fitness trackers can use this technology to record health-related parameters, including the number of steps taken or the distance travelled, heart rate, blood pressure, daily caloric burn, and sleep patterns.

The majority of implantable cardiac devices alert patients to the possibility of magnetic field interaction with various electronics. Patients are cautioned, for instance, against carrying a cell phone in a breast pocket close to a pacemaker.

They emphasized the need for further research among people using these devices and across a larger cohort of devices and also enhance the safety of patients via industry and research collaboration.

(Source: https://www.theguardian.com/technology/2023/feb/22/wearable-fitness-trackers-could-interfere-with-cardiac-devices-study-warns)