Strong magnets in newer portable electronic devices like the Apple AirPods Pro charging case or Microsoft Surface Pen can interfere with pacemakers and implantable cardioverter defibrillators, researchers reported.

Corentin Féry

“We show that there is a risk of deactivating the therapy of these medical devices if some electronic objects with magnets are placed near the chest of the patients,” Corentin Féry, MSc, a research engineer at the University of Applied Sciences and Arts Northwestern Switzerland, Institute for Medical Engineering and Medical Informatics in Muttenz, Switzerland, told Healio. “The key word is caution for wearers of ICDs and pacemakers. The risk for death is real for them since a tachycardia will not be detected if a device with a strong magnet is deactivating their implant. Our tests on some everyday objects, such as the iPhone 12 Pro Max or the Microsoft Surface Pen, lead us to say that it is necessary to keep a distance of at least 1 inch between the implants and these devices. We also recommend not to carry electronic objects in a pocket close to the chest, or to fall asleep with such devices.”

Investigating magnetic strength

The researchers investigated several portable electronic devices (PEDs), including the Apple AirPods Pro and its wireless charging case, the Microsoft Surface Pen and the Apple Pencil (second generation), comparing their magnetic field strength with the iPhone 12 Pro Max. Using a magnetic mapper with 64 magnetic sensors, researchers measured the magnetic field strength of the products at various distances. The PEDs were also placed incrementally closer to five defibrillators from two representative manufacturers (Boston Scientific: Inogen, Teligen and Cognis; Medtronic: Protecta and Viva Quad) until a therapy deactivation occurred. According to the FDA, a minimal field strength of 10 G is required for CV implantable devices to trigger to magnet mode.

The findings were published in Circulation: Arrhythmia and Electrophysiology.

The researchers found the farthest point where a 10 G intensity was measured is located about 2 cm (0.78 in) from the surface for the Apple products and at 2.9 cm (1.14 in) for the Microsoft Surface Pen. Magnet reversion mode was triggered at a distance between 8 mm and 18 mm for the tested PEDs.

“Our study found that PEDs other than the iPhone 12 have magnetic susceptibility and, thus, have the potential to inhibit lifesaving therapies,” the researchers wrote.

Although the test results showed the maximum distance for a possible ICD interaction, researchers said for safety, the minimal distance is between 0.8 cm (0.31 in) for the iPhone 12 Pro Max and the Apple Pencil (second generation) and 1.8 cm (0.71 in) for the Microsoft Surface Pen and the opened charging case of the Apple AirPods Pro.

“Clinicians should warn their patients to be cautious when using electronic devices,” Féry told Healio. “Since we have not tested all electronic devices on the market, we suggest caution with any device that has magnets.”

Sven Knecht

Sven Knecht, DSc, a research engineer at the Cardiovascular Research Institute Basel at University Hospital Basel, University of Basel in Switzerland, noted that the magnet mode does deactivate the therapy but not the detection of the tachycardia.

“Furthermore, the risk of death is theoretically possible if the deactivation of the ICD by the portable electronic device occurs during a lethal, hemodynamically relevant tachycardia,” Knecht told Healio. “This likelihood might, however, be relatively low.”

More research needed

A major limitation of the study was that it was not conducted on ICDs implanted in patients, Féry said, adding the researchers need to perform in vivo tests with the electronic devices, as well as highlight the potential risk with other classes of objects, such as watches or e-cigarettes.

As Healio previously reported, the FDA issued a warning in May that certain cellphones and smartwatches containing high field strength magnets may cause some implanted medical devices, particularly cardiac devices, to suspend normal operations when in proximity to the magnet. The FDA noted at the time that many implanted medical devices such as pacemakers and ICDs are designed with a “magnet mode” to allow safe operation during certain medical procedures such as MRI. Placing certain cellphones and smartwatches too close to the implanted device can cause the device to switch into magnet mode when it is not supposed to, suspending normal operations, the agency stated.

The American Heart Association recommends keeping cellphones at least 6 inches away from ICDs or pacemakers by using it on the ear opposite from the implantation and to avoid keeping the cellphone in a front chest pocket.

N.A. Mark A. Estes

“The current study extends observations on magnetic field interactions with even more devices containing magnets,” N.A. Mark A. Estes, MD, professor of medicine and director of the Clinical Cardiac Electrophysiology Fellowship Program at the Heart and Vascular Institute of the University of Pittsburgh School of Medicine, and an AHA volunteer, said in a press release. “Patients with cardiac electronic implantable devices should be instructed to keep all electronic devices that can generate a magnetic field several inches from their pacemakers or ICDs.”