Many portable electronic devices (PEDs) were found to have magnetic susceptibility, making them potential culprits of inhibiting lifesaving therapies of cardiovascular implantable devices (CIEDs). These findings were published as a research letter in Circulation: Arrhythmia and Electrophysiology.

The magnetic mode of many CIEDs was designed to easily and in a noninvasive manner set the devices in a standardized mode. This mode primarily results in the suspension of tachycardia detection or asynchronous pacing for cardioverter defibrillators or pacemakers, respectively. This is achieved by placing a dedicated magnet with a strength of greater than 100 Gauss (G) directly to the trigger at a distance of 30 mm. However, the magnetic mode can be triggered using a magnet with a minimal strength of 10 G at approximately 20 mm.

It has been reported that the iPhone 12 Pro Max contains magnets and was found to have a clinically identifiable interference in vivo among 3 of the 3 patients evaluated and ex vivo among 8 of the 11 patients.


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In this study, investigators from the University Basel in Switzerland assessed the wireless charging case of Apple AirPods Pro, the Microsoft Surface Pen, the second-generation Apple Pencil, and the iPhone 12 Pro Max. The 3-dimensional strength of the magnetic fields was modeled, and the minimal safe distance for each device was estimated.

The investigators determined the minimal safe distance of the Apple AirPods Pro wireless charging case when closed was 10 mm and when open was 18 mm, the Microsoft Surface Pen was 18 mm, the second-generation Apple Pencil was 8 mm, and iPhone 12 Pro Max was 8 mm.

This study found that common PEDs have the potential to inhibit lifesaving CIED therapies due to their magnetic properties. CIED carriers should be aware of potential harms and avoid placing PEDs in their breast pocket.

This study was limited by including only a few devices. Additional investigation is needed to determine safe distances of other devices, such as smartwatches and e-cigarettes.

Disclosure: An author declared affiliations with industry. Please refer to the original article for a full list of disclosures.

Reference

Féry C, Desombre A, Quirin T, et al. Magnetic field measurements of portable electronic devices: The risk inside pockets for patients with cardiovascular implantable devices. Circ Arrhythm Electrophysiol. Published online March 1, 2022. doi:10.1161/CIRCEP.121.010646