June 10, 2021 -- A recent study bolsters existing evidence that powerful magnets in some Apple iPhones can interfere with implantable electronic heart devices.
The small study, published June 2, also suggests some devices may be more susceptible than others.
The iPhone 12 Pro Max with MagSafe technology interfered with devices implanted in three consecutive patients who had heart tests and in 8 of 11 implantable defibrillators and pacemakers still in their original packaging.
The results, published in the Journal of the American Heart Association, are consistent with a widely publicized single-patient report this February and evidence of electromagnetic interference with fitness wristbands and e-cigarettes.
The MagSafe technology supports wireless charging and is optimized by a ring-shaped array of magnets. While magnet mode activation has been shown to occur in implantable devices that are exposed to some magnetic fields, the field strength of the iPhone 12 Pro Max can be much greater when in direct contact, the researchers determined.
"If this becomes a standard in a lot of the new smartphones or companies start to use stronger magnets ... then we will see more and more of these consumer electronic and device interactions," senior author Michael Wu, MD, of Brown University in Providence, RI, says.
In a May advisory on these possible interactions, the FDA also cautioned that the number of consumer electronics with strong magnets is expected to increase over time.
That trend appears to be already under way, with Forbes reporting in February that the MagSafe batteries will be "getting stronger" as part of upgrades to the iPhone 13. Meanwhile, Bloomberg, reported in advance of Apple's annual developers conference this week, that an upgraded version of MagSafe is in the works to support wireless charging for its iPad. (MagSafe has not been used previously in iPads.)
Although Apple has acknowledged that the iPhone 12 contains more magnets than prior iPhone models, it says "they're not expected to pose a greater risk of magnetic interference to medical devices than prior iPhone models." The company maintains a page that specifically warns about the potential for interactions and advises consumers to keep the iPhone and MagSafe accessories more than 6 inches away from medical devices.
Older generation iPhones have not shown this risk, with only one case of interference reported with the iPhone 6 and an Apple Watch in 1,352 tests among 148 patients with implanted devices and leads from 4 different manufacturers.
In the new study, interference was triggered in all three patients when the iPhone 12 Pro Max was placed on the skin over the device.
As to whether manufacturers should build CIEDs less susceptible to today's stronger magnets, Wu says said it's worth exploring but there are pros and cons.
While magnets in consumer devices have the potential to inhibit lifesaving therapies, a magnet is also very useful in certain medical settings. Magnets can be used as a quick way to ensure pacing without worrying about electronic noise during surgery, or to deactivate a defibrillator if there’s noise resulting in inappropriate shocks, for example
"It would require an overhaul of a lot of the devices going forward and I think that's something that's worth exploring, especially now that a lot of devices are using wireless communication, Bluetooth, and other communication technology," he says
Even though the study is small, it does represent many of the available devices and has clinical implications, given that people often put their smartphones in a breast pocket, says Wu
"This report highlights the importance of public awareness regarding an interaction between CIEDs and a recently released smartphone model with magnetic charging capability," Wu and colleagues concluded.
Apple was contacted for comment but had not responded at press time.