The warning, published in journal HeartRhythm, raised ‘possible safety concerns around MagSafe technology’ and heart implants.
If an iPhone 12 is brought into close proximity to some with a pacemaker, there is a chance the latter could stop working.
The doctors also warned that the the problem may not be unique to the iPhone, and could be a problem for any magnets inside future phones, too.
The warning was in response to earlier research that showed Apple’s MagSafe technology had inhibited a pacemaker made by the company Medtronic.
After the original research came out, also published in HeartRhythm, Apple updated its support documents, advising that iPhones should be kept at least six inches away from a pacemaker during normal use and a foot away if the device is using wireless charging.
The support also noted that iPhone 12s ‘aren’t expected to pose a greater risk of magnetic interference to medical devices than prior iPhone models.’
Both Apple and Medtronic argue that the additional magnets in the form of MagSafe technology shouldn’t be more likely than any regular phone to turn off pacemakers.
In a statement, Medtronic said it ‘analysed iPhone technology and found it presents no increased risk with Medtronic implantable cardiac rhythm devices, like pacemakers, implantable defibrillators and cardiac resynchronisation therapy defibrillators.’
Apple have been contacted for comment.
In the original study, a researcher was able to deactive a patient’s implanted defibrillator by holding an iPhone 12 over the device.
However, the study was only on a single participant and only used an iPhone 12 – it’s unclear what would have happened if a regular phone was used.
Heart devices deactivating in proximity to magnets is expected behaviour, and most doctors will warn against anything magnetic coming into close contact with it.
In Apple’s updated support device, it says to ‘consult your doctor and medical device manufacturer for information that is specific to your medical device and whether you need to maintain a safe distance of separation between your medical device and iPhone or any MagSafe accessories.’
It also adds: ‘If you suspect iPhone or any MagSafe accessories are interfering with your medical device, stop using your iPhone or MagSafe accessories.’