Researchers Find That the iPhone 12 Can Deactivate a Defibrillator [Corrected]

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Photo: Caitlin McGarry/Gizmodo

A new study published by cardiologists indicates that the iPhone 12 can interfere with implantable cardioverter defibrillators (or ICDs) if the phone is placed close to a patient’s heart. But the study, which was designed to look at whether the magnetic array that enables the iPhone 12's new MagSafe charging technology had an effect on ICDs, raises more questions than it answers.

Apple’s newest iPhones have a circular array of magnets built into their backs, which allows them to snap to a MagSafe charging puck or compatible accessory (such as a phone case). But defibrillators, some of which can also perform the function of a pacemaker, have a switch that can be deactivated with an external magnetic field, and when researchers from the Henry Ford Heart and Vascular Institute placed an iPhone 12 above the heart of a patient with an implanted Medtronic defibrillator, its operations were suspended every time.

The iPhone 12 placed directly above a person’s heart will interfere with a pacemaker’s operations.
The iPhone 12 placed directly above a person’s heart will interfere with a pacemaker’s operations.
Photo: Heart Rhythm Society

“Once the iPhone was brought close to the ICD over the left chest area, immediate suspension of ICD therapies was noted which persisted for the duration of the test,” the authors of the study, published last week in HeartRhythm, write. “This was reproduced multiple times with different positions of the phone over the pocket.”

As 9to5Mac notes, Apple acknowledges this is a risk: “iPhone contains magnets as well as components and radios that emit electromagnetic fields. These magnets and electromagnetic fields may interfere with medical devices, such as pacemakers and defibrillators. Though all iPhone 12 models contain more magnets than prior iPhone models, they’re not expected to pose a greater risk of magnetic interference to medical devices than prior iPhone models.”


So the question remains as to whether the iPhone 12 is more likely to interfere with a defibrillator or pacemaker than other devices. The researchers pointed to studies that indicate smartphones without the kind of magnetic arrays found in the latest iPhone have a low risk of interfering with ICDs, but also noted that devices like fitness trackers have also been found to deactivate a pacemaker. More research is needed, preferably testing a wider range of phones and more ICDs, to determine if the iPhone 12 is riskier to use for patients with pacemakers and defibrillators than other phones are. (Pacemakers and defibrillators function differently, but both are implanted devices that can be affected by electronics with magnetic fields. Some defibrillators also function as pacemakers.)

Due to the way these implantable devices are designed, they can be easily activated or deactivated by ambient sources with magnetic fields, including a Fitbit or a vape pen, according to medical news service Medical Xpress. This doesn’t have to be the case, but changing it will require medical device manufacturers to redesign their products.


Until more research is done, if you have a pacemaker or defibrillator and also own an iPhone 12—or any device that includes magnets—consult your doctor to see what distance they recommend you keep the device away from your heart. At the very least, you might not want to wear your phone in a pocket directly over your chest.

Correction, 1/14/2021, 10:25 a.m.: An earlier version of this article incorrectly stated that the study was performed using a Medtronic pacemaker. It was actually performed using a defibrillator. We have clarified the article with this correction and regret the error.