Can cell phones deactivate pacemakers?

In recent months, various media accounts have cropped up warning of potentially harmful interactions between Apple iPhones and pacemakers. These concerns were stoked, in part, by Apple’s own guidance most recently issued in July 2021.

“Under certain conditions, magnets and electromagnetic fields might interfere with medical devices. For example, implanted pacemakers and defibrillators might contain sensors that respond to magnets and radios when in close contact,” according to the company. “To avoid any potential interactions with these types of medical devices, keep your Apple product a safe distance away from your medical device (more than 6 inches / 15 cm apart or more than 12 inches / 30 cm apart if wirelessly charging). Consult with your physician and your device manufacturer for specific guidelines.”

Although this statement sounds ominous, experts have expressed various opinions on its exigence. Let’s take a closer look.

FDA guidance

In addition to cell phones, many consumer electronic devices contain magnets and electromagnets—and that goes for products like AirPods, tablets, smartwatches, and others, notes Apple.

The FDA warns that devices like these that are equipped with high-field strength magnets can cause implantable devices such as pacemakers and defibrillators to switch to “magnet mode” and cease normal operations until the offending device is moved farther away, according to recent studies.

Ordinarily, magnet mode permits the safe operation of medical devices during medical procedures such as MRI. The safety measure kicks in when a physician places a high-field strength magnet near the patient. Once this outside magnetic field is removed, the device returns to normal.

In the presence of high-strength magnets, an implantable device with magnetic safe mode either stops working or changes its function. A cardiac defibrillator, for instance, may stop detecting tachycardic events. Alternatively, the device may switch to asynchronous mode and fail to detect two or more events at the same time.

“The FDA is aware of published articles which describe the effect that sufficiently strong magnetic fields can turn on the magnetic safe mode when in close contact,” the agency wrote. “The FDA also conducted its own testing on some products that use the high field strength magnet feature and have confirmed the magnetic field is both consistent with the publications and strong enough to turn on the magnetic safety mode of the medical devices in question. The FDA believes the risk to patients is low, and the agency is not aware of any adverse events associated with this issue at this time.”

In addition to maintaining 6 inches of distance between implantable devices and cell phones or so forth, the FDA recommends users not carry consumer electronics in a pocket over the implant device, check the device with a home-monitoring system if available, and consult with a healthcare provider if symptoms or concerns arise.

Debate on impact

In a pair of dueling editorials published in Heart Rhythms, authors take different approaches to concerns over the interactions between implantable devices and iPhones.

In a letter to the editor titled “Lifesaving therapy inhibition by phones containing magnets,” the authors tested the proposed interaction involving the iPhone 12 in a patient with a Medtronic implantable cardioverter-defibrillator. The iPhone was placed over the left chest area and immediate discontinuation of function transpired. This outcome resulted when the device was placed in multiple positions over the pocket. 

“We hereby report an important public health issue concerning the newer-generation iPhone 12, which potentially can inhibit lifesaving therapy in a patient, particularly when the phone is carried in an upper chest pocket,” wrote the authors. “Contemporary studies have shown minimal risk of electromagnetic interference from ICDs and older-generation smartphones not having a magnetic array.”  

The researchers also pointed to a recent case report presenting magnetic interference from a fitness tracker wristband that was able to suspend function in an ICD from a distance of 2.4 cm. They recommended that physicians should warn their patients of possible interference with implants. 

In another letter to the editor, titled “Phone interaction with CIEDs: Problem or not,” authors take exception to the alarming title of the aforementioned missive. They noted that the recommendation to avoid placement of a mobile phone over a cardiac implantable electronic device has been around for decades, and well before the advent of the iPhone 12.

“It is critically important that lay communications not exaggerate the interactions,” they wrote. “The magnet interaction typically is quite brief, and no existing defibrillators can be permanently deactivated with magnet application. Likewise, the interaction with pacemakers almost always is more of an annoyance in pacing in an asynchronous mode than it is a safety concern. Patients need to be reassured that they are safe.”

Finally, the authors recommended that when discussing with patients, the descriptions of such interactions should be framed to inform rather than to alarm.

To our readers: For more information about adopting emerging cardiology research into your practice, please stay tuned for our new Clinical Commentary product. This product will be released in September 2021 and features insights, analysis, and recommendations from David Brown, MD, a board-certified cardiologist and professor of medicine at Washington University in St. Louis, MO.