Back in January, researchers warned that the iPhone 12 lineup and MagSafe accessories could potentially deactivate implanted medical devices. Now, the American Heart Association has released a study that corroborates these findings on a larger scale, noting that several devices from three major companies were “found to have magnetic susceptibility.” Gizmodo reports: The initial study published in HeartRhythm was done on a single patient with a Medtronic implantable cardioverter-defibrillator (ICD). It was an important finding in terms of awareness, but raised questions as to whether this would impact ICDs from all device makers if the iPhone 12 lineup posed a greater risk than other magnetized devices, and what the impact on pacemakers might be. The AHA’s study offers a few preliminary insights into what those answers might be. In the study, researchers observed the impact of an iPhone 12 Pro Max on both ICDs and pacemakers from multiple device makers, as well as conducted both in vivo and ex vivo tests. In vivo refers to tests done on actual patients with an implanted medical device, while the ex vivo tests were done on 11 unboxed devices. The devices tested came from Medtronic, Abbot, and Boston Scientific. (You can see exactly which ICDs and pacemakers were tested in the study itself.)
In 100% of the three in vivo tests, the iPhone 12 Pro Max triggered the devices’ magnet reversion mode. That said, the Boston Scientific pacemaker was found to be less susceptible as it only triggered a temporary response. In ex vivo testing, magnetic interference was detected in 8 out of 11 devices, or 72.7%. There are a few things to note here. How seriously a device is impacted may depend on the sensors or components used. The study notes that magnetic interference can occur when medical devices are exposed to magnetic fields as little as 10G. According to the researchers, the iPhone 12 Pro Max has a magnetic field strength of over 50G. However, the ex vivo devices tested didn’t respond uniformly. Some were only temporarily disrupted, others had sustained asynchronous pacing, and three weren’t impacted at all. The researchers suggest that in the case of a Boston Scientific Accolade MRI pacemaker, the device may not have been affected because it requires a magnet stronger than 70G. After the HeartRhythm study was published, Apple issued additional guidance urging consumers with implanted medical devices to keep iPhone 12 devices more than 6 inches away, or more than 12 inches if wirelessly charging. It also recommended those people consult with both their physician and device manufacturer.