Apple smartphone wireless charging system can cause magnet interference on cardiac implantable electrical devices (CIED) with the potential to hinder lifesaving therapy. In a study in the June 15 Journal of the American Heart Association, researchers tested for magnetic interference on three consecutive patients with previously implanted CIEDs as well as 11 CIEDs still in their packages. In all three patients, placing an iPhone 12 Pro Max on their skin over the CIED activated magnet reversion mode in the CIED. Magnet reversion mode blocks tachytherapies in implantable cardioverter defibrillators and causes asynchronous pacing in pacemakers. When placed over packaged CIEDs, the iPhone activated magnet reversion mode in eight of 11 devices. Though the sample size was small, the authors note the results are consistent with studies of electromagnetic interference with other electronic devices, including e-cigarettes, fitness watches, and wireless headphones. The authors recommend that patients with CIEDs discuss smartphone use precautions with their heart rhythm specialist.