The magnet- activated switch in implanted cardiac devices including cardioverter defibrillators (ICD) and permanent pacemakers (PPM) are known to be susceptible to interference from consumer devices with built in magnets.
Patients with ICD’s and Pacemakers have long been given the recommendation to keep mobile phones more than 6 inches from their devices. A study published in JACC showed a minimal risk of interference from ICD’s and smartphones, but with the arrival of Apple’s iPhone 12 series launched in late 2020, the mobile phone does have the ability to deactivate ICD’s and PPM’s.
ICD’s and cardiac pacemakers are designed to respond to nearby magnets by changing their function. This disablement of therapy is a safety feature of ICD’s & PPM’s.
One of the advanced technologies Apple put in the new iPhone 12 series was ‘an array of magnets around the wireless charging coil’ for pairing with various MagSafe fitted chargers and accessories.
HeartRhythm reported that when an iPhone 12 was placed over an implanted Medtronic ICD, it immediately suspended the therapies of the ICD which lasted for the duration of the test. This means that should the patient go into ventricular tachycardia or fibrillation, the ICD would no longer be effective.
When the same test was carried out on an implanted pacemaker the iPhone changed the pacemaker to an asynchronous mode, which limits the pacemaker to fixed rate pacing only.
Apple have recently changed their advice concerning the iPhone 12 and now advise ‘ To avoid any potential interactions with these devices, keep your iPhone and MagSafe accessories a safe distance away from your device more than 6 inches/15cm apart or more than 12inches/30cm apart if charging wirelessly’.
Patients should be reassured that if their ICD or PPM suffer interference from being too close to a phone or charger, it is designed to resume normal operation when you move away.
Heartrhythm also reported that ‘magnets used in the wristbands of fitness trackers and smart watches can interfere with implanted cardiac devices, with possible complications including ICD deactivation and PPM mode switch. Patients should be made aware of this risk and advised to keep their wristbands at least 6 inches away from their cardiac devices and not to wear them to sleep’.