Preventing smartphone induction of magnet mode in cardiac implantable electronic devices

Introduction Wireless charging capable smartphones may interact with cardiac implantable electronic devices (CIED). We hypothesized that magnetic shielding with a steel plate placed at the back of a smartphone may prevent interaction. Methods Sixteen CIED (6 pacemakers, 10 ICD) from all manufacturers were consecutively implanted in a subcutaneous and submuscular location in an isolated porcine thorax and connected to an interactive heart simulator. Two smartphones (Apple iPhone 14, Google Pixel 8 Pro) were placed on top of the implantation site and signs of magnet mode induction were recorded. Results The Apple iPhone induced magnet mode in 7 of 16 (44%) subcutaneously placed CIED. Placed in a magnetic phone case, the Apple iPhone induced magnet mode in 6 of 16 (38%) of devices. Magnet mode induction was successfully prevented in all cases by placing a 1mm thin steel plate at the back of the smartphone. The Google Pixel did not induce magnet mode in any of the 16 devices, even with a magnetic case. Submuscular CIED placement resulted in no occurrence of magnet mode induction by any smartphone. All devices were still able to be interrogated and responded to a CIED magnet. Conclusion The Apple iPhone induces magnet mode in close to half of subcutaneously placed CIED due to its MagSafe magnet. Neither a smartphone utilizing the Qi wireless charging standard nor magnetic smartphone cases confer the same risk. Submuscular CIED placement or magnetic shielding with a steel plate prevent magnet mode induction. The future Qi2.0 standard may exacerbate interaction risks.