When the All-Purpose Tool Fails: Manufacturer-Specific Time Dependency of Magnet Mode in Cardiac Implantable Electronic Devices

<b>Background:</b> Previously unreported, the induction of the magnet mode is time-dependent, according to the cardiac implantable electronic device (CIED) manufacturer, directly after device interrogation. The aim of this study was to systematically investigate the response of CIED from all major manufacturers to the application of a magnet. <b>Methods:</b> CIED from all manufacturers were utilized and connected to an interactive heart simulator (InterSim III, IB Lang). After the end of CIED interrogation, a CIED magnet was placed over the device, and the response was analyzed. <b>Results:</b> Fifteen ICD and eight pacemakers were included. ICDs from the manufacturers Abbott, Boston Scientific, Medtronic and Microport reacted immediately to magnet application by inhibiting antitachycardia function directly after interrogation. In the Biotronik ICD, the magnet mode was only inducible five to seven minutes after the end of the interrogation. In addition, after eight hours of magnet application, the antitachycardia function was automatically and permanently reactivated in all Biotronik ICDs. Pacemakers of Biotronik, Abbott, Boston Scientific, and Microport responded immediately after device interrogation regarding the magnet application. In contrast, Medtronic pacemakers responded only 1.5 min after device interrogation. <b>Conclusions:</b> Magnet mode induction directly after CIED interrogation is manufacturer-specific. Our findings might be of importance when performing invasive procedures with devices that cause electrical interference and in palliative care.