Clinical Use of Magnets in Contemporary Cardiac Implantable Electronic Devices: A State-of-the-Art Review

UNSTRUCTURED ABSTRACT Magnet application remains a rapid, widely available method to modify cardiac implantable electronic device (CIED) behavior when programmers are not immediately accessible. However, contemporary magnet responses vary across manufacturers, device types, programming states, battery status, MRI modes, telemetry sessions, and sensor technologies. This review summarizes clinically relevant magnet responses in pacemakers, cardiac resynchronization systems, implantable cardioverter-defibrillators (ICDs), and subcutaneous ICDs. In pacing systems, magnet placement usually induces asynchronous pacing at a manufacturer- and battery-dependent rate, although programmable options may allow electrogram storage or no response. In ICDs, magnet application generally suspends tachyarrhythmia therapies without affecting bradycardia pacing; effects on arrhythmia detection vary by manufacturer and device configuration (e.g. MRI protection modes, telemetry, or advanced battery depletion). Safe use requires device identification, awareness of manufacturer-specific exceptions, continuous monitoring, and post-event interrogation when clinically indicated, because misunderstanding magnet behavior may cause inappropriate pacing or unintended loss of defibrillator protection.