Zavato- My experience with AICDs is that each manufacturer has a different design. In some, the magnet will turn off the defibrillator part, in some the pacer part, some will reset the programmed settings, in some nothing at all. It generally takes a powerful magnet very close to the device. Anything greater than 18 inches would require a very strong magnet, more than what you would normally be exposed to. The best device is to call the manufacturer and also talk to your Cardiologist/Electrophysiologist to ask. They may or may not know since it is an uncommon question but it all will depend on the specific device, model and maybe even serial number of the device. Most have an alarm that is audible through the skin that alerts if the defibrillator is de-activated. Best to stay at least 18 inches or further away. It will not trigger a shock but may turn off the defibrillator until the device is reset by a technician/programmer.