Does getting hit with a tazer hurt someone with an implantable defibrillator?

No: There is a theoretic risk, but it is small. The device produces a strong current for only a few seconds. The current is not sufficient to damage the icd directly. It could cause the icd to falsely detect an arrhythmia, but not one of sufficient duration to have the icd respond. Reports in humans and experimental testing in animals have not shown significant adverse effects.

Not a good idea: I have never seen a sudy on this topic, but any electrical noise can make it think that the heart is going too fast, although it would have to be sustained. Also, a person with a defibrillator usually has a weak heart, so the stress of being shocked might trigger an arrythmioa or a myocardial infarction.