Actually, that's a positive thought: deliberate usage of inductive coupling at very close range wasn't a problem to the rest of the device, to the point of such charging being included in the device.

The prime concern is that oscillating fields could interfere with the low-voltage low-current stimulus leads, inducing convulsions or worse. Secondary concern is overloading & frying the device.

I knew there was something I was going to ask my cardio doc a few days ago...we discussed potential problems with electric cars instead (user's manual is filled with "Warning! Pacemaker users stay away so we don't have to get this car medically certified!"-type notices).