This article doesn't exactly answer the OP question, but it does mention two different settings - a "drive stun" and "full deployment".
It also mentions that people react differently to being tasered depending on any health issues. I can't imagine that someone with a pacemaker should try it.
Thinking about defibs which interrupt signals to the heart (a muscle) and training which tells everyone to say "standby" so that you are not touching the person who is receiving the defib.
I would not be the one who would try touching someone being tasered to find the answer