5mA is generally considered the 'annoying shock' level, where you feel it, but no real harm results. As others have mentioned, nothing is certain in this world.
The electrocution I witnessed - breathing and heart stopped cold, WAS able to re-start manually - was almost certainly at a very low current level. The current exited the mans' temple ... apparently causing the brain to shut down. This path would call for much less current that 'through the heart.' Through means not quite understood by medicine, the body actually does a pretty good job of directing current around the heart.
