Yes it will, because if they have hit points left, it does not strike the heart or even the body if they have enough hit points. The person rolls over in their sleep and the attack "misses" for the amount of damage the attack does, or some other luck, skill, divine intervention hp damage description.
Or maybe it stabs them, their heart bursts and instantly repairs itself, and does it over and over again for the next 4 stabs too or maybe they can survive without a heart.
Morover, there is nothing in here about being willing. In the case we were talking about (being suicidal). just because I demonstrate no regard or concern for my life does not mean the divine intervention or luck or whatever doesn't continue on.
The only time you get struck for huge gory wounds like a stab in the heart is when you drop to 0.
Please provide where the rules state this.