Heath's death in the comics was a result of a series of unlucky events. A large horde of zombies surrounded him and his group, and despite their best efforts, he couldn't escape and was ultimately taken down.
Heath met his end in a rather unexpected and tragic way. It was during a chaotic zombie attack that overwhelmed him.
Heath died in the Walking Dead comics when he was caught off guard by a sudden and intense zombie onslaught. There wasn't much he could do to survive that overwhelming situation.