Feb 1970 - Iron Man 22

Well, the brain damaged boxer that Tony hired to be Iron Man didn't die, and Tony decides that despite the fact that he has a synthetic heart that could fail at any moment, he will be Iron Man himself. He then, of course, gets into a big fight with two different villains involved and Tony's current GF seemingly dies via electric shock from one of the villains. I can't remember which one, but he was wearing fancy armor.
Anyways...now Tony has a broken, synthetic heart.