Iron Man: Rapture (2010 series) #1

Tony Stark suffers a serious heart attack; Pepper Potts has him rushed to the hospital. His life is saved but the doctor recommends a heart transplant. Tony is impatient and doesn’t trust the doctors so he goes home, assuring his beloved Pepper that he knows what he’s doing….

As Pepper, Rhodey, and Dr. Serrano (psychologist) watch, Tony operates on himself, installing an artificial heart he designed. He refuses to do the follow-up with the doctors, refuses the meds prescribed, and won’t do the recommended exercises. Instead, he insists he feels like a new man and doesn’t want to stop. Pepper and Rhodey meet with the doctor but there’s little he can do; Tony grows impatient with his friends asking about his health. Pepper grows increasingly worried about what he’s doing but he tries to assure her that all is good. But he claims to be getting better while increasingly shutting them out as he is building a new mechanized body for himself. Finally, Tony allows a tech named Steve to come down to see what he’s doing. Steve enters the lab and discovers an AI has formed—then he is killed by Tony Stark 2.0, taking over Tony Stark’s cyborg body….