While Tony Stark/Iron Man has been around since 1963’s “Tales of Suspense” #39, the idea of his life-saving power source being embedded in his chest is a fairly recent one. In his comic book debut, much like in the movies, Stark’s suit prevents shrapnel from piercing his heart, but it’s not integrated into his body. The core piece of his original suit is a simple electromagnetic chest plate that he must always wear, but it’s totally external.
Of course, like his MCU counterpart, Tony’s comic book tech has seen countless upgrades and reimaginings over the years. But the chest cavity we see in the early MCU movies was never originally part of his character. In fact, his original suits were so relatively low-tech that he’d have to plug them into the wall like he was charging his phone.
Pepper famously gave Tony a keepsake — his rudimentary original arc reactor — in the first “Iron Man” movie. It served as proof that “Even Tony Stark has a heart.” And while that may be true, the movies make it hard to tell where exactly it can exist within his body after his accident.
