As a young ensign at Starbase Earhart, Jean-Luc Picard fought three Nausicaans and was stabbed through the heart, leaving him with an artificial heart.
In 2327, shortly after graduating from Starfleet Academy, Ensign Jean-Luc Picard was waiting for his first assignment at Starbase Earhart with his friends Corey Zweller and Marta Batanides. After Zweller cheated a group of Nausicaans at dom-jot, Picard picked a fight with them, and one stabbed him through the heart. He survived with an artificial heart.
The injury taught Picard a lasting lesson about recklessness. In 2369, when the artificial heart failed and he lay near death, Q allowed him to relive the fight and avoid it, but the resulting cautious life left him an unremarkable officer, so Picard chose to accept the original timeline.