Gastrin, Connor McMichael, and a 2026 first-round pick were traded to the Blues from the Capitals in exchange for Jordan Kyrou on Tuesday.
Gastrin was selected 37th overall in 2025, but he'll be on the move to a new organization less than a year later. The Swedish forward had 24 points in 39 regular-season games with MoDo in HockeyAllsvenskan, the second-tier Swedish league, in 2025-26. Gastrin also appeared in one playoff game with AHL Hershey. It's not yet clear whether Gastrin will spend 2026-27 with AHL Springfield or if he'll be loaned back to a European team.