D'Agostini had two goals, two assists and 26 penalty minutes in 40 games for the Montreal Canadiens this season, and scored 12 goals with nine assists and 16 penalty minutes in 53 games in 2008-09. He was Montreal's sixth-round draft pick in 2005.
D'Agostini is expected to join St. Louis for a game Thursday in Dallas. To make room, the team assigned 36-year-old forward Derek Armstrong to their American Hockey League affiliate in Peoria, Ill.
To get D'Agostini, St. Louis sent prospect Aaron Palushaj to Montreal. Palushaj is 20 and was the 44th overall pick in the 2007 draft. He had five goals and 17 assists in 44 games for Peoria this season.
The Blues traded center Yan Stastny to Vancouver to get Labrie, a 23-year-old forward who had five goals, one assist and 69 penalty minutes for Manitoba of the AHL. Signed by Vancouver as a free agent in 2007, he will report to Peoria.
Stastny has played in parts of four NHL seasons, all with the Blues, with six goals, 10 assists and 58 penalty minutes. He spent most of this season in Peoria. In four games with St. Louis, he had one goal.