The Sens had acquired his NHL rights at last year's NHL Draft from the Columbus Blue Jackets for a third-round pick, though Filatov did not appear to like his new assignment, deciding to leave for the KHL in December.
Filatov was selected 6th overall pick by the Jackets in the 2008 NHL Draft, but only managed a total of six goals and seven assists for 13 points in his 44 games in Columbus.
He recorded one assist and no goals in his nine games with the Senators this year before he was reassigned to the AHL.
Since the KHL salary cap will not apply to stars returning from the NHL, there is a good chance that Filatov could make a lot more money in Russia next season than any NHL team would have paid him.
While Filatov is a restricted free agent in the NHL on July 1, the Senators would have to give him a qualifying offer by June 25 to retain his rights for free agency.