Aho will be rested for Wednesday's matchup with Pittsburgh, Andrew Gross of Newsday reports.
Aho missed time as recently as April 9 against the Rangers due to an upper-body issue, so the decision to give him the night off shouldn't come as a surprise. Without the 28-year-old Swede in the lineup, the Isles will need to either bring a player up from the minors or hope that Noah Dobson (upper body) is ready to play.