Nothing on the client itself, but if the service account was also the Backup Exec default account OR used as the account to backup resources you will possibly have to change those as well.
Also if that service account was used to administer Backup Exec itself (i.e the administrator was logging in as that account to operate the Backup Exec console) then there may items such as Encryption Keys and Resticted Login Accounts configured inside Backup Exec that may not work if the account used to create them is disabled or no longer exists in Active Directory, as such if you intended to delete the old account completely you may have to recreate some items within Backup Exec.
