Victory-Class Stardestroyers are "left-overs" from the late Clone Wars era if I remember correctly, and those have been around in Star Wars since, well atleast since TIE Fighter in -94 was it? But I think it's older than that.
The Victory-Class idea is much older than most people think though. It can trace it's origin from the planing of A New Hope back in the -70's. It was originally going to be the second ship we would see flying over the camera in the opening scene.
So it's not entirelly EU craft.