When exporting AutoCAD files, you can export rooms and areas as closed polylines. The exported polylines match the boundaries of rooms in Revit LT. The room boundaries are exported onto a single layer. That layer is turned off by default in the AutoCAD file.
The polylines include the following XDATA information for room boundaries: Name, Number, Occupancy, Occupant, Department, and Comments. The polylines include the following information for area boundaries: Name and Comments.