A gas turbine engine includes an interstage seal assembly positioned in a plenum between the compressor section and turbine section. The seal assembly includes an annular seal member positioned in the plenum adjacent to the compressor section for restraining a fluid flow between the compressor section and the turbine section, and an annular heat shield member positioned in the plenum adjacent to the turbine section for limiting heat transfer from the turbine section to the compressor section. The annular heat shield member includes a plurality of slots formed on a surface of the heat shield member in a radial direction of the annular heat shield member.