I have a 55" Samsung above my woodburning fireplace. No mantle. I installed a heat hood and also mounted a small CPU fan behind the TV. I have no issues with heat what-so ever and burn a fair amount of wood. It's been 3 years. The small fan helped a ton it pushes the heat down and out.
I built my own 2 years ago. Everything has worked out fantastic. In fact, I've added inner trays to some of the drawers. Here is my Imgur link from my reddit DIY post.
http://imgur.com/a/nm9Bz
Enjoy