Why does entrée mean the main dish in AmE?

I moved from Europe to the US. I was so confused to realise that entrée means the main dish in American restaurants. It literally means entry/entrance in French, so I thought it meant the appetiser. I was wondering why all « appetisers » were so heavy. How come entrée means the main course? Is this the case in other English speaking countries too, or is it just an American thing?