More of the issue will be the requirement of chip+pin in most of the EU. Only a few banks have these available in the US.

Last trip to the UK I called Chase to let them know, they said it would be good for just 90 days and at that point I'd need to call again. After a disasterous few days in Australia with no source of funds because my credit cards stopped working was no fun.

But, um, being gone for a few years... you might need to call and ask.