Sync EndNote library with Mendeley

I use Mendeley as a PDF manager/annotator, but EndNote is my primary reference manager. Since my Endnote library is constantly changing, I want Mendeley to automatically sync and mirror changes in my EndNote library. With the manual way to update, which is to reimport xml file routinely, I'm afraid annotated PDFs will be overriden, and it is tedious chore. I need Mendeley to update the PDFs in tandem with changes and additions I make to my EndNote library.