DP:
I'll assume here that I know WHY you are asking the question (although correct me if I'm wrong).
Doing a surgical internship will not help you with your future career plans. Most surgical interns are not operating much nor are they really obtaining high level surgical skills. You might get some benefit over your colleagues in IM when doing procedures but its a really painful way to do so when a lot of surgical internship is floor/scut work.
What you need to do, MANY years from now when the time comes, is to decide between interventional cardiology or cardiothoracic surgery. Do you want to be a surgeon or a proceduralist?
Don't do a surgical intern year because you think it will help you in being an interventional cardiologist...those few skills you pick up that intern year will be lost by the time you get to your fellowship in IC.