In reading their milestones and innovations, it looks to me like a very good cardio department.

Some thoughts for you in question form:
Do you have a family/primary care doctor? Have you spoken to him since yesterday? Can he recommend a good board certified cardiologist (FACC?)?
Do you need pre- approval for stress tests from your health insurance company?

They instructed you to return to the ER if you have any more pains. You have, yet you haven't. Why? Just the bad vibes from the local ER? Not a good reason.
I do wish you the very best outcome from this.