The resource that I used is from Coding Strategies,
Navigator for Comprehensive Cardiology
I purchased this out of pocket and found I liked this publication better than Dr. Z's book, which my employer purchased for me. I also had an older copy of Coding Companion and didn't find it to be all that helpful. The Coding Strategies book is more like a textbook than a reference book.
I took the exam this past December and, at the time, had been coding cardiology for 1.5 years. I found the exam easier than the CPC or COC and finished in about 3.5 hours. I passed with 83%.
As Codergirl said, know your EP and peripherals. Our EP doesn't do EP procedures at our hospital so I had never coded these before. Also, our Interventionalists don't do that many peripheral procedures, but at least I had experience coding these.
Remember that you can miss 45 questions and still pass so if you know your other stuff you could totally bomb EP or peripherals and still pass. When I took the exam I figured there were about 30 questions that I wasn't that confident on. This included all of the EP, some of the peripherals, and (should I admit this
) about 5 questions that were really long and I just didn't feel like reading. I estimated that I would do no worse than 50% on these. I also estimated that I would get 90% on the rest of the exam. So I estimated I would pass with 82%. As I mentioned, I passed with 83%.
Good luck, and if you have any other questions don't hesitate to ask.