Dianal-Belive it or not an EKG is not too accurate. Below is part of an article I found. Personally, I would much rather have a cardiologist run tests on me before a surgery. They use much more accurate testing methods that show detailed images and / or the actual functioning of your heart rather than relying on electrical impulses. I also had to see a cardiologist prior to my surgery.
"The study of 500 patients found a false positive reading between 77 and 82 percent in patients screened by electrocardiogram, and a false negative reading between 6 percent to 7 percent in the same patient population..."