While both tests are very good, the echo is not going to check the electrical system of the heart. It checks the pumping action as well as the wall thicknesses of the heart primarily. The EKG checks the electrical system primarily but can also show if the wall thickness of the heart is not normal. Each test is specialized. I worked as an EKG supervisor for awhile, I am not sure, based on what you wrote if the electrodes were placed correctly. The one below the clavicle was if it was placed BETWEEN the bones not over the clavicle itself.