Generally speaking, an ejection fraction on a nuclear stress test is less about the exact numbers and more about a generalization (normal, mildly abnormal, or abnormal). A normal ejection fraction is >65%. At the upper ends nuclear stress tests are not great at specifics. If your heart chamber sizes are small (and this is a normal variant seen in people) we find the volumes (and thus the ejection fraction) to be less precise. The interpretation of test results like this, in the majority of cases, would be considered fine.