Stress test said my ejection fraction was 40% echo said it was 30%, why the difference ,which is more accurate?

You must mix up.cardiac stress electrocardiogram test(run on the treadmill or inject medicine) can not detect the ventricle function;ejection fraction.This test mainly for indirectly detect cardiac arteries arteriosclerosis through EKG change during exercise.Echo(usually perform after run on treadmill) is use ultra sound to out line the structure and movement of the heart and can show the ventricle function.The best way to read the ventricle function is cardiac catheterization.