An ECG cannot diagnose CHF. The best diagnostic test for congestive heart failure is echocardiogram coupled with Doppler flow studies.. These studies will help the Dr determine the EF% as well as
whether the heart is failing on the left side, the right side, or both.
Physicians may recommend angiography if they suspect that blockage of the arteries is contributing to heart failure. This test, unlike the Echo, is invasive.