For heart failure, it looks like it's going to be an ABIM accredited fellowship. This means that you have to have finished cardiology first.
As for Echo, UCSF, UAB, and MGH have spots. It's either a one or a two year program. I don't know how helpful it will be in helping you match for cardiology. From experience and asking other people around, doing a chief year or a research fellowship are better ideas. But I can be wrong.