Hi, I've just seen this thread.
My son who is now 4 had an Echogenic Intracardiac Focus picked up on the 20 week scan. It was so scary and I spent the rest of the pregnancy stressing out about it. Other things came up too like being small for dates.
He was just fine but I did have to mentally prepare myself for the possibility of him having Downs syndrome. When he was born I was checking him over for signs. It was so hard but looking back I don't know what I was so worried about. Not because the marker means nothing. Nobody is sure about that even now but more because Downs isn't the huge deal I thought it was.
If this is the only marker that has come up, I would try to put it to the back of your mind as much as possible. Some hospitals don't even tell you if they find one because they believe it is nothing to be worried about.