I think you need to see a GI dr--It is some sort of acid related syndrome--Be mindful of what you eat each day--do you drink coffee? soda? Don't worry about a heart attack--If it was that--you would have had the big one by now and be gone--You have an ulcer or GERD--and need to get on meds and change your diet--Stop worrying--not your heart--Hepkitty
A low ejection fraction--and 40-45% is rather low--is NEVER the result of a GI disorder! Good grief.
However, you should be reassured by your good stress test and EKG. Those, especially the stress test, are very good indicators.
You say you have a newborn? How long ago did you give birth? The reason I ask is that there is a somewhat rare heart condition that occurs either during during the last month of pregnancy or within 5 months of giving birth, and one of the characteristics is an ejection fraction below 45%. It is called postpartum cardiomyopathy. For unknown reasons, the heart gets kind of weak as a result of pregnancy and pumps less efficiently than it used to.
Now, don't freak out (at least not too much), because it sounds as though your heart is in otherwise good shape. You are not likely to keel over and die, but this is something that definitely should be looked into. It IS treatable with diet and medications, and for people like you, who don't have bad symptoms, the outlook is very good. Just a few weeks ago, there was a discussion on this forum of a young mother who was diagnosed with it, and she had no symptoms at all. In fact, she was planning to run a marathon, but she was simply advised to wait a little longer for that.
I think you should definitely have another echo to check things out, and it would be a good idea to ask specifically about postpartum cardiomyopathy. It is rare enough that there's a good chance your regular MDs may never have seen it.
Since you're obviously pretty stressed (and who wouldn't be?), I'm sorry to have to mention this possibility, but again, if that's what's going on, it IS treatable. And if that's not what's going on, then at least it has been ruled out.
Try to get some rest tonight. It would be perfectly OK to call your PCP back tomorrow for a little more advice.