Not a doctor…but:
http://my.clevelandclinic.org/heart/disorders/heartfailure/ejectionfraction.aspx
It’s a measurement of the percentage of blood that’s removed from that chamber on each stroke. A higher number means the the heart is more efficient. A low number could indicate some sort of damage related to a heart attack or heart disease with 40% being the threshold for diagnosis of heart failure… according to the website.
Potentially serious, but with it seems a long list of causes. I suppose a misread ultrasound could be to blame too. I would assume a CT or MRI is more accurate. Some folks also might just live “on the edge” and be normally healthy, especially if you have no other symptoms.
Again, not a cardiologist, just interpreting what I read.