Sorry to hear of your condition! Your condition raises the question what caused the infarction (heart cell negrosis...death) in view of no ischemia (lack of blood flow usually due to blocked vessels)?
I experienced an almost similar situation about 4 years ago when I was hospitalized with having had an MI (silent) causing congested heart failure. EF was 29-13%, enlarged heart and CAD (ischemia) was the underlying cause. There was heart muscle damage, but a stent implant and medication revitalized heart cells and now the EF is 59
% and heart size is normal.
Can damaged cells be reversed to normal funcitonality? Yes, depending on cause and other factors. Wall movement impairment causing lower than normal EF (normal is 55-75%, and below 29% is heart failure) can be the result of HYPERNATING or STUNNED heart cells and reversed. You can google for more information, but as I remember the underlying cause would be ischemia!?
An EF of 45% is not dangerously low and what I read from your post it should be a lot lower due to the degree of muscle damage and location as well as an enlarged heart?! Surgery is not an option unless there is pathological angiogenesis (growth, tumor with its own blood supply, etc.). Is that the problem?