I am not sure but I have seen posts on here from people whose EF is 15%...I would say this would put them at great danger for a sudden cardiac event...but I am not a doctor...
My Ejection Fraction has been as low as 15%. Remember, these numbers are not always right on target - there is room for error. When I was 15% I was still functional - not running around the block but functional
My EF has been as low as 13%. A well-compensated heart/vascular system may do better with a low EF and a person with a higher EF may experience congested heart failure.
What will happen when the EF is too low, the blood/oxygen from the lungs will backup and cause pulmonary edema and the individual will virtually drown in the fluids that leak into the lungs due to respiration condition and a weaker person will decompensate and succumb. Or the heart will enlarge and contractions will become even weaker and eventually the lack of adequate blood flow to the brain and heart, etc. will cause a coma and death. Also an enlarged heart can cause arrhythmia and fatal MI.