What causes a lowered ejection fraction?

[Nick550]

I've been sick for the last 3 months with fatigue, lightheadedness whenever standing or sitting up, a cough producing green phlegm throughout the day, and palpitations as well as some chest pain. I've been to a number of doctors who don't know what's wrong but they say it might be viral.

I see a cardiologist yearly due to my bicuspid aortic valve and I last saw him in October where I had a normal ejection fraction of 65%. I've been to 2 cardiologists since all of this who said my ejection fraction was 45% then 49%. My question is what would cause this significant decrease within 8-9 months? Would a viral infection this log cause that?

[updownleftright]

I've had multiple echos and I've had my ejection fraction come back from as low as 50 to as high as 65. There are multiple factors that can affect an echo. The technician performing the echo and the machine being used are two of the most common reasons for inaccurate echo readings. A drop in EF from 65% to 45% is very large for such a short amount of time.

[ed34]

echo scans are not that accurate for EF. A paper was written after a comparison was made between MRI and echo estimations for EF. The conclusion was that echo scans are very often up to 10% inaccurate UNLESS a contrast agent is injected into the patients first, which they tend not to do. So your EF is very likely to be 45-55 and 50 is normal anyway. SOME doctors use 55 as normal, but the majority are happy with 50. If there was no abnormality of the heart structure seen, and the diastolic and systolic movements of the muscle looked fine, I can't see any problem.
With regards to the green substance This can be an infection but your white cell count would have been elevated in your blood tests to confirm this. What you seem to be describing is Acute bronchitis which should clear up on its own within 3 weeks. This could account for the chest pains.

[Nick550]

I've actually gotten a ton of blood work done; everything came back normal. The 3 cardiologists I've seen all did echocardiograms that determined my EF. My most recent visit measured 45-50% and he told me that's on the low end of normal and its low for my age, me being 22. But he did not have an explanation for why it is low.

[Flycaster305]

Green phlegm can indicate an infection, I've been told.  I'm not a health professional, but know that it is a value that can change, especially when different tests for EF are administered, and can change very quickly.  That said, an EF of 45% is very close to normal.  You also mentioned seeing at least 2, maybe 3 Cardio doctors.  What tests were administered to determine the EF rating?  
My approach would be find a primary GP doctor you trust who would find a base line with blood tests, and refer you to doctors based upon the results.  Blood tests can quickly tell if a viral infection is present or if there is a change in your heart condition, I can tell you from personal experience.
Keep us informed.