Best test for Ejection Fraction

[sailing123]

I've have several test over six month period to determine the health of my heart, several Echocardiograms, a Nuclear Stress Gated Spect, and an MRI.  The MRI and Nuclear Stress Gated Spect, showed an ejection fraction of 59%.  My Echocardio has varied between a low of 45 and, 51, & high of 56.  Which of these test is most accurate?  Should I consider a MUGA, as I've heard this is the most sensative non-invasive test.

I have a dilated left ventricle but was diagnosed with an athlete's heart.  After several months of not working out my heart size is back to normal, so this seems likely.  

[skydnsr]

kenkeith seems to know a lot more than I do about the different ways of measuring EF, so I'll defer to him on that, but I have always heard that echo is notoriously unreliable.  What I was told about echo is that it gives you an estimate that is based on a model.  If any of the assumptions of the model are untrue for you, then the estimate will be inaccurate for you.  Perhaps the model was not designed for extreme athletes.

If it were me, and if my heart was now back to normal size, and I felt well, I don't believe I would want to do any more tests.  I would be wondering more about whether "athlete's heart" is a pathological condition, or simply a normal response to extreme training.   In other words, are there any adverse consequences to having athlete's heart?  If not, then why worry?

[kenkeith]

As is the heart rate, blood pressure, etc. the EF (ejection fraction) is an estimate and measurement that is always in flux to maintain a balance of blood flow between the right and left side. The simple, every second/minute dilation of the left ventricle increases the EF, reduction decreases EF.

An athlete's heart muscle increases contractility strength...a resting heart rate can be less than 60 bpm.  Top-level training is often associated with morphological changes in the heart, including increases in left ventricular chamber size, wall thickness, and mass. That is different from a normal dilated heart and an abnormal dilated heart (the increased size will decrease EF).

You might want to average all estimated measurements, and that should be close to what is your functioning EF.  Because chamber size is the metric for volume of blood pumped with each stroke, you can evaluate the heart's LV functionality by what is called fractional shortening.  LV diastolic (end point) minus LV systolic (end) divided by LV diastolic times 100.  Reference range is 18 to 42%.  Above 30 is considered normal, 26 to 30% represents mild decrease in ejection fraction, below is abnormal.  The significance is the heart's ability to fill (relaxation) and is the systole phase and the strength to contract is the diastole phase.