Enlarged Atrium

Hello!  My mother just had a heart exam because she keeps feeling palpitations in her heart...  They have done an echo and it came back as a left atrium (septumn) moderately dilated.  Everything else came back normal.  They said usually that with the left atrium being dilated ,they see the left ventricle dilated as well - but they didn't see that on her.  They also said her valves looked great.  On the report, it says her ejection fraction is 65%.  Left atrium is 45mm (Normal is less than 43mm).

We are trying to figure out a couple things...

1)  What would be causing her palpitations if everything else is normal?  (Or at least it looks normal via the tests)

2)  What causes the enlarged left atrium alone?

She does have a history of heart disease.  (Her mother passed away at age 67 from heart failure.  Her mother also had diabetes, total hysterectomy, total left hip, high blood pressure)

My Mom also found out two years ago that her LP(a) is 94, which is extremely high (it is supposed to be less than 30) and she is borderline diabetic.  Right now she is working on that - trying to lose some weight and eat healthy.

Here is my Mom's stats:

Height:  5' 4"
Weight:  202lbs
Age:  52
Race:  Caucasian

Surgeries:  Total hysterectomy

Other current problems:  Thyroid nodules (waiting to do a biopsy and see if they have changed at all in the last few months)


Any information you could provide would be great!

Thank you!