A leaky mitral valve caused left atrium enlargement in me, but not to a serious degree until I was in "senior" age years. I underwent surgery to repair the valve to stop the growth.
The echo is the method use to determine my heart size.. and if slightly enlarged but stable there is no action indicated in my experience, it may simply be a case you heart is larger than "normal".
This noted, an enlarged left atrium is can contribute to, lead to, atrial fibrillation. I think it could be a good idea to have the size checked every couple of years to establish it the size is growning. I'd also take a low dose aspirin to help mitigate blood clotting which could, but unlikely, result for even a short run of AFib.
Actually, I'm not sure where you attached them, since I can't read them anyway, it's not a problem.
Mild Left Atrium Enlargement.
https://en.m.wikipedia.org/wiki/Left_atrial_enlargement
The correct determination for Left Atrial Enlargement would be the Echo Cardiogram. I've been reading a page that describes your exact circumstances. The person that read the EKG was adament that Left Atrial Enlargement existed, and questioned the competence of the Echo Technician. After thorough investigation, it was revealed that the echo was indeed correct, no Left Atrial Enlargement existed.
Apparently a distortion in the P-Wave is the EKG way of interpreting Left Atrial Enlargement. From the article, it says: "It underscores poor sensitivity of ECG in the diagnosis of LAE ."
I'd rely on the echo tests. Ask your doctor the next time you're there, if not Mild Left Atrial Enlargement, what may be affecting the P-Wave.
Here's an interesting image that shows the parts of the EKG Tracing and where the P-Wave is located.
https://en.m.wikipedia.org/wiki/Electrocardiography#/image/File:EKG_Complex_en.svg