left atrial enlargement

My son is 13 and ADHD he takes Adderall (adderrall) XR he just had an EKG that said he had an abnormality, left atrial enlargment. I've read about hypertension in children, but I don't think that that would be his problem. Every 3 months he has a check up for the ADHD and his blodd pressure is checked each time. And we have never had any worries. We have just went to have an Echocardigram, what else could cause problems in children if there isn't any heart related problems in the family? Where do I go from here? I'm so scared!!! Everyone says just wait for the results.
Tracy

[kenkeith]

An echo will determine if your son has mitral valve stenosis (narrow opening) and that condition can cause higher than normal pressure that results in LAE.  That condition would be the highest probability based on your son's age (valve abnormality can be congenital), but an EKG is not a very reliable source, and there are many false positives, but it requires further examinations to substantiate or dismiss.