My daughter has just turned six and is being followed for aortic regurgitation secondary to valve damage done by a VSD (surgically closed). At various times it has been classified as mild or mild-moderate. Right now they are classifying her with moderate AR because she has pan-diastolic retrograde flow, enlarged LV (z score of 2.8), and a regurgitation jet measured at 3.1 (cm I think?). Her LV z-score and regurgigant jet have worsened with every echo, otherwise all other parameters have looked relatively stable. Her cardiac function (ejection fraction and shortening fraction etc.) all look completely normal. He said he didn't know why her LV is enlarged, and that it is not related to her AR. (This is a new cardiologist as we recently moved).
He then asked if she has any symptoms and I told him that she is tiring much more easily (all of sudden back to falling asleep in the car, sleeping in later) and is showing decreasing stamina during typical play. She gets out of breath when on the playground or running around with siblings pretty quickly, but it doesn't seem to bother her and she doesn't complain of any pain or feeling poorly. It's pronounced enough that family members and neighbors/friends are commenting on it constantly and asking me if she's sick or if she's coming down with something. She's constantly complaining she's "tired", laying around for awhile (15-20 min) and then bouncing back up to happily play. We did take her to the pediatrician and they ruled out thyroid issues, anemia, and mono.
The cardiologist told me that it is not possible for mild-to-moderate AR to cause symptoms and that symptoms like I am describing can only be seen with severe AR. Is it possible for moderate AR to cause symptoms like I am describing? This is a very noticeable decline in the past 6-8 months and I've always been taught to look for horses before zebras. Before I start chasing down obscure and random, I'd like to make sure we've thoroughly examined the most obvious.