Not if really mild
You're a 25 year old man and if you're either reasonably athletic or a little bit fat, you're perfectly entitled to have a big right ventricle.
Do everything you can to get that sleep apnea
managed. Try to make some life / attitude adjustments so that you won't be trapped by anxiety
-- your physician's a great guide here. You may never find the cause of the heart block
. Best wishes.