fisher,
Dont put the horse before the cart.
The ecg is an electrical picture of the heart. The pediatric ecg has some differences from an adult ecg. One of these differences can represent changes consistant with RVH in an older pediatric patient and be normal in a younger patient. Typically the change in ecg takes place between ages 3-8. This is most likely why it was recommended to check again in a year.
RVH comes from overload on the chamber of the heart. An echocardiogram is an actual picture of the heart and more accurate for detecting structural changes. This most likely would be the next step.
Don't worry about treatment and outcomes before you find out if this is just a normal variant. I'm not a pediatrician or a pediatric cardiologist, my next step would be to see and discuss testing with either of those if he were my child.
hope this helps.