Heart Failure Prognosis

Well, it isn't confirmed yet, but I'm expecting to find out tomorrow that my ~12 year old boy may be in congestive heart failure. I had xrays taken about three weeks ago mainly to look at his teeth as he suffers from malocclusion that requires trims and such about every 6 weeks. In the xray though his lungs were cloudy. After over 2 weeks of antibiotics (Baytril and Doxycycline), his lungs looked the same if not worse. I have an echo scheduled tomorrow. I know there are medications for heart failure, but I am curious if anyone here has experience with this. If so, how long has your chin been on these meds ? I'm just trying to get an idea of the possibilities. Can a chin be on heart meds successfully for years?

Any thoughts are appreciated?