HELP!! Scared! MUGA dropped

[shelli]

I initially started with a muga of 65 prior to Herceptin. It dropped to 41 at the lowest point. I continued with Herceptin the entire time. I took herceptin for 52 weeks continuously. Now that I have finished herceptin in Feb. my last scan is now at 49%. Both my onco & cardio don't seem to be concerned. I have also been on Toprol 25mg. daily for several years due to an arrhthmia called bigeminy whereby every other heartbeat is abnormal. I have bad fatigue and sometimes some shortness of breath but I'm not sure if it can be directly correlated to the drop in EF or just from all the treatment I've had.
I wasn't too concerned because I was more fearful of the cancer than the potential heart damage which often recovers when the treatment is completed. The doctors are not sure now if my EF will improve more over time. They seemed to believe that 50 and over is normal & that mine was slightly below and not a big deal or cause for any concern. I was also told that the Muga is more accurate than an Echo and they show slightly different things. Muga shows more functioning of the heart than Echo. Also had a CT Angiogram of heart which was fine.