[sadie]

Your dr should order another test after your A/C regimen to compare it to your original score.
The reason I had an echo done after my Muga score of 55% was because of the big drop from 71% on my original score. The tech wrote in the report that the drop could possibly be from a technical malfunction.
Well, it turned out that the Muga was pretty accurate, because the echo score was 58%. My onc tests me every 3 months.
BUT......My onc did tell me that if my score went below 55%, she would not continue with Herceptin because Herceptin could bring the score down even lower.
I have seen other women post saying that their dr told them that if their score went below 50% they would take a break from Herceptin.
By the way, anything above 50% is considered normal.