Heart issue Herceptin

I am two weeks into radiotherapy and went in yesterday to have my next Herceptin treatment. Was pretty shocked when I was told I couldn't have it done because of weakening of my heart muscle. I didn't expect that! Seeing a cardiologist next week. Feeling pretty scared! Hopefully will be able to resume Herceptn soon. My oncologist said that the can happen to 1 in 5 women. Can anyone tell me if the are in a similar situation and how long before they resumed treatment? Thanks Vanessa