Im a breast cancer patient but half way through my heceptin. my doctor stopped my treatment because my heart is only working at 42 percent ?

Should improve: Most pts whose cardiac function declines while on herceptin, (trastuzumab) will have the function return to baseline if the drug is dropped. Interestingly, once the drug is again resumed, most don't have a relapse of this cardiac decline. Repeat the scan of the heart in a month, and see where the cardiac function stands.

Cardiotoxic: Cardiotoxicity occurs in 2-4% of cases with terceptin. This means the drug can cause your heart to weaken. A normal ejection fraction is 50% or greater. If yours is down to 42%, it's time to stop the drug.

Herceptin (trastuzumab): That chemo agent can cause weakness of the heart muscle and if your ejection fraction is only 42% then your doctor is being appropriately cautious.

It does happen in so: Herceptin (trastuzumab) has effects on the heart and can lower its pumping function(ejection fraction(ef)). Normal value is 50-55%; so 42% is not too bad. It will recover by the time they check it again in 3-4 wks, so it is a good idea to stop Herceptin (trastuzumab) unless you have not yet had at least 6 months of therapy with herceptin(in which case the oncologist can go back and complete it provided the ef has recovered.