Summary
This phase III trial studies compares prophylactic beta blocker therapy with carvedilol versus no prophylaxis in preventing cardiac toxicity in patients with human epidermal growth factor receptor (HER)-2-positive breast cancer that has spread from where it first started (primary site) to other places in the body (metastatic). A beta-blocker, such as carvedilol, is used to treat heart failure and high blood pressure, and it may protect the heart from the side effects of chemotherapy.