TrAstuzumab Cardiomyopathy Therapeutic Intervention With Carvedilol

Breast cancer patients undergoing trastuzumab-based HER2-directed therapy are at risk of heart function decline or heart failure symptoms, but it is unknown if, when, and for how long cardiovascular protective strategies, e.g. with a beta-blocker, could help. This study randomly assigns those taking curative-intent trastuzumab-based HER2-directed therapy to the beta-blocker carvedilol-either when significant heart function decline or subtle early signs of heart injury (either by elevation of a cardiac blood biomarker, i.e. cardiac troponin, or by an abnormal heart ultrasound marker, i.e. global longitudinal strain) are noted, or preventatively before beginning trastuzumab-based HER2-directed therapy. This study will further randomly assign those patients on carvedilol to either discontinuation at the end of trastuzumab-based HER2-directed therapy or continuation for another year, providing much needed clinical trial data on what the best strategy ("tactic") for those at risk of cardiotoxicity with trastuzumab-based HER2-directed therapy is.