This is a single-center, randomized clinical trial that seeks to determine if a risk guided treatment strategy that initiates carvedilol in high risk breast cancer patients prior to doxorubicin and/or trastuzumab is safe, tolerable, and feasible. Subjects who are identified as having elevated CTX Risk by an internally validated clinical risk score (exceeding a pre-specified risk threshold) will be randomized to individually-dosed, open-label carvedilol or usual care. Investigators will use a stratified randomization according to trastuzumab therapy (yes/no) to ensure balance across treatment regimen. Clinical, echocardiographic, and biomarker data will be collected on all patients at baseline and standardized time intervals during and after therapy at approximately 3, 6, 9, 12, and 24 months.