Inclusion Criteria:

• * ≥18 years of age,
• * new or locally recurrent diagnosis of HER2+ breast cancer that will be treated with curative intent
• * planned HER2-directed (any therapy targeting HER2 signaling including Trastuzumab +/- pertuzumab or trastuzumab-emtansine (T-DM1) Nerantinib and lapatinib will not be considered. "HER2-directed therapy" or "anti-HER-2".

Exclusion Criteria:

• * history of HF of any class and type, or diagnosis of cardiomyopathy in the past,
• * LVEF \<50% at screening,
• * intolerance to beta-blocker,
• * baseline use of any beta-blocker for coronary artery disease including myocardial infarction
• * current ACE inhibitor or ARB therapy for hypertension in the presence of diabetes and/or for chronic kidney disease/proteinuria,
• * on active therapy with amiodarone, sotalol, or any other antiarrhythmic
• * Diagnosis of asthma with current daily use of anti-asthmatic therapy
• * heart rate \< 50 BPM at screening (average of 3 most recent readings)
• * history of or current sick sinus syndrome,
• * AV block grade II or higher (unless patient has a permanent pacemaker) at screening,
• * systolic blood pressure \< 90 mmHg at screening (average of 3 most recent readings)
• * severe hepatic dysfunction, as defined by NCI ODWG (total bilirubin \>3x ULN, any AST elevation) or Child Pugh C class
• * pregnancy
• * Metastatic breast cancer (distant metastases)
• * Active systemic treatment for non-breast cancer