ERBB2 and congestive heart failure: The three arms of TACTIC, which will be compared with regard to protection against EF declines and congestive heart failure, include: (1) carvedilol prior to HER2-directed therapy; (2) carvedilol initiated after documentation of subclinical cardiac dysfunction/injury, defined by an abnormal global longitudinal strain (GLS) or cardiac troponin (cTn) elevation; and (3) carvedilol initiated after onset of congestive heart failure or a drop in EF (by >10% in patients whose LVEF is ≥50%, or by ≥5% in those with a decrease to< 50%).