JUdicious Surveillance for Trastuzumab Induced Cardiotoxicity in the First Year

"Participants will be randomized to judicious imaging (decreased imaging frequency based on HF risk category) or SOC (imaging every 3 months). Participants who do not have any HF risk factors will be categorized as low risk, while participants with at least one risk factor will be categorized as intermediate risk for HF.~Low Risk (zero risk factors): imaging before cycles 1 and 9 of HER2-TT (i.e., at baseline and near the halfway mark, corresponding to 2 fewer studies than SOC in Year 1), then after the end of HER2TT. This translates to imaging every 6 months for uninterrupted adjuvant HER2TT.~Intermediate Risk (any risk factors): imaging before cycles 1, 6, and 12 of HER2-TT (i.e., at baseline and near the 1/3 and 2/3 marks, corresponding to 1 fewer study than SOC in Year 1), then at end of HER2TT. This translates to imaging every 4 months for uninterrupted adjuvant HER2TT."