Dear colleague,   We are planning a RCT to test the hypothesis that less frequent cardiac imaging during Her2 targeted therapy (HER2TT) is the preferred strategy in women without prior cardiac disease. We want your input to help us design the study so that the outcomes are meaningful and so that the results will change practice. After excluding women with existing cardiac disease, the control arm will receive cardiac imaging every 3 months. The intervention arm will utilize imaging as follows: a) every 6 months in women without cardiac risk factors receiving anthracycline-free regimens, or  b) every 4 months in remaining women with cardiac risk factors and/ or anthracycline use.  Multiple outcomes need to be considered when deciding on an optimal imaging strategy. Therefore, we are planning that the primary outcome will be a hierarchical composite endpoint of multiple relevant outcomes, ranked from more important to less important. The outcomes we will consider, in order of descending