Trastuzumab is an effective treatment for HER2-positive breast cancer. Current guidelines recommend withholding trastuzumab in patients experiencing a significant asymptomatic decline in left ventricular function. In this commentary, we discuss the survival benefits afforded by trastuzumab juxtaposed against the risk of trastuzumab-mediated cardiotoxicity. It is not known whether the net benefit of continuing trastuzumab in the setting of mild cardiotoxicity outweighs the associated risks. We describe a potential approach undertaken by our group, and others, and call for a randomized trial.