The invention provides methods and compositions for reducing, preventing or reversing cardio toxicity side effects associated with certain therapeutic agents. The invention also provides methods and compositions for treating heart dysfunction including heart failure, and for reversing the effects of myocardial infarction. The various aspects of the invention involve the use of ligand dimers, such as neuregulin dimers, that selectively induce the dimerization of certain EGF receptors in cardiac tissue.
