Approximately one-third of pts have a familial form, including those cases due to mutations in genes encoding sarcomeric proteins. Other causes include previous myocarditis, toxins (ethanol, certain antineoplastic agents [doxorubicin, trastuzumab, imatinib]), connective tissue disorders, hemochromatosis, sarcoidosis, muscular dystrophies, “peripartum.” Impaired LV function owing to severe coronary disease/infarction or chronic aortic/mitral regurgitation may behave similarly.