Research has shown that women aged 65 and older who have breast cancer experience higher rates of heart failure compared to their age-matched counterparts, ranging from 29% of women with breast cancer who received no chemotherapy to 38% of women who received treatment with anthracyclines. However, little is known about the association between heart failure and long-term survival in older women with breast cancer, and it is unclear how the relative contribution of heart failure to mortality risk varies by breast cancer stage.