A 45-year-old woman underwent a modified radical mastectomy 4 years ago. She was treated for multiple bone metastases with cyclophosphamide, doxorubicin, and fluorouracil for 6 months. She is complaining of exertion on exercise, swelling of the legs, and swelling around eyes in the morning. On examination, she has bilateral rales in the lungs, S1, S2 audible, S3, S4 gallop present. Her BP is 149/117 mm Hg, PR is 80/min, and RR is 18/min. What is the most likely cause for her cardiac condition?