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 exeion 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 and S4 gallop is present. Her BP is 149/117 mm Hg, PR is 80/min, and RR is 18/min. What is the MOST likely cause of her cardiac condition?

This patient is showing features of congestive hea failure which has most probably resulted from the use of doxorubicin. It is a leading cause of chemotherapy induced hea disease, it cause this during therapy, weeks after completion of therapy or unexpectedly after years. Traditionally, the cardiac-limiting dose of doxorubicin has been described as 550 mg/m2, when this drug is combined with cyclophosphamide cardiotoxicity is noted at a lower dose of 300 mg/m2. During acute therapy ECG changes occur in 30% of patients and usually regress in weeks. The occurrence of early ECG abnormalities does not predict cardiomyopathy and is not an indication to discontinue therapy. If an otherwise stable oncology patient develops persistent sinus tachycardia, ventricular dysfunction and impending CHF should be suspected. Ref: Hurst's The Hea, 13e chapter 94, By Andrew L. Smith; Wendy M. Book.