A case of chemoradiotherapy-associated cardiotoxicity that developed into acute heart failure with progressive subendocardial fibrosis

We describe the case of a 61-year-old Japanese woman who developed acute heart failure 5 years after chemoradiotherapy for breast cancer. The patient received less than the cardiotoxic dose of docetaxel, epirubicin, cyclophosphamide, and fluorouracil and experienced no cardiovascular complications in the 5 years between the onset of chemoradiotherapy and the onset of acute heart failure. Cardiac catheterization was performed and elevation of end diastolic pressure of both ventricles was observed. Endomyocardial biopsy showed progressive replacement fibrosis in the subendocardium. Normal thickness of the right endocardium is <20 μm. Surprisingly, our patient had a fibrous subendocardium that was 100–200 μm thick. Ultrastructural abnormalities similar to those observed in anthracycline cardiotoxicity were evident on electron micrographs. This case report demonstrates the unique pathophysiology of heart failure in a patient who received less than the cardiotoxic dose of antineoplastic agents. Recent protocols have decreased the dosage of cardiotoxic agents; however, even these reduced doses might not be safe for all Japanese individuals and may cause subclinical cardiovascular damage and late-onset heart failure. Clinicians should monitor cancer survivors carefully, even if antineoplastic agents were administered under the cardiotoxic dose.