Metastatic HER2-Positive Breast Cancer Complicated by Recurrent Treatment-Related Heart Failure

What happened, in summary

A 65-year-old woman with metastatic HER2-positive breast cancer was admitted with worsening shortness of breath and difficulty breathing while lying down. Seven years earlier, she had developed cardiomyopathy after 4 cycles of anthracycline treatment for breast cancer. Her heart function improved only partially afterward.

When multiple breast-cancer metastases later required treatment, she received 2 cycles of pertuzumab, trastuzumab, and docetaxel. Within about a month, her heart function deteriorated sharply and she developed severe recurrent heart failure. A genetic evaluation identified a likely pathogenic TNNT2 variant, raising concern that she may have had an underlying susceptibility to treatment-related cardiomyopathy.

She received drainage of pleural fluid and intensive heart-failure treatment, and her symptoms improved enough for discharge after 10 days. Her cancer treatment was then changed to gemcitabine. Three months later, her heart function had improved substantially. She subsequently died from septic shock caused by bile duct obstruction.