Myocardial dysfunction caused by abemaciclib: a case report.

A 68-year-old female patient with metastatic breast cancer presented 12 weeks after starting chemotherapy with abemaciclib and fulvestrant with breathlessness, peripheral edema, and weight gain. Brain natriuretic peptide (BNP) and troponin I levels were raised above normal, and chest radiography revealed an increase in the cardiothoracic ratio from 47% before chemotherapy to 55%. The transthoracic echocardiogram showed a reduction in left ventricular ejection fraction from 76% before chemotherapy to 68%. Contrast-enhanced cardiac magnetic resonance imaging (MRI) revealed delayed accumulation in the interventricular septum. Under the diagnosis of abemaciclib-induced myocardial dysfunction and heart failure, abemaciclib was discontinued, and enalapril and furosemide were started. Two months later, imaging revealed a cardiothoracic ratio of 47% with a left ventricular ejection fraction of 73%. A cardiac MRI after three months was normal. This case report demonstrates that cardiac dysfunction caused by abemaciclib is reversible if detected early and treated appropriately. © The Japan Society of Clinical Oncology 2021.