Acute Reversible Atypical Takotsubo Cardiomyopathy Following Trastuzumab and 5-Fluorouracil in a Young Patient.

Combined therapeutic regimens, including molecular targeted agents, are considered standard treatment for advanced gastric and gastroesophageal junction cancer. We present an extremely rare case of acute reversible cardiac dysfunction in a 20-year-old patient after administration of trastuzumab plus 5-fluorouracil for the treatment of metastatic gastroesophageal junction cancer. During the first day of chemotherapy, the patient complained of retrosternal pain radiating to the scapular regions bilaterally. Infusion was immediately stopped, and signs of myocardial ischemia were depicted on the electrocardiogram (ECG) with a positive high-sensitivity troponin T assay, confirming the diagnosis of acute coronary syndrome. Echocardiography revealed global left ventricular hypokinesia and severe systolic dysfunction. After appropriate treatment, the patient recovered, and three days later, he had preserved left ventricular function. Coronary angiography ruled out coronary artery disease. The reported case of acute and severe reversible cardiac dysfunction due to a specific combination regimen in a patient with low pre-treatment risk of cancer therapy-related cardiovascular toxicity (CTR-CVT) highlights the gaps in evidence regarding the risk assessment tools for Heart Failure Association-International Cardio-Oncology Society (HFA-ICOS), representing an atypical variant of takotsubo cardiomyopathy. This case underscores the importance of developing personalized surveillance protocols during therapeutic interventions to mitigate potential adverse effects.