Diagnosis and Management of a Patient With 5-Fluorouracil-Induced ST Elevation and Nonsustained Ventricular Tachycardia as a Late Presentation of Cardiotoxicity and Successful 5-Fluorouracil Rechallenge

5-fluorouracil (5-FU) is an antimetabolite drug that is used in the treatment of a variety of carcinomas, including breast, gastric, pancreatic, colon, and rectal cancers. It is usually administered to decelerate and prohibit cancer cell proliferation. It acts by inhibiting the enzyme thymidylate synthase by blocking thymidine formation required for deoxyribonucleic acid (DNA) synthesis. The most common clinical manifestation of 5-FU cardiotoxicity is chest pain related to coronary vasospasm. Patients experiencing cardiotoxicity induced by 5-FU present with signs and symptoms of acute coronary syndromes with elevated cardiac biomarkers (troponin), and their ECGs often reveal ST segment changes. There can be two distinct clinical presentations, early or late presentation of cardiotoxicity. Early toxicity can occur during the infusion, whereas late presentation of toxicity can occur 1-2 days after the infusion. Usually, with early toxicity, troponin elevation may be evident. However, in late presentation of cardiotoxicity symptoms, troponin elevation and/or ECG changes may be undetectable. Our case has a unique presentation of 5-FU toxicity in a patient developing ST elevation and non-sustained ventricular tachycardia (VT) as a late presentation of cardiotoxicity.