Acute reversible left ventricular systolic dysfunction associated with 5-fluorouracil therapy: a rare and increasingly recognised cardiotoxicity of a commonly used drug

5-Fluorouracil (5-FU) is the third most common chemotherapeutic agent for treating solid cancers and the second most common to cause cardiotoxicity. We present a rare case of acute reversible severe left ventricular systolic dysfunction associated with 5-FU. A 54-year-old woman with a history of stage IV gastric cancer presented with features of transient ischaemic attack after receiving the first dose of FLOT (5-FU, leucovorin, oxaliplatin and docetaxel). During the diagnostic workup, it was found that her ejection fraction was severely reduced to 15% with features of global hypokinesis, which later improved back to 65% within 13 days. These cases challenge our current understanding of the underlying mechanisms of this cardiotoxicity. Additionally, even though the patient did not experience any cardiac symptoms, it is important to monitor these patients closely as they are at high risk for fatal complications like arrhythmia and thrombus formation.