BACKGROUND: 5-Fluorouracil (5-FU) is a mainstay chemotherapeutic agent for gastrointestinal malignancies but carries a recognized risk of cardiotoxicity, most often manifesting as coronary vasospasm that can mimic acute myocardial infarction. This report describes the case of a 50-year-old woman with ST-elevation myocardial infarction (STEMI) due to coronary artery vasospasm during continuous infusion of 5-FU as part of the first round of FOLinic acid (leucovorin), Fluorouracil (5-FU), and OXaliplatin (FOLFOX) chemotherapy for colorectal carcinoma.

CASE REPORT: A 50-year-old woman with colorectal carcinoma receiving her first cycle of FOLFOX developed severe chest pain during a continuous infusion of 5-FU. Initial emergency department evaluation was reportedly unremarkable, and she was discharged after symptomatic improvement with ketorolac. She returned emergently with recurrent crushing chest pain; a repeat electrocardiogram showed hyperacute T waves and ST-segment elevation, prompting ST-elevation myocardial infarction activation and transfer for emergent catheterization. Coronary angiography revealed no obstructive coronary artery disease. Echocardiography demonstrated a severely reduced left ventricular ejection fraction (LVEF) of 30% to 35% with apical akinesis, consistent with 5-FU-induced cardiomyopathy. 5-FU was permanently discontinued, and the patient was treated with vasodilator therapy, with complete resolution of symptoms and normalization of ventricular function on follow-up echocardiography.

CONCLUSIONS: 5-FU can precipitate life-threatening coronary vasospasm and a fully reversible cardiomyopathy even during a first chemotherapy cycle, in the absence of obstructive coronary artery disease. Early recognition, prompt drug interruption, and a multidisciplinary cardio-oncology approach, including an individualized decision between permanent discontinuation and carefully supervised rechallenge, are essential to guide safe oncologic decision-making.

Keywords: Case Reports, Coronary Vasospasm, Fluorouracil, Colorectal Neoplasms, Cardiomyopathies