BACKGROUND
Fluorouracil (5-FU) can induce coronary vasospasm that mimics ST-segment elevation myocardial infarction. During multi-agent chemotherapy, attribution to a single agent is difficult. This case illustrates diagnostic uncertainty when transient ST-segment elevation resolves with vasodilators and coronary evaluation is deferred.
CASE REPORT
A 71-year-old man with locally advanced gastric adenocarcinoma presented with intermittent chest pain 2 days after starting cycle 1 of 5-FU, oxaliplatin, docetaxel, and durvalumab. The initial electrocardiogram showed mild lateral ST-segment depression. Approximately 2 hours later, severe chest pain developed with ST-segment elevation in V2-V6 and II, III, and aVF. Pain and ST-segment elevation resolved within approximately 45 minutes of intravenous diltiazem and nitroglycerin, and planned cardiac catheterization was not performed. High-sensitivity troponin values were 27, 44, and 55 ng/L on Day 0 and 16 ng/L on Day 5; no intervening measurements were obtained, and the peak was not captured. Echocardiography showed an ejection fraction of 57% without wall motion abnormalities. Computed tomography pulmonary angiography excluded pulmonary embolism. Coronary angiography, coronary computed tomography angiography, stress testing, and cardiac magnetic resonance imaging were not performed. No chest pain recurred during approximately 1 week of follow-up on isosorbide mononitrate and amlodipine.
CONCLUSIONS
Transient ST-segment elevation during multi-agent chemotherapy can reflect drug-associated coronary vasospasm. However, in the present case, obstructive coronary disease, thrombotic acute coronary syndrome, and immune checkpoint inhibitor myocarditis were not excluded, and no single agent could be implicated. Resolution with vasodilators did not establish the diagnosis. Deferring coronary evaluation was a case-specific decision, not a recommended approach.

Keywords: Cardio-Oncology; Cardiotoxicity; Coronary Vasospasm; Fluorouracil; Myocardial Infarction; Myocardial Ischemia; Antineoplastic Combined Chemotherapy Protocols