5-Fluorouracil–Induced Microvascular Vasospasm Diagnosed by Coronary Functional Testing

The 5-fluorouracil (5-FU) component of 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) chemotherapy is a known cause of coronary vasospasm. Diagnosis can be difficult, often leading to interruption of chemotherapy. A 53-year-old man with a history of colorectal cancer developed new-onset angina after initiation of FOLFOX chemotherapy. He underwent a left heart catheterization, coronary functional testing (CFT), and acetylcholine (ACh) provocation. ACh provocation elicited similar angina, consistent with microvascular vasospasm. This prompted initiation of calcium-channel blockers and adjustments to chemotherapy administration, preventing further angina. CFT with ACh provocation should be considered in patients undergoing chemotherapy with 5-FU. As 5-FU coronary vasospasm is often transient, ACh provocation can identify patients who would benefit from calcium-channel blockers and changing 5-FU administration from continuous to bolus dosing. This case highlights the utility of CFT in identifying and guiding treatment in suspected cases of 5-FU-associated coronary vasospasm.