Effort myocardial ischemia during chemotherapy with 5-fluorouracil: an underestimated risk

Abstract

Background: Effort-induced myocardial ischemia (EMI) has been seldom described. Aims of our study were (A) to evaluate the prevalence of EMI during long-lasting 5-FU infusion; (B) to identify possible risk factors of EMI during 5-FU infusion.

Patients and methods: For the purpose (A), we prospectively evaluated a group of patients undergoing in-hospital continuous infusion (c.i.) of 5-FU. Patients with rest ischemia were excluded. Among 358 consecutive patients, 21 (5.9%) had rest ischemia; 109 could not perform a stress test. The remaining 228 patients underwent a treadmill stress test (TST) after >46 h of 5-FU infusion. For the purpose (B), we compared the characteristics of patients with EMI (including 3 previously described in a 2001 paper) with those without EMI.

Results: Among 228 patients, 16 (6.9%) had EMI. These 16 had a second TST after stopping 5-FU: in 14, it was negative, 2 patients with coronary artery disease had milder ischemia. The whole group of 231 (including 3 described in a previous paper) patients undergoing TST included 148 males and 83 females, with mean age of 57.5. Cardiovascular risk factors were present in 178 of them. Eight patients had ischemic heart disease. Among 19 patients with EMI, 7 had angina, 12 silent ischemia. ST segment at ECG was elevated in 10 patients, depressed in 9. Comparing the group with toxicity and the one without, the only significant difference was the complaint of atypical symptoms at rest before the TST. No difference was observed as regards: chemotherapy schedule (chronic c.i. in 49, 5 days in 178, FOLFOX type in 12), coronary risk factors or heart disease.

Conclusions: EMI is as frequent as rest ischemia during 5-FU infusion. Patients undergoing 5-FU continuous infusions should be adviced to avoid unusual efforts, to refer any cardiac symptom, and should be investigated for EMI.

Keywords: 5-FU; 5-FU effort ischemia; 5-fluorouracil; cardiotoxicity; chemotherapy cardiotoxicity; fluorouracil toxicity.