The Role of Vasospasm and Microcirculatory Dysfunction in Fluoropyrimidine-Induced Ischemic Heart Disease

Cardiovascular diseases and cancer are the leading cause of morbidity and mortality globally. Cardiotoxicity from chemotherapeutic agents results in substantial morbidity and mortality in cancer survivors and patients with active cancer. Cardiotoxicity induced by 5-fluorouracil (5-FU) has been well established, yet its incidence, mechanisms, and manifestation remain poorly defined. Ischemia secondary to coronary artery vasospasm is thought to be the most frequent cardiotoxic effect of 5-FU. The available evidence of 5-FU-induced epicardial coronary artery spasm and coronary microvascular dysfunction suggests that endothelial dysfunction or primary vascular smooth muscle dysfunction (an endothelial-independent mechanism) are the possible contributing factors to this form of cardiotoxicity. In patients with 5-FU-related coronary artery vasospasm, termination of chemotherapy and administration of nitrates or calcium channel blockers may improve ischemic symptoms. However, there are variable results after administration of nitrates or calcium channel blockers in patients treated with 5-FU presumed to have myocardial ischemia, suggesting mechanisms other than impaired vasodilatory response. Clinicians should investigate whether chest pain and ECG changes can reasonably be attributed to 5-FU-induced cardiotoxicity. More prospective data and clinical randomized trials are required to understand and mitigate potentially adverse outcomes from 5-FU-induced cardiotoxicity.