Fluoropyrimidine and bevacizumab therapy induced myopericarditis mimicking STEMI (peak troponin 457 ng/L) in a 71-year-old man, which resolved completely at 6-month follow-up.
Case Report (n=1)
Multimodality imaging, particularly CMR, is essential in distinguishing chemotherapy-induced myopericarditis from STEMI to prevent unnecessary interventions and allow safe continuation of oncologic therapy.
Abstract Background Fluoropyrimidines such as 5-fluorouracil (5-FU), when used in combination with bevacizumab are associated with diverse cardiotoxic effects including vasospasm, myocarditis and myopericarditis. These toxicities may closely mimic acute coronary syndrome (ACS), creating diagnostic uncertainty and risk of inappropriate management. Cardiac Magnetic Resonance (CMR) is central in distinguishing inflammatory myocardial injury from ischemic pathology. Case Summary A 71-year-old man undergoing long-term maintenance FOLFIRI–bevacizumab for metastatic colorectal cancer presented with acute chest pain and inferior ST-segment elevation 12 days after chemotherapy. Coronary angiography demonstrated non-obstructive coronary artery disease without a culprit lesion. Serial ECGs showed dynamic evolution from ST elevation to widespread T-wave inversion, while peak high-sensitivity troponin reached 457 ng/L. Initial echocardiography revealed normal left ventricular ejection fraction. CMR performed one week later demonstrated subepicardial late gadolinium enhancement and elevated regional T2 signal in the lateral segments, fulfilling the 2018 Lake Louise criteria for myopericarditis. Chemotherapy was withheld and the patient was treated with colchicine, beta-blockade, and intermittent nitrates. Six-month follow-up imaging showed complete recovery of systolic function, permitting safe reintroduction of FOLFIRI–Bevacizumab. Discussion This case highlights a diagnostically challenging presentation of fluoropyrimidine-associated myopericarditis masquerading as ST-elevated myocardial infarction (STEMI). Synergistic endothelial injury from 5-FU and bevacizumab may lower the threshold for cardiotoxicity even after multiple well-tolerated cycles. Multimodality imaging particularly CMR was essential in confirming myocardial inflammation, excluding ischemia, and guiding treatment decisions. Increased awareness of chemotherapy-related STEMI mimics is critical to prevent unnecessary interventions and allow safe continuation of oncologic therapy following cardiac recovery.
Singh et al. (2026) conducted a case report in Fluoropyrimidine-associated myopericarditis mimicking STEMI (n=1). Colchicine, beta-blockade, and intermittent nitrates was evaluated on Clinical and systolic function recovery. Fluoropyrimidine and bevacizumab therapy induced myopericarditis mimicking STEMI (peak troponin 457 ng/L) in a 71-year-old man, which resolved completely at 6-month follow-up.