Should the left internal mammary artery (LIMA) be imaged before radiotherapy in cases of unexpected early acute coronary syndrome?

Abstract

Abstract Funding Acknowledgements None. Case A 41-year-old male patient presented to the cardiology outpatient clinic with a complaint of exertional chest pain persisting for the past 4 months, along with occasional palpitation attacks. In his medical history, aside from being diagnosed with lymphoma 15 years ago, there were no known additional comorbidities. The electrocardiogram (EKG) revealed sinus rhythm (84 beats/minute), and the blood tests showed creatinine: 0.81 mg/dL, WBC: 11.26 mm^3, LYM: 3.69 mm^3. Transthoracic echocardiography demonstrated an ejection fraction (EF) of 60%, with no additional pathologies except for grade 1 diastolic dysfunction. Considering the presence of typical chest pain, coronary imaging was performed to assess for stable angina. The coronary imaging revealed a lesion extending from the left main coronary artery (LMCA) to the proximal left circumflex artery (CX), with an 80% stenosis in the mid-segment of the LMCA, a 60% stenosis at the narrowest point of the CX proximal segment, and an 80% stenosis in the proximal right coronary artery (RCA). The left circumflex artery obtuse marginal branches (CX OM) appeared thin and extensively diseased (Figure-1) The patient was promptly scheduled for early coronary artery bypass grafting (CABG), transferred to the cardiac surgery intensive care unit, and underwent a successful coronary bypass procedure with LAD-LIMA, Ao-saphenous-IM-saphenous-CxOM1 (sequential) grafting. Throughout the postoperative follow-up period, the patient continued to experience exertional chest pain despite medical treatment. A repeat coronary angiography was performed, revealing that the bypass grafts were opened, but a diffuse 80% stenosis was detected at the mid-segment of the LIMA graft, prior to the anastomosis.(Figure-2) Successful stent placement was performed at the narrowest point of the LIMA mid-segment (Figure-3).The patient had no anginal complaints during post-procedure follow-up and has been stable under observation. Discussion Routine clinical practice does not involve LIMA imaging in patients who have undergone diagnostic coronary angiography with multi-vessel involvement and a CABG decision. However, the use of coronary artery bypass graft surgery (CABG) may entail a risk of rendering the graft unusable due to extensive mediastinal fibrosis and radiation-induced damage to the left or right mammary artery. Therefore, in patients with a history of radiation exposure in the thoracic region and a CABG decision, the visualization of the intermammary artery during coronary angiography and the consideration of alternative grafts, such as the radiation-free radial artery, or the necessity for high-risk percutaneous stent implantation, should be discussed.figure-1figure-2