Abstract The impact of coronary artery disease (CAD) on all–cause mortality and overall disabilities is well–established. Percutaneous and/or surgical coronary revascularization procedures dramatically reduced the occurrence of adverse cardiovascular events in patients suffering with atherosclerosis. Specifically, guidelines from the European Society of Cardiology on the management of myocardial revascularization promoted coronary artery by–pass graft (CABG) intervention in patients with specific alterations in coronary tree due to higher beneficial effects of this procedure as compared to percutaneous one. Left internal mammary artery (LIMA) is one of the best–performing vessels in CABG procedures due to its location and its own structural characteristics. Nevertheless, non–invasive assessment of its patency is challenging. Doppler Ultrasonography (DU) might perform as a reliable technique for non–invasive evaluation of the patency of LIMA. Data from literature revealed that DU may detect severe (>70%) stenosis of the LIMA graft. In this case, pulsed–wave Doppler might show peak diastolic velocity/peak systolic velocity < 0.5 and diastolic fraction < 50%). Stress test might also be adopted for the evaluation of patency of LIMA through DU. The aim of this narrative review is to evaluate the impact of DU on the evaluation of the patency of LIMA graft in patients who undergo follow–up after CABG intervention. The aim of this narrative review is to evaluate the impact of DU on the evaluation of the patency of LIMA graft in patients who undergo follow–up after CABG intervention.