We report the case of a 47-year-old woman who was admitted to the cardiac department for worsening dyspnea. The last chest computed tomography (CT) showed a rapid increase in pulmonary artery dimension (65 mm in 2019, 76 mm in 2021). The symptoms reported by the patient were due to important extrinsic compression of the left main coronary artery (LMCA). In this case, it is very difficult to choose the best therapeutic strategy. In the end, we decided to treat the left main coronary for prevention. After 3 months no new clinical symptoms have developed.