The goal of this observational study is to test the association between high levels of Galectin-3 and the occurrence of post-operative atrial fibrillation after isolated coronary artery bypass grafting (CABG). The main question\[s\] it aims to answer are: * Is Galectin-3 an accurate biomarker to predict higher risk of developing post-operative atrial fibrillation? * Are high levels of Galectin-3 associated to other post-operative complications and major adverse cardiovascular events? Participants will be enrolled during pre-operative evaluation and a peripheral blood sample collection will be performed in the 24h before CABG. Participants will then be followed for a period of 12 months (daily during hospitalization and 3 appointments after hospital discharge) to determine whether patients with higher levels of Galectin-3 will have worse outcomes.