This prospective cohort study aims to investigate postoperative cognitive dysfunction in patients undergoing off-pump coronary artery bypass grafting. Eligible patients will be enrolled before surgery and followed after surgery. Cognitive function will be assessed using the Montreal Cognitive Assessment before surgery and at predefined postoperative time points. Perioperative clinical information, including preoperative assessment data, intraoperative monitoring parameters, and postoperative clinical data, will be collected. The study will evaluate the occurrence of postoperative cognitive dysfunction and explore its association with perioperative factors.