Patient
The study was designed as a retrospective observational study and approval to conduct this study was obtained from Ethics Committee of Shanghai Changhai Hospital. This study included a consecutive series of patients in the department of cardiothoracic surgery center between January 2012 and December 2019 who were underwent OPCABG treatment. Excluded from the study were patients who preoperatively were treated with antipsychotic drugs, and those with a history of mental problem, head injury, neurological dysfunction, patients conversion to CPB and those who underwent emergency operations or reoperations1,22-25.