Cohort Study of Postoperative Cognitive Dysfunction After Off-Pump Coronary Artery Bypass Grafting

This is a prospective observational cohort study of patients undergoing off-pump coronary artery bypass grafting. The study aims to investigate postoperative cognitive dysfunction and its association with perioperative clinical factors. Eligible patients will be enrolled before surgery and followed after surgery according to the study protocol.

Baseline information will be collected before surgery, including demographic characteristics, medical history, comorbidities, laboratory test results, and preoperative cognitive assessment. Intraoperative and postoperative data will also be collected, including anesthesia-related variables, surgical information, hemodynamic and monitoring parameters, postoperative clinical status, and relevant complications.

Cognitive function will be assessed before surgery and at predefined postoperative time points using standardized cognitive assessment tools, such as the Montreal Cognitive Assessment. Postoperative cognitive dysfunction will be determined according to the predefined criteria based on changes in cognitive assessment results from baseline to postoperative follow-up.

The study will describe the incidence of postoperative cognitive dysfunction after off-pump coronary artery bypass grafting and evaluate the association between perioperative factors and postoperative cognitive outcomes. The results may help improve understanding of postoperative cognitive dysfunction in this surgical population and provide evidence for perioperative risk assessment and clinical management.

• Off-Pump Coronary Artery Bypass Grafting (Procedure): Off-pump coronary artery bypass grafting is performed as part of routine clinical care for patients with coronary artery disease. The study protocol does not assign participants to this procedure or to any additional intervention. This observational study will collect perioperative clinical data and follow patients after surgery to assess postoperative cognitive dysfunction.

Primary outcomes

• Incidence of Postoperative Cognitive Dysfunction [Postoperative Day 7, or 1 Day Before Hospital Discharge if Discharged Before Postoperative Day 7]: Postoperative cognitive dysfunction will be evaluated by comparing postoperative Montreal Cognitive Assessment scores with preoperative baseline scores. Preoperative cognitive function will be assessed using the Montreal Cognitive Assessment 1 day after hospital admission. Postoperative cognitive function will be assessed using the Montreal Cognitive Assessment on postoperative day 7 or, if the patient is discharged before postoperative day 7, 1 day before hospital discharge. Postoperative cognitive dysfunction is defined as a decline in the postoperative Montreal Cognitive Assessment score of at least 1 standard deviation compared with the preoperative baseline score.

Secondary outcomes

• Change in Montreal Cognitive Assessment Score [Postoperative Day 7, or 1 Day Before Hospital Discharge if Discharged Before Postoperative Day 7]: The change in Montreal Cognitive Assessment score will be calculated by comparing the postoperative score with the preoperative baseline score. Preoperative cognitive function will be assessed 1 day after hospital admission, and postoperative cognitive function will be assessed on postoperative day 7 or, if the patient is discharged before postoperative day 7, 1 day before hospital discharge.
• Length of Intensive Care Unit Stay [through ICU discharge, an average of 3 days]: The length of intensive care unit stay will be recorded as the number of days from admission to the intensive care unit after surgery to discharge from the intensive care unit.
• Length of Postoperative Hospital Stay [through hospital discharge, an average of 7 days]: The length of postoperative hospital stay will be recorded as the number of days from the date of surgery to the date of hospital discharge.
• Incidence of Postoperative Complications [through hospital discharge, an average of 7 days]: Postoperative complications during hospitalization will be recorded, including cardiovascular, respiratory, neurological, renal, infectious, thromboembolic, and wound-related complications.
• Duration of Postoperative Mechanical Ventilation [through ICU stay, an average of 3 days]: The duration of postoperative mechanical ventilation will be recorded as the time from postoperative intensive care unit admission to successful discontinuation of mechanical ventilation.
• Incidence of Postoperative Nausea and Vomiting [through hospital discharge, an average of 7 days]: Postoperative nausea and vomiting during the postoperative hospitalization period will be recorded based on medical records.
• Incidence of In-Hospital Mortality [through hospital discharge, an average of 7 days]: In-hospital mortality will be recorded as death from any cause during the postoperative hospitalization period.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Age 18 years or older
* Scheduled to undergo elective off-pump coronary artery bypass grafting
* American Society of Anesthesiologists physical status classification I to IV
* Able to complete preoperative cognitive assessments, including the Mini-Mental State Examination and the Montreal Cognitive Assessment
* Written informed consent provided by the patient or family member

Exclusion Criteria:

* Emergency surgery
* Pre-existing diagnosed cognitive impairment or history of psychiatric disease
* Preoperative cognitive impairment
* Severe neurological disease, such as sequelae of stroke, that may interfere with cognitive assessment
* Severe visual or hearing impairment that prevents completion of cognitive assessment
* Inability to understand Chinese or presence of language communication barriers

• Wenjun Liu, PhD, Principal investigator, Beijing Anzhen Hospital