Cognitive Outcomes in Elderly High-Risk Patients 1 Year After Off-Pump Versus On-Pump Coronary Artery Bypass Grafting. A Randomized Trial

Objective: Age is considered to be the strongest predictive factor of postoperative cognitive dysfunction (POCD) after cardiac surgery. Coronary artery bypass grafting (CABG) without the use of cardiopulmonary bypass is considered to be less harmful to the patient, especially in terms of neurological complications.

Methods: The study was a sub-study of the randomized best bypass surgery trial that compares off-pump to on-pump treatment, with respect to peri- and postoperative morbidity in patients with a moderate to high-predicted preoperative risk. We investigated cognitive outcomes. A total of 120 elderly patients (mean age 76 years, SD 4.5 years) underwent cognitive testing before surgery, of which 90 patients (47 vs 43) were available for retesting at 1 year (mean 370 days) postoperatively, using a neuropsychological test battery that included seven parameters from four tests. POCD was defined as the occurrence of at least two deficits out of the seven possible scores. Secondary analysis was performed based on definition of 20% decline in cognitive scores compared to baseline, and using z-score analysis.

Results: The incidence of POCD was 19% (95% CI 9-33) in the off-pump group and 9% (95% CI 3-22) in the on-pump group (p=0.18). There were no significant differences in the incidence of cognitive decline between the off-pump and on-pump group regardless of the definition applied.

Conclusions: We were unable to detect that CABG surgery without cardiopulmonary bypass was associated with significantly better cognitive outcome in elderly high-risk patients 1 year after the operation.