Absence of cognitive decline one year after coronary bypass surgery: comparison to nonsurgical and healthy controls

Cognitive decline after open-heart surgery has been the subject of a number of conflicting reports in recent years. Determination of possible cognitive impairment due to surgery or use of cardiopulmonary bypass is complicated by numerous factors, including use of appropriate comparison groups and consideration of practice effects in cognitive testing.

Neuropsychological data were gathered from 46 healthy controls, 42 cardiac patients referred for percutaneous coronary intervention (PCI), and 43 cardiac patients referred for coronary artery bypass grafting (CABG). Fourteen cognitive function tests were utilized at baseline and at three time points after surgery (3 weeks, 4 months, 1 year). Measures showing acceptable test-retest reliability based on intraclass correlations were compared using regression-based reliable change indices.

No clear pattern of group differences or change at follow-up emerged. A greater percentage of CABG patients than controls worsened in seven tests (three at 1 year), but a greater percentage of PCI patients than controls also worsened in seven tests (three at 1 year). Generalized estimating equations showed only two tests (Wechsler Adult Intelligence Scale, Third Edition, Digit Symbol, and Hopkins Verbal Learning Test, Revised, Total Recall) to be significantly different between groups from baseline to 1 year. Interestingly, compared with healthy controls, more PCI patients than CABG patients worsened in the former of those two tests, whereas more PCI and CABG patients improved on the latter.

Using healthy controls and a relevant nonsurgical comparison group to contend with important methodological considerations, current CABG procedure does not appear to create cognitive decline.