Neurocognitive dysfunction after coronary artery bypass surgery: A systematic review

Objective: Substantial, albeit scattered, evidence suggests that coronary a rtery bypass grafting may impair cognitive function. As methods and definit ions differ greatly across studies, the reported incidence of cognitive dec line after coronary bypass surgery varies widely as well. The aim of the pr esent study was to systematically review those studies on cognitive decline that are relatively comparable and meet with certain quality criteria. Methods: Four electronic databases and the references of several abstract b ooks and earlier reviews were used to identify relevant literature. Stringe nt criteria, based in part on the 1994 consensus meeting on assessment of n eurobehavioral outcomes after cardiac surgery, were used to assess the stud ies that were found. In total, 256 different titles were found, of which 23 met with the formulated selection criteria. Results: Twelve cohort studies and eleven intervention studies were evaluat ed. A pooled analysis of six highly comparable studies yielded a proportion of 22.5% (95% confidence interval, 18.7%-26.4%) of patients with a cogniti ve deficit (a decrease of at least 1 standard deviation in at least two of nine or ten tests) 2 months: after the operation. Conclusions: Neurocognitive dysfunction is a frequently occurring complicat ion of coronary artery bypass grafting. The etiologic contribution of cardi opulmonary bypass to this complication will remain unclear until a randomiz ed trial that directly compares off-pump and on-pump bypass surgery is carr ied out.