Defining neuropsychological dysfunction after coronary artery bypass grafting

Background. Despite the large body of literature documenting the presence of cognitive decline after coronary artery bypass grafting, there is little consensus as to the frequency and extent of cognitive impairment. One potential reason for this lack of agreement is the absence of uniform criteria for assessing cognitive decline. Methods. Two hundred thirty-two patients underwent cognitive testing the day before operation and were examined before discharge, and at 6 weeks and 6 months after grafting. For comparative purposes, five different sets of criteria were used to define cognitive decline. Results. There was little agreement between the criteria as to which patients declined at each test period. The incidence of decline ranged from 66% to 15.3% before discharge, 34% to 1.1% at 6 weeks, and 19.4% to 3.4% at 6 months. Conclusions. A large variation in reported incidence of cognitive decline after coronary artery bypass grafting can be attributed to the different criteria used to define cognitive impairment.