Background: Cognitive impairment after coronary artery bypass grafting (CABG) is well recognized, but previous investigations have been limited by lack of an appropriate control group. We compared changes in cognitive performance at 3 and 12 months after CABG with those in a control group of patients with comparable risk factors for coronary artery disease (CAD) who had not undergone surgery.
Methods: Patients undergoing CABG (n = 140) and demographically similar nonsurgical control subjects with CAD (n = 92) completed baseline neuropsychological assessment and were followed prospectively at 3 and 12 months. Cognitive function was evaluated with a battery of neuropsychological tests assessing the cognitive domains of attention, language, verbal and visual memory, visuoconstruction, executive function, and psychomotor and motor speed.
Results: The CABG patients who were tested in their hospital rooms before surgery had lower scores for timed tests; however, after adjustment for demographic variables and testing location there were no statistically significant differences between the CABG and nonsurgical control subjects in baseline neuropsychological test performance. Both groups improved from baseline to 3 months; the only statistically significant group difference was a greater improvement in the CABG group with regard to verbal memory. At 12 months there were no statistically significant differences between the two groups.
Conclusions: The prospective longitudinal neuropsychological performance of patients with CABG did not differ from that of comparable nonsurgical control subjects with CAD at 3 months or 1 year after base line examination. This suggests that the previously reported cognitive decline during the early postoperative period after CABG is transient and reversible. Continued follow-up will determine whether a specific "late decline" occurs in CABG patients but not in nonsurgical control subjects with similar risk factors for cardiovascular and cerebrovascular disease.