Background: It is widely assumed that decline in cognition after coronary artery bypass grafting (CABG) is related to use of the cardiopulmonary bypass pump. Because most studies have not included comparable control groups, it remains unclear whether postoperative cognitive changes are specific to cardiopulmonary bypass, general aspects of surgery, or vascular pathologies of the aging brain.
Methods: This nonrandomized study included four groups: CABG patients (n = 140); off-pump coronary surgery (n = 72); nonsurgical cardiac controls (NSCC) with diagnosed coronary artery disease but no surgery (n = 99); and heart healthy controls (HHC) with no cardiac risk factors (n = 69). Subjects were evaluated at baseline (preoperatively), 3 months, and 12 months. Eight cognitive domains and a global cognitive score, as well as depressive and subjective symptoms were analyzed.
Results: At baseline, patients with coronary artery disease (CABG, off-pump, and NSCC) had lower performance than the HHC group in several cognitive domains. By 3 months, all groups had improved. From 3 to 12 months, there were minimal intrasubject changes for all groups. No consistent differences between the CABG and off-pump patients were observed.
Conclusions: Compared with heart healthy controls (HHC), the groups with coronary artery disease had lower cognitive test scores at baseline. There was no evidence that the cognitive test performance of coronary artery bypass grafting (CABG) patients differed from that of control groups with coronary artery disease over a 1-year period. This study emphasizes the need for appropriate control groups for interpreting longitudinal changes in cognitive performance after CABG.