Several studies have demonstrated the occurrence of “late” cognitive decline approximately 5 years after CABG surgery. However, because most of these studies did not include a control group, a causal link to the use of cardiopulmonary bypass has not been established. The study by van Dijk and colleagues examines the etiology of the late decline by comparing cognitive outcomes 5 years after randomization to either conventional on-pump or off-pump surgery.
Regardless of the choice of methods to define cognitive decline, they found a comparable incidence of late decline at 5 years in their 2 study groups. It thus confirms findings from previous randomized studies that have not found reduced incidence of cognitive decline with off-pump surgery during weeks to months after surgery, but this is the first prospective randomized study comparing cognitive outcomes 5 years after on- or off-pump surgery. Their findings are important because they suggest that factors other than the use of cardiopulmonary bypass are responsible for the late cognitive decline. The authors suggest that normal aging and test-retest variability may account for some of the late cognitive decline. We have previously suggested that normal aging in the context of vascular disease of the brain may be important determinants of late decline and agree that the findings by van Dijk et al emphasize that patient characteristics may be more important for predicting degree of late decline than type of intervention.
Selnes OA, Baumgartner WA. Type of Intervention and Predicting Late Decline. Arch Surg. 2007;142(7):595. doi:10.1001/archsurg.142.7.595