Cognitive deficits following coronary artery bypass grafting: prevalence, prognosis, and therapeutic strategies

There is increasing recognition that coronary artery bypass grafting (CABG) may be a risk factor for subtle cognitive decline although the presence and pattern of such decline has varied across studies. Cognitive deficits may present as short-term memory loss, executive dysfunction and psychomotor slowing. Although they are usually are not severe enough to meet criteria for mild cognitive impairment or vascular dementia, they lower quality of life and add to hospitalization and out-of-hospital costs. Proposed mechanisms include surgical-related trauma, genetic susceptibility (eg, apolipoprotein E4 allele), microembolization, other vascular or ischemic changes, and temperature during surgery. Depression and anxiety levels predict subjective perception of these deficits more than objective cognitive performance. Both nonpharmacologic (eg, emboli reduction, temperature, or glucose management) and pharmacologic (eg, dexanabinol, glypromate, nootropics) strategies to prevent post-CABG cognitive deficits are under investigation. Given the large numbers of subjects who may already have CABG associated cognitive deficits, clinical trials of agents being tested for Alzheimer's disease (eg, donepezil, rivastigmine, memantine, neramexane, ginkgo) may also be informative. The results of multicenter long-term outcome studies (with matched control groups) as well as ongoing treatment trials will more conclusively address some of these issues. These data emphasize the need for clinicians to monitor cognitive function before and after coronary bypass surgery, and to educate patients.