Asymptomatic Carotid Artery Stenosis and Cognitive Outcomes After Coronary Artery Bypass Grafting

Abstract

Conclusion: Asymptomatic >50% carotid stenosis is a risk factor for cognitive decline after coronary artery bypass grafting (CABG). Summary: Patients anticipate CABG will improve their quality of life (Koch CG et al, Semin Cardiothorac Vasc Anesth 2008;12:203-17). Preservation and improvement of psychologic emotional well-being enhances quality of life. Neuropsychologic disorders are being more frequently addressed in the care of the postoperative patient. Cerebrovascular disease and coronary artery disease potentially put patients at risk for cognitive decline. In this report, the authors correlate asymptomatic carotid stenosis with cognitive decline after coronary artery bypass grafting (CABG). They sought to detect the incidence of cognitive decline after CABG, identify risk factors associated with such cognitive decline, and investigate a possible link between cognitive performance and asymptomatic carotid stenosis. The authors studied 127 patients who underwent CABG. The patients underwent a neuropsychologic examination that included seven cognitive tests and two scales for evaluation of mood disorders. The patients were tested the day before surgery and before discharge from the hospital. Testing revealed that early postoperative decline was common and was detected in 46% of patients. Postoperative cognitive decline was associated with low cardiac output syndrome perioperatively (P < .05), postoperative bleeding (P = .03), longer duration of surgery (P = .02), and longer intensive care unit stay and postoperative mechanical ventilation time (P < .05). Multivariate regression analysis indicated carotid artery stenosis of >50% was a strong independent predictor of postoperative cognitive decline (odds ratio, 26.9; 95% confidence interval, 6.44-112.34). Comment: The authors' data indicate an association between cognitive decline after CABG and the presence of >50% carotid stenosis. One cannot, however, derive from this data that the carotid stenosis itself leads to cognitive decline after CABG. Indeed, we know that repair of asymptomatic carotid stenosis before CABG has minimal, if any, impact on more obvious clinical end points such as stroke and death after CABG. This study did not have cerebral imaging before and after CABG to correlate with the neurophysiologic testing. At this time, it seems more likely the carotid stenosis is more of a marker for more advanced preexisting intracranial vascular disease potentially associated with cognitive decline after CABG than a potential target for intervention to decrease cognitive decline after CABG.