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Encephalopathy More Common Than Stroke After Bypass Surgery

This study highlights that encephalopathy is more common than stroke after bypass surgery and documents factors that increase the post-bypass risk for each condition.

In an attempt to characterize further the neurologic sequelae of coronary artery bypass grafting (CABG), these authors conducted a large, prospective, single-center study of 2711 patients who underwent CABG.

Perioperative encephalopathy was more than twice as common as stroke (6.9% vs. 2.7%). The authors show that predictive models can be developed for encephalopathy. In this patient group, factors predictive of encephalopathy included older age, prior stroke, carotid bruit, hypertension, and diabetes, as well as longer time on cardiopulmonary bypass. Perioperative risk factors for stroke included prior stroke, hypertension, and diabetes. Not surprisingly, patients with postoperative encephalopathy (defined as confusion, agitation, seizures, faulty cognition, or delirium within 24 hours after CABG) had longer hospitalizations and higher mortality rates than patients who had neither encephalopathy nor stroke.

The authors propose possible causes of the encephalopathy, including hypoperfusion, microembolic load, medications, and renal failure. They note that diffusion-weighted images have demonstrated an increased incidence of acute infarctions in both encephalopathy and stroke; they suggest that ischemia is a critical component of encephalopathy. Logistic regression analysis determined that certain factors such as those found in this study could, theoretically, identify patients at risk for post-CABG neurologic complications that might be prevented if the surgical and anesthetic procedures were altered.

Comment: This prospective analysis of a large number of patients undergoing CABG highlights the importance of encephalopathy as a more common neurologic complication than stroke. Although the authors suggest that these complications might be preventable, in practice the suggested changes are extremely difficult to implement. The observation that encephalopathy and stroke are associated with increased mortality and length of stay is no surprise and highlights the importance of reducing their incidence, if possible.

— Jon Brillman, MD

Dr. Brillman is Professor and Chairman, Department of Neurology, Drexel University College of Medicine and Allegheny General Hospital, Pittsburgh, PA.

Published in Journal Watch Neurology November 21, 2002

Citation(s):

McKhann GM et al. Encephalopathy and stroke after coronary artery bypass grafting: Incidence, consequences, and prediction. Arch Neurol 2002 Sep; 59:1422-8.

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