Mental Decline After Coronary-Artery Bypass Surgery
Mental Decline After Coronary-Artery Bypass Surgery
http://www.coloradohealthnet.org/CHNReports/mentaldecline_bypass.html?printit
Mental Decline After Coronary-Artery Bypass Surgery
Longitudinal Assessment of Neurocognitive Function after Coronary-Artery Bypass Surgery, by Mark F. Newman, Jerry L. Kirchner, Barbara Phillips-Bute, Vincent Gaver, Hilary Grocott, Robert H. Jones, Daniel B. Mark, Joseph G. Reves, James A. Blumenthal, for the Neurological Outcome Research Group and the Cardiothoracic Anesthesiology Research Endeavors Investigators; The New England Journal of Medicine, February 8, 2001; Related Editorial, Coronary-Artery Bypass Surgery and the Brain, by Ola A. Selnes, Ph.D. and Guy M. McKhann, M.D., Johns Hopkins University.
Background
Here is the important background information that the authors give us:
cognitive or mental decline is recognized as a complication after cardiac surgery,
the incidence of the mental decline has changed little over the past 15 years despite advances in techniques for anesthesia, surgery, and the protection of organs,
elderly patients are at substantially increased risk for mental decline after surgery,
many clinicians have minimized the importance of post-operative mental decline because the decline appears to be transient in a substantial number of patients,
yet, in many patients, the decline has been shown to persist for at least 6 months. No studies have measured the course of the decline over a long term.
Purpose of This Study
The authors undertook this study to determine the course of mental change during the 5 years after coronary-artery bypass surgery.
Participants and Methodology
A total of 261 patients undergoing elective coronary-artery bypass surgery at the Duke Heart Center from March 1989 through November 1993 were enrolled in the study. The patients were given a brief set of neurocognitive tests before surgery, again on the day before discharge, and at 6 weeks, 6 months, and 5 years after their surgery. The tests measured the ability of the patients to:
repeat in numerical order a series of numbers presented to them orally and then to repeat the numbers in reverse order,
reproduce from memory a series of geometric shapes,
reproduce randomly generated numbers matched with symbols, and
connect with a line a series of numbers and letters in sequence.
These 4 factors represent the mental domains for verbal memory and language comprehension; abstraction and visuospatial orientation; attention and concentration; and visual memory. Mental decline was defined as 1 standard deviation in performance in any 1 of the 4 domains. One standard deviation represents a 20% decline in function.
Results
Here is what the study found:
mental decline was found in 53% of the patients at discharge,
the incidence of decline decreased to 36% at 6 weeks and 24% at 6 months.
but, 5 years after surgery, the incidence of mental decline increased to 42%,
those patients who did not have early postoperative mental decline, also did not have long-term decline,
in contrast, the patients who did have early postoperative decline, also had a long-term decline that was similar to that at discharge.
Authors? Summary and Conclusions
The authors summarize their findings as follows: Patients whose mental function declines immediately after surgery are at increased risk for long-term mental decline and a reduced level of overall mental functioning. Moreover, certain patients are at greater risk for early postoperative mental decline than others. In this study, patients who had early decline were more likely to be older and have a lower level of education than those who did not have early decline.
The authors suggest that patients who have early cognitive decline may be candidates for aggressive intervention strategies to prevent the late cognitive deterioration that this study documents.
Related Editorial
The authors of the editorial note that stroke and postoperative delirium are two of the more serious mental complications of coronary-artery bypass surgery. Postoperative delirium occurs after coronary-artery bypass surgery in about 10-30% of patients and may be related in part to anesthesia.
The editorial also suggests that the late decline in mental performance may be related to the surgical procedure itself. For example, in some patients, manipulation of the aorta during the surgery releases clots that can occlude vessels in the brain.
They urge that patients undergoing coronary-artery bypass surgery would benefit from postoperative changes in their diets, medications, and lifestyle.
Ed Asks: What Should You Do With This Report?
If you are about to undergo elective coronary artery bypass surgery, you should take this article to your doctor, surgeon, and anesthesiologist and ask which protective procedures are most appropriate for you. If, after surgery, you are found to have cognitive decline, you should ask about changes in your diet, medications, and lifestyle that may protect you against later decline.