Apr 4 2008
For many years, assumptions have lingered that Coronary Artery Bypass Surgery Grafting (CABG) produces measurable cognitive impairment, either because of the surgery or use of cardiopulmonary bypass.
Recent studies have failed to resolve the issue, because of complications in cognitive testing processes and comparison methods. Thus, despite improvements in surgical procedures, the weight of evidence across decades of clinical research has continued to suggest that CABG produces some degree of cognitive impairment.
Now a team led by Todd K. Rosengart, M.D., Chief of Cardiothoracic Surgery and Co-Director of the Heart Center at Stony Brook, and colleagues, have completed a more definitive study showing that one year after coronary bypass surgery, patients showed no measurable cognitive impairment. An article detailing the study was published in the January 2008 issue of The Annals of Thoracic Surgery.
"For those undergoing surgery, the idea that repairing their hearts could cause damage to their mental powers is very stressful,” Dr. Rosengart comments. “Now, as a result of this research, we can reassure our patients that this risk is insignificant.”
Two groups of cardiac patients were selected, one referred for CABG and the second for percutaneous coronary intervention (PCI). A third group, a cohort of healthy control subjects similar to the cardiac patients in age and education, was also recruited.
The groups were tested to obtain baseline measurements and the surgical patients were again tested three weeks, four months and 12 months after surgery. Fourteen age-specific examinations that included processing speed, language, learning and memory, fine motor dexterity and more were administered each time.
Twenty-nine CABG patients, 37 PCI patients and 40 in the “healthy” control group completed the full series of assessments. The result after careful statistical analysis: no clear pattern of change in cognitive function, or differences between the groups, was demonstrated.
“Improvements in CABG surgical technique that have been introduced over the past decade may have resulted in better preservation of cognitive function after open heart surgery compared with earlier analyses,” the authors comment.
While their study was limited in sample size and by its observational nature, using healthy controls plus a relevant nonsurgical comparison group provided advantages over other studies, Dr. Rosengart's team notes. Larger studies can usefully investigate subgroup risk factor, they recommend, so that CABG candidates who could suffer cognitive impairment may be better identified.
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