Early Cognitive Impairment After CABG Harbinger of Later Cognitive Decline

Cognitive decline following coronary artery bypass grafting (CABG) can persist for years, especially among patients with impaired cognitive function at the time of discharge following surgery.

In a prospective investigation, Dr. Mark F. Newman and associates, of Duke University Medical Center in Durham, North Carolina, administered a battery of five neurocognitive tests to 261 patients. Assessments were performed just before surgery, at discharge approximately 7 days after surgery, and at 6 weeks, 6 months, and 5 years after surgery. A total of 172 patients completed the followup.

“The key important finding of the trial was that acute cognitive dysfunction occurring after bypass surgery predicted long-term cognitive decline at 5 years,” Dr. Newman told Reuters Health.

The investigators observed cognitive decline in 53% of patients at discharge and in 36%, 24%, and 42% at the succeeding time points. Significant differences were noted at 5 years in patients with and without evidence of early postoperative decline. In those without, the composite cognitive index score at 5 years was approximately the same as the baseline level.

“In contrast,” Dr. Newman’s group writes in The New England Journal of Medicine for February 8, “the composite cognitive index score of patients who had early postoperative cognitive impairment declined below baseline levels to a level similar to that assessed at discharge.”

The association between perioperative and long-term cognitive decline remained significant after adjustment for factors such as age, educational level, and baseline score.

“Because we have come so far in reducing mortality and severe complications, we are looking at making a fairly safe operation safer,” Dr. Newman remarked, “so I wouldn’t want people who need the surgery not to have it. But it brings up the importance of early–what we considered in some ways transient–changes in long-term function.”

Sex, duration of cardiopulmonary bypass, and duration of aortic cross-clamping were not associated with long-term decline. However, left ventricular ejection fraction approached significance, “indicating that patients with cardiac dysfunction may be at increased risk for overall cognitive decline after cardiac surgery,” the authors write.

In an editorial, Drs. Ola A. Selnes and Guy M. McKhann, of Johns Hopkins University in Baltimore, suggest that embolic material released during the manipulation of the aorta may occlude small and large vessels. Their recommendation for patients at increased risk of late cognitive decline after CABG is medications and changes in diet and lifestyle to slow the progress of vasculopathy.

N Engl J Med 2001;344:395-402,451-452.