Heart surgery not linked to cognitive decline

By Anthony J. Brown, MD

NEW YORK (Reuters Health) - People who've undergone coronary bypass surgery are often noted to have some degree of mental impairment later on, but new findings indicate that the operation is not to blame for this.

Researchers found that the cognitive decline seen in such patients is comparable to that seen in similar heart disease patients who have not undergone surgery.

"This was surprising to us," Dr. Ola A. Selnes told Reuters Health, but the finding did indicate that the explanation for the late mental decline could not be specifically related to the use of a heart-lung machine during the bypass operation, as had been thought.

"We now think that patients with coronary artery disease also have some degree of vascular disease involving the brain, and this, in combination with normal age-related changes, is most likely to account for the mild late cognitive changes," said Selnes.

Selnes, from Johns Hopkins University in Baltimore, and colleagues used standard tests to assess the cognitive performance of 152 coronary bypass patients and 92 similar heart patients treated medically. They were evaluated at the start of the study and then again after 12 and 72 months.

Mild cognitive decline was seen in both groups, and the degree of change was comparable. Likewise, the percentage of patients in each group with test scores indicating clinical impairment at 72 months was similar, the investigators report in the Annals of Neurology.

In addition to the unexpected main finding, Selnes said his team was also surprised that "memory was not one of the cognitive domains where we found the most significant degree of late decline."

This finding is important, he said, "in dispelling the myth that coronary artery bypass grafting is associated with an increased risk of developing Alzheimer's disease."

SOURCE: Annals of Neurology, May 2008.