Cognition Impaired After Bypass Surgery in Smokers

Martha Kerr

November 14, 2006

November 14, 2006 (Chicago) — Cognition can be adversely affected by cardiopulmonary bypass graft surgery in patients who smoke, even when there are no complications with the surgical procedure itself, researchers announced here at the American Heart Association (AHA) 2006 Scientific Sessions.

Postoperative cognitive decline is seen in as many as 75% of patients undergoing heart surgery, James P. Slater, MD, a cardiac surgeon at Morristown Memorial Hospital in New Jersey, told meeting attendees. A history of smoking more than doubles that risk above normal baseline levels.

Dr. Slater and colleagues prospectively assessed cognitive function before and after bypass surgery in 240 patients. The data were then analyzed to assess smoking as an independent predictor of cognitive impairment. In the study group, 68% were smokers or former smokers.

"Patients were 2 times more likely to have a cognitive decline if they had a history of smoking," Dr. Slater told AHA meeting attendees, "and 60% of smokers showed evidence of some cognitive decline." Other risk factors for cerebrovascular disease, including older age and lower educational level, were also associated with impaired cognitive function.

Dr. Slater said there is evidence that as many as 75% of all bypass patients have some cognitive decline.

He described the case of a 71-year-old woman who smoked. After undergoing bypass surgery, "she complained that she couldn't get past Thursday on The New York Times crossword puzzle, but she couldn't explain why." Before surgery, she was able to routinely complete the Sunday puzzle, the most difficult level.

The surgery itself increases risk," Dr. Slater said, "and we know inhaled nicotine is a vasoconstrictor and bad for the brain. Chronic vasoconstriction could result in decreased oxygen delivery to brain tissue over time."

In addition, "the heart-lung bypass machine itself poses a risk" of impaired cognition, Elliott Antman, MD, professor of medicine at Harvard University in Boston, Massachusetts, and a national spokesperson for the AHA, told Medscape.

From a goal of simple patient survival after bypass surgery when it was first being performed in the 1970s and 1980s, surgeons are now in a position to be able to "fine-tune" patient outcome, with the goal of minimizing adverse neurocognitive effects, Dr. Slater commented.

"This is good news," Dr. Antman said. "We're always looking for ways to prevent neurocognitive decline, and this [smoking] is a potentially correctable problem.

"If we can convince a patient to stop smoking by informing him of the cognitive effects, we could reduce the risks back to background levels," Dr. Antman added.

Dr. Slater has no relevant financial relationships, he said, but the study was designed to assess the effects of the Somanetics INVOS 5100B (Somanetics Corporation, Troy, MI), a device that noninvasively measures oxygen levels in the brain during surgery. Dr. Antman reported no relevant financial relationships.

AHA Scientific Sessions 2006: Abstract 2327. Presented November 13, 2006.

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