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No Link Between Bypass Surgery, Memory Loss

Underlying Heart Disease, Not Surgery, Linked to Subtle Mental Decline

By Charlene Laino
WebMD Health News

Reviewed By Louise Chang, MD

Oct.14, 2009 (Baltimore) -- Despite reports to the contrary, having bypass surgery to help your heart does not harm your brain, researchers report.

In a new study, no support was found for a link between heart bypass surgery and memory loss or other mental declines. The underlying heart disease that led patients to have heart bypass surgery was associated with memory loss, however.

"The good news is that the cognitive decline is very subtle, so subtle that people thought the changes were part of [the memory loss that accompanies] normal aging," says Johns Hopkins School of Medicine neuropsychologist Ola A. Selnes, PhD.

The findings were presented at the annual meeting of the American Neurological Association (ANA).

Heart Bypass Surgery

Heart bypass surgery involves rerouting blood around clogged arteries to improve the supply of blood and oxygen to the heart.

Researchers from Duke University first raised concerns about the long-term impact of the surgery on memory and mental function in a highly publicized study eight years ago. The researchers reported that more than a third of patients with coronary artery disease still had measurable mental decline five years after having heart bypass surgery.

But the Duke researchers did not compare the bypass patients to people with coronary artery disease who underwent treatments other than bypass surgery or to healthy adults with no heart disease, Selnes says. So it was not clear if the mental declines were caused by the heart bypass surgery, the heart disease that prompted the surgery, or by natural aging.

The new study involved 69 heart-healthy people and 326 people with coronary artery disease. Coronary artery disease is usually caused by the buildup of plaque on the inside of the coronary arteries, the blood vessels that supply oxygen-rich blood to the heart muscle.

Of the 326, about half had bypass surgery, one-fourth took medications, and the rest underwent off-pump surgery in which the surgeon operates on the beating heart. "It's a very demanding operation," Selnes says.

Plaque Buildup Probably Cause of Mental Decline

During four checks over the next four years, there were no significant differences in memory or other mental functions between the heart patients who had bypass, those who took medications, and those who had off-pump surgery.

At four years, however, all three groups of heart patients scored significantly worse on tests of memory, decision-making, and visuospatial relations than the heart-healthy people.

"What matters is whether you have coronary artery disease, not what treatment you receive," Selnes tells WebMD. "If your doctor recommends bypass surgery, you shouldn't avoid it because of concerns about cognitive decline."

Craig Blackstone, MD, PhD, a researcher at the National Institute of Neurological Disorders and Stroke who is on the ANA's executive council, says the findings make sense.

People who have plaque buildup in the vessels leading to the heart probably have plaque buildup in the arteries leading to the brain that can lead to cognitive decline, he says.

Combination of Risk Factors Predicts Mental Decline

The researchers then performed a second study to determine which people with coronary artery disease are most likely to experience memory loss and other mental declines.

The study involved about 150 heart patients who underwent bypass surgery, 150 heart patients who took medication, and 69 people with no known risk factors for heart disease.

"As expected, people who were older and had less education experienced faster cognitive decline," Selnes says. Having plaque buildup in all three of the main heart arteries and a history of irregular heartbeats known as atrial fibrillation also predicted faster memory loss and mental decline.

But people with coronary artery disease at greatest risk of mental decline were those with a combination of risk factors, including high blood pressure, a past stroke, and diabetes, the study showed.

Blackstone tells WebMD that many of the risk factors for coronary artery disease, such as high blood pressure and smoking, are also risk factors for plaque buildup in the brain and cognitive decline.

"If you do things to prevent one, you can prevent the other," he says.

SOURCES: 134th Annual Meeting of the American Neurological Association, Baltimore, Oct. 11-14, 2009.

Ola A. Selnes, PhD, department of neuropsychology, Johns Hopkins School of Medicine, Baltimore.

Craig Blackstone, MD, PhD, National Institute of Neurological Disorders and Stroke.

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