WASHINGTON — There doesn't appear to be any difference in long-term cognitive function following coronary artery bypass graft or stenting.
This finding comes from an assessment of cognitive function at 6 years in 152 patients whose coronary artery disease (CAD) was treated with coronary artery bypass graft (CABG) and 92 patients whose CAD was treated with stents. Dr. Guy McKhann, professor of neurology and neuroscience at Johns Hopkins University, Baltimore, and his colleagues found that cognitive declines noticed after surgery are related to the presence of vascular disease. “The real attention should be on modifying risk factors,” he said, adding: “We think that how these people do is very much dependent on how their brains are going in [to surgery].”
In terms of cognitive change over 6 years, there was minimal decline, but essentially these two groups were the same, Dr. McKhann reported at the annual meeting of the American Neurological Association. The average Mini-Mental State Examination (MMSE) score was 27.4 for the CABG group and 27.9 for the stent group. The average Center for Epidemiologic Studies-Depression (CES-D) scale score was 9.5 for the CABG group and 9.0 for the stent group. (See table.)
The issue of long-term cognitive decline following coronary artery surgery is an important one, given that there continues to be uncertainty over the best approach to treat coronary artery disease—surgery or stenting. “This issue of late decline has gotten into this debate” and is used as an argument for stenting rather than surgery, he said.
“We don't think there is any selective long-term decline after CABG that cannot be seen in other groups with significant coronary artery disease. We don't think late decline should be an issue in the choice of what procedure you're going to have done,” said Dr. McKhann.
The researchers have been studying the issue of neurologic outcomes following coronary surgery since 1992. “What we set up then was a prospective evaluation of all heart surgery patients within the intensive care unit,” said Dr. McKhann.
Starting in 1997, the work that Dr. McKhann and his colleagues were doing with acute-care patients became a four-arm study involving those undergoing conventional CABG, those with off-pump CABG, cardiac controls who received stents, and heart-healthy controls lacking traditional risk factors for heart disease. The researchers looked at cognition at baseline, 3 months, 1 year, 3 years, and 6 years.
In this CAD intervention population, 3%–5% have strokes, 10%–15% have encephalopathies, and about 25% have short-term cognitive problems. In-hospital mortality is 22% following a stroke, 7.5% following encephalopathy, and 12% following both.
“If you have coronary artery disease … you're going to be lower at baseline than the heart-healthy controls but not in all cognitive domains,” he said.
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