May 27, 2008 — Cognition among people with heart disease declines over time, regardless of whether they undergo bypass surgery or receive alternative forms of treatment, according to a new study published in the May issue of the Annals of Neurology.
The 6-year observational study provides further evidence that the cognitive decline of heart patients is due to vascular disease that might be curbed by heart-healthy lifestyle practices such as diabetes management, being a nonsmoker, and blood-pressure control, said 1 of the study authors, Guy M. McKhann, MD, professor of neurology at Johns Hopkins University School of Medicine, in Baltimore, Maryland.
"We think these are people who have vascular disease of the brain going into the study, whether they're in the surgery or nonsurgery group. I think we're watching the progression of vascular disease of the brain over a 6-year period," he told Medscape Neurology & Neurosurgery.
The finding could mean that the heart disease treatment pendulum, which began to swing in favor of stents after observations that surgery resulted in cognitive decline, might well swing back toward surgery, said Dr. McKhann.
Back to Surgery?
The Johns Hopkins researchers compared the cognitive status of 152 patients undergoing elective or urgent coronary artery bypass grafting (CABG) and 92 cardiac patients receiving other treatments such as stents or pharmaceuticals.
The patients completed a medical history review and a battery of standardized neuropsychological tests at baseline, 3 months, 1 year, 3 years, and 6 years. Tests included the Mini Mental State Examination (MMSE), the Center for Epidemiological Studies Depression Scale (CES-D), and the Functional Status Questionnaire (FSQ). Among the functions observed were memory, motor speed, attention, and the ability to plan ahead. The investigators controlled for influences of education, age, and sex.
The 2 treatment groups began with about the same cognitive scores, and both showed improvements from baseline to 1 year. However, all patients experienced subsequent similar declines in performance for all cognitive domains. "We found no statistically significant or clinically meaningful differences in the degree of decline in cognitive test performance over time between the CABG patients and the nonsurgical comparison patients," the authors wrote.
Language and Memory Not Affected
Interestingly, unlike in Alzheimer's disease, where memory is affected, the most striking areas of cognitive decline in these heart patients were those related to decision making — for example, tasks requiring speed of processing or speed of response — and those requiring executive function, said Dr. McKhann. "Things like language and memory are not particularly affected" in these groups, he said.
In comparing the degree of cognitive change in the 2 groups, the authors stated that for the CABG patients, the only statistically significant declines were in visuoconstruction — for example, naming common items from pictures (P < .01) — and executive function (P = .02). For the nonsurgical group, declines were statistically significant in visuoconstruction (P < .01) and motor speed (P = .01).
For MMSE performance, mean scores at baseline and at 72 months were similar in the 2 groups. At baseline, 5% of the CABG and 6% of the nonsurgical patients had MMSE scores below normal (< 24). From baseline to 72 months, the average within-patient change on the MMSE was a decline of 0.22 for the CABG group and 0.16 points for the nonsurgical patients.
The results of this research could mean an increase in cardiac surgery, Dr. McKhann told Medscape Neurology & Neurosurgery. In recent years, many doctors veered away from surgical interventions after observational evidence pointed to its negative effect on cognition; 1 study found that 40% of people treated with CABG had significant cognitive decline, said Dr. McKhann.
Many believed the culprit was the pump used during bypass surgery. "The pendulum swung way over to the stents for awhile, 1 of the arguments being that if you have heart surgery, you're hurting your brain, but now we’re saying that that evidence isn't there," said Dr. McKhann. "There may be reasons for choosing the stent, but that [cognitive decline with surgery] isn't one of them."
Safety of Stents Questioned
Another argument for revisiting the surgical approach is that the long-term safety of stents is now being questioned, added Dr. McKhann.
The study highlights the need to examine the impact on the brain, as well as the heart, of risk factors such as smoking, uncontrolled diabetes, and high blood pressure. "We have always been thinking in terms of the heart; if we do this [particular behavior] we prevent heart attacks and deaths, but what about the brain?" said Dr. McKhann. "What helps the heart helps the brain."
This study is part of continuing research involving 4 groups (the other 2 are patients undergoing off-pump heart surgery and heart-healthy controls). The already-published 3-year data on all groups uncovered evidence that all heart patients have some degree of cognitive decline compared with heart-healthy controls, which could be attributed to cerebral vascular disease, said Dr. McKhann.
The study was supported by the National Institutes of Health, the Charles A. Dana Foundation, and the Johns Hopkins Medical Institution.
Ann Neurol. 2008;63:581-590.Abstract
Medscape Medical News © 2008 Medscape
Cite this: Pauline Anderson. Cognitive Decline Among Heart Patients Similar With or Without CABG - Medscape - May 27, 2008.
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