Contrary to
previous research, coronary artery bypass patients showed no decline in
mental functioning five years after their surgery, physicians at Würzburg
University Hospital report.
Studies at
Johns Hopkins University in Baltimore and Duke University, Durham, N.C.,
had indicated mental declines take place in a significant number of patients
five years after bypass operations. The Würzburg authors suggested
the difference might be due to the attention given to the patients' overall
circulatory system health in the new study.
"As in other
studies, we also had no control group, but we additionally studied vascular
risk factor control," lead investigator Wolfgang Müellges told United
Press International. "Our main results contrast to a previously reported,
and potentially alarming, 42 percent rate of (bypass) patients who suffer
from a long-term post-operative cognitive decline."
Müellges
said he and colleagues attempted to reduce such risks by focusing on post-operative
vascular care.
"Many of the
individuals had stopped smoking, many were prescribed statins, and many
took steps to control their diabetes and hypertension," he said.
The researchers
gave 52 bypass patients a battery of psychological tests that measured
cognitive functioning before their operations, upon discharge from the
hospital and approximately five years later. "No patient showed a decline
in neuro-psychological test performance as compared to baseline," they
reported.
"Vascular risk
factor control was good in all patients, possibly contributing to the favorable
outcome."
Ola A. Selnes,
neuropsychological director of the cognitive neurology clinic at Johns
Hopkins Hospital in Baltimore, told UPI the Hopkins study found a "significant"
drop in cognitive ability five years after bypass surgery, although the
exact number has not been published.
"If this decline
could be prevented just by tightening up the post-operative control of
these potential risk factors, that would be an extraordinary event in medicine,"
Selnes told UPI. "But it's strictly speaking a hypothesis at this point."
Selnes added,
"The question is, what is the explanation? Is this something preventable
or inevitable? ... It's a crucial question. It has to be answered. You
can imagine what that public health implications are if that is the case."
Mark F. Newman,
chair of the department of anaesthesiology at Duke University Medical Center,
praised the methodology of the Würzburg study, but noted it was a
relatively small sample: 52 compared with about 170 in the Duke study --
of which he was lead author -- and said the Duke patients tended to be
three to four years younger.
Newman told
UPI his study probably was begun earlier than the Würzburg study,
so "you may have some improvements in surgical technique that are resulting
in improved long term outcome."
Some researchers
think longer times on the external heart-lung machines during bypass surgery
may be associated with some loss of cognitive ability, as may prolonged
anaesthesia. As techniques have improved, bypass operation times have shortened.
In addition,
many people having bypass surgery are older and have vascular problems
that could lead to stroke and cognitive decline independent of surgery.
None of the
studies has used a control group of older people without bypass surgery
to measure normal decline in cognitive functioning.
Timothy Gardner,
spokesman for the American Heart Association and chief of cardiothoracic
surgery at University of Pennsylvania in Philadelphia, told UPI, "It's
a great worry to a lot of people who have to have bypass surgery and I
find this small study very encouraging."
About 500,000
Americans have coronary artery bypass surgery every year.
The research
is reported in the Sept. 10 issue of the journal Neurology.
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Copyright 2002 by United
Press International.
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