Heart Surgery and Quality of Life
DURHAM, N.C. -- After demonstrating earlier this year that
more than 40 percent of coronary artery bypass patients have
measurable cognitive declines five years after surgery, Duke
University Medical Center researchers have now shown that these
patients also have a worse quality of life.
The researchers say that their findings provide compelling
evidence that more research is needed in developing strategies
that can be employed either before or during surgery to protect
"Given the trends of operating on the hearts of older and
older patients, the effects on cognitive functioning must be
considered if we are to restore the quality as well as the
quantity of life," said Duke anesthesiologist Dr. Mark Newman,
who led a team of Duke investigators whose findings were
published Dec.7 in the December issue of the journal
The Duke study was supported by grants from the National
Heart, Lung and Blood Institute, as well as the American Heart
"We should spend as much attention on ways to improve the
protection of the brain, and thus the quality of life, as has
been spent in preserving the health of heart tissue," Newman
said. "While it is generally appreciated that heart surgery
improves the quality of life, it appears that these cognition
issues can be a factor limiting quality of life
In February, the Duke team published in The New England
Journal of Medicine the results of the largest study of its
kind, which showed that five years after heart surgery, 42
percent of patients had measurable cognitive decline. In this
study, 261 heart surgery patients took the same battery of
standardized cognition and quality-of-life tests at different
intervals during a five-year.
While the researchers reported the results of the cognition
tests in February, the current paper is an analysis of seven
standardized tests that measure different aspects of quality of
life, ranging from employment status, depression, social
support and physical limitations.
"In this additional analysis of quality-of-life data, we
found a consistent and broad association between the decline in
cognitive function and worse quality of life, independent of
the recognized effects of age, gender, diabetes and education,"
Newman added. "With reduced cognition, patients are less likely
to be working, are more likely to be depressed or anxious, and
have a reduced ability to maintain normal functions of
Researchers used the following seven standardized tests,
which, when taken together, provided a broad indication of how
a patient perceives their quality of life:
* The Duke Activity Status Index, a 12-item scale that
measures a patient's physical capacity for such everyday
activities as walking, personal grooming, sexual relations and
* The Medical Outcomes Study 36-Item Short Form Health
Survey, which measures respondents perceptions of their overall
* The Center for Epidemiological Studies Depression Scale, a
20-question test which measures symptoms of depression.
Patients rate the degree to which they have experienced
depression on such items as "I had crying spells" or "I feel
* The Spielberger State and Trait Anxiety Inventory, a
40-item test that measures current and chronic anxiety.
Patients rate such items as "I feel nervous" or "I feel
worried" on a four-point scale.
* The Mini-Mental State Examination is a general assessment
of cognitive functioning which tests such areas memory, reading
and writing capabilities, orientation, mathematical
calculations and language.
* The Perceived Social Support Scale, a 12-item scale
measuring how strongly patients agree that there "is a special
person who is around when I am in need" and "my family really
tries to help me."
* Working Status, a one-item scale ranging from full-time
employment to disabled.
"By tapping into a broad range of measures, we tried to get
an overall picture of quality of life, and across all the
measurements we used, there was a consistent and significant
association between impaired cognitive function and quality of
life," Newman said. "While similar associations have been drawn
in other diseases, no one before has looked at these issues in
heart surgery patients.
Coronary artery bypass grafting (CABG) is a surgical
procedure performed more than 600,000 times a year in the
United States for the treatment of coronary artery disease.
Typically, surgeons use pieces of blood vessels from other
parts of the body to "bypass" clogs in coronary arteries,
thereby restoring blood flow to the heart.
The researchers say it is likely that many factors
contribute to the cognitive declines, although they believe
that blood clots caused by the heart-lung bypass machine
commonly used in CABG surgery is an important underlying cause.
This machine essentially pumps and oxygenates the blood for the
body while surgeons operate on the stopped heart. Researchers
believe that tiny blood clots form and travel to the brain,
causing cell death in effected areas.
The Duke team is investigating strategies to better
understand cognitive decline with the hope of developing ways
to protect the brain. These strategies include minimally
invasive surgery, which does not require the heart-lung
machine, as well as re-warming patients at a slower rate after
surgery. The Duke team has even found a genetic component that
may contribute to cognitive decline. Patients with the E-4
variant of the APOE gene (which has also been linked to early
onset Alzheimer's disease) tend to do worse than patients with
other variants of the gene.
Joining Newman in this study were Duke researchers Dr.
Hilary Grocott, Dr. Joseph Mathew, William White, Dr. Kevin
Landolfo, Dr. Jerry Reves, Dr. Daniel Laskowitz, Dr. Daniel
Mark and James Blumenthal. All are members of the Duke
Neurological Outcome Research Group and the Cardiothoracic
Anesthesiology Research Endeavors group.