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Senior Citizen Health & Medicine
Exercise Test on Elderly Helps Predict Death Risk
from Heart Failure
Previously used to predict hospitalizations in
patients with systolic heart failure
May 30, 2007 A simple exercise successfully
tested on elderly patients with congestive heart failure may help
predict mortality risk in those with heart failure and help doctors to
better tailor treatment strategies, according to new research from Wake
Forest University Baptist Medical Center.
"This may allow doctors to better assess patient
risk, and could help them determine the most appropriate plan of care
based on the prognosis of the patient," said Dalane Kitzman, M.D., a
professor of cardiology and senior researcher on the project.
In the current issue of the Journal of Cardiac
Failure, Kitzman and colleagues report on a study involving 147 patients
with congestive heart failure, which is the inability of the heart to
pump enough blood to keep up with the body's demands. Congestive heart
failure affects about 4.8 million Americans, with 550,000 new cases
diagnosed each year. The primary symptom is shortness of breath.
The goal of the study was to evaluate a test that
measures the lungs' efficiency at consuming oxygen and expiring carbon
dioxide. The test has been shown to predict future hospitalizations in
patients with systolic heart failure, a type in which the left chamber
of the heart is too weakened to pump blood efficiently.
The researchers wanted to determine if the test is
also appropriate for patients with diastolic heart failure, a more
recently recognized form in which the heart muscle is stiff and cannot
take in enough blood with each beat.
"Although the prevalence of diastolic heart failure
is increasing, we know very little about how to predict which patients
are at the highest risk of death," said Kitzman.
Previous studies on predicting mortality have
focused on systolic heart failure patients. The current study was the
first to compare the pulmonary test in three groups: older adults with
diastolic heart failure, older adults with systolic heart failure and
healthy volunteers of the same age.
The mean age of participants was 70.
"It is important for researchers not only to focus
on potential treatments for diastolic heart failure, but to also develop
the best method to assess the severity of their condition ," said Brian
Moore, M.S., lead author of the study.
For the study, researchers measured pulmonary
efficiency by analyzing oxygen consumption and carbon dioxide expiration
during an exercise session on a stationary bicycle.
"This is an important measure in heart failure
patients because it may help us to understand the cause of some of the
symptoms of shortness of breath and exercise intolerance," said Moore.
"The test has been previously reported as a good indicator of how
serious the disease is in patients with systolic heart failure."
Previous research has shown that a test score of 34
is a threshold for increased risk of death. In the current study,
patients with systolic heart failure had a mean score of 37, which
suggests an increased risk of mortality. Patients with diastolic heart
failure had a mean score of 34, suggesting lower risk. The group of
healthy older adults had a mean score of 32.
About 45 percent of study participants with
diastolic heart failure had a score greater than 34 compared to 59
percent of participants with systolic heart failure having a score that
high.
The results are similar to findings in large
population-based studies showing that mortality is considerably lower in
diastolic heart failure compared to systolic heart failure. Combined
with the new results, this suggests the exercise test can potentially
predict mortality in individual patients.
"The study highlights an important physiologic
principal of exercise intolerance and identifies a novel marker to
assign risk," said Vinay Thohan, M.D., associate professor of cardiology
and director of the heart failure service at Wake Forest Baptist.
"This measure has been validated in patients with
systolic heart failure and this form of testing is routinely performed
for all patients who undergo evaluation for heart transplantation at our
medical center. "Now, we may be able to use this test for patients with
diastolic heart failure as well."
The researchers said future studies should examine
whether treatments for heart failure can modify the results and reduce
the risk of mortality.
Editors Notes:
The study was funded by the National Institutes of
Health, and the Claude D. Pepper Older Americans Independence Center of
Wake Forest University.
Co-researchers were Peter H. Brubaker, Ph.D., with
Wake Forest University, and Kathryn P. Stewart, a registered diagnostic
cardiac sonographer, with Wake Forest Baptist.
Wake Forest University Baptist Medical Center is an
academic health system comprised of North Carolina Baptist Hospital and
Wake Forest University Health Sciences, which operates the university's
School of Medicine. U.S. News & World Report ranks Wake Forest
University School of Medicine 18th in family medicine, 20th in
geriatrics, 25th in primary care and 41st in research among the nation's
medical schools. It ranks 35th in research funding by the National
Institutes of Health. Almost 150 members of the medical school faculty
are listed in Best Doctors in America.
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