Highest Danger for Heart Attack Comes from Fat
Around the Heart
Older people with highest levels of heart fat almost
five times more likely to have calcified coronary plaque
July 30, 2008 Obesity may increase a senior
citizens risk of developing a number of diseases and physical problems,
but when it comes to risk of heart attack, having excess fat around the
heart may be worse than having a high body mass index or a thick waist,
according to researchers from Wake Forest University Baptist Medical
Center and colleagues reporting in the August issue of the journal
Obesity.
The study was among the first to explore whether
there is a link between fat deposits around the heart, known as
pericardial fat, and the development of hard, calcified plaque in
the arteries. Calcified plaque itself is not considered risky, but it is
associated with the presence of less stable fatty deposits that can lead
to heart attack and stroke.
"The distribution of body fat may be as important
as the amount of body fat in determining risk of heart attacks," said
Jingzhong Ding, M.D., lead author and an assistant professor of
gerontology. "Even a thin person can have fat around the heart."
The researchers examined data from the Multi-ethnic
Study of Atherosclerosis (MESA), a $68 million study involving 6,800
participants nationwide, to explore their hypothesis that fat around the
arteries in the heart contributes to inflammation and to increased risk
of fatty deposits in the vessels.
In addition to its role as energy storage, fat is
considered to be an "organ" that produces proteins and hormones that
affect metabolism and health. Ding's study is based on a new idea in
medicine that excess fat around the heart and other organs may impair
their function.
Pericardial fat, or stores of fat around the heart,
is known to have a higher secretion of inflammatory cytokines, proteins
that regulate inflammation, than fat stored just under the skin. The
scientists suspect that constant exposure of inflammatory proteins
produced by fat around the heart may accelerate the development of
atherosclerosis.
For the analysis, the researchers measured the
volume of pericardial fat in 159 study participants who were 55 to 74
years old. Calcified coronary plaque was observed in 58 percent of
participants.
Participants were divided into four groups based on
the volume of pericardial fat. Those in the group with the highest
levels of fat were almost five times (4.65) more likely to have
calcified coronary plaque.
The scientists found that while the volume of
pericardial fat was related to levels of calcified coronary plaque, body
mass index and waist circumference were not related.
"Our findings suggest that local fat deposits,
rather than total body fat, are most related to calcified coronary
plaque," said Ding.
"Inflammatory mediators released from pericardial
fat may promote inflammation in local coronary arteries and lead to
coronary atherosclerosis."
Ding hopes to continue the research to learn more
about whether the buildup of fat around the heart can be prevented.
"Because coronary heart disease kills so many
people, it is imperative to find new treatments and prevention
strategies," he said.
Editors Notes:
The study was sponsored by the National Heart,
Lung, and Blood Institute and the Wake Forest University Claude D.
Pepper Older Americans Independence Center.
Co-researchers were Stephen Kritchevsky, Ph.D.,
Gregory Burke, M.D., and Jeffrey Carr, M.D., all with Wake Forest,
Tamara Harris, M.D., National Institute on Aging, Robert C. Detrano,
M.D., Los Angeles Biomedical Research Institute, and Moyses Szklo, M.D.,
the Johns Hospkins Bloomberg School of Public Health.
Wake Forest University Baptist Medical Center (www.wfubmc.edu)
is an academic health system comprised of North Carolina Baptist
Hospital, Brenner Children's Hospital, Wake Forest University
Physicians, and Wake Forest University Health Sciences, which operates
the university's School of Medicine and Piedmont Triad Research Park.
The system comprises 1,154 acute care, rehabilitation and long-term care
beds and has been ranked as one of "America's Best Hospitals" by U.S.
News & World Report since 1993. Wake Forest Baptist is ranked 32nd in
the nation by America's Top Doctors for the number of its doctors
considered best by their peers. The institution ranks in the top third
in funding by the National Institutes of Health and fourth in the
Southeast in revenues from its licensed intellectual property.
