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Studies Find Link Between Heart Disease and Inflammation
Two studies an
ocean apart illustrate the growing importance of inflammation
as a contributor to heart attack, stroke, and other cardiovascular
diseases, according to a study reported in the New
England Journal of Medicine.
 In
the US, researchers at the Harvard School of Public Health
report that blood levels of C-reactive protein, a molecular
marker of inflammation, rank with cholesterol levels as indicators
of future coronary heart disease.
And in England,
researchers at the London School of Hygiene and Tropical Medicine
report that an ordinary infection, such as the flu, may raise
the risk of heart attack or stroke over the next few days because
of an inflammatory effect on blood vessels.
Inflammation
Associated with Atherosclerosis
Inflammation
is the process by which the body responds to injury or infection.
Lab evidence and results from clinical and population studies
suggest that inflammation is important in atherosclerosis, the
process by which fatty deposits build up in the lining of arteries,
according to the American Heart Association
(AHA).
The British study
was undertaken because inflammation is known to play a long-term
role in cardiovascular disease, says study author Liam Smeeth,
a senior lecturer in epidemiology.
The idea that
an infection could have an immediate damaging effect on the
endothelium, the delicate lining of the blood vessels, came
from lab work done by Dr. Patrick Valliance of University College
London, Smeeth notes. So, the British researchers looked at
the record of infections reported by nearly 40,000 people who
had had a stroke or heart attack.
"The risk of
both events were substantially higher after a diagnosis of systemic
respiratory tract infection and were highest in the first three
days," the researchers report. Urinary tract infections also
raised the risk, but to a lesser extent, the study found.
There was one
bit of good news: Getting vaccinated against influenza, tetanus,
or pneumonia did not increase the risk of a cardiovascular event,
as the researchers suspected might happen.
"Either it [vaccination]
produces no inflammatory effect or it has an effect only in
a subgroup of people," Smeeth says. "That is reassuring news."
The Harvard report
used data from two studies that have been following more than
120,000 health professionals, male and female, for many years.
They underwent a large number of blood tests, including markers
of inflammation, at the start of the study.
The researchers
looked at those levels in the 239 women and 265 men who had
heart attacks or died of heart disease over the next six to
eight years.
A high level
of C-reactive protein - more than 3 milligrams per liter of
blood - increased the risk of such an event by nearly 70 percent,
compared to a reading lower than 1 milligram per liter, after
adjusting for the presence of two other risk factors, diabetes
and high blood pressure, the researchers found.
Blood levels
of cholesterol and other lipids were stronger predictors of
trouble, but "the level of C-reactive protein remained a significant
contributor to the prediction of coronary heart disease," they
report.
Right now, measuring
blood levels of C-reactive protein are "supplementary to measuring
traditional risk factors," such as cholesterol, blood pressure,
and obesity, says Dr. Nieca Goldberg, chief of women's cardiac
care at Lenox Hill Hospital in New York City, and a spokeswoman
for the AHA.
"There are individuals
in whom we would want to measure C-reactive protein, such as
those who have coronary disease but no other risk factors and
those at borderline or intermediate risk," she says. "But we
are not at the point where we would use it as the sole determinant
of risk."
Jennifer K. Pai,
a research associate at the Harvard School of Public Health
and lead author of the journal report, says she agreed with
that assessment.
"Using it [C-reactive
protein levels] in conjunction with these other risk factors
probably would be best," Pai says.
Always consult
your physician for more information.
|
A study published
recently in Circulation: Journal of the
American Heart Association shows that high levels of
C-reactive protein and other inflammation markers may signal
rapid progression of coronary artery disease (CAD) in patients
with chest pain.
“This is
the first study to assess the specific question of whether elevated
levels of inflammation markers predict the rapid evolution of
CAD stenosis in patients with stable angina (chest pain),”
says Juan Carlos Kaski, M.D., one of the study’s lead
authors.
Coronary artery
stenosis is the narrowing of the coronary arteries, the vessels
which supply blood to the heart muscle.
“The study
is important because it confirms a role for inflammation in
the rapid progression of CAD, and may open new areas of research
to identify and test agents that may reduce inflammation,”
says Dr. Kaski, professor of cardiovascular science at
the University of London and head of the department of cardiological
sciences at St. George’s Hospital Medical School.
Patients with
a rapid increase in stenosis severity (‘progressors’)
had higher levels of inflammatory markers and markers of macrophage
(white blood cell) activation.
Researchers studied
124 patients with stable angina, defined as chest pains that
never escalated to a major cardiac event over three months or
more.
These patients,
84 of whom were men, underwent an initial angiogram between
January and June 2000 to measure stenosis in their coronary
arteries. They were placed on waiting lists for non-urgent
coronary angioplasty after the angiogram. They had a second
angiogram within three to 12 months of the first one.
Researchers assessed
differences in stenosis between the first and second angiograms
in 321 lesions. They considered a stenosis of at least
50 percent diameter reduction to be significant and progressing,
and a lesion less than 50 percent to be mild.
In three to 12
months, CAD progression occurred in 28 percent of patients. Of
these 35 “progressors,” 51 percent had a 10 percent
or greater diameter reduction of at least one pre-existing partial
blockage.
Twenty-six percent
had a greater than 30 percent diameter reduction of a pre-existing
blockage. Seventeen percent of patients developed a new
blockage and 6 percent experienced progression of a partial
blockage to total blockage.
Always consult
your physician for more information. |
