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HEART and BRAIN
8/18/04 <link>
Stress tests and heart attack risk
New research shows that a stress test like a treadmill test may not
detect blocked arteries in a huge percentage of cases (up to 56%)! To
detect blockages missed by stress tests, calcium tests are being
recommended. It is unfortunate that insurance does not appear to cover
such preventive tests (in part because of the nature of the insurance system in
the U.S. where emphasis is on fixing problems rather than preventing
them). But it appears to be good "insurance" for suspected
heart patients to get the calcium test done even at their own cost -- if the treadmill test looks
"normal". Here's more from this
MSNBC/Reuters article:
Stress
tests aimed at detecting blocked arteries in patients may miss more
than half the cases of early heart disease, U.S. researchers
reported on Tuesday.
Scientists
found that 56 percent of patients who breezed through their stress
tests in fact had significant hardening of the arteries needing
treatment with diet, exercise, statin drugs, aspirin and other
medications.
"Our
findings demonstrate that a relatively high number of patients who
had normal readings on their stress tests had a calcium score of
greater than 100, a score that is accepted as implying the need for
aggressive medical treatment," said Dr. Daniel Berman, Director
of Cardiac Imaging at Cedars-Sinai Medical Center in Los Angeles.
His
team tested patients already considered at moderate risk of heart
disease. "They usually had at least one risk factor,"
Berman said in a telephone interview.
Most
were men over 45 or women over 55, smokers, people with high
cholesterol or high blood pressure, diabetes or a close relative
with early heart disease, they reported in this week's issue of the
Journal of the American College of Cardiology.
The
1,195 patients in the study had no evidence of heart disease, had
stress tests and then a procedure called coronary calcium scanning
within six months.
A
stress test uses a treadmill or an exercise bike to get a person's
heart working, and an electrocardiogram and blood pressure cuff to
measure heart function.
Calcium
tests important for long-term events
The calcium test uses a quick burst of specialized X-rays called
a computed tomography, or CT scan, to find evidence of plaques that
block arteries.
Among
the 1,119 patients who had normal stress tests, 56 percent had
calcium scores greater than 100, and 31 percent of patients had
scores greater than 400, Berman found.
Calcium
scores of zero are the "best" scores. Patients with
calcium scores from 100 to 400 are at increased risk for cardiac
events such as heart attacks, while patients with scores above 400
have the highest risk for a heart attack.
"Stress
test results are very important for short-term events that occur
over the next couple of years," Berman said in a telephone
interview.
"The
calcium test results are important for long-term events that will
occur in five years to a decade or so."
No
one is certain how calcium is involved in blocking arteries, but as
plaque is formed inside the blood vessel, calcium deposits form too.
Berman said he has found calcium readings directly correlate with
how much blood-blocking plaque there is.
So
patients with higher calcium scores "have a process going on in
their arteries," Berman said.
Because
heart disease is the No. 1 killer in most developed countries,
Berman believes that most men over 45 and most women over 55, as
well as smokers, people with high cholesterol and other risk
factors, should have a calcium scan.
The
problem is that most insurers will not pay for it, he said.
"It's
about a $400 test," Berman said. "Most third-party
carriers are not paying for it."
7/12/04 <link>
Cholesterol
level guidelines changed
Also reported in the NYT.
Apparently, the new guidelines were created "by the National
Cholesterol Education Program, [and] the guidelines are endorsed by the
American Heart Association, the American College of Cardiology and the
National Heart, Lung and Blood Institute. A panel of the education
program examined five major studies involving cholesterol-lowering
medicines."
Bottomline:
- LDL < 70 desired for very high risk heart
patients (previously 100)
- LDL < 100 desired for people with moderately
high risk of heart attacks (down from 130)
3/22/04 <link>
Do
heart attacks occur more because of severely blocked arteries or because
of sudden bursting of unstable plaques?
This New York Times article by Gina Kolata provides some commentary on
recent findings which suggests the latter is the more important problem.
Given this finding, it appears more and more that tracking inflammation
is increasingly the smarter thing to do to understand heart attack risk
better, given how inflammation tends to make plaques
unstable.
Here is the article:
A new and emerging understanding of
how heart attacks occur indicates that increasingly popular aggressive
treatments may be doing little or nothing to prevent them.
The artery-opening methods, like bypass surgery and stents, the widely
used wire cages that hold plaque against an artery wall, can alleviate
crushing chest pain. Stents can also rescue someone in the midst of a
heart attack by destroying an obstruction and holding the closed
artery open.
But the new model of heart disease shows that the vast majority of
heart attacks do not originate with obstructions that narrow arteries.
Instead, recent and continuing studies show that a more powerful way
to prevent heart attacks in patients at high risk is to adhere
rigorously to what can seem like boring old advice — giving up
smoking, for example, and taking drugs to get blood pressure under
control, drive cholesterol levels down and prevent blood clotting.
Researchers estimate that just one of those tactics, lowering
cholesterol to what guidelines suggest, can reduce the risk of heart
attack by a third but is followed by only 20 percent of heart
patients.
"It's amazing and it's completely backwards in terms of
prioritization," said Dr. David Brown, an interventional
cardiologist at Beth Israel Medical Center in New York.
Heart experts say they understand why the disconnect occurred: they,
too, at first found it hard to believe what research was telling them.
For years, they were wedded to the wrong model of heart disease.
"There has been a culture in cardiology that the narrowings were
the problem and that if you fix them the patient does better,"
said Dr. David Waters, a cardiologist at the University of California
at San Francisco.
The old idea was this: Coronary disease is akin to sludge building up
in a pipe. Plaque accumulates slowly, over decades, and once it is
there it is pretty much there for good. Every year, the narrowing
grows more severe until one day no blood can get through and the
patient has a heart attack. Bypass surgery or angioplasty — opening
arteries by pushing plaque back with a tiny balloon and then, often,
holding it there with a stent — can open up a narrowed artery before
it closes completely. And so, it was assumed, heart attacks could be
averted.
But, researchers say, most heart attacks do not occur because an
artery is narrowed by plaque. Instead, they say, heart attacks occur
when an area of plaque bursts, a clot forms over the area and blood
flow is abruptly blocked. In 75 to 80 percent of cases, the plaque
that erupts was not obstructing an artery and would not be stented or
bypassed. The dangerous plaque is soft and fragile, produces no
symptoms and would not be seen as an obstruction to blood flow.
That is why, heart experts say, so many heart attacks are unexpected
— a person will be out jogging one day, feeling fine, and struck
with a heart attack the next. If a narrowed artery were the culprit,
exercise would have caused severe chest pain.
Heart patients may have hundreds of vulnerable plaques, so preventing
heart attacks means going after all their arteries, not one narrowed
section, by attacking the disease itself. That is what happens when
patients take drugs to aggressively lower their cholesterol levels, to
get their blood pressure under control and to prevent blood clots.
Yet, researchers say, old notions persist.
"There is just this embedded belief that fixing an artery is a
good thing," said Dr. Eric Topol, an interventional cardiologist
at the Cleveland Clinic in Ohio.
In particular, Dr. Topol said, more and more people with no symptoms
are now getting stents. According to an analysis by Merrill Lynch,
based on sales figures, there will be more than a million stent
operations this year, nearly double the number performed five years
ago.
Some doctors still adhere to the old model. Others say that they know
it no longer holds but that they sometimes end up opening blocked
arteries anyway, even when patients have no symptoms.
Dr. David Hillis, an interventional cardiologist at the University of
Texas Southwestern Medical Center in Dallas, explained: "If
you're an invasive cardiologist and Joe Smith, the local internist, is
sending you patients, and if you tell them they don't need the
procedure, pretty soon Joe Smith doesn't send patients anymore.
Sometimes you can talk yourself into doing it even though in your
heart of hearts you don't think it's right."
Dr. Topol said a patient typically goes to a cardiologist with a vague
complaint like indigestion or shortness of breath, or because a scan
of the heart indicated calcium deposits — a sign of atherosclerosis,
or buildup of plaque. The cardiologist puts the patient in the cardiac
catheterization room, examining the arteries with an angiogram. Since
most people who are middle-aged and older have atherosclerosis, the
angiogram will more often than not show a narrowing. Inevitably, the
patient gets a stent.
"It's this train where you can't get off at any station along the
way," Dr. Topol said. "Once you get on the train, you're
getting the stents. Once you get in the cath lab, it's pretty likely
that something will get done."
One reason for the enthusiastic opening of blocked arteries is that it
feels like the right thing to do, Dr. Hillis said. "I think it is
ingrained in the American psyche that the worth of medical care is
directly related to how aggressive it is," he said.
"Americans want a full-court press."
Dr. Hillis said he tried to explain the evidence to patients, to
little avail. "You end up reaching a level of frustration,"
he said. "I think they have talked to someone along the line who
convinced them that this procedure will save their life. They are told
if you don't have it done you are, quote, a walking time bomb."
Researchers are also finding that plaque, and heart attack risk, can
change very quickly — within a month, according to a recent study
— by something as simple as intense cholesterol lowering.
"The results are now snowballing," said Dr. Peter Libby of
Harvard Medical School. "The disease is more mutable than we had
thought."
The changing picture of what works to prevent heart attacks, and why,
emerged only after years of research that was initially met with
disbelief.
Early attempts to show that opening a narrowed artery saves lives or
prevents heart attacks were unsuccessful. The only exception was
bypass surgery, which was found to extend the lives of some patients
with severe illness but not to prevent heart attacks. It is unclear
why those patients lived longer; some think the treatment prevented
their heart rhythms from going awry, while others say that the detour
created by a bypass might be giving blood an alternate route when a
clot formed somewhere else in the artery.
Some early studies indicated what was really happening, but were
widely dismissed. As long ago as 1986, Dr. Greg Brown of the
University of Washington at Seattle published a paper showing that
heart attacks occurred in areas of coronary arteries where there was
too little plaque to be stented or bypassed. Many cardiologists
derided him.
Around the same time, Dr. Steven Nissen of the Cleveland Clinic
started looking directly at patients' coronary arteries with a
miniature ultrasound camera that he threaded into blood vessels. He
found that the arteries were riddled with plaque, but almost none of
it was obstructing blood vessels. Soon he began proposing that the
problem was not the plaque that produced narrowings but the hundreds
of other areas that were ready to burst. Cardiologists were skeptical.
In 1999, Dr. Waters of the University of California got a similar
reaction to his study of patients who had been referred for
angioplasty, although they did not have severe symptoms like chest
pain. The patients were randomly assigned to angioplasty followed by a
doctor's usual care, or to aggressive cholesterol-lowering drugs but
no angioplasty. The patients whose cholesterol was aggressively
lowered had fewer heart attacks and fewer hospitalizations for sudden
onset of chest pain.
The study "caused an uproar," Dr. Waters said. "We were
saying that atherosclerosis is a systemic disease. It occurs
throughout all the coronary arteries. If you fix one segment, a year
later it will be another segment that pops and gives you a heart
attack, so systemic therapy, with statins or antiplatelet drugs, has
the potential to do a lot more." But, he added, "there is a
tradition in cardiology that doesn't want to hear that."
Even more disquieting, Dr. Topol said, is that stenting can actually
cause minor heart attacks in about 4 percent of patients. That can add
up to a lot of people suffering heart damage from a procedure meant to
prevent it.
"It has not been a welcome thought," Dr. Topol said.
Stent makers say they do not mislead doctors or patients. Their new
stents, coated with drugs to prevent scar tissue from growing back in
the immediate area, are increasingly popular among cardiologists, and
sales are exploding. But there is not yet any evidence that they
change the course of heart disease.
"It's really not about preventing heart attacks per se,"
said Paul LaViolette, a senior vice president at Boston Scientific, a
stent manufacturer. "The obvious purpose of the procedure is
palliation and symptom relief. It's a quality-of-life gain."
11/14/02 <link>
Inflammation
is a more significant indicator of heart attacks than LDL cholesterol
Research study published in the New England Journal of Medicine (also
see MSNBC
report) shows
that C-reactive protein (CRP), which is produced by the body when
inflammation occurs, is a potent indicator of heart attack risk. This
protein can be tested very easily using an inexpensive blood test. This
is considered a very significant finding in the medical community. Other
excerpts:
- "...Biologists
have known since the 1950s that virtually everyone develops thickened,
cholesterol-filled patches in some of their arteries, starting in early
adulthood. Heart attacks and strokes occur when one of those
"plaques" breaks open, causing a blood clot to form and
blocking the flow of blood and delivery of oxygen. If the obstruction is
not quickly cleared, the tissue downstream -- heart muscle or brain
cells -- dies."
- "Research over the
last decade suggests that inflammation -- the complicated marshaling of
immune-system cells and chemicals at the site of an injury -- tends to
make plaques unstable. It appears that people with elevated CRP either
have plaques that are more inflamed, or have a jumpier inflammatory
response overall that makes their plaques more prone to rupture."
- "In the new research,
Ridker and his colleagues at Brigham and Women's Hospital, in Boston,
studied about 28,000 women age 45 or older participating in the Women's
Health Study. Over an eight-year period, those whose CRP levels were
in the top 20 percent for the entire group had 4.5 times the risk of
suffering a heart attack or stroke as those in the bottom 20 percent.
For LDL cholesterol, the risk to people in the top bracket was 2.2
times that of people in the bottom [our emphasis]..."
11/1/02 <link>
Higher
heart attack risks from job stress
Thirty-year study in Finland reports twice the risk of heart attacks for
those in stressful jobs.
9/04/02
<link>
Walking reduces heart attacks and strokes in
women
Just
released study in the New England Journal of Medicine indicates
walking the equivalent of 2.5 hours a week, "briskly" helps
cut heart attack/stroke rates by a third. Backs up earlier
study, also reported in the same journal in 1999, showing walking at
~3 mph for 3 hours/week reduced heart attacks by 30-40% and walking for
5 hours a week cut the risk by ~50%. Evidently, "with exercise,
blood pressure and blood sugar decrease. In addition, amounts of
"good" cholesterol increase while amounts of "bad"
cholesterol decrease"
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