Myths and Misconceptions about Heart
Disease
How to Prevent Heart Attacks
The Heart Facts
of Life
It
is an Electron Beam Tomography scan of the coronary arteries (the
vessels which carry blood and oxygen to the heart muscle).
The
scanner detects and measures calcium in the coronary arteries, which is the
marker for atherosclerosis (the accumulation of cholesterol plaque in the
arteries). The test is non-invasive
with no pain, using no injections, chemicals or incisions.
You just lie on a table, hold your breath for a few seconds and let the
scanner take pictures of your heart. The
complete process only takes a few minutes.
The
non-invasive EBCT scan measures coronary disease in a way which many doctors now
believe is more important than the percentage of blockage (referred
to as stenosis or occlusion). The
scan measures the amount of calcium plaque within your coronary arteries.
This measurement indicates the level of atherosclerosis in a person,
i.e., the more calcium you have, the more plaque you have and therefore the greater the chance that you
will suffer a heart attack or need surgery in the future unless you take early
steps to prevent this.
Many authoritative
studies have shown that an EBCT scan is highly sensitive for detecting Coronary
Artery Disease. A negative test is also a very powerful indicator that the
patient does not have heart disease.
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How good is this technology?
EBCT
was cited as
one of the top 10 research advances in heart disease and stroke for 1999 by
American Heart Association.
The Food and Drug Administration of USA has given 510(K) market clearance
for use of this machine to perform non-invasive Electron Beam Angiogram in
November 1999, and EBCT is the only scanner in the world approved for this
procedure.
This technology has
been validated by more than 15 years of rigorous testing at top universities and
medical centers around the world and there are more than 1000 publication of
scientific research papers in major international medical journals.
Scientific
publications include two important papers from Germany in Radiology
February 2000; one demonstrating the accuracy of EBCT for the study of coronary
stents, the other showing the advantage of EBCT for detection of pulmonary
embolism. Another study from Beijing in the Journal of Invasive Cardiology
February 2000 showed the ability of EBCT to evaluate coronary stents with 100%
neg. predictive accuracy. The
American Heart Association published a
study in Circulation
February 2000 showing EBCT to be more sensitive than nuclear medicine or
exercise treadmill testing in sub-clinical individuals.
Atherosclerosis is
the name for the cholesterol plaque buildup inside your coronary arteries.
The presence of atherosclerosis in your coronary arteries means the
presence of Coronary Artery Disease. The
greater the amount of plaque build up, the higher would be the risk of a heart
attack because most heart attacks are due to plaque rupture or ulceration. When
atherosclerosis advances to a stage where the blockage prevents normal blood
flow to the heart muscle, it is called obstructive
Coronary Artery Disease.
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The prevalence of
coronary atherosclerosis increases with age, and is about 50% in the 50 year old
population.
An Electron Beam CT
scan can both detect and measure the extent of coronary calcification, and can
identify those people at greatest risk of a heart attack. However, it should be noted that there are many people
between 50 and 70 who have no
coronary calcium whatsoever, which means that they have a very low risk
of having obstructive Coronary Artery Disease or heart attacks.
A plaque
detector or coronary calcium scan will be able to tell you whether you have
heart disease. It can detect
heart disease at its very early stage, even before any cardiac symptoms are
noticeable and even before your stress test indicate any abnormality.
This is especially beneficial for those who have no symptoms but who may
have one or more of the following cardiac risk factors :
-
age
(males above 40, females above 45)
-
smoker
-
high
cholesterol
-
inactive
lifestyle
-
family history of heart
disease
-
high blood pressure
-
overweight
-
diabetes
If you wish to find
out how blocked your arteries are, a
non-invasive Electron Beam Angiogram(EBA) will be able to do so to
an accuracy of greater than 90%. This
involves the use of non-ionic (to minimize risk of allergies) contrast or dye
injected through a vein in the arm. The
computer then reconstructs the images to enable you and your doctor to visualize
the coronary arteries in 3D. The
EBA will give valuable information to the patient and his doctor prior to a
traditional invasive angiogram and is useful for certain indications depending
on the condition of the individual.
A normal EBA means
that the patient does not have to undergo an invasive
angiogram. However an invasive
angiogram may still be needed when severe obstructive coronary artery disease is
diagnosed and when it is necessary to undergo angioplasty or bypass surgery.
The indications for EBA are
as follows:-
-
“Symptomatic”
patients with mild to moderate
coronary calcification
-
“Sub-clinical”
patients with severe coronary calcification
-
Follow-up
of coronary angioplasty, coronary bypass
-
Follow-up
of coronary patency post MI or stent
-
Assessment
of coronary artery congenital or acquired
anomalies
-
"Low
risk" patients with abnormal stress tests
Most other tests in
cardiology, such as exercise stress ECG or stress thallium or stress
echocardiograms detect abnormality in heart function and therefore only reliably
detect heart disease when the disease is so advanced that it hinders your heart
from working properly.
An
EBCT scan looks
directly at the coronary arteries and measures the plaque burden and it can
detect heart disease at a very early stage, usually many years before a person
becomes symptomatic.
Each test in cardiology serves a specific
purpose. EBCT coronary artery scanning is the best available screening test for
detecting early heart disease, and is usually performed before any of the other
cardiac tests, including a stress test. The
stress test still has a role to play, and it is useful to determine whether a
patient has ischaemia due to severe obstructive coronary artery disease which
requires urgent angioplasty or bypass surgery.
What
if I have already passed an exercise stress test or stress thallium test ?
This means that your
heart function is normal, even when you are pushed to peak exertion.
But it does not mean that you have no coronary atherosclerosis. Your
coronary arteries may not be clean, i.e. you may have plaque build up but it is
not causing any obstruction to blood flow yet. There
are patients who die suddenly of a
heart attack despite having a negative stress test.
This fact, first published in The New England Journal of Medicine in
1989, seems paradoxical. Most
people still believe that heart attacks happen when coronary arteries become
severely blocked. In reality, most
heart attacks occur due to plaque rupture or ulceration, and can happen even
when the blood vessel is not even 50% blocked.
What
if I
have already had a heart attack,
angioplasty or bypass surgery ?
For
individuals who have had a heart attack, bypass
operation or angioplasty, an EBA can be done to check the conditions of the
patient’s heart arteries, the patency of post-bypass grafts or post PTCA
vessels. The calcium score is also useful for it can provide a benchmark against
which your doctor can measure any future progression of the heart disease.
It is also important that anyone who has had a heart attack, coronary
angioplasty or bypass surgery should inform his/her siblings and/or grown-up
children about the availability of this test because heart disease is often a
hereditary disease.
Who
should take this test ?
Men over the age of
40 and women over the age of 45 should actively consider taking an EBCT scan.
The more risk factors for heart disease you have, e.g.
high cholesterol, high blood pressure, smoking, diabetes, obesity, sedentary
lifestyle, high stress lifestyle, family history of heart disease, etc., the
more important it is that you ask your doctor to recommend you for a scan. If you are younger than 40, then upon your doctor’s
recommendations, you may also take the EBCT scan if you have multiple risk
factors.
Is
it safe to have a EBCT
scan ?
A patient is only
subjected to a small amount of radiation, approximately equivalent to the
radiation received during one abdominal x-ray.
As such, the scan is safe for everyone, although pregnant women are
advised against doing so to avoid any radiation.
The EBA involves
injection of a non-ionic dye and carries a small risk of allergic reactions, e.g
rashes.
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What
happens if the test shows that I have coronary calcium ?
The results show, on
an artery-by-artery basis, the amount of any calcium deposited.
The total amount of calcium (the
calcium score) is then compared to the scores of other individuals of your
age. If you do have calcium
deposits, your doctor will consider your overall health condition and advise
and/or treat you accordingly. The main objective is to ensure that your risk of
heart attack is reduced and your heart disease does not progress to a
significant late disease stage.
Do
I need a referral from my doctor to get a Heartscan ?
You can ask your family doctor to do a cardiac assessment on you to determine
your cardiac risk, ie whether you are in the low, intermediate or high risk
category. You can also come directly to our centre
whereby you will be seen by our specialist cardiologist. Our consultant will
be able to advise you on whichever scan you will need.
The information contained in this website is not a substitute
for medical advice or treatment or replaces consultation with your doctor.
Copyright © 2001 [Mahameru International Medical Center Sdn Bhd]. All rights reserved.
Revised: March 10, 2008
.
