 Dr.
Rogal has a special interest in preventative cardiology, non-invasive
imaging and valvular disease. He co-founded the Integrative Medicine
Program for cardiovascular disease at Saint Barnabas Medical Center
and Newark Beth Israel Medical Center, one of the largest integrative
medicine programs for cardiac patients in the United States. Dr. Rogal
has published several journal articles and is a diplomat of the American
Board of Internal Medicine and a Fellow of the American College of
Cardiology. He serves as a board member of the Heritage Affiliate
of The American Heart Association.
In this month’s interview, we asked Dr. Rogal to share with us
the answers to some of the most common questions he hears from patients.
In order to understand the answer
to this question, we need to talk about evidence-based medicine, which
is really the integration of clinical research trials, a physician’s
clinical expertise and also patient values (what suits the patient).
Clinical research is based on a systematic observation of patients and
treatments. In essence, what we are trying to do is take large groups
of patients, assign them to different therapies and in some cases, assign
a group to a placebo so we can see the result of no treatment. We then
compare the outcomes.
It is very important when we design two groups of patients to compare,
that we randomly put those patients into two different treatment groups
to prevent selection bias. We must insure that the groups that we are
studying are roughly equivalent. And we also have to define the groups
that we are studying. As clinicians we must ensure that there is relevance
of the group under study to our patients. And, finally, it is always
better if a study is large because we are able to detect small differences
in treatment with large numbers of patients. So, those are the important
elements in comparing two groups of patients and the intervention of
a particular therapy in those two groups.
So, how does a clinical trial work? In hormone replacement trials,
previous analysis had demonstrated that hormone replacement therapy
in post-menopausal women might lower the risk of heart disease. It turned
out, after the performance of the Women’s Heart Initiative which
was a randomized, controlled trial of 16,000 post-menopausal women that,
in fact, hormone replacement therapy does not prevent heart disease
in that patient population. In fact, it turned out that there was a
selection bias – those women who were treated with hormone replacement
therapy were also doing other things that might result in a lower risk
of heart disease. So, the study was not comparing equivalent groups.
The Women’s Heart Initiative actually took that bias
out of the research and then properly answered the question, so our
whole view of hormone replacement therapy was changed.
A second issue is Vitamin E, long talked about
as potentially beneficial in patients because of a lot of basic science
that was done regarding the substance. But in large, randomized, controlled
trials, results actually showed that Vitamin E does not, in fact, protect
against heart disease. And, in some cases, may have been detrimental.
So, when we introduce a substance like Vitamin E into a complex biological
system like a human being, it is sometimes very difficult to predict
what the outcome might be.
Relevant to the issue of heart medications are the questions of congestive
heart failure and the use of beta blockers. For many years, when I was
in training, the experts taught that the use of a beta blocking drug,
which is a heart slowing drug, is not beneficial in congestive heart
failure patients. We were told not to use those drugs. Basic science
taught us to look a little bit differently at this issue and then very
large, randomized, controlled trials were performed which told a totally
different story. Now we understand that beta blockers are bedrock medications
in that diagnosis.
So, things will often change as clinical trials are performed. Evidence-based
medicine is really what cardiologists base their decisions on. Evidence-based
medicine is the application of various treatments and the testing of
those treatments using statistical methods.
This question
addresses the issue of coronary artery calcium
scoring. In previous questions, we spoke about
risk and how physicians assess a person’s
risk for having coronary artery disease or atherosclerosis of
the coronary arteries. Traditionally, what we have
used is the Framingham Risk Score (http://www.nhlbi.nih.gov/about/framingham/riskabs.htm),
which uses several elements; age, family history,
level of HDL or “good cholesterol,” blood
pressure levels and history of smoking. When we
put all of those things together, we can determine
what your risk is for a coronary event.
- If you have a Framingham Risk Score under 10%
(that is a 10% risk of having a coronary event
in the next ten years) then your risk is low.
That represents about 35% of the population.
- If you are in the 10-20% range, that is the
intermediate group and the group that we’re
very concerned about because about half of all
coronary events actually occur in the intermediate
group.
- If you are in the high group, which has a greater
than 20% risk of having a coronary event in the
next ten years – those patients are much
easier to manage because the chances of having
a coronary event in that situation is substantially
high and justifies a high level of intervention.
We use the coronary artery calcium scoring in
addition to the Framingham Risk Score because it
adds another variable with which we can quantify
the patient’s risk of having a coronary event
in the future.
What this test does, is use a CT scanner to measure
the presence of coronary calcium in the coronary
vessel. We know that coronary calcium is part of
developing plaque in the coronary vessel. We also
know that zero calcium does not mean that you do
not have any plaque, but it is associated with
a good prognosis. The CT scan time is literally
seconds, the test can be completed in 15 to 20
minutes. There is a very low radiation dose
and neither dye nor radioisotope is used during
the test. What we are trying to do is to match
treatment intensity to the patient’s risk
of having the disease. If you are a high-risk patient,
that would justify more intense therapy to address
coronary artery disease.
So, in 2007, the American College of Cardiology
published a consensus document and they came to
several very useful conclusions:
- coronary artery calcium measurement does predict
coronary events, out to 3 to 5 years;
- coronary artery calcium scoring independently
predicts outcome over and above the traditional
risk factors (i.e., the Framingham Risk Score);
- calcium scoring may also help risk stratified patients
in the intermediate group – the group in which
50% of coronary events occur.
In order
to answer this question, we have to talk a little
bit about cardiac catheterization, which is an
invasive test in which a physician threads a catheter
from an artery in the leg up to the heart, injects
the coronary arteries with a dye and takes pictures
of the dye as it flows through the vessels and
thereby detects blockages. This is an invasive
test that requires at least a same-day admission
to the hospital.
A 64-slice CT scan does at least that much and
a bit more. We are able to detect coronary artery
blockages without the invasive aspect of cardiac
catheterization. This test is done in a CT scanner
in an outpatient setting.
In some aspects, 64-slice CT is actually better
than cardiac catheterization.
- It is excellent at detecting congenital coronary
artery problems, which are sometimes difficult
to define by cardiac catheterization.
- It is much better at defining diseases of a
structure called the aortic loop, a vessel leaving
the heart.
- Very importantly, it is better at defining
what we call sub-critical disease. You can have
a stress test, and it can be negative, but you
can still have a blockage in an artery which
is under 70%. A 64-slice CT scan will catch that – we
are able to see things as small as 10-20% and
that is important because we know that those
plaques can grow and become considerably worse
if the intensity of therapy is not adequate.
So, 64-slice CT scanning is a fairly simple experience
for the patient. The scan time is quite short.
There is a fair amount of preparation and there
is a fair amount of recovery afterward, since you
are injected with dye. The dye is the same as in
cardiac catheterization, so in patients who have
kidney disease we have to exert caution. In addition,
we depend on very slow heart rates in order to
make the scan as clear as possible. So we have
to administer drugs called beta blockers which
are difficult to use in patients who have lung
disease, patients who have low blood pressure or
those with excessively slow heart rates. And, because
of the radiation that’s delivered during
the test, the dye that is given and also the cost,
this is definitely not a screening test for all
at-risk patients.
Our current dilemma in the work up of patients
with coronary artery disease is to detect what
we call the sub-critical plaque. That is what we
are referring to when we talk about plaque that
is less than 70%. And, we need to find those plaques
in patients who are in that intermediate risk group
because those patients may have a low Framingham
Risk Score, may, in fact, have a negative stress
test but, after all of that information is acquired,
could still have a coronary event in the next year.
64-slice CT scanning is superb in detecting that
patient. It is of great use in the patient who
has had an equivocal stress test (one that is not
diagnostic) and is also very useful in those patients
for whom we suspect a false-positive stress test
(that is, the test is abnormal and the patient
does not have the disease). We would much rather
do a non-invasive test than subject that patient
to a full cardiac catheterization. And, finally,
it is also useful in patients with valve disease
whom, by echocardiography, we know may need their
valves replaced and we want to do a simpler, less
invasive test to determine if they also have coronary
artery problems.
The bottom line is that 64-slice CT is an evolving
technology, it’s a very
powerful technology, and it is extremely useful in those situations we reviewed.
But, randomized, controlled trials are required in order to find its true place
in cardiac work up in the future.
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