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Making an informed choice
for the best heart test
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Functional versus anatomic assessment
If you have chest pain and consult your doctor, you
may be given a choice of tests to assess the likelihood
of narrowing of your heart arteries. The question on
everyone’s mind is what test should be the first test
you should do if you have chest pain? Should it be:
functional heart tests such as treadmill testing; stress
echocardiography (assessing heart function using an
ultrasound during stress testing); nuclear myocardial
perfusion scan (injecting radioisotopes into the blood
and assessing the distribution of radioactive isotopes
in the heart muscle); cardiac rubidium PET scan
(injecting rubidium radioisotope into the blood and
assessing the distribution of rubidium isotopes in the
heart muscle)? Or should it be anatomic imaging of the
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heart arteries using coronary computed tomography
angiogram (CCTA)?
Generally, functional stress tests involve the use of
exercise or drugs to stimulate the heart and attempt
to look for evidence of imbalance of blood flow in the
heart muscles caused by blocked arteries which are
not present at rest but are present when the heart is
stressed. They do not provide heart arteries visualisation.
But CCTA involves the injection of an iodine-based
contrast dye into the arm vein and the use of highspeed
X-Rays to get 3D images of the heart arteries within
seconds.
First line of investigation
Over the last decade, there has been an increasing
use of CCTA to diagnose coronary artery disease.
In the national healthcare system in the United
Kingdom, CCTA is recommended as the first-
line investigation for patients with chest pain. The
American Heart Association, American College of
Cardiology and other international bodies guidelines
on Cardiac CT considers it appropriate to use CCTA
as an investigation for most chest pains. For the
asymptomatic, the UK guidelines recommended the
use of non-contrast CT scan of the heart arteries to
look for calcium deposits (calcium score).
Generally, there is substantial data to show that
increased presence of calcium deposits in the walls
of the heart arteries is correlated with increased
degeneration and narrowing of the heart arteries.
The amount of calcium present is represented as the
Agaston score or calcium score. The CG95 recommends
GlobalHealthAndTravel.com
REFERENCE
A
patient of mine related how her husband, who
had passed his treadmill testing with flying
colours during his recent annual health check,
died within minutes before her eyes after complaining
of shortness of breath and chest tightness. You may
wonder how then is it possible to die of a heart attack
after having passed a treadmill test?
Treadmill testing belongs to a group of functional
heart tests which involves stressing the heart function
and trying to ascertain whether there is sufficient blood
flow to the heart muscles. As the heart arteries cannot
be visualised by functional tests such as treadmill
testing, it is not surprising that in some patients with
significant blockage of their heart arteries, the treadmill
test may be “negative” and is not able to detect the
underlying disease.