Coronary Calcium Score in the Evaluation of Diabetic Patients without Coronary Arteries Disease Symptoms-Juniper Publishers
JUNIPER PUBLISHERS-OPEN ACCESS JOURNAL OF CARDIOLOGY & CARDIOVASCULAR THERAPY
Diabetic patients are more likely to have an acute
coronary syndrome or even sudden silent death. Among the diabetic
population there is the paradox of an early onset of coronary disease
and a late diagnosis due to the absence of a striking clinic. Angina in
the diabetic patient usually has an atypical presentation. The technique
described by Agatston to quantify coronary calcium consists in
measuring the total area of calcified coronary plaque in pixels, cut by
cut, assigning a score. Coronary artery calcification has been shown to
be an excellent measure of atherosclerotic load in epicardial vessels.
The calcium in coronary arteries is related to cardiac events in the
general population and its quantification is consistently higher in
patients with clinic coronary disease. The presence of vascular
calcification may provide an additional reason for both the physician
and the patient to adopt more intensive prevention strategies on risk
factors.
Abbreviations: CAS: Coronary Artery Calcification; CCS: Coronary Calcium Score
Introduction
Diabetic patients are more likely to have an acute
coronary syndrome or even sudden silent death. It is postulated that the
basis of silent ischemia is an autonomic neuropathy with involvement of
the cardiac sensory innervations [1]. Among the diabetic population
there is the paradox of an early onset of coronary disease and a late
diagnosis due to the absence of a striking clinic. Angina in the
diabetic patient usually has an atypical presentation. It occurs with a
frequency that varies between 20% and 44% according to the studies. The
pain can be located at the mandible angle, neck or epigastrium, and it
also can be associated with vomiting [2]. The prevalence of acute
myocardial infarction in the diabetic population is increased in all
ages. In addition, the existence of diabetes annuls the epidemiological
benefit of the female sex for ischemic heart disease. The Framingham
study showed that the prevalence of age-adjusted acute myocardial
infarction in adults from 35 to 65 years old was twice as high for
diabetic men as for non-diabetic men and triple for diabetic women than
for women free of this disease. These data are similar in studies
carried out in other populations [3]. The survival after an acute
myocardial infarction is also significantly reduced in the diabetic
population, basically
due to the higher frequency of complications such as early stage
mortality, cardiogenic shock, myocardial rupture, acute arrhythmias and
heart failure [4].
Intimal calcification of the coronary arteries is
part of the evolutionary process of atherosclerosis at that level. It
occurs almost exclusively in the arterial segments affected by this
process, usually in small amounts during the initial stages of
atherosclerotic lesions, and more frequently in lesions and advanced
ages [5,6]. Although there is a positive correlation between site and
quantity of coronary calcium and percent coronary stenosis in the same
anatomical site, the relationship is nonlinear and has large confidence
limits [7].
The coronary arteries calcification is almost
exclusively in the context of atherosclerosis, except in patients with
renal failure where there may be calcification not related to
atherosclerosis. The technique described by Agatston [8] to quantify
coronary calcium consists in measuring the total area of calcified
coronary plaque in pixels, cut by cut, assigning a score. The Agatston’s
calcium score is obtained as a result of the multiplication of the area
of the calcified lesion by a factor dependent on the peak signal
intensity of the lesion. Coronary artery calcification (CAS)
has been shown to be an excellent measure of atherosclerotic
load in epicardial vessels. The calcium in coronary arteries
is related to cardiac events in the general population and its
quantification is consistently higher in patients with clinic
coronary disease [9,10].
Coronary calcium score (CCS) determined through multiple
detector computed tomography is an excellent noninvasive
method for detecting coronary atherosclerosis in subclinical
stages. This technique establishes the presence of calcium in
the wall of coronaries arteries predicting the risk of coronary
events in the long term. Subjects with no CAC or low CCS are less
likely to present cardiovascular events than those with elevated
scores [11]. At present, the use of CCS focuses on two clinical
areas of interest: 1) Risk assessment in asymptomatic patients,
with the purpose of modifying and potentially improving their
lifestyle. 2) Its use in symptomatic patients as a means to select
which of them may require hospitalization, additional diagnosis
or invasive procedures.
As a general line and based on a consensus, patients may be
divided into groups according to the extension of the disease:
Absence of calcification; minimal calcification (1-10); mild (11-
100); moderate (101-400); severe (401-1000); and extensive
(more than 1000). Patients may also be divided according
to percentile of age, gender, and ethnicity [9]. A CCS greater
than 1000 is associated with a 25% annual risk of having
a cardiovascular event (and therefore translates a need for
aggressive treatment measures in these patients). Budoff et al.
[12] point out that the best way to assess the test result is to use
the absolute value of coronary calcium, using values of 100 and
400 to differentiate between patients at low and very high risk.
The PREDICT study [13], which included 589 patients with type
2 Diabetes Mellitus without a history of cardiovascular disease,
showed a CCS of less than 10AU in 23.4% and a CCS greater than
400AU in 25.5%. Anand et al. [14] reported a higher prevalence
in asymptomatic diabetics, since 46.3% had a CCS greater than
10 AU. In a recent comparative study lead in Cuba by Peix et
al. [15], the CCS in diabetic patients was 74.1±168.8AU vs
5.2±14.6AU in controls, p<0.01. Furthermore they found that the
13.6% diabetic patients had a CCS greater than 100AU. On the
other hand, in the presence of a score of zero, there is a small
probability of disease in patients with low to intermediate risk,
even in those showing symptoms [16]. Moreover; it denotes
that the disease does not show great extent, which is a good
prognostic indicator. The absence of calcium in the coronary
determines an annual risk close to 0.1% [17]. The presence of
vascular calcification may provide an additional reason for both
the physician and the patient to adopt more intensive prevention
strategies on risk factors such as smoking, hypertension, lipids
and glycemic control.
Literature review shows that Coronary calcium score play
an important role in the diagnostic evaluation of atherosclerotic
heart disease, especially in the diabetic patient. The possibility
of removing extensive coronary disease by means of a calcium
score zero, or indicating the presence of an extensive disease
when it is severely increased, justifies the use of this method
in the initial or joint evaluation, in asymptomatic patients with
suspected coronary artery disease and in cardiovascular risk
stratification.
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