These results were confirmed by an
important epidemiological study conducted on a range of 10377 asymptomatic
patients, 40% female, with an average age of 53 + 0,102 who underwent Coronary
Calcification research studies using EBCT, and who presented two or more risk
factors.
I Patients with risk factors were prevalent:
family history of coronary-artery disease (69%), hypercholesterolemia (62%),
hypertension (44%), smoking (40%), diabetes (9%).
La The Agatston method was used to determine
results.
57% of the patients had a scores of < 10.
Prevalent scores were 11-100, 101-400, 401-1000
and > 1000 were 20%, 14%, 6% and 3%, respectively.
The average score was 133 + 0,9 with values
ranging between 12 and 1070 for Males in an age group between 40 and 80 years
old.
For the women in the same age group, results varied between 7 and 291, and such
a difference between the two sexes results as highly significant.
Coronary calcium is an independent and
statistically high significant death risk indicator (p<0.001).
The relatively correct risk for greater risk
factors was 1,64 / 1,74 / 2,54 / 4,03 respectively for score values of 11-100,
101-400, 401-1000 and over 1000.
When the CSI values were compared with the
Framingham model to calculate the risk of death or myocardial infarction within
10 years, the CSI values demonstrated greater predictive value.
A multivariable model was used according to
CSI values to predict mortality within 5 years in relation to the various risk
categories according to the Framingham model.
For low-risk patients, mortality risk within 5
years varied between 0,9 and 3,9% for CSI values less than 10 and greater than
1000, respectively.
For moderate -risk patients, mortality risk
within 5 years varied between 1.1% and 9% for CSI values less than 10 and
greater than 1000, respectively.
For high-risk patients, mortality risk within 5
years varied between 2% and 12% for CSI values less than 10 and greater than
1000, respectively. (Leslee J. Shaw, PhD Paolo Raggi, Radiology 2003;
228:826?833).
All the causes of
mortality within 5 years in relation to Clinical characteristics and the Calcium
Score values of the study population.
According to studies conducted by A.
Beker e Coll. (Am Heart J 2008.), in a population of asymptomatic patients,
independent of coronary risk factors, patients with a future risk of myocardial
infarction cardiac death can be identified through Coronary-artery Calcification
determination. Similarly, future major cardiac events can be excluded in
patients where Coronary-artery Calcification could be excluded. In fact patients
with a calcium score over 75° percentile present 11% of major cardiac events per
year. On the other hand, those with a calcium score of 0 present only 0,7% of
major cardiac events per year (cardiac revascularization events (CR) Myocardial
infarction (MI), cardiac death (CD)).
Tab.
Frequency of cardiac revascularization events (CR) Myocardial infarction (MI),
cardiac death (CD) in all patients, in patients with a 0 Agatston score, and in
patients with an Agatston score over 75 percentile
(Beker et Al. American Heart Journal
Volume 155, Number 1, 2008;155:154-60)
Initially assessments were obtained with greater
precision using EBCT(Electron Beam Computer Tomography).
At present multi-row- detector- computer
assisted tomography (16-320-slice MDCT) can be used with excellent results both
for performing contrast-enhanced CT Coronary Angiography(CTA) as well as for
calcium score index determination.
This provides an excellent correlation with the
calcium score determinations performed using EBCT techniques, but less moving
artefacts.
Tests performed with ECG multiple detectors and
retrospective synchronisation, present less inter-test variability, if compared
with EBCT studies.
In many studies, Coronary Angiography using CT
methods has demonstrated a negative predictive value of 96-98% and a positive
value of 59-85%.
In spite of the fact that it is a method that is
still under experimentation, with the new 64-320 slice multi-detector row CT it
is possible to identify fibrous as well as calcified plaques.
The patient is exposed to very low radiation
levels and this varies between 1mS to assess the calcium score and 9 mS. for
contrast-enhanced CT Coronary Angiography (CTA).
New equipment is specifically designed to
reduce patient exposure to X-rays.
