CIMT stands for Carotid Intima Media Thickness and refers to the combined
thickness of the inner two layers (intima and media) of the carotid
artery, which lies in the neck.
Genetics and environmental factors (including diet, exposure to
pro-atherosclerotic substances such as cigarette smoke, and physical
inactivity/lack of exercise) combine over time to cause inflammation of
the inner layers of the artery and the formation of plaque on the inner
lining of the arterial wall. The process of plaque formation is known as
atherosclerosis. This thickening can be measured using ultrasound and
sophisticated edge-detection software to quantify the amount of disease
present. The measurement of the thickness of the intima and media layers
of the common carotid artery is predictive of future events (i.e.
stroke, myocardial infarction, and heart attack).
CIMT can be measured using ultrasound technology. It is a painless,
noninvasive test that can be performed easily in the physician's office.
The CIMT scan is brief (potentially as short as 5 minutes), does not
require the patient to disrobe, is noninvasive (no needles), and does
not expose the patient to radiation. It is relatively inexpensive and
provides valuable information about an individual's risk of experiencing
a heart attract, stroke, or MI.
If you are using a CardioHealth® Station, the CIMT measurement will be
accurately and automatically performed by the system’s advanced software
algorithms. The CIMT result and report will be available immediately
following completion of the test.
Multiple studies indicate that
CIMT measurement detects the presence or absence of atherosclerotic
disease and also allows for assessment of the degree of atherosclerotic
burden better than other noninvasive cardiovascular tests available. It
is recommended by both the American Heart Association and the American
College of Cardiology.
The carotid ultrasound scanning procedure:
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Can
help assess the risk of future cardiac and cerebrovascular events.
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Allows
earlier detection and intervention
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Allows
more accurate risk stratification in asymptomatic patients than do
traditional risk factors
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Can
also provide information about the presence or absence of visualized
carotid plaque
CIMT testing has been used in research for over 20 years. It has only been
available in clinical settings since 2002. CIMT testing has been
validated in many published studies in the most reputable journals. CIMT
has been used in large epidemiologic trials as well as large outcome
studies as a surrogate end point for clinical events. CIMT is probably
the most studied methodology used to assess large numbers of patients in
epidemiologic studies to determine either the correlation of Carotid
Intima Media Thickening to clinical events or the correlation of CIMT to
other known risk factors. There is a high correlation between the
disease found in this procedure and the disease found through pathology
samples. The amount of disease found in the common carotid artery
correlates highly to the amount of disease found elsewhere in the body,
including in the coronary vasculature.
In the November 2010 updated guidelines for assessment of cardiovascular
risk in asymptomatic adults, the American College of Cardiology
Foundation/American Heart Association Task Force gave carotid intima-media
thickness on ultrasound a Class IIa recommendation. “Measurement of
carotid artery IMT is reasonable for cardiovascular risk assessment in
asymptomatic adults at intermediate risk.”
The American Heart Association recommends this test for all patients
over 45 years of age, and younger if the patient has multiple risk
factors (Family History, Hyperlipidemia, Dyslipidemia, Hypertension,
Metabolic Syndrome etc). As previously noted, patients that are believed
to be at intermediate risk for heart disease and stroke are ideal
candidates for this procedure. At its annual Prevention Conference V,
the American Heart Association concluded that "Carotid artery B-mode
ultrasound imaging is a safe, noninvasive, and relatively inexpensive
means of assessing subclinical atherosclerosis. The technique is a valid
and reliable means of measuring IMT, an operational measure of
atherosclerosis. The severity of carotid IMT is an independent predictor
of transient cerebral ischemia, stroke, and coronary events such as MI.
In asymptomatic persons > 45 years old, carefully performed carotid
ultrasound examination with IMT measurement can add incremental
information to traditional risk factor assessment."
In July of 2003, Dr. Pam Douglas, President of the American College of
Cardiology at the time, recommended CIMT as an effective screening tool.
This recommendation was based on the following facts: 1) CIMT is highly
predictive for presence of coronary and cerebral disease. 2) It is
highly predictive for the development of stroke, TIA and heart attack.
3) The relationship of carotid disease to disease of the coronaries is
the same as one coronary to another. 4) Carotid IMT has the most data as
a diagnostic tool for arteriosclerosis. (Transcript ACCEL interview -
July 2003)
The test has been cleared by the Food and Drug Administration (FDA).
Also, you should note that while numerous ultrasound systems are
available, the CardioHealth® Station is the only FDA-cleared, automated,
real time system for measurement of CIMT.
Leading physicians across the country have added CIMT to their primary
prevention as an initial risk assessment tool and as a secondary
prevention tool to monitor the affect of prescribed treatment over time.
Unlike coronary calcium scoring, CIMT can show disease regression.
CIMT testing has been shown to provide incremental additional data to
risk prediction and is the only imaging test which has been recommended
by the American Heart Association for that purpose.
Testing over time can shed light on the efficacy of treatment by tracking
thickening (progression) or thinning (regression) of the intima media
thickness. Change in plaque area and size can also be visualized.
Unlike conventional CIMT testing, the CardioHealth® Test can be
completed in a single step. Other systems require a 2-step
procedure: 1) First, a sonographer takes sonographic images, and 2)
second, sends them to a separate software program or to an external
reading service, where the ultrasound images are analyzed and the CIMT
measurement is performed. With the CardioHealth® Station, the
CIMT measurement is obtained automatically and the results are available
as soon as the scanning procedure is completed.
In general, the test will take about 10 minutes of the patient's time to
complete, but testing can often be completed more quickly. The patient
is not required to disrobe and the procedure is well tolerated.
There are no special requirements.
Despite advances in patient education, cardiovascular disease remains the
#1 killer in our population. Estimates indicate that with the increasing
incidence of Metabolic Syndrome and Diabetes, morbidity and mortality
may increase over the next 20 years. Even though there has been some
improvement in cardiovascular disease assessment and intervention in
men, there has been little progress regarding the detection and
prevention of cardiovascular disease in women.
As many as 50% of those who died from heart attacks or strokes had no
previous signs or symptoms. This test allows early intervention and
prevention of disease which has the potential to catch more of these
patients so they can be treated before they experience an event. In
fact, some studies have shown that showing these patients their test
results may help to improve their adherence to prescribed treatments.
Traditional risk factors such as cholesterol and blood pressure may be
misleading. As many as 50% of those who died from heart attacks or
strokes had normal "lipid" profiles. Carotid IMT will catch more people
with disease who may have been shown to be normal on other tests like
stress echo, standard lipid panels, and other blood/urine screens.
Carotid ultrasound scanning with CIMT measurement is a cost effective
diagnostic tool which provides health value and saves lives.
CIMT is more accurate in predicting disease than any other risk factor
alone. CIMT measurement is an independent risk factor even in the
absence of any other identifiable risk factors.
Studies have shown a high (>90%) correlation between atherosclerotic
disease found in the common carotid and disease found elsewhere in the
body, such as in the coronary arteries that supply the heart muscle.
There is a very high correlation between the thickness of the intima
media and other risk factors. Perhaps most important is CIMT's
correlation and ability to predict coronary and cerebral events.
CIMT has been shown in large-scale, prospective studies (ARIC Study,
MESA Study, others) to be an independent predictor of heart attack and
stroke. Moreover, CIMT and presence/absence of carotid plaque provide
the most incremental predictive value over traditional risk factors
alone.
