Frequently asked questions about Carotid Intima Media Thickness Testing (CIMT)
What is CIMT?
CIMT stands for Carotid intima media thickness and refers to the thickness of the inner layers of the artery.
What does the thickness of the vascular lining indicate ?
Genetics and environmental factors (including diet, exposure to carcinogens such as cigarette smoke, and exercise - or the lack of exercise, etc) 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. 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).
What is an IMT test?
It is a painless noninvasive test utilizing digital ultrasound technology and digital sophisticated edge detection software. The test can be performed easily in the physician's office.
The CIMT scan is brief (approximately 10 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.
What information does the CIMT test provide?
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 procedure:
- Can predict future cardiac and cerebrovascular events.
- Allows earlier detection and intervention
- Allows more accurate risk stratification in asymptomatic patients than do traditional risk factors
- Can distinguish between different types of plaque providing further information about stable and unstable plaque
How long has CIMT testing been used in clinical practice?
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.
Does this test also detect and predict disease in women?
This test is felt to be as predictive in women as it is in men and helps to eliminate the dilemma clinicians have experienced in diagnosing and treating women for heart disease.
How accepted is this test in clinical practice.?
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). 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 Douglass, President of the American College of Cardiology recommended CIMT as an effective screening tool. This stems from the fact that 1) It 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).
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.
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.
What other information can the CIMT test provide to the clinician?
Research has shown a correlation between CIMT and chronological age. Using Framingham age coefficients, and published studies which correlate homogenous populations to age and CIMT measurements, the standard report generated by CardioRisk as part of the CIMT procedure, provides an arterial age coefficient which compares a persons chronological age to their arterial age. Applying this information in conjunction with other risk assessment tools such as the Framingham calculator, can provide patients with an easy to understand surrogate of their own risk for heart attack or stroke.
Can CIMT testing also be employed to monitor progression or regression of disease?
Testing over time can shed light on the efficacy of treatment by tracking thickening or thinning of the intima media as well as tracking the degree of involvement by plaque indicating change in size, number of plaques and plaque characteristics.
How long does it take to complete CIMT testing of one patient?
The test has two parts. A sononographer takes sonographic images and sends them to the CardioRisk IMT Technical Center where they are measured or read by a Registered Vascular Technician (RVT). In general it will take about 10 minutes of the patient's time to complete the test. The patient is not required to disrobe and the procedure is well tolerated.
Are there any special requirements for a patient prior to the test?
There are no special requirements.
Why is this testing important for my patient?
Cardiovascular disease is 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.
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.
It is a cost effective diagnostic tool which provides health value and saves lives.
How accurate is CIMT as a predictive tool?
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.
Progression of disease over time is another independent risk factor.
Studies have shown a 96% correlation between the disease found in the common carotid and the disease found elsewhere in the body. 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 was more accurate at predicting CAD than was an Angiogram.
What is the benefit of employing Cardiorisk Laboratories as a provider of services?
- Use of experienced sonographers who employ a specific and patented (pending) scanning protocol
- Guaranteed reliability and reproducibility of results through ongoing quality control and quality assurance
- CardioRisk conducts regular quality control testing and regular inter - and intra variability testing. The inter and intra variability data is reviewed and compiled by an academic biostatistician at the University of Utah School of Medicine.
- No need to purchase expensive equipment
- No need to employ and train a sonographer
- On call physician to physician clinical and medical support
- Ongoing continuing medical education
- Clinical resources and patient tools
CardioRisk Laboratories believes that scanning technique is of the utmost importance to provide reproducibility of data. Scanning protocols are still being tested and evaluated and are evolving. CardioRisk is dedicated to providing high quality scans and to ongoing monitoring of data and statistical analysis.
If you are interested in offering this procedure to patients at your office, please call us at: 888.724.7484 extention 705. or click here.