Medical Policy: 02.02.14
Original Effective Date: June 2012
Reviewed: January 2016
Revised: February 2014
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services were rendered. Exclusions, limitations or exceptions may apply. Benefits may vary
based on contract, and individual member benefits must be verified. Wellmark determines medical
necessity only if the benefit exists and no contract exclusions are applicable. This medical
policy may not apply to FEP. Benefits are determined by the Federal Employee Program.
This Medical Policy document describes the status of medical technology at the time the document was developed. Since that time, new technology may have emerged or new medical literature may have been published. This Medical Policy will be reviewed regularly and be updated as scientific and medical literature becomes available.
Coronary heart disease (CHD) accounts for 27% of all deaths in the United States. Major risk factors for CHD have been identified by the National Cholesterol Education Program (NCEP) Expert Panel. These risk factors include elevated serum levels of low-density lipoprotein (LDL) cholesterol, total cholesterol, and reduced levels of high-density lipoprotein (HDL) cholesterol. Other risk factors include a history of cigarette smoking, hypertension, family history of premature CHD, and age.
Measurement of the carotid intima-media thickness (CIMT) is a non-invasive test where the lining of the carotid arteries is measured with the use of B-mode ultrasound. The intima is the innermost layer of the artery and the media is the middle layer of the artery. The intima-media thickness is measured for the objective of detecting preclinical or subclinical cardiovascular disease. Measurement of the CIMT is considered to be a surrogate marker for the measurement of atherosclerosis, which correlates with the presence of coronary atherosclerosis. This has led to the theory that it may represent an independent marker, separate from the traditional risk factors for cardiovascular disease and stroke.
The intima-media thickness (IMT) is measured and averaged over several sites in each carotid artery. Imaging of the far wall of each common carotid artery yields more accurate and reproducible IMT measurements than imaging of the near wall. Two echogenic lines are produced, representing the lumen- intima interface and the media-adventitia interface. The distance between these two lines constitutes the IMT.
At this time, there is a lack of standardization of measurement and imaging protocols. It is not clear whether generalized IMT or focal plaque formation is of more importance. The literature also indicates that there are gender and age related differences with IMT. A definition of what is considered expected normal limits that take into account these differences has not been established. It is not evident from the literature that CIMT is able to improve on risk prediction above what is provided by utilization of traditional risk factors or the effect of these measurements on patient outcomes.
In October 2009, the U.S. Preventative Services Task Force (USPSTF) published a systemic review of CIMT within the scope of a larger recommendation statement entitled “Coronary Heart Disease: Screening Using Non-Traditional Risk Factors”. Coronary heart disease is the most common cause of mortality in adults in the United States. Treatment to prevent CHD events by modifying risk factors is currently based on the Framingham risk model, which sorts individuals into low, intermediate or high risk groups. If the risk model could be improved, treatment might be better targeted, thereby maximizing screening benefits and minimizing harms. The most likely opportunity to improve the model is use of additional risk factors to reclassify those in the intermediate risk group to either high or low risk.
The U.S. Preventative Services Task Force (USPSTF) concludes that the current evidence is insufficient to assess the balance of benefits and harms of using the nontraditional risk factors discussed in this statement to screen asymptomatic men and women with no history of CAD to prevent CHD events.
The nontraditional risk factors include in this recommendation are high sensitivity C reactive protein (hs-CRP), ankle brachial index (ABI), leukocyte count, fasting blood glucose level, periodontal disease, carotid intima-media thickness (carotid IMT), coronary artery calcification (CAC) score on electron beam computed tomography (EBCT), homocystein level and lipoprotein(a) level.
2010 Practice Guidelines, Assessment of Cardiovascular Risk in Asymptomatic Adults
The guidelines indicate the measurement of carotid artery IMT is reasonable for assessment of cardiovascular risk assessment in asymptomatic adults at intermediate risk. The guidelines note an increased CIMT reading may be used as a guide in determining clinical utility, but evidence has not demonstrated improvements in outcomes when incorporating CIMT measurement into treatment decision making. Additionally, the guidelines state “clinical tools integrating carotid IMT within global risk scoring system are not available. The incremental value of carotid IMT and cost effectiveness beyond that available from standard risk assessments to improve overall patient outcomes is not established.”
Carotid IMT is not recommended for routine measurement in clinical practice for risk assessment for first atherosclerotic cardiovascular disease (ASCVD) event.
In February 2003, SonoCalc® (SonoSite) was cleared for marketing by the U.S. Food and Drug Administration (FDA) through the 510(k) process. The FDA determined that this software was substantially equivalent to existing image display products for use in the automatic measurement of the IMT of the carotid artery from images obtained from ultrasound systems. Subsequently, several other devices have been approved through the 510(k) process.
Ultrasonographic measurement of carotid artery intima-media thickness (CIMT) as a technique of identifying subclinical atherosclerosis is considered investigational for use in the screening, diagnosis, or management of atherosclerotic disease.
Based on peer reviewed medical literature the available studies do not define how the use of CIMT in clinical practice improves outcomes. Also, there is no scientific literature that directly tests the hypothesis that measurement of CIMT results in improved patient outcomes and no specific guidance on how measurements of CIMT should be incorporated into risk assessment and risk management. The existing evidence is insufficient to determine the impact of this technology on net health outcomes. Therefore, carotid intima-media thickness (CIMT) is considered investigational for the use in the screening, diagnosis or management of atherosclerotic disease.
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*Current Procedural Terminology © 2012 American Medical Association. All Rights Reserved.