Medical Policy: 02.02.14
Original Effective Date: June 2012
Reviewed: January 2017
Revised: February 2014
Benefit determinations are based on the applicable contract language in effect at the time the 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 30.8% 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 cholesterol (LDL-C), total cholesterol, and reduced levels of high-density lipoprotein cholesterol. Other risk factors include a history of cigarette smoking, hypertension, family history of premature CHD, and age.
Ultrasonographic measurement of the carotid intima-media (or intimal-medial) thickness (CIMT) refers to the use of B-mode ultrasound to determine the thickness of the 2 innermost layers of the carotid artery wall, the intima and the media. Detection and monitoring of intima-medial thickening, which is a surrogate marker for artherosclerosis, may provide an opportunity to intervene earlier in atherogenic disease and/or monitor disease progression.
The carotid arteries can be well-visualized by ultrasonography, and ultrasonographic measurement of the carotid intima-media thickness (CIMT) has been investigated as a technique to identify and monitor subclinical artherosclerosis. B-mode ultrasound is most commonly used to measure CIMT. 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.
Measurement of carotid intima-media (or intimal-medial) thickness (CIMT) is primarily meant to assess risk for future disease, and therefore can be evaluated as a prognostic measure. Assessment of a prognostic measure typically focuses on 3 categories of evidence: 1) technical performance; 2) prognostic value (i.e. significant association between the test result and health outcomes); and 3) impact on health outcomes (i.e. demonstration that use of the prognostic information clinically can alter clinical management and/or improve health outcomes compared with patient management without use of the prognostic tool). In some cases, it is important to evaluate whether the test provides incremental information above the standard workup to determine whether the test has utility in clinical practice.
For individuals who are undergoing cardiac risk assessment who receive ultrasonic measurement of carotid intima-medial thickness, the evidence includes large cohort studies and systematic reviews. Some studies correlate increased CIMT with many other commonly used markers for risk of coronary heart disease (CHD) and with risk for future cardiovascular events. A 2012 meta-analysis of individual participant data by Lorenz et. al. found that CIMT was associated with increased cardiovascular events although CIMT progression over time was not associated with increased cardiovascular event risk. In a systematic review by Peters et. al. (2012), the added predictive value of CIMT was modest, and the ability to reclassify patients into clinically relevant categories was not demonstrated. The results from these reviews and other studies have demonstrated the predictived value of CIMT is uncertain, and the predictive ability for any level of population risk cannot be determined with precision. In addition, available studies do not define how use of CIMT in clinical practice improves outcomes. 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 evidence is insufficient to determine the effects of the technology on health 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. (Grade N (No Recommendation For or Against); Level of Evidence B (Limited populations evaluated; data derived from a single randomized trial or nonrandomized studies); ACC/AHA Class III (No benefit – procedure/test not helpful).
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.