|Subject:||Computed Tomography to Detect Coronary Artery Calcification|
|Policy #:||RAD.00001||Current Effective Date:||07/10/2012|
|Status:||Reviewed||Last Review Date:||05/10/2012|
This document addresses use of electron beam computed tomography (EBCT), helical computed tomography (CT) and multi-slice spiral CT (MSCT) scanning to detect coronary artery calcium (CAC). The rapid image acquisition time of these CT scanning techniques eliminates motion artifact related to the beating heart and thus, permits visualization of CAC. In asymptomatic individuals, CAC has been investigated as a risk factor for coronary artery disease and has been used to further evaluate individuals with known coronary artery disease (CAD). Assessment of CAC may also be done in conjunction with CT scanning to visualize the coronary arteries, (referred to as CT angiography, or CCTA).
Note: Please see the following related document for additional information:
Investigational and Not Medically Necessary:
The use of electron beam computed tomography (EBCT), helical CT or multi-slice spiral (also known as multi-row detector) CT (MSCT) is considered investigational and not medically necessary for the detection of coronary artery calcium, including, but not limited to, the following indications:
Diagnostic technologies are commonly evaluated according to a sequential three step assessment of analytic validity, clinical validity and clinical utility. Analytic validity refers to the ability of a CT scan to accurately and reliably detect CAC. The data is typically reported as a "calcium score," which represents the total atherosclerotic plaque burden. Clinical validity refers to the relationship between the detected CAC and CAD. Finally, clinical utility refers to how CAC scores can be used to improve treatment management of CAD.
While it is recognized that electron beam or helical CT scans can detect and quantify CAC, the major questions regarding these techniques relate to clinical validity and utility. For example, in the United States cardiac risk assessment is currently based on the Framingham Risk Score (FRS), which is used as the basis for various prevention strategies for CAD. The FRS is derived from various, easily obtained, clinical and laboratory values, such as age, lipid profile, blood pressure and smoking status. Therefore, a key question is whether an assessment of CAC will improve these traditional risk assessment techniques. Additionally, it is important to understand how CAC risk assessment will be integrated into overall treatment management, particularly in those who are considered at intermediate risk. For example, epidemiologic and observational studies may demonstrate that CAC is an independent risk factor for CAD, but improved risk assessment is not clinically meaningful if this information cannot be used to improve treatment management.
CAC has also been used to evaluate symptomatic individuals as an initial test to guide further cardiac function or imaging tests, based on the calcium score. For example, a low calcium score may be used to rule out CAD in symptomatic individuals, potentially deselecting these people for angiography. Again, in this setting it is important to understand how measurement of CAC will be integrated into the management of the individual, particularly given the wide variety available of noninvasive diagnostic techniques, ranging from different types of exercise tests, echocardiography and nuclear medicine tests.
The following discussion is based primarily on review of a variety of consensus documents, scientific statements and guidelines addressing the clinical validity and clinical utility of CT detection of CAC.
Consensus Reports, Guidelines and Scientific Statements:
In 2000, an American College of Cardiology/American Heart Association Expert Consensus paper stated that EBCT measurement of CAC is not recommended for diagnosing obstructive CAD, because of the imaging device's low specificity (high percentage of false-positive results) or for screening of asymptomatic individuals, because of the lack of incremental value in EBCT screening over other readily available risk assessment methods (O'Rourke, 2000).
In 2004, the United States Preventive Services Task Force (USPSTF) issued updated recommendations on screening asymptomatic adults for coronary heart disease (CHD, also known as CAD) seen in primary care settings. The USPSTF gave a "D"* recommendation against routine screening with EBCT scanning for CAC, for either the presence of severe coronary artery stenosis or the prediction of CHD events in adults at low risk for CHD. This recommendation was supported by at least fair evidence that screening asymptomatic adults for CHD is ineffective or that harms outweigh benefits. The USPSTF gave an "I"** recommendation to support or reject EBCT scanning for CAC for either the presence of severe coronary artery stenosis or the prediction of CHD events, in adults at increased risk for CHD events. This recommendation was based on insufficient evidence to recommend for or against routinely providing screening services in this adult population (USPSTF, 2004; see the Definitions section for an explanation of the rating system).
In 2005, the American Heart Association (AHA) published a consensus statement regarding the role of noninvasive testing of women with suspected CAD (Mieres, 2005). The consensus statement considered the incremental value of CAC scores, compared to traditional risk factor assessment, and focused on one observational study that included a large number of women. The report concluded that additional studies were needed to establish female-specific cut points of CAC scores defining high risk status in women. The consensus statement offered the following conclusion:
Additional high-quality data are needed from larger cohorts that specifically address CAD outcomes in women to more precisely establish female specific CAC risk cut points and to more precisely quantify the incremental prognostic value beyond the measurement of conventional coronary risk factors. Until then, consistent with recent consensus statements, CAC testing for CAD risk detection should be limited to clinically selected women at intermediate risk.
In 2006, the AHA published a scientific statement on the assessment of CAD by cardiac computed tomography (Budoff, 2006). Most of the document reviewed the clinical utility of CAC scoring for determining prognosis and diagnosis. Within this document, there were no Class I* or IIa** recommendations regarding coronary artery calcium detection by CT. The following IIb recommendations were offered:
A 2007 clinical consensus document co-written by the American College of Cardiology Foundation and the American Heart Association (ACCF/AHA) provided updated information on CAC measurement (Greenland, 2007). This document notes that Clinical Expert Consensus Documents concern topics for which, "The evidence base, the experience with the technology and/or the clinical practice are not considered sufficiently well developed to be evaluated by the formal American College of Cardiology/American Heart Association (ACC/AHA) Guidelines process. Often the topic is the subject of considerable ongoing investigation." Therefore, this document acknowledged the lack of rigorous evidence addressing the clinical utility of CAC measurement.
The findings of this expert panel were consistent with the prior AHA scientific statement (Budoff, 2006) in that the Committee judged that it may be reasonable to consider use of CAC measurement in asymptomatic individuals with intermediate CHD risk. This was based on the possibility that such persons might be reclassified to a higher risk status if high CAC scores are found; thereby subsequent treatment management may be modified. However, there was inadequate data to show that changes in management result in improved health outcome. The Committee did not recommend use of CAC measurement in other selected groups, such as those with low or high CHD risk (based on the FRS). However, this paper noted, "In general, CAC measurement has not been compared to alternative approaches to risk assessment in head-to-head studies. Therefore, the question of whether there is evidence that CAC measurement is better than other potentially competing tests for intermediate risk patients for modifying cardiovascular disease risk estimate cannot be adequately answered from the available data." In addition, the ACCF/AHA 2010 guideline for asymptomatic individuals agrees that "Evidence is not available to show that risk assessment using CAC scoring improves clinical outcomes by reducing mortality or morbidity from CAD" (Greenland, 2010).
The USPSTF issued another recommendation statement on using nontraditional risk factors in CHD risk assessment in 2009 which concluded 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 CHD to prevent CHD events." (Grade: I [Insufficient] Statement, current evidence is insufficient to assess the balance of benefits and harms of the service. Evidence is lacking, of poor quality, or conflicting, and the balance of benefits and harms cannot be determined). The nontraditional risk factors included 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), CAC score on EBCT, homocysteine level, and lipoprotein(a) level.
In 2010, the American College of Cardiology Foundation Appropriate Use Criteria Task Force published appropriate use criteria for cardiac computed tomography (Taylor, 2010). The task force used a process which combines evidence-based medicine and practice experience by engaging a technical panel in a modified Delphi exercise. It should be noted that the technical requirements of a Rand Modified Delphi approach (Gordon, 2009) were not strictly adhered to in this report and resulted in obtaining a consensus of individuals on the panel rather than an evidence-based approach.
In 2011, the Institute for Clinical Systems Improvement updated its Healthcare Guideline for Preventive Services for Adults. They recommend against routine screening for coronary artery calcium in those individuals at low risk for coronary heart disease events.
The 2006 AHA scientific statement noted that there is growing evidence that CAC scores are an independent predictor of CAD, (i.e., proof of clinical validity). However, it is still unknown how this information can be integrated into treatment management to improve health outcomes, (i.e., clinical utility). This gap in the data is reflected by the consensus, rather than evidence-based, approach in developing recommendations and appropriateness criteria (Budoff, 2006).
In 2006, Anand and colleagues published a study specifically evaluating CAC scores as a risk stratification tool in 510 subjects with uncomplicated type II diabetes. Myocardial perfusion studies were performed in all subjects with high CAC scores and in a random sample of the remaining subjects. The trial participants were followed for a mean of 2.2 years for cardiovascular events. The authors reported that CAC scores were superior to established cardiovascular risk factors for predicting silent myocardial ischemia and short-term outcome. It should be noted that the CAC scores were not used to direct treatment management.
The Multi-Ethnic Study of Atherosclerosis (MESA) Trial is an ongoing, multi-center, prospective longitudinal study of asymptomatic individuals across four racial/ethnic groups to evaluate the long-term cardiovascular outcomes with a ten year follow-up of 6,772 asymptomatic participants after baseline risk assessment (including CAC measurement). The MESA study was launched in 2000. Interim results (median follow-up 3.9 years) suggest that the CAC score is a predictor of subsequent clinically significant CHD and may provide predictive information beyond that provided by standard risk factors, (i.e., the FRS) (Detrano, 2008). The authors reported that after adjustment for standard risk factors, a doubling of the CAC score resulted in a 20% increase in the risk of a major coronary event (myocardial infarction/death from CHD) and a 25% increase in the risk of any coronary event. A limitation of this study was variation in CT acquisition and reading methods across the six study centers. The authors also caution against using the absolute calcium scores cited in the study and note that ethnic-specific calibrations of CAC scores are needed to adjust for baseline differences between different ethnic groups. Another limitation of this interim report is the small number of measured clinical events (72 non-fatal MI, 17 fatal coronary events, 73 angina pectoris).
The data, collected thus far, from the MESA Trial have been studied and reported in multiple published articles, one of which was conducted by Lakoski and colleagues (2007) who looked at CAC scores and risk of future coronary events in women. This MESA cohort study included 3,601 asymptomatic women, age 45 to 84 years, and judged to be at low risk for coronary disease based on FRS. The authors concluded that the presence of CAC in women at low FRS risk was predictive of future CHD and cardiovascular events. Compared with women with no detectable CAC, low risk women with a CAC score greater than 0 were at increased risk for CHD (HR 6.5, 95%; CI 2.6-16.4) and cardiovascular events (HR 5.2, 95%; CI 2.5-10.8). Low risk women with advanced coronary artery calcium (CAC score greater than or equal to 300) had a risk of 8.6% for having a cardiovascular event over a 3.75 year period, compared with 0.6% in low risk women with CAC score of 0 and 1.9% in low risk women with CAC score 1-99.
Another publication reported on a cohort of 5,878 asymptomatic subjects taken from the MESA population with a median follow-up of 5.8 years. Analysis of risk for coronary events was conducted comparing use of the conventional FRS System alone to inclusion of CAC scores, as part of the risk stratification model. With the addition of CAC to the model, an additional 23% of those who experienced events were reclassified as high risk, and an additional 13% who did not experience events were reclassified as low risk. In total, only 5.1% of the total MESA population was reclassified as a result of CAC scores. Limitations of this study include the need for validation of the results in broader trial populations. The authors acknowledge that higher event rates and different rates of reclassification may have been seen if the study population contained a larger proportion of higher risk individuals. Trial results may have changed with longer follow-up; also the fact that all CAC scores were revealed to both participants and their treating physicians may have impacted the five-year results seen in this trial (Polonsky, 2010).
Budoff and colleagues used a large observational data base of 25,253 asymptomatic individuals undergoing CAC scoring to develop risk-adjusted multivariable models incorporating CAC scores to predict all cause mortality (Budoff, 2007). The authors reported that the CAC score provided incremental information, in addition to traditional risk factors in the prediction of all-cause mortality.
The Early Identification of Subclinical Atherosclerosis by Noninvasive Imaging Research (EISNER) trial looked at the use of CAC screening tests on the impact of medical management and CAD risk (Rozanski, 2011). A total of 713 participants were randomized into the no-scan group while 1424 participants were randomized into the scan group. Participants then returned for a clinic visit at 4 years at which time a questionnaire was used to determine CAD risk factors. The primary end point was change in the CAD risk profiles including a change in global risk determined by FRS. In the scan group, participants experienced a greater reduction in mean systolic blood pressure, serum LDL cholesterol level and reduced waist circumference. The participants in the scan group also showed more of a tendency to lose weight compared to the no-scan group. The 2 groups did not differ in exercise activity, smoking behavior or glucose measurements. CAD risk, as summarized by FRS, rose in the no-scan group but remained the same in the scan group. The authors caution generalizing the findings of this study to the general population. They could not adequately assess CAC scanning on diabetics and smokers due to the small number of participants with these risk factors. They also could not determine the extent to which CAC scanning drove CAD risk profiles as opposed to more intensive use and adherence to medications. Dietary habits were lacking in this study and an exercise activity measurement was by self-report as opposed to objective measurements. Further trials are necessary to determine whether these findings can be applicable to different populations and to determine whether CAC screening translates to reductions in adverse clinical events.
The role of CAC scoring, particularly for determining its incremental value for risk stratification in those with intermediate FRS, continues to be studied. Although observational studies suggest that CAC scores may predict risk for future coronary events, there is insufficient evidence in the literature, to date, to demonstrate how screening with CAC will impact treatment management and clinical outcomes (Bonow, 2009). Also, the evidence continues to show variability in the accuracy of test results from various CT scanners, as well as ongoing concerns about the variable amounts of radiation exposure delivered by these scans (Bluemke, 2008; Budoff, 2006, Gerber, 2009; Gibbons, 2009 Kramer, 2007).
The presence of extensive CAC precludes the use of CT coronary angiogram (CCTA). Therefore, an assessment of CAC is often performed in combination with CCTA. Many of the recently published studies of CAC explore its role in conjunction with CCTA. These studies are not considered in this document. CCTA is addressed separately in RAD.00035.
Computerized axial tomography, also called CT, CT scan, or CAT scan, is an x-ray technique that uses an x-ray-sensing unit which rotates around the body, along with a computer to create cross-sectional images. The images are generated by a computer synthesis of x-ray transmission data obtained for many different directions in a given plane. EBCT and spiral or helical CT scans are types of CT scans that have very high speeds of image acquisition which eliminate the motion artifact of the beating heart, and thus, permit imaging of CAC. Since CAD may remain silent until a major catastrophic event occurs, it has been hypothesized that detection of coronary calcium in asymptomatic individuals could provide additional data on cardiac risk; this could potentially lead to changes in diet, lifestyle, and treatment management. It is thought that these changes could potentially reduce the risk of myocardial infarction (MI).
Computed tomography (CT): An imaging technique that creates multiple cross-sectional images of the body by using special x-rays and computer enhancement to detect disease or abnormalities.
Coronary artery disease: A disease characterized by narrowing or blockage of the blood vessels that supply blood to the heart.
Electron beam CT (also known as Ultrafast CT): A type of CT that uses an electron gun rather than a standard x-ray tube to generate x-rays, thus permitting very rapid scanning, on the order of 50-100 milliseconds per image.
Framingham Risk Scoring System (FRS): The most-commonly used, multi-variable scoring system (in the U.S.) and the most extensively validated quantitative assessment tool for determining an individual's potential risk of developing CHD and of experiencing a significant coronary event. It includes the following major risk factors: gender, total cholesterol, high-density lipoprotein (HDL) cholesterol, systolic blood pressure (or on treatment for hypertension), cigarette smoking, and age.
Helical CT (also known as spiral CT scanning): A type of CT that creates images at greater speed than conventional CT by continuously rotating a standard x-ray tube around the individual so that data are gathered in a continuous spiral or helix rather than individual slices.
Multislice spiral CT (MSCT) (also known as multi-row detector CT or MDCT): A technical evolution of helical CT, it uses CT machines equipped with an array of multiple x-ray detectors that can simultaneously image multiple sections during a rapid volumetric image acquisition..
Tomograph: An apparatus for moving an x-ray source in one direction as the film is moved in the opposite direction, thus showing in detail a predetermined plane of tissue while blurring or eliminating detail in other planes.
Note: According to the USPSTF Task Force ratings on strength of recommendations, the USPSTF grades its recommendations according to one of five classifications (A, B, C, D, I) reflecting the strength of evidence and magnitude of net benefit (benefits minus harms) as follows:
A.— The USPSTF strongly recommends that clinicians provide [the service] to eligible patients. The USPSTF found good evidence that [the service] improves important health outcomes and concludes that benefits substantially outweigh harms.
B.— The USPSTF recommends that clinicians provide [this service] to eligible patients. The USPSTF found at least fair evidence that [the service] improves important health outcomes and concludes that benefits outweigh harms.
C.— The USPSTF makes no recommendation for or against routine provision of [the service]. The USPSTF found at least fair evidence that [the service] can improve health outcomes but concludes that the balance of benefits and harms is too close to justify a general recommendation.
*D.— The USPSTF recommends against routinely providing [the service] to asymptomatic patients. The USPSTF found at least fair evidence that [the service] is ineffective or that harms outweigh benefits.
**I.— The USPSTF concludes that the evidence is insufficient to recommend for or against routinely providing [the service]. Evidence that the [service] is effective is lacking, of poor quality, or conflicting and the balance of benefits and harms cannot be determined. (USPSTF, 2004)
The following codes for treatments and procedures applicable to this document are included below for informational purposes. A draft of future ICD-10 Coding (effective pending final Health and Human Services [HHS] compliance date) related to this document, as it might look today, is included below for your reference. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.
When services are Investigational and Not Medically Necessary:
|71250||Computed tomography, thorax; without contrast material|
|S8092||Electron beam computed tomography (also known as ultrafast CT, cine CT)|
|414.00-414.9||Chronic ischemic heart disease|
|429.2||Cardiovascular disease, unspecified|
|V81.0||Special screening for ischemic heart disease|
|ICD-10 Diagnosis||ICD-10-CM draft codes; effective pending final HHS compliance date:|
|I25.10-I25.119||Atherosclerotic heart disease of native coronary artery|
|I25.6||Silent myocardial ischemia|
|I25.700-I25.799||Atherosclerosis of coronary artery bypass graft(s) and coronary artery of transplanted heart with angina pectoris|
|I25.810-I25.812||Atherosclerosis of other coronary vessels without angina pectoris|
|I25.9||Chronic ischemic heart disease, unspecified|
|I51.9||Heart disease, unspecified|
|Z13.6||Encounter for screening for cardiovascular disorders|
When services are also Investigational and Not Medically Necessary:
|75571||Computed tomography, heart, without contrast material, with quantitative evaluation of coronary calcium|
|ICD-10 Diagnosis||ICD-10-CM draft codes; effective pending final HHS compliance date:|
Peer Reviewed Publications:
Government Agency, Medical Society, and Other Authoritative Publications:
|Web Sites for Additional Information|
Electron Beam Computed Tomography
High-Speed Computed X-Ray Tomography
Multirow Detector CT (MDCT)
Multislice Spiral CT (MSCT)
Rapid Acquisition X-Ray Computed Tomography
Ultrafast® Computed Tomography (CT)
The use of specific product names is illustrative only. It is not intended to be a recommendation of one product over another, and is not intended to represent a complete listing of all products available.
|Reviewed||05/10/2012||Medical Policy & Technology Assessment Committee (MPTAC) review. Updated Rationale, Definitions, References, and Web Sites for Additional Information.|
|Reviewed||05/19/2011||MPTAC review. Updated Rationale, Definitions and References.|
|Reviewed||05/13/2010||MPTAC review. No change to stance. The Rationale and References were updated.|
|01/01/2010||Updated coding section with 01/01/2010 CPT changes; removed CPT 0144T, 0147T, 0149T, 0151T deleted 12/31/2009.|
|Revised||05/21/2009||MPTAC review. No change to stance. As part of a cardiac risk assessment for symptomatic individuals and in conjunction with CCTA have been added to the examples of indications considered investigational and not medically necessary. The Rationale, Background, References and Coding sections have been updated.|
|Reviewed||05/15/2008||MPTAC review. No change to stance. The Rationale section was updated with the results of the recently published MESA Trial (Detrano, 2008; Lakoski, 2007). References were updated also.|
|Reviewed||02/21/2008||MPTAC review. No change to stance. The phrase "investigational/not medically necessary" was clarified to read "investigational and not medically necessary." This change was approved at the November 29, 2007 MPTAC meeting. References were updated.|
|Reviewed||03/08/2007||MPTAC review. No change to stance. The Rationale, References, and Coding sections were updated.|
|Reviewed||03/23/2006||MPTAC review. No changes to stance. References were updated.|
|01/01/2006||Updated coding section with 01/01/2006 CPT/HCPCS changes.|
|11/17/2005||Added reference for Centers for Medicare and Medicaid Services (CMS) – National Coverage Determination (NCD).|
|Revised||04/28/2005||MPTAC review. Revision based on: Pre-merger Anthem and Pre-merger WellPoint Harmonization.|
|Pre-Merger Organizations||Last Review Date||Document Number||Title|
|Anthem, Inc.||01/29/2004||RAD.00001||Electron Beam Computed Tomography (EBCT), Whole Body CT Scanning|
|WellPoint Health Networks, Inc.||12/02/2004||4.01.09|
Ultrafast Computerized Tomography (CT) Scanning for Coronary Disease