|Subject:||Computed Tomography to Detect Coronary Artery Calcification|
|Policy #:||RAD.00001||Current Effective Date:||06/28/2016|
|Status:||Reviewed||Last Review Date:||05/05/2016|
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).
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:
The presence of CAC has been associated with an increased risk of cardiovascular events. The rapid image acquisition time of these EBCT, CT, and MSCT 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). The role of CAC as an independent predictor of risk in the assessment, either alone or in combination with conventional risk factors, of both asymptomatic and symptomatic individuals has been studied.
Risk Assessment in Asymptomatic Individuals
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 10-year follow-up of 6,772 asymptomatic participants after baseline risk assessment (including CAC measurement). The MESA study was launched in 2000. Detrano (2008) published interim results (median follow-up 3.9 years) that suggest that the CAC score is a predictor of subsequent clinically significant coronary heart disease (CHD) and may provide predictive information beyond that provided by standard risk factors, (that is, the Framingham Risk Score [FRS]). 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, and 73 events of angina pectoris).
The data, collected thus far, from the MESA Trial have been studied and reported in multiple published studies, 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 3601 asymptomatic women, age 45 to 84 years, 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 (hazard ratio [HR] 6.5, 95% confidence interval [CI], 2.6-16.4) and cardiovascular events (HR 5.2, 95% CI, 2.5-10.8). Low-risk women with advanced 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.
Polansky (2010) reported on a cohort of 5878 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 5-year results seen in this trial.
Using 6814 asymptomatic intermediate-risk participants from the MESA population, Yeboah (2012) sought to improve the prediction accuracy and reclassification into high- and low-risk categories using 6 risk markers (CAC, carotid intima-media thickness, ankle-brachial index, brachial flow-mediated dilation, high-sensitivity C-reactive protein, and family history of CHD). With a median follow-up of 7.6 years, 94 participants had a CHD event (defined as myocardial infarction, angina followed by revascularization, resuscitated cardiac arrest, or CHD death) and 123 participants had a CVD event (defined as stroke or CVD death). With a hazard ratio of 2.60 (95% CI, 1.94-3.50), CAC was independently associated with incident CHD in multivariable analysis. Ankle-brachial index had a hazard ratio of 0.79 (95% CI, 0.66-0.95), high-sensitivity C-reactive protein had a hazard ratio of 1.28 (95% CI, 1.00-1.64), and family history had a hazard ratio of 2.18 (95% CI, 1.38-3.42). Carotid intima–media thickness and brachial flow–mediated dilation were not associated with incident CHD in multivariable analyses (HR 1.17 [95% CI, 0.95-1.45] and HR 0.95 [95% CI, 0.78-1.14]) respectively. The improvement in discrimination was assessed by comparing the area under the receiver operator characteristic curves (AUC) in models with and without the risk markers. For CAC, the incident CHD and the incidence of CVD, the AUC for the Framingham Risk Score alone was 0.623 FRS with CAC 0.784 (p<0.001). Based on the presence of CSC, 51.1% of participants who had incident CHD and 54.9% of those who did not have incident CHD during follow-up period were reclassified either to low or high risk by the addition of CAC to the FRS; the net correct reclassification for events were 25.5% and 40.4% respectively. The authors caution that CAC imaging exposes individuals to ionizing radiation and the benefits and risks associated with incidental findings detected during CAC imaging remain unclear.
Budoff and colleagues (2007) used a large observational database of 25,253 asymptomatic individuals undergoing CAC scoring to develop risk-adjusted multivariable models incorporating CAC scores to predict all cause mortality. 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 low-density lipoprotein (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 two 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 against 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.
Nasir and colleagues (2012) reported on 44,052 asymptomatic individuals with traditional risk factors reported by questionnaire (current cigarette smoking, dyslipidemia, diabetes, hypertension, and family history of CHD) and sought to examine the relationship between the risk factors and CAC for predicting all-cause mortality. Participants were followed for a mean of 5.6 years. Individuals were classified as low risk (having no risk factors and CAC of zero), intermediate risk (1-2 risk factors and CAC 1 to 100) and high risk (greater than or equal to 2 risk factors and CAC greater than 100). A total of 19,898 individuals had no CAC on screening, 14,181 individuals had a CAC score of 1 to 100, 5739 individuals had CAC score of 101 to 400, and 4234 individuals had CAC score greater than 400. For risk factors, 18,819 had zero risk factors, 10,093 had 1 risk factor, 8754 had 2 risk factors and 6386 individuals had greater than 2 risk factors for CAD. There were 901 deaths in the study population. For those with no risk factors for CAD, the annualized mortality rate was 1.84 deaths per 1000 person-years (95% CI, 1.62–2.09), 4.13 (95% CI, 3.60–4.75) for those with 1 risk factor, 5.78 (95% CI, 5.07–6.59) for those with 2 risk factors, and 9.11 (95% CI, 8.00–10.38) for those with greater than or equal to 3 risk factors. Looking at the CAC scores, the annualized mortality rate was 0.87 deaths per 1000 person-years (95% CI, 0.72–1.06) for those with CAC=0, 2.97 (95% CI, 2.61–3.37) for those with CAC scores 1 to 100, 6.90 (95% CI, 6.02–7.90) for those with CAC scores 101 to 400, and 17.68 (95% CI, 5.93–19.62) deaths per 1000 person-years among those with CAC scores greater than or equal to 400. This study is limited by the fact that all participants were referred for CAC testing and were not considered to be a random sample of the population and the risk factors were self-reported. There is also a lack of cardiovascular-specific mortality data.
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.
Risk Assessment in Symptomatic Individuals
Tota-Maharaj (2012) conducted a literature review of articles to evaluate the utility of CAC for low- to intermediate-risk individuals with chest pain. The authors looked at CAC scores in individuals with indeterminate chest pain symptoms and the sensitivity and specificity of CAC score for predicting obstructive CAD and the use of CAC in the triage of individuals who present to the emergency room with chest pain using the gatekeeper approach. In review of articles from five studies with a combined enrollment of more than 1000 participants, the sensitivity of CAC was found to be 96% to 100% with a specificity of 30% to 58% of CAC greater than 0 for obstructive CAD. The authors note that the "the absence of calcification does not always completely rule out the disease" and conversely "the detection of CAC may overestimate the clinical significance of CAD present in a given symptomatic patient." The authors propose a chest pain algorithm that uses an individual's likelihood of CAD based on their risk factors for CHD events and the nature of their chest pain followed by CAC scoring. Their recommendation is that if CAC scoring is 0 in low-risk individuals then no further testing is necessary. The authors note that further prospective randomized research is necessary to confirm that their algorithm is safe and effective in these individuals.
A study by Kim (2012) looked at the clinical implications of symptomatic individuals with a CAC score of zero. The authors looked at the medical records of 2088 individuals with symptoms of CAD who had CAC scoring. A total of 1114 individuals had a CAC score of zero. Of those 1114 individuals, 158 had detection of coronary artery plaques and obstructive CAD was found in 48. The follow-up period was 1033 days and included gathering data for major adverse cardiac events. Follow-up was completed by review of medical records and/or telephone interviews. For the 48 individuals with obstructive CAD and CAC score of zero, 25 of them had early elective revascularization. There were 14 major adverse cardiac events consisting of cardiac death, myocardial infarction, unstable angina, and late revascularization. This study is limited by its retrospective design and all of the individuals were from the same ethnic background so it cannot be applied to the general population.
Consensus Reports, Guidelines and Scientific Statements
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, acknowledging the lack of rigorous evidence addressing the clinical utility of 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.
The findings of this expert panel were consistent with the 2006 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).
In 2013 the ACC/AHA published a guideline on the assessment of cardiovascular risk (Goff, 2013). Their recommendation is that if after quantitative risk assessment, a risk based treatment decision is uncertain, CAC may be considered to inform treatment decision making. Their recommendation is classified as IIb which is defined as the procedure/treatment may be considered, but additional studies with broad objectives are needed and additional registry data would be helpful.
In 2014, the American Heart Association (AHA) updated their consensus statement regarding the role of noninvasive testing of women with suspected ischemic heart disease (IHD) (Mieres, 2014). The statement notes that for symptomatic women, the sensitivity for the presence of detectable CAC for the diagnosis of obstructive CAD is 96%-100% with a specificity of 40%-66% when compared to invasive coronary angiography. However, the consensus statement also notes that there are clinical trials starting which will further define the medical management and provide additional information about referring women to invasive angiography for stable IHD.
In 2009, the United States Preventive Services Task Force (USPSTF) issued recommendations on using nontraditional risk factors in coronary heart disease risk assessment. The USPSTF gave an "I"** recommendation against screening asymptomatic men and women with no history of CHD to prevent CHD events. The nontraditional risk factors listed in this recommendation include CAC score on EBCT. This recommendation was based on a review of eight cohort studies. Five of the eight studies were rated as fair quality, and while the eight included studies reported statistically significant relative risks for coronary events with increasing CAC scores, none of the studies addressed an intermediate-risk cohort, none of the studies were population-based or free of selection bias, and none of the studies had appropriately measured or controlled for traditional risk factors. (USPSTF, 2009; see the Definitions section for an explanation of the rating system).
The role of CAC scoring, particularly for determining its incremental value for risk stratification in those with intermediate FRS, continues to be studied. Although randomized controlled trials and observational studies suggest that CAC scores may predict risk for future coronary events, the evidence shows variability in the accuracy of test results from various CT scanners and there is insufficient evidence in the literature, to demonstrate how screening with CAC will change or impact treatment management and clinical outcomes.
Note: The presence of extensive CAC precludes the use of 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 (2009), 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 recommends the service. There is high certainty that the net benefit is substantial.
B— The USPSTF recommends the service. There is high certainty that the net benefit is moderate or there is moderate certainty that the net benefit is moderate to substantial.
C— Clinicians may provide this service to selected participants depending on individual circumstances. However, for most individuals without signs or symptoms there is likely to be only a small benefit from this service.
*D— The USPSTF recommends against the service. There is moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits.
**I— The USPSTF concludes that the 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 following codes for treatments and procedures applicable to this document are included below for informational purposes. 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:
|S8092||Electron beam computed tomography (also known as ultrafast CT, cine CT)|
|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|
Peer Reviewed Publications:
Government Agency, Medical Society, and Other Authoritative Publications:
|Websites for Additional Information|
Electron Beam Computed Tomography
High-Speed Computed X-Ray Tomography
Multi-row Detector CT (MDCT)
Multi-slice 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||05/05/2016||Medical Policy & Technology Assessment Committee (MPTAC) review. Updated Description/Scope, Rationale, and References sections. Removed ICD-9 codes from Coding section.|
|Reviewed||05/07/2015||MPTAC review. Updated Rationale, Coding and References sections.|
|Reviewed||05/15/2014||MPTAC review. Updated Rationale and References.|
|Reviewed||05/09/2013||MPTAC review. Updated Rationale, Definitions and References.|
|Reviewed||05/10/2012||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|