![]() | Medical Policy |
| Subject: | Computed Tomography to Detect Coronary Artery Calcification | ||
| Policy #: | RAD.00001 | Current Effective Date: | 07/15/2009 |
| Status: | Revised (Coding updated 01/01/2010) | Last Review Date: | 05/21/2009 |
| Description/Scope |
This document addresses use of electron beam computed tomography (EBCT), helical CT and multi-slice spiral CT 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 coronary artery calcium. In asymptomatic patients, CAC has been investigated as a risk factor for coronary artery disease and has been used to further evaluate patients with known coronary artery disease.
Note: This document only addresses CT detection of CAC. Assessment of CAC may also be done in conjunction with CT scanning to visualize the coronary arteries, (referred to as CT angiography, or CCTA). CCTA is addressed in RAD.00035 Coronary Artery Imaging: Contrast-Enhanced Coronary Computed Tomography Angiography (CCTA) and Coronary Magnetic Resonance Angiography (MRA).
| Position Statement |
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:
| Rationale |
General Considerations:
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 coronary artery calcium (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 coronary artery disease. Finally, clinical utility refers to how CAC scores can be used to improve patient management of coronary artery disease.
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, which is used as the basis for various prevention strategies for coronary artery disease. The Framingham Risk score 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 patient management, particularly in patients considered at intermediate risk. For example, epidemiologic and observational studies may demonstrate that CAC is an independent risk factor for coronary artery disease, but improved risk assessment is not clinically meaningful if this information cannot be used to improve patient management.
CAC has also been used to evaluate symptomatic patients 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 coronary artery disease in symptomatic patients, potentially deselecting patients for angiography. Again, in this setting it is important to understand how measurement of CAC will be integrated into the management of the patient, 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:
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 American College of Cardiology Foundation Quality Strategic Directions Committee Appropriateness Criteria Working Group published appropriateness criteria for cardiac computed tomography, including evaluation of CAC (Hendel, 2006). This report took a consensus approach to the evaluation of test performance of these technologies within specific clinical scenarios. A total of four CT indications addressing CAC were rated as follows:
For risk assessment in the general population of asymptomatic individuals, CAC measurements were rated:
For risk assessment with prior test results when patient is asymptomatic, CAC measurements were rated:
Conclusions:
The 2006 AHA scientific statement noted that there is growing evidence that CAC scores are an independent predictor of coronary artery disease, (i.e., proof of clinical validity). However, it is still unknown how this information can be integrated into patient 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.
Clinical Studies:
A literature search focused on studies published since the 2005 review period noted in the 2007 clinical consensus document. (Greenland 2007). While these studies have further assessed CAC as a risk assessment tool, there are still no studies detailing how this information can be used to improve patient management. Representative studies are reviewed below.
In 2005, Anand and colleagues published a study specifically evaluating CAC scores as a risk stratification tool in 510 patients with uncomplicated type II diabetes (Anand 2005). Myocardial perfusion studies were performed in all patients with high CAC scores and in a random sample of the remaining patients. The patients 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 patient management.
The MESA Trial (Multi-Ethnic Study of Atherosclerosis) 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 coronary artery calcium score is a predictor of subsequent clinically significant coronary heart disease and may provide predictive information beyond that provided by standard risk factors, (i.e., the Framingham Risk Score). (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).
Another study of the MESA cohort (Lakoski, 2007) 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 coronary artery calcium in women at low FRS risk was predictive of future coronary heart disease and cardiovascular events. Compared with women with no detectable coronary artery calcium, 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 ≥ 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.
Budoff and colleagues used a large observational data base of 25,253 asymptomatic patients 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.
Conclusions:
Although the above studies suggest that the coronary artery calcium score may be an independent predictor of coronary artery risk, they were not designed to demonstrate an improved clinical outcome, as the result of coronary artery calcium screening. There is currently no direct evidence that risk stratification using coronary calcium scores improves patient outcomes, i.e., the clinical utility of coronary artery calcium measurement is, as yet, unproven.
Note:
The presence of extensive coronary artery calcium 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 considered separately in RAD.00035.
| Background/Overview |
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. Electron beam CT 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 coronary artery calcium. Since CAD may remain silent until a major catastrophic event occurs, it has been hypothesized that detection of coronary calcium in asymptomatic patients could provide additional data of cardiac risk, potentially leading to changes in diet, lifestyle, and patient management that potentially could reduce the risk of myocardial infarction (MI).
| Definitions |
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): is 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: 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 coronary heart disease 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): is a type of CT that creates images at greater speed than conventional CT by continuously rotating a standard x-ray tube around the patient so that data are gathered in a continuous spiral or helix rather than individual slices
Multislice spiral CT (MSCT) also known as mult-row detector CT or MDCT: is a technical evolution of helical CT, and uses CT machines equipped with an array of multiple x-ray detectors that can simultaneously image multiple sections of the patient during a rapid volumetric image acquisition; currently available MDCT machines may have 4, 8, 16, 32, 40 or 64 detectors
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 U.S. Preventive Services Task Force (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)
According to the American College of Cardiology/American Heart Association/European Society of Cardiology (ACC/AHA/ESC) guideline recommendations documents, the following are the definitions of Classifications of Recommendations, as expressed in the ACC/AHA/ESC format:
*Class I: Conditions for which there is evidence and/or general agreement that a given procedure or treatment is beneficial, useful, and effective.
Class II: Conditions for which there is conflicting evidence and/or divergence of opinion about the usefulness/efficacy of a procedure or treatment.
**Class IIa: Weight of evidence/opinion is in favor of usefulness/efficacy.
***Class IIb: Usefulness/efficacy is less well established by evidence/opinion.
Class III: Conditions for which there is evidence and/or general agreement that a procedure/treatment is not useful/effective and in some cases may be harmful. (Hendel, 2006)
| Coding |
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:
| CPT | |
| 71250 | Computed tomography thorax without contrast material |
| HCPCS | |
| S8092 | Electron beam computed tomography (also known as Ultrafast CT, Cine CT) |
| ICD-9 Diagnosis | |
| 414.00-414.9 | Chronic ischemic heart disease |
| 429.2 | Cardiovascular disease, unspecified |
| V81.0 | Special screening for ischemic heart disease |
When services are also Investigational and Not Medically Necessary:
| CPT | |
| 75571 | Computed tomography, heart, without contrast material, with quantitative evaluation of coronary calcium |
| ICD-9 Diagnosis | |
| All diagnoses |
| References |
Peer Reviewed Publications:
Government Agency, Medical Society, and Other Authoritative Publications:
| Web Sites for Additional Information |
| Index |
Cine Computed X-Ray Tomography
Computed Tomography, Electron Beam
Helical CT
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.
| Document History |
| Status | Date | Action | ||
| 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 | Medical Policy & Technology Assessment Committee (MPTAC) review. No change to stance. As part of a cardiac risk assessment for symptomatic patients 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
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