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DESCRIPTIONThe expression levels of various genes in circulating white blood cell or whole blood samples have been reported to discriminate between cases of obstructive coronary artery disease (CAD) and healthy controls. Multiplex gene expression testing can be combined with other risk factors to predict the likelihood of obstructive CAD in patients who present with chest pain or other suggestive symptoms, or in asymptomatic patients who are at high risk of CAD. These tests have potential to improve the accuracy of predicting CAD likelihood. A commercially available Gene Expression Score (GES) test, Corus CAD™, has been developed and validated for this purpose in nondiabetic patients.
Heart disease is the leading cause of death in the U.S. and together with cerebrovascular disease, accounted for 31% of deaths in 2007. Patients with signs and symptoms of obstructive coronary artery disease (CAD), the result of a chronic inflammatory process that ultimately results in progressive luminal narrowing and acute coronary syndromes, may be evaluated with a variety of tests according to prior risk. Coronary angiography is the criterion standard for diagnosing obstructive CAD, but it is invasive and associated with a low but finite risk of harm. Thus, coronary angiography is recommended for patients at a high prior risk of CAD according to history, physical findings, electrocardiogram, and biomarkers of cardiac injury. For patients initially assessed at low to intermediate risk, observation and noninvasive diagnostic methods, which may include imaging methods such as coronary computed tomographic angiography, may be recommended. Nevertheless, even noninvasive imaging methods have potential risks of exposure to radiation and contrast material. In addition, coronary angiography has a relatively low yield, despite risk stratification recommendations. In one study of nearly 400,000 patients without known CAD undergoing elective coronary angiography, approximately 38% were positive for obstructive CAD (using the CAD definition, stenosis of 50% or more of the diameter of the left main coronary artery or stenosis of 70% or more of the diameter of a major epicardial or branch vessel that was more than 2.0 mm in diameter; result was 41% if using the broader definition, stenosis of 50% or more in any coronary vessel). Thus, methods of improving patient risk prediction prior to diagnostic testing are needed.
A CAD classifier has been developed based on expression levels, in whole blood samples, of 23 genes plus patient age and sex. This information is combined in an algorithm to produce a score from 1 to 40, with higher values associated with a higher likelihood of obstructive CAD. The test is marketed as Corus CAD™ (CardioDx, Inc., Palo Alto, California). The intended population is stable, nondiabetic patients suspected of CAD either because of symptoms, a high-risk history, or a recent positive or inconclusive test result by conventional methods.
Clinical laboratories may develop and validate tests in-house and market them as a laboratory service; laboratory-developed tests (LDTs) must meet the general regulatory standard of the Clinical Improvement Act (CLIA). The Corus CAD™ test is available under the auspices of CLIA. Laboratories that offer LDTs must be licensed by CLIA for high-complexity testing. To date, the U.S. Food and Drug Administration has chosen not to require any regulatory review of these tests.
Related medical policies are as follows:
POLICYGene expression testing to predict coronary artery disease (CAD) is considered investigational for all indications, including but not limited to prediction of the likelihood of CAD in stable, nondiabetic patients.
POLICY GUIDELINESInvestigative is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized as a generally accepted standard of good medical practice for the treatment of the condition being treated and; therefore, is not considered medically necessary. For the definition of Investigative, “generally accepted standards of medical practice” means standards that are based on credible scientific evidence published in peer-reviewed medical literature generally recognized by the relevant medical community, and physician specialty society recommendations, and the views of medical practitioners practicing in relevant clinical areas and any other relevant factors. In order for equipment, devices, drugs or supplies [i.e, technologies], to be considered not investigative, the technology must have final approval from the appropriate governmental bodies, and scientific evidence must permit conclusions concerning the effect of the technology on health outcomes, and the technology must improve the net health outcome, and the technology must be as beneficial as any established alternative and the improvement must be attainable outside the testing/investigational setting.
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.
POLICY HISTORY07/29/2011: Approved by Medical Policy Advisory Committee.
07/17/2012: Policy reviewed; no changes.
10/15/2013: Policy reviewed; no changes.
08/04/2014: Policy reviewed; description updated. Policy statement revised to add "for all indications, including but not limited to prediction of the likelihood of CAD in stable, nondiabetic patients" for clarification. It previously stated: Gene expression testing to predict coronary artery disease is considered investigational.
07/20/2015: Code Reference section updated for ICD-10.
11/02/2015: Policy description updated regarding tests. Policy statement unchanged. Investigative definition updated in policy guidelines section.
SOURCE(S)Blue Cross Blue Shield Association policy # 2.04.72
This may not be a comprehensive list of procedure codes applicable to this policy.
Unlisted chemistry procedure