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Optical coherence tomography (OCT) is an imaging technique that uses near-infrared light to image the coronary arteries. Potential applications in cardiology include evaluating the characteristics of coronary artery plaques for the purpose of risk stratification and following coronary stenting to determine the success of the procedure.
Optical coherence tomography (OCT) has important similarities to intravascular ultrasound (IVUS), and also important differences. Ultrasound (US) uses acoustic waves for imaging, while OCT uses near-infrared electromagnetic light waves. OCT generates cross-sectional images by using the time delay and intensity of light reflected from internal tissue structures. The main obstacle to OCT is the difficulty of imaging through blood, necessitating saline flushes or occlusion techniques to obtain images. Frequency-domain OCT (FD-OCT) is a newer generation device that partially alleviates this problem by allowing faster scanning and less need for blood clearing.
OCT has higher resolution than US but more shallow penetration of tissue. Tissue resolution of up to 5 to 10 μm has been achieved, which is approximately 10 times greater than US. However, the technique is limited by its inability to penetrate more than several millimeters in depth. This is compared with IVUS, which has a penetration depth of approximately 10 mm.
One goal of intravascular imaging has been to risk stratify atherosclerotic plaques regarding their risk of rupture. Intravascular US has defined a “vulnerable” coronary plaque that may be at higher risk for rupture. Characteristics of the vulnerable coronary plaque include a lipid-rich atheroma with a thin fibrous cap. Other features of vulnerable plaques include a large lipid pool within the vessel wall, a fibrous cap of 6 μm or less, and macrophages positioned near the fibrous cap.
Another goal of intravascular imaging is as an adjunct to PCI with stent placement. Stent features that are often evaluated immediately postprocedure include the position of the stent, apposition of the struts to the vessel wall, and presence of thrombus or intimal flaps. These features are a measure of procedural success and optimal stent placement. Subsequent follow-up intravascular imaging at several months to one year poststenting can be used to evaluate neo-endothelialization on the endoluminal surface of the stent. The presence of neointimal coverage of drug-eluting stents and the absence of stent thrombosis have been correlated with favorable outcomes. Therefore, the adequacy of neointimal coverage has been proposed as an intermediate outcome in clinical trials of stenting.
There are several OCT systems that have been cleared for marketing through the U.S. Food and Drug Administration’s (FDA’s) 510(k) program. For example, Lightlab Imaging (acquired by St. Jude Medical in 2010) received FDA marketing clearance in April 2010 for its C7 Xr® Imaging System and in August 2011 for its next generation frequency domain C7 Xr® Imaging System. In January 2013, it received clearance based on substantial equivalence for its next generation C7 Xr® Imaging System with Fractional Flow Reserve (Illumien™ Optis™) system.
Optical coherence tomography is considered investigational when used as an adjunct to percutaneous coronary interventions with stenting.
Optical coherence tomography is considered investigational in all other situations, including but not limited to, risk stratification of intracoronary atherosclerotic plaques and follow-up evaluation of stenting.
POLICY EXCEPTIONSFederal Employee Program (FEP) may dictate that all FDA-approved devices, drugs or biologics may not be considered investigational and thus these devices may be assessed only on the basis of their medical necessity.
POLICY GUIDELINESInvestigative service is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized by certifying boards and/or approving or licensing agencies or published peer review criteria as standard, effective medical practice for the treatment of the condition being treated and as such therefore is not considered medically necessary.
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.
POLICY HISTORY03/22/2012: Approved by Medical Policy Advisory Committee.
04/17/2013: Policy reviewed; no changes.
03/13/2014: Policy reviewed; no changes.
03/06/2015: Policy reviewed; description updated regarding intravascular imaging and OCT systems. Policy statements unchanged.
SOURCE(S)Blue Cross Blue Shield Association policy # 2.02.29
CODE REFERENCEThis may not be a comprehensive list of procedure codes applicable to this policy.