1. Aetna considers intravascular ultrasound (IVUS) medically necessary for any of the following situations:
   
   
   1. As a clinical decision-making tool to evaluate the need for an intracoronary interventional procedure in a symptomatic member whose angiogram shows 50 to 70% stenosis(es); or
   2. As a conclusive study to assess suspected left main stem coronary artery disease not revealed by coronary angiography; or
   3. As a method for both guidance of placement of endoluminal devices and immediate assessment of the results of intracoronary interventional procedures (i.e., angioplasty, atherectomy, stenting), including those performed on coronary grafts; or
   4. As a guidance for placement of vena caval filter.

2. Aetna considers the clinical application of IVUS in screening for coronary artery disease and its use in other coronary procedures experimental and investigational.

3. Aetna considers the clinical application of IVUS experimental and investigational for angioplasty and stenting of non-coronary arteries, and other non-coronary arterial procedures (other than vena caval filter placement) because its use for these indications has not been validated by clinical studies.

See also CPB 520 - Magnetic Resonance Imaging of the Cardiovascular System - Cardiac MRI.

Angiography is limited in determining the anatomic severity of coronary artery stenoses because it represents only a projectional image of the vessel lumen without providing any information concerning vascular wall architecture. Catheter-based intravascular ultrasound (IVUS) has been developed in the last few years to provide this unique perspective for viewing vascular disease and the effects of intervention. As a complement to the information provided by coronary angiography, it has the unique ability to study vessel wall morphology in vivo, accurately displaying the details of vessel structure and tissue characterization by providing such critical information as the presence and degree of calcified plaque, quantifying luminal dimensions, and characterizing the composition of stenotic lesions into soft plaque, hard plaque, calcification, and type of thrombus.

Although these devices have only been available for a relatively short time, an array of studies demonstrating numerous diagnostic and therapeutic applications in interventional cardiology have been reported. The maturity of the technology is such that IVUS currently has a place as a clinical decision-making tool in patients with symptoms and intermediate lesions, as a provisional study to assess left main stem disease suspected but not disclosed by coronary angiography, and as a method for both guidance of endoluminal devices and immediate assessment of the results of therapeutic techniques, including balloon angioplasty, atherectomy, and intravascular stent deployment.

More research is needed to answer some important questions regarding the whole array of potential applications of IVUS. Newer developments under scrutiny include combined devices, looking-forward ultrasound, high frequency probes, imaging wires, tissue characterization and three dimensional technology.

Its use in peripheral vascular disease remains as a research tool for investigation of blood vessel compliance, dynamic changes in the vessel wall caused by disease or pharmacologic intervention, and elucidation of the morphologic changes associated with the natural history of atherosclerosis. It has not been proven that changes in treatment made based on the results of intravascular ultrasound improve health outcomes in patients with non-coronary vascular diseases.

Intravascular ultrasound has been used as a guidance for for placement of inferior vena cava filters. Ashley et al (2001) reported that IVUS is a more accurate method of localizing the renal veins and measuring vena cava diameter for placement of vena cava filters than contrast venography. Mathews et al (2003) noted that imaging of the vena cava prior to the insertion of an inferior vena cava (IVC) filter is mandatory to assess IVC diameter and patency, delineate anatomy and venous anomalies, and to direct filter placement for appropriate deployment and avoidance of complications. The standard imaging technique is vena cavography, although alternative methods to evaluate the IVC include carbon dioxide venography, trans-abdominal duplex ultrasound, and IVUS.

Wellons et al (2004) stated that reports have demonstrated the benefit of prophylactic inferior vena cava filter (IVCF) placement to prevent pulmonary embolism. This study evaluated the potential for the bedside placement of a removable IVCF under "real-time" IVUS guidance.  A total of 20 trauma patients underwent intensive care unit placement of a removable IVCF with IVUS guidance. All patients had ultrasonography of the femoral veins after placement to rule out post-procedure femoral vein thrombosis and radiographs to identify filter location. Nineteen of 20 IVCFs were placed at approximately the L2 level as verified by radiography. One patient had a large IVC (34 mm) and underwent bilateral common iliac IVCF placement under IVUS. Within 3 weeks of placement, 12 IVCFs were retrieved. Of the remaining 8 patients, 6 had indications for permanent implantation, 2 had contralateral deep venous thrombosis, and 1 had ipsilateral deep venous thrombosis. The authors concluded that bedside insertion of a removable IVCF with IVUS guidance and its removal are simple, safe, and accurate. Passman et al (2005) stated that bedside placement of ICVF by using either trans-abdominal duplex ultrasonography or IVUS has been shown to be safe and effective. The authors reviewed techniques for bedside filter placement with trans-abdominal duplex ultrasonography, IVUS with dual venous access, and IVUS with single venous access. They noted that trans-abdominal duplex ultrasonography and IVUS remain their preferred techniques for filter placement when feasible, especially in critically ill and immobilized patients.

de Ribamar Costa et al (2007) stated that in the drug-eluting stent (DES) era, stent expansion remains an important predictor of re-stenosis and sub-acute thrombosis. Compliance charts are developed to predict final minimum stent diameter (MSD) and area (MSA). The objectives of the study were 2-fold: (i) to evaluate DES expansion by comparing IVUS-measured MSD and MSA against the values predicted by compliance charts and (ii) to compare each DES against its bare-metal stent (BMS) equivalent. These researchers enrolled 200 patients with de novo coronary lesions treated with single, greater than 2.5-mm Cypher (Cordis, Johnson & Johnson, Miami Lakes, FL) (sirolimus-eluting stent [SES], n = 133) or Taxus (Boston Scientific, Natick, MA) (paclitaxel-eluting stent [PES], n = 67) stent under IVUS guidance without another post-dilation balloon. They used a comparison cohort of 65 equivalent BMS (Express 2 [Boston Scientific], n = 37; Bx Velocity [Cordis, Johnson & Johnson], n = 28) deployed under similar conditions. The DES achieved only 75 % +/- 10 % of predicted MSD and 66 % +/- 17 % of predicted MSA; this was similar for SES and PES. Furthermore, 24 % of SES and 28 % of PES did not achieve a final MSA of 5 mm(2), a consistent predictor of DES failure. The SES achieved 75 % +/- 10 % of predicted MSA versus 75 % +/- 9 % for Bx Velocity (p = 0.9). The PES achieved 79.9 % +/- 14 % of predicted MSA versus 79 % +/- 10 % for Express 2 (p = 0.8). Lesion morphology, arc and length of calcium, stent diameter and length, and implantation pressures did not affect expansion. The authors concluded that compliance charts fail to predict final MSD and MSA. A considerable percentage of DES does not achieve minimum standards of stent expansion. The SES and PES achieve similar expansion to their BMS platform, indicating that the polymer coating does not affect DES expansion in vivo. However, stent expansion can not be predicted from pre-intervention IVUS lesion assessment.

The randomized TAXUS II trial evaluates the polymer-based paclitaxel-eluting Taxus stent in slow- and moderate-release formulations. Tsuchida et al (2007) examined the consistency between angiographic and IVUS outcomes of late lumen loss (late loss) and neointimal growth to measure restenotic plaque load in Taxus and BMS. Serial angiographic and IVUS analyses were available in 155 event-free patients (BMS, n =  74; Taxus stent, n = 81) after the procedure, at 6 months, and at 2 years. For this sub-analysis, quantitative coronary angiographic (QCA) and IVUS measurements were used to derive late loss and neointimal volume. From after the procedure to 6 months, QCA and IVUS showed matching results for the 2 groups with significant decreases in late loss and neointimal volume in the Taxus versus the control group. From 6 months to 2 years, QCA and IVUS measurements also showed results similar to those in the control group, demonstrating neointimal compaction over time. However, in the Taxus group, QCA late loss showed a non-significant decrease from 6 months to 2 years, whereas IVUS neointimal volume increased. The authors concluded that although QCA and IVUS results were similar over the first 6 months, long-term assessment of changes in re-stenotic plaque load showed discrepant findings for the Taxus stent. These findings suggest the need for critical re-evaluation of current end points and the use of more precise techniques to detect lumen and stent boundaries.

Hoffmann and colleagues (2008) stated that the impact of incomplete stent apposition (ISA) after drug-eluting stent implantation determined by IVUS on late clinical events is not well-defined. These researchers assessed the clinical impact of ISA after sirolimus-eluting stent (SES) placement during a follow-up period of 4 years.  Intravascular ultrasound at angiographic follow-up was available in 325 patients (SES, n = 180; BMS, n = 145); IVUS images were reviewed for the presence of ISA defined as one or more unapposed stent struts. Frequency, predictors and clinical sequel of ISA at follow-up after SES and BMS implantation were determined. Incomplete stent apposition at follow-up was more common after SES (n = 45 (25 %)) than after BMS (n = 12 (8.3 %), p < 0.001). Canadian Cardiology Society class III or IV angina at stent implantation (odds ratio (OR) = 4.69, 95 % CI 2.15 to 10.23, p < 0.001) and absence of diabetes (OR = 3.42, 95 % CI 1.05 to 11.1, p = 0.041) were predictors of ISA at follow-up after SES placement. Rate of myocardial infarction tended to be slightly higher for ISA than for non-ISA patients. When only SES patients were considered, major adverse cardiac event free survival at 4 years was identical for those with and without ISA at follow-up (11.1 % versus 16.3 %, p = 0.48). The authors concluded that ISA at follow-up is more common after SES implantation than after BMS implantation. Considering the current very sensitive IVUS definition, ISA appears to be an IVUS finding without significant impact on the incidence of major adverse cardiac events even during long-term follow-up.