«PacifiCare’s medical management guidelines represent the recommendation of the PacifiCare Medical Management Guideline (MMG) committee. They are ...»
- post-revascularization procedure to rule out in-stent restenosis or assess bypass grafts in asymptomatic patients
- routine screening in asymptomatic patients or patients at low risk of CAD Although CTA may be a possibility to rule out in-stent restenosis, routine application of CT to assess patients with coronary stents can currently not be recommended. Visualization of the stent lumen is often affected by artifacts, and especially the positive predictive value is low.
Although CTA may be useful in carefully selected patients with bypass grafts, the inability to reliably visualize the native coronary arteries in patients post-CABG poses severe restrictions to the general use of CT angiography in post-bypass patients.
Coronary CTA should only be considered when the potential risks posed by catheterization outweigh the potential risks posed by the somewhat less accurate detection of clinically significant CAD by CTA. In addition, coronary CTA is not suitable for patients who are likely to require coronary angioplasty or stenting since CTA will not allow these patients to avoid cardiac catheterization in any event, and this is the primary advantage of coronary CTA.
Cardiac CT Cardiac computed tomography, with or without contrast, using 32-slice or greater technology, is proven for assessing Cardiac Computed Tomography (CT), Coronary Artery Calcium Scoring and Cardiac CT Angiography - Commercial Medical Management Guideline
cardiac structure/anatomy for the following:
- pulmonary vein anatomy prior to ablation procedure
- coronary vein mapping prior to placement of biventricular pacemaker or biventricular implantable cardioverter defibrillator
- coronary arterial mapping, including internal mammary artery, prior to repeat sternotomy
- suspected cardiac mass (tumor or thrombus) or pericardial disease in patients with technically limited images from echocardiogram, magnetic resonance imaging (MRI) or transesophageal echocardiogram (TEE) Cardiac computed tomography, with or without contrast, using 32-slice or greater technology, is proven for assessing cardiac function when the primary procedure with which it is associated is proven.
1. The risk for coronary heart disease in asymptomatic patients is based on Framingham risk criteria which estimate the risk of developing CHD within a 10-year time period. In general, low risk will correlate with a 10-year absolute CHD risk less than 10%, and moderate risk will correlate with a 10-year absolute CHD risk between 10-20%. High risk is defined as the presence of diabetes or a 10-year absolute CHD risk of greater than 20%. (Wilson, 1998) The Framingham
Scoring Sheet is available at:
http://www.framinghamheartstudy.org/risk/index.html Accessed April 7, 2009.
2. The pre-test probability for CAD in symptomatic patients is based on age, gender and symptoms and is defined as
- High - greater than 90% pre-test probability
- Intermediate - between 10% and 90% probability
- Low - between 5% and 10% pre-test probability
- Very low - less than 5% pre-test probability Typical (definite) angina is defined as substernal chest pain or discomfort that is provoked by exertion or stress and relieved by rest and/or nitroglycerin.
Atypical (probable) angina is defined as chest pain or discomfort that lacks one of the characteristics of typical angina.
Non-anginal chest pain is defined as chest pain or discomfort that meets one or none of the characteristics of typical angina.
(Gibbons, 2002) The complete chart is available as an attachment at the end of this policy or at:
http://www.acc.org/qualityandscience/clinical/guidelines/exercise/exercise_clean.pdf Accessed April 7, 2009.
3. Surgical risk determination is based on a review of the clinical evidence, including medical research cited by the
American College of Cardiology (ACC)/American Heart Association (AHA) guidelines, and is defined as follows:
- Low-risk surgery (reported risk of cardiac death or myocardial infarction (MI) less than 1%) - endoscopic procedures, superficial procedures, cataract surgery, breast surgery, ambulatory surgery.
- Intermediate-risk surgery (reported risk of cardiac death or myocardial infarction (MI) is 1-5%) - intraperitoneal and intrathoracic surgery, carotid endarterectomy, head and neck surgery, orthopedic surgery, prostate surgery.
- High-risk surgery (reported risk of cardiac death or myocardial infarction (MI) is greater than 5%) - aortic and other major vascular surgery, peripheral vascular surgery. (Fleisher, 2007) Additional information Chest pain syndrome is defined as symptoms consistent with obstructive CAD including, but not limited to, chest pain, Cardiac Computed Tomography (CT), Coronary Artery Calcium Scoring and Cardiac CT Angiography - Commercial Medical Management Guideline chest tightness, burning, dyspnea, shoulder pain and jaw pain (Hendel, 2006).
For additional information when submitting claims, see the Materials for Clinical Review attachment at the end of this policy.
For additional information, see the following related medical policies:
Transthoracic Echocardiography Single Photon Emission Computed Tomography Myocardial Perfusion Imaging (SPECT MPI)
Regulatory Requirements U.S. Food and Drug Administration (FDA): Cardiac computed tomography equipment is regulated by the FDA, but
products are too numerous to list. See the following web site for more information (use product code JAK ). Available at:
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfPMN/pmn.cfm. Accessed April 7, 2009.
Multislice CT technology has evolved rapidly over the past several years, beginning with 4-slice scanners that were first introduced in 1998. Since then, 8-, 10-, 16, 32-, 40-, and 64-slice scanners have been approved and available for diagnostic use. Advances in technology, including the availability of dual source CT scanners, are expected to continue at a rapid pace.
In July 2008, the U.S. Food and Drug Administration (FDA) notified health professionals, warning them of the possibility that x-rays used during CT examinations may cause some implanted and external electronic medical devices to malfunction. Devices affected include pacemakers, defibrillators, neurostimulators, and implanted or externally worn
drug infusion pumps. The notice provides recommendations for reducing potential risk. Available at:
html#ft1. Accessed April 7, 2009.
Research Evidence Coronary artery disease (CAD) is the leading cause of morbidity and mortality in the United States. CAD occurs when the arteries that supply blood to heart muscle become hardened and narrowed due to the buildup of cholesterol and plaque (atherosclerosis). As the buildup grows, less blood can flow through the arteries, depriving the heart muscle of blood and leading to chest pain (angina) or a heart attack (myocardial infarction).
The standard method for assessing the coronary arteries is coronary angiography, also called cardiac catheterization, an invasive and time-consuming procedure. To avoid catheterization and potential complications associated with coronary angiography, less invasive techniques using computed tomography (CT) technology have been developed.
Because the heart is in motion, a fast type of CT scanner is used to create high-quality images. Electron beam computed tomography (EBCT) takes multiple images very rapidly to avoid blurring. Multidetector CT (MDCT) or multislice CT (MSCT) spiral scanners have multiple rows of detectors (e.g., 16, 40, 64) that take many images of the heart at the same time. Dual source CT scanners use two x-ray sources and two detectors at the same time. To enhance visualization of the coronary arteries, an intravenous contrast agent may be used. Although cardiac CT uses radiation, it is a small amount.
Cardiac Computed Tomography (CT), Coronary Artery Calcium Scoring and Cardiac CT Angiography - Commercial Medical Management Guideline Coronary artery calcium (CAC) scoring Background Coronary artery calcium scoring uses cardiac CT, a noninvasive, radiographic technique, to detect calcium deposits in coronary arteries. The test does not require the injection of contrast dye. Coronary artery calcification is associated with atherosclerosis, and it has been proposed that detection of coronary calcification may be an early predictor of heart disease. Both EBCT and MDCT are used to detect calcium buildup in the arteries. Following the test, a calcium or Agatston score is given based on the amount of calcium found in the coronary arteries. The higher the Agatston score, the greater the amount of atherosclerosis. The calcium coverage score takes into account not only the amount, but also the distribution, of calcium build-up in the coronary arteries.
Research Electron beam computed tomography (EBCT) is a noninvasive imaging technique that can detect calcium deposits in coronary arteries. These calcium deposits are often associated with atherosclerotic plaques, and it has been proposed that detection of coronary calcification can provide an early and sensitive method of diagnosing coronary artery disease (CAD). A number of studies have demonstrated that EBCT is a sensitive, noninvasive method of detecting coronary calcification, and, in many patients, EBCT-derived coronary calcium scores can accurately predict the extent of CAD.
Although EBCT cannot be used in place of conventional coronary angiography, there is evidence that EBCT may aid in risk stratification in symptomatic patients with inconclusive test results or atypical chest pain to determine if additional cardiac testing is indicated. There is also some evidence that EBCT scores are equal or superior to traditional risk factors in predicting cardiac risk in asymptomatic individuals, however, it is unclear how the detection of coronary calcification should influence the management of these individuals, and an overall health benefit has not been proven. (Hayes, 2003) Coronary calcium scores measured with electron-beam computed tomography (EBCT) scanners predict future coronary events such as heart attack and need for revascularization procedures. The predictive value of these scores has been demonstrated in symptomatic and asymptomatic patients at high and low risk of heart disease. Coronary calcium scores appear to have predictive value over and above that of risk factors such as age, blood pressure, and cholesterol levels (and the widely used Framingham risk score, which combines these and other factors) in asymptomatic high-risk patients.
However, there is no published evidence that coronary calcium screening lowers coronary artery disease (CAD) mortality or otherwise improves health outcomes. Also, a negative EBCT result does not mean that a patient has zero risk of heart disease. While EBCT may never be used for widespread CAD screening, its use as a diagnostic test will increase for asymptomatic patients at intermediate-to-high risk for developing cardiovascular disease and in symptomatic (e.g., atypical chest pain) patients who undergo exercise stress testing or other cardiac testing with inconclusive results. EBCT may be useful in helping to determine which patients would benefit most from pharmacologic therapy, such as cholesterol-lowering medication, and which patients should undergo coronary angiography to detect obstructive CAD.
(ECRI, 2004) Multi-Ethnic Study of Atherosclerosis (MESA) Sponsored by the National Institutes of Health (NIH), MESA studied the characteristics of subclinical cardiovascular disease (disease detected non-invasively before it has produced clinical signs and symptoms) and the risk factors that predict progression to clinically overt cardiovascular disease or progression of the subclinical disease. MESA researchers studied a diverse, population-based sample of 6,500 asymptomatic men and women aged 45-84 who were recruited from 6 U.S. communities from 2000 to 2002.
Brown, et al. calculated the calcium coverage score (CCS) for participants in the MESA study in whom calcified plaque was detected with CT. The calcium coverage score represents the percentage of coronary arteries affected by calcified plaque versus an overall measure of plaque burden. The prospective study included 6814 men and women aged 45 to 84 years. Investigators compared CT data from 3252 participants with calcification of the coronary arteries and 3416 subjects without calcification. The purpose of the study was to correlate the new CCS with risk factors and cardiovascular Cardiac Computed Tomography (CT), Coronary Artery Calcium Scoring and Cardiac CT Angiography - Commercial Medical Management Guideline events and to compare this association with traditional calcium scores. While the investigators noted that the CCS does have limitations, especially since it depends on an accurate tracing of the coronary arteries down their entire length, the study showed that the CCS was a better predictor of cardiovascular events compared with calcium scores that account for a generalized burden of calcification. The CCS, as well as the Agatston and mass calcium scores, were significant predictors of coronary heart disease events, but the coverage score was a better predictor of future coronary events than both scores, especially among patients with low Agatston scores. (Brown, 2008) As part of the MESA trial, Detrano et al. performed scanning for coronary calcium in a population-based sample of 6722 men and women, of whom 38.6% were white, 27.6% were black, 21.9% were Hispanic, and 11.9% were Chinese. The study subjects had no clinical cardiovascular disease at entry and were followed for a median of 3.8 years. No major differences among racial and ethnic groups in the predictive value of calcium scores were detected. (Detrano, 2008) McClelland et al. published detailed tables and figures describing the racial/ethnic distribution of coronary calcium in a relatively unbiased population sample. (McClelland et al., 2006) See the following website for additional information on the MESA study. http://www.mesa-nhlbi.org. Accessed April 7, 2009.