At a cost of only $400, new EBCT scan challenges the angiogram
February 1, 1998 6 minutes read
At a cost of only $400, new EBCT scan challenges the angiogram
But savings come at a high price
The new electron beam computed tomography (EBCT) scan (Imatron’s Ultrafast) is not for every facility; it’s pricey and payers are not that enthusiastic yet about reimbursing for it, especially when it’s used for screening. Even for hospitals that can afford the capital outlay, the scanning technique is not quite ready for prime time. It represents a competitive advantage only where the population base is in excess of a million. EBCT and its next generations will offer a great deal of hope in years to come, however, and what follows should give you some insight into what one imaging expert calls the future of cardiology.
The EBCT scan at Rush-Presbyterian-St. Luke’s Medical Center in Chicago costs the patient a total of $395 and takes about five minutes to complete. By contrast, an angiogram long considered the gold standard can cost from $3,000 to $5,000 depending upon conditions, and an exercise EKG takes 5 to 12 minutes to complete, costs up to $400, and detects only about 70% of patients with heart disease. (See chart detailing diagnostic sensitivity, p. 14.) The rub? The EBCT machine requires a capital outlay of $1.6 to $1.9 million, and reimbursement can be dicey for now. (See related story on EBCT reimbursement, p. 17.)
"This technology is expensive," says S. Lewis Meyer, CEO of San Francisco-based Imatron. "To justify the capital outlay for the EBCT, a facility has to scan at least 25 to 30 patients a day." Facilities such as the Cooper Clinic in Dallas and Rush-Presbyterian manage to yield that volume. At this stage in the adoption of coronary artery scanning, you need a population base in excess of a million to make an investment in EBCT pay off.
"A capital investment seems large only if you can’t pay for it," continues Meyer, "so if you can bring your utilization up to those numbers, it becomes a feasible investment. You wouldn’t see an Ultrafast CT scanner in Flagstaff, AZ, for example, but you’d see one in Phoenix. There are about 45 systems nationwide right now."
High-volume screening procedures are usually attached to relatively low-cost devices. In contrast, the EBCT requires an expensive machine that produces an inexpensive procedure. For example, a mammography unit sells for about $150,000, and you’d never consider using a device like a positron-emission tomography scanner as a screening tool. Nevertheless, facilities around the country are making money selling procedures, but their volumes be very large.
"Once this procedure is treated like a heart mammogram,’ achieving those types of volumes will be feasible," says Meyer. All the data say that by diagnosing subclinical coronary artery disease and intervening, you can save lives. But the time period is not three or five years, but is somewhere in the seven-to-10 year frame.
"The payer side is short-term focused," continues Meyer. "It’s an economic reality that if they can’t get a pay back in two to three years, they’re not interested. We’re not addressing this disease the way we should be. If the reimbursement issue were less of a challenge, we’d find more asymptomatic sick people and would be able to significantly reduce the toll of heart disease."
Four recent studies are worth considering when evaluating the EBCT. Most researchers studying its use laud the technique for detecting lesions and calcium plaque. A minority are not so sure that plaque deposits are accurate predictors of heart attack risk.
The new technique has been under investigation at medical centers in United States and Europe for the past few years for diagnostic use and focused, risk-stratified screens. Charles B. Higgins, MD, professor of radiology at the University of California in San Francisco presented results of a study at the December meeting of the Radiological Society of North America in Chicago. He said that the scan is helpful in following up with patients who have undergone angioplasty.
"We’re ready to say [EBCT] can replace coronary angiograms in some patient groups, particularly those who are not known to have a coronary artery blockage and are undergoing tests to rule it out."
A recent multicenter study found that the EBCT scanner accurately detected the presence of calcium deposits in 95% of the 427 patients who proved to have heart disease.1 Matthew Buddoff, MD, a cardiologist at Harbor-UCLA Medical Center in Torrance, CA, who headed the study, states that the process proved "effective, safe, relatively inexpensive, and very fast." The researchers caution that while EBCT can be a strong indicator of artery blockage, it should be seen as an initial tool to determine if further tests such as coronary angiography are necessary.
Another study conducted at the National Heart, Lung, and Blood Institute reinforced those findings and reported that the scan can detect stenotic lesions and calcific plaque not discernible by angiography.2 The study cited the case of a 34-year-old asymptomatic male who exercised regularly, did not smoke, was within 5% of his ideal body weight, but had a family history of heart disease. Exercise treadmill and stress thallium testing failed to reveal significant disease or obstruction of coronary arterial blood flow. An EBCT scan, however, did reveal a total calcium score of 147 well above normal range. Author Jeffrey Hoeg, MD, wrote that the scan showed a "rampant atherogenic process independent of conventionally recognized cardiovascular disease risk factors."
One study questions scan’s effectiveness
A study from South Bay Heart Watch in Torrance casts some doubt on claims that the scan can accurately predict heart disease and that a negative result can rule out heart attack.3 Researchers demonstrated that calcium deposits in the heart’s arteries were indeed detected by the EBCT but are not accurate predictors of heart attacks and death from heart disease. More than 300 middle-aged to elderly patients underwent the EBCT scan and were followed for three years. Even those with little or no calcium in their arteries had subsequent heart attacks and disease.
Shortly after that, a study from Essen, Germany, resulted in data that explained that in the earlier findings the extent of calcification does not correlate directly with stenosis severity, but rather with atherosclerotic burden, hence cardiac risk.
The German study compared EBCT with intravascular ultrasound and angiography and demonstrated that EBCT can detect signs of preclinical heart disease before artery narrowing occurs, as well as rule out disease with 91% accuracy.4 Compared with angiography, EBCT yielded a sensitivity of 66%, a specificity of 78%, a positive predictive value of 39%, and a negative predictive value of 91%. Comparisons with ultrasound yielded similar results.
Researchers touted the noninvasive characteristics of the scan, saying that risky, expensive, and unnecessary invasive tests can be avoided. The study was the first to compare all three techniques in human beating hearts.
Dietrich Baumgart, MD, lead investigator in the German study stated that EBCT is not yet ready to replace the invasive techniques, however. "We think it is a good screening tool for those with risk factors for coronary artery disease such as high cholesterol levels, elevated blood pressure levels, or a positive family history. But patients in whom we do find significant calcification should undergo a stress test in order to define if ischemia induced by coronary artery stenosis is present, which then would be regarded as an indication for coronary angiography. Thus, unnecessary invasive tests could be avoided."
EBCT patients lie with their arms over their head as they would when undergoing a traditional CT scan. An EKG monitor triggers the machine when the heart is at rest, and that’s when the pictures are taken. Because the EBCT is so fast, as many pictures as are necessary can be taken within 30 seconds. The patient is in and out of the machine in five minutes, and a unit can screen 50 to 60 patients a day. (See photos, p. 15.)
Bob Kufchak, RT, CT technologist at Children’s Hospital of Buffalo (NY), says "Because of the scanner’s ability to obtain images at such a rapid rate, it’s ideal for pediatric use. We don’t have to sedate the children."
Older CT scanning devices need approximately one second to acquire an image far too long to capture the detail necessary to evaluate a moving heart. EBCT requires only a tenth of a second. To view a short video representation of an EBCT scan of a 60-year-old male with a type III dissection of the aorta, go to this Web site: http://everest.radiology.uiowa.edu/DPI/nlm/apps/aorta/aaadis/aaadis.html.
References
1. Budoff MJ, Georgiou D, Brody A, et al. Ultrafast computed tomography as a diagnostic modality in the detection of coronary artery disease. Circulation 1996; 93:898-904.
2. Hoeg JM. Evaluating coronary heart disease risk: Tiles in the mosaic. JAMA 1997; 277:1409.
3. Secci A, Wong N, Tang W, et al. Electron beam computed tomographic coronary calcium as a predictor of coronary events: Comparison of two protocols. Circulation 1997; 96: 1,122-1,129.
4. Baumgart D, Schmermund A, Goerge G, et al. Comparison of electron beam computed tomography with intracoronary ultrasound and coronary angiography for detection of coronary atherosclerosis. J Am Coll Cardiol 1997; 30:57-64.
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