Lawrence M. Boxt, MD

Questions remain from practitioners, payers, and administrators regarding the economic impact of coronary CT angiography on established diagnostic modalities and the effects on reimbursement within imaging. To address these concerns, we have developed the CCTA Data Registry, which now consists of more than 20,000 cases. Preliminary results indicate that coronary CTA is being utilized appropriately and affects savings for the healthcare system.

The benefits of CCTA are plentiful to the practitioner and the patient, yet they appear less obvious to some payers. The key benefit to payers is potential cost savings, but they are concerned that CCTA may increase imaging study volumes, thereby costing the system money.

For the payer and the healthcare system to realize a savings from CCTA, the procedure must replace, not accompany, other diagnostic imaging modalities. CCTA is reimbursed, where applicable, well below the global reimbursement rates for both nuclear perfusion testing and diagnostic catheter angiography. Consequently, a savings is inherent whenever CCTA is substituted for either of these more costly diagnostic procedures. Substitutions for catheter angiography are particularly appealing to the payer, as the global reimbursement for diagnostic catheterization is approximately 300% that of CCTA.

The key concerns of payers are centered on overutilization of CCTA. Three primary trends have the potential to encourage over-, and perhaps inappropriate, utilization trends:

broad use of CCTA as a screening test; and

If CCTA becomes simply an additional "layered" diagnostic test, the system has realized no benefit or savings. The prospect of the practitioner ordering a nuclear perfusion study followed by a CCTA and then followed by a diagnostic catheterization alarms payers. In an era of severe scrutiny regarding diagnostic testing, the layered test will not be tolerated.

Using CCTA for the sole purpose of screening patients absent symptoms and without risk or at low risk for coronary artery disease can also lead to overutilization. The underlying concern that CCTA could evolve into a screening tool is legitimate, but patient screening is not the intent or scope of CCTA. The American College of Cardiology, American College of Radiology, Society of Cardiovascular Computed Tomography, and others have developed appropriateness criteria for CCTA that establish guidelines for proper use of this technology.

Another avenue to overutilization and potential inappropriate utilization is reimbursement without regulation. Payers must safeguard against this by allowing reimbursement only to those sites complying with the established competency statements and standards.

While current coverage policies vary by carrier and by region, the majority contain many similar components. However, it is critical to verify the elements of any specific policy with local carriers.

Most policies stipulate that the scanning equipment suitable to perform coronary CTA must be 64 slices or the equivalent thereof. While the clinical appropriateness criteria vary among carriers and policies, most accept the following as appropriate indications for CCTA:

following an equivocal nuclear perfusion study;

in postrevascularization patients having CAD symptoms;

pre-electrophysiology anatomic mapping; and

Coronary calcium scoring, while potentially yielding clinically relevant data, remains a screening test and is consequently considered a "retail service," with the patient paying directly for this procedure.

We included 15,710 cases of 64-slice CCTA from 26 practices/hospitals across the U.S. in our analysis. All procedures were conducted between November 2005 and November 2006. (The number of cases has since surpassed 20,000, and a preliminary examination shows the data are consistent with this present analysis.) We obtained from the practice databases clinical indications for CCTA, diagnostic imaging procedure volumes, global allowable reimbursement rates, normal catheterization rates, and patient volumes.

Economic forecast data include every CCTA patient at the included practices. From the cohort, we determined whether each patient had undergone any additional diagnostic imaging procedures within 30 days prior to or following CCTA. This 60-day period defines a diagnostic episode of care and is necessary to prevent inaccurate results that may occur longitudinally with symptom presentation in the chronic cardiac patient.

In the 12 months after implementation of CCTA, practices saw a 5% and 8% drop in diagnostic catheter angiography and nuclear perfusion studies, respectively, despite an overall 10% growth rate within the patient volumes in each practice (Table 1).

A good barometer of the impact of a CCTA program is the percentage of patients having "normal" or "essentially normal" diagnostic catheter angiographies. A successful CCTA program should ideally reroute those moderate-risk patients to the CCTA lab in lieu of traditional angiography, thereby reducing the number of normal results stemming from the diagnostic catheterization lab.

Our figures indicate a decline in normal results among catheterization patients. The observed 5% decline following CCTA implementation suggests that CCTA is being used appropriately and that it is adding clinical value to the overall diagnostic imaging program (Table 2).

Among states and payers that currently allow CCTA reimbursement, the most common clinical indications include known CAD, prior revascularization, chest or precordial pain, shortness of breath, valve disorders, and angina. These indications allow the cardiovascular practitioner to noninvasively image the intermediate-risk patient and monitor disease progression in the patient with known disease. Furthermore, these indications limit the scope of patients who qualify for CCTA, thereby preventing utilization of the modality as a screening technique. The clinical indications used by practitioners in this analysis suggest that these practices apply a very narrowly defined scope of indications for which CCTA is being ordered and adhere to the recently released ACC Appropriateness Criteria for CCTA (Figure 1).

The potential diagnostic imaging clinical pathways for patients who have undergone CCTA angiography are limited to 11 mathematical possibilities. Of these, only nine were used among the patients in this analysis. They are summarized as five diagnostic pathways. Additionally, we grouped six combinations of tests, each one using three modalities, into four layered tests.

Diagnostic Pathway 1-CCTA: Each CCTA alone will be substituted for the cost of a nuclear perfusion study, as the symptomatic patient would be assessed at some diagnostic imaging entry point. Therefore, multiply every patient in Diagnostic Pathway 1 by the difference between the $1311 allowable for a perfusion study and the $1000 allowable for a CCTA ($311). This figure determines the direct impact of Diagnostic Pathway 1 (Table 3).

There are indirect savings to the healthcare system from this clinical pathway as well. Established clinical data support the statement that 25% of patients who enter the system with nuclear perfusion imaging will have equivocal or abnormal results, thereby progressing to catheter angiography in the absence of CCTA services. These indirect savings, at $2800 per case, are significant but were not included in this direct analysis.

Diagnostic Pathway 2-nuclear perfusion followed by CCTA: The patient proceeding from nuclear perfusion testing to CCTA will have had an either abnormal or equivocal nuclear study. Diagnostic Pathway 2 is a true substitution of CCTA for cath. In the absence of a CCTA program, the patient with an abnormal or equivocal nuclear study would instead progress to catheterization. Multiply every Diagnostic Pathway 2 patient by the difference between the global allowable for a cath procedure ($2800) and the $1000 allowable for a CCTA ($1800).

Diagnostic Pathway 3-CCTA followed by diagnostic catheter angiography: In Diagnostic Pathway 3, the symptomatic patient enters the diagnostic imaging pathway at CCTA, which is substituted for a nuclear perfusion study. This pathway, like Diagnostic Pathway 2, is a true substitution of an imaging modality by CCTA, which provides the less invasive and less expensive entry point. Multiply every Diagnostic Pathway 3 patient by the difference between the global allowable for a nuclear perfusion study ($1311) and the $1000 allowable for CCTA ($311).

Diagnostic Pathway 4-CCTA followed by nuclear perfusion: Patients who enter the diagnostic imaging pathway with CCTA and then progress to a nuclear perfusion study make up Diagnostic Pathway 4. A fraction of patients with an abnormal CCTA will require a perfusion study to evaluate the hemodynamic impact of the lesion(s). This pathway does not add or subtract a test, as this is a clinically appropriate pathway. In the absence of a CCTA program, the practitioner would start at nuclear perfusion and potentially find a functional deficit requiring cath for anatomic evaluation.

Diagnostic Pathway 5-cath followed by CCTA: Patients first undergo a diagnostic catheter angiography and then progress to CCTA. This could occur for a variety of reasons, but the substitution is a CCTA for a nuclear perfusion study. In these cases, the physician did not obtain the data needed from diagnostic catheterization alone, and, in the absence of a CCTA program, a nuclear perfusion study would have been ordered. Multiply every Diagnostic Pathway 5 patient by the difference between the global allowable for a nuclear perfusion study ($1311) and the $1000 allowable for a CCTA ($311).

Layered tests: These patients have all three diagnostic tests, which may occur for a variety of reasons. Since this pathway includes all three imaging modalities, and this is a major concern of the payers, we will multiply the number of patients on this pathway by the mean global reimbursement for CCTA ($1000). The layered tests are nuclear perfusion followed by CCTA followed by cath, nuclear perfusion followed by cath followed by CCTA, CCTA followed by nuclear perfusion followed by cath, and CCTA followed by cath followed by nuclear perfusion.

With the graying of the U.S. upon us, patient volumes, and consequently imaging volumes, are increasing annually. Mathematically, the studied practices showed an average 10% mean patient growth rate during the analyzed period. This could have caused diagnostic catheter angiographies to increase from 46,532 to 51,185. These additional procedures would equate to increased reimbursement of $13,028,400 if using global allowables. Instead, diagnostic catheter angiography volumes decreased to 44,111, which may be due largely to the 64-slice CCTA program appropriately guiding moderate-risk patients to CCTA.

Similarly, nuclear perfusion studies could have increased from 143,847 to 158,231 during the study period, assuming a 10% growth rate. The additional nuclear perfusion studies would equate to increased reimbursement of $18,857,424 when using global allowables. Contrary to any predictive models, the actual number of perfusion studies decreased by 11,470 in the 12 months following CCTA implementation, saving the healthcare system $15,037,170.

The data from this analysis suggest that multislice CCTA reduced diagnostic catheterization rates, despite 10% overall growth in patients served. The data also suggest that CCTA, which is a less expensive and more patient-friendly imaging modality, was used as a substitute for many nuclear perfusion studies.

As outlined in the economic forecast (Table 3), with CCTA reimbursed at a $1000 allowable, the annual savings to the healthcare system for these 26 practices alone was approximately $7,568,388, despite a 10% average growth in patient volume during the measured period.

Coronary CTA has emerged as an important noninvasive diagnostic technique for coronary disease as well as other cardiac problems (Figure 2). It is anticipated that CCTA will dramatically alter the diagnostic paradigm for coronary artery disease. The results of this analysis strongly suggest that, in the practices evaluated, CCTA is being utilized appropriately and that CCTA adds clinical value to patient management while affecting a cost savings for the healthcare system. This conclusion is supported by the narrowly defined and appropriate clinical indications followed by these practices, which are supported by established clinical appropriateness criteria. A decline in diagnostic procedural volumes for stress perfusion imaging and diagnostic catheter angiography following implementation of CCTA further supports this conclusion.

The economic analysis in this study predicts significant savings to the healthcare system following the implementation of a CCTA program. Despite an increase in the number of patients served at the institutions involved in this analysis, a decline in nuclear perfusion studies and invasive angiographic procedures occurred. The reduction among these procedures resulted in savings to the healthcare system of more than $7.8 million within this cohort of patients. The savings on a per-patient basis for diagnostic imaging was $481.

Dr. Fine is with CVI3 in Beaufort, SC. Dr. Ridner is with The Heart Center in Huntsville, AL. Dr. Wilke is with Shands Healthcare-University of Florida in Jacksonville. Dr. Cole is with Cardiology Associates of Mobile in Mobile, AL. Dr. Callister is with Tennessee Heart and Vascular Institute in Hendersonville. Dr. Myers is with St. Thomas Cardiology Associates in Nashville. Dr. Boxt is with North Shore Health System in New York City. Ms. Gates-Striby is with The Care Group in Indianapolis.

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Articles

Coronary CT angiography saves lives and money: 20,000-plus cases prove it

Progress in the management of patients with heart disease has always been closely tied to radiologists' expertise in cardiac imaging. But we have to move away from lumenology and toward a more cellular and molecular focus to fully appreciate modern noninvasive cardiac imaging.

After Roentgen discovered the x-ray in 1898, radiologists quickly found plain-film examination of the heart useful to diagnose valvular and myocardial heart disease. The ability of angiocardiography to document specific intracardiac defects played a central role in the dramatic growth of cardiac surgery to palliate and cure congenital malformations of the heart. The development of coronary artery bypass surgery and, subsequently, percutaneous angioplasty and stent placement-all of interventional cardiology, in fact-is derived directly from catheter-based, film-recorded cineangiocardiography.

Progress in the diagnosis of ischemic and congenital heart disease reflects ongoing developments and improvements in echocardiography, nuclear cardiac imaging, MRI, and now ECG-gated multislice CT.

Our clinical paradigm for managing patients with atherosclerotic cardiovascular disease is based on the association between reduction of arterial luminal narrowing shown on imaging and relief of clinical symptoms. In other words, we select patients for their chest pain syndromes. Those who have luminal coronary arterial stenoses are traditionally treated by coronary artery bypass graft surgery and more recently by percutaneous angioplasty and stent placement.

This approach brings symptomatic relief. Except in the case of CABG surgery for left main coronary stenosis, however, we obtain no improvement in patient longevity. We improve the quality of life by removing symptoms, but we do not alter the quantity of life.

The focus on luminal narrowing and its relationship with coronary artery blood flow reveals only part of the picture. Our increased understanding of the cellular and molecular biologic basis of atherosclerotic disease has shed a great deal of light on earlier observations made using coronary arteriography. These observations were correct, but they were initially considered less important and only really appreciated in retrospective analysis of a series of angiograms. The physical limitations of angiographic methods were insensitive to the morphologic changes needed to support new and evolving theories of atherogenesis; there was no imaging correlate of the "new" atherosclerotic process.

Current MR and CT scanners sample volumes of space and are very sensitive to calcium and fat deposition. This allows high-resolution data set acquisition that can be displayed in arbitrary tomographic sections, 3D representations, or visualization of an organ. The ability of these scanners to resolve fat and calcium supports their value in plaque characterization. Observations made on MR and CT scans reflect our understanding of fatty plaque formation and the remodeling changes that result in their characteristic non-flow-limiting stenoses.

Medicine is undergoing a paradigm shift in our understanding of atherosclerosis. This is reflected in how we detect and manage atherosclerotic heart disease. The developing concept of the fat-laden plaque at risk helped explain some angiographic observations made in patients with chest pain syndromes. What we now call fatty plaques were probably observed on older cineangiograms but were ignored or considered of minimal consequence. These "lumpy-bumpy" lesions rarely limited flow, so they did not produce flow-limiting stenosis (Figure 1). No regional myocardial ischemia was induced, and no chest pain was experienced. Only at the time of plaque rupture and acute coronary thrombosis do these lesions become symptomatic.

Yet to improve longevity, we must address fatty plaques. The shift from symptomatic relief based on luminal narrowing to prevention and aggressive medical therapy supported by arterial wall (plaque) imaging will mobilize our resources toward identification of patients at risk, methods of early detection, efficient and consistent means of image interpretation, and clinical outcome analysis. At the heart of this shift lies arterial plaque characterization.

The ability of MRI to provide accurate, reliable image and physiologic data in a clinically timely manner will determine its niche in the armamentarium of cardiac imaging modalities. From its early development and application, MRI has been praised as a noninvasive, multifunction cardiac imaging technique. Its image-derived morphologic and physiologic data, invaluable for the evaluation of children and adults with congenital heart disease and adult patients with ischemic heart disease, have been helpful. But cardiac MRI remains a rather sparsely practiced subspecialty that is widely unavailable, and clinical practitioners are not familiar with its utility.

The development of the electron-beam CT scanner began in earnest the application of CT technology to the problem of cardiac imaging. The ability to acquire image data rapidly enough to obtain sharp, clear images of the cardiac chambers and myocardium encouraged further applications of digital computer technology to medical imaging. Both EBCT and multidetector spiral CT produce a data set reflecting the 3D distribution of tissue attenuation of x-ray photons. The ability of MR and CT to identify and characterize atherosclerotic plaque will support their role in our new model of cardiovascular disease.

The great advance of CT over MR, and, I believe, the landmark advance of the 64-detector CT scanner, is reflected in the data set obtained. The x-ray photon exposure a patient receives during an ECG-gated MSCT exam produces an image data set of contrast and temporal resolution equal to or better than that obtained from the microwave exposure in an MRI exam. The isovolumetric voxels generated by 64-slice contrast-enhanced ECG-gated spiral CT, however, provide the substrate for a geometric (fourfold) leap in spatial resolution (Figure 2). More important, the acquisition of cube-shaped image elements allows distortion-free reconstruction in planes away from the axial acquisition (Figure 3). Furthermore, 3D reconstructions will more accurately reflect the appearance of the anatomic structure than does an angiographic projection image or conventional MR tomographic display.

If this improvement results in management strategies that improve longevity, it will support the shift from organ imaging to organ visualization. The visual display reflects what the organ looks like, rather than a parametric representation of some morphologic or physiologic aspect of the organ. MRI and CT can produce such imagery. Differences in patient throughput, image quality, and confidence in and accuracy of diagnosis will affect clinical indications. The future role of both modalities will depend on their ability to affect clinical outcome as well as on the economic, professional certification, and radiation safety issues related to their practice.

We now have a two-stop shop. Two noninvasive, multifunction cardiac imaging techniques are available for use. Issues concerning clinical experience, cost, patient risk, and effect on clinical outcome will nudge each modality into a clinically relevant, market-based imaging niche. In these defined and supportable arenas, MR and CT imaging of the heart will play an important role in our new approach to cardiovascular disease.

Dr. Boxt is director of cardiac MRI and CT in the cardiology division and radiology department at North Shore University Hospital in Manhasset, NY.

Lawrence M. Boxt, MD

Articles

Coronary CT angiography saves lives and money: 20,000-plus cases prove it

64 slices let CT join MR in a two-stop cardiac shop