New CT Angiography Classification System: CAD-RADS Explained

Tricia Ward


June 24, 2016

Editor's Note: Ricardo C. Cury, MD (Miami Cardiac and Vascular Institute, Radiology Associates of South Florida), a noninvasive cardiovascular radiologist and past president of the Society of Cardiovascular Computed Tomography (SCCT), is the lead author of a new standardized system to classify and report patient data for CT angiography (CTA).[1] Medscape interviewed him about the CAD-RADS™ (Coronary Artery Disease Reporting and Data System) classification.

Medscape: Can you briefly describe the goal of developing this system?

Dr Cury: The main goal of CAD-RADS is to facilitate the decision-making regarding patient management. It's a reporting and data system that will improve the communication of coronary CTA results to referring physicians. If the results are reported in a consistent fashion, we minimize variation.

There are other imaging classifications that are very well established, such as BI-RADS for mammography. It's really minimized variation, standardized care, and guided patient management, with the ultimate goal of improving quality of care and improving patient outcome.

Medscape: What organizations were involved in developing CAD-RADs?

Dr Cury: This is a very important point. This was developed through 18 months of intense work. It was a multisociety, multidisciplinary writing group from the SCCT, the American College of Cardiology (ACC), the American College of Radiology, and the North American Society for Cardiovascular Imaging.

Medscape: The wording says, "Endorsed by the ACC." Were they involved in the writing or did they just review it?

Dr Cury: There were dedicated members of the ACC involved in the writing group. The document went through the normal approval of the ACC by the cardiac imaging council, and we had approval by the board of directors of all the societies.

Medscape: Who do you expect will use the new classification system?

Dr Cury: It will be primarily radiologists, cardiologists, and cardiac imagers. A CAD-RADS classification of 0-5 will go in every CTA report (Table). Over time, clinicians will become familiar with it. For example, they will understand that a patient with a CAD-RADS of 0 has no plaque and no stenosis; therefore, there is no coronary artery disease, so manage accordingly. A CAD-RADS of 4A, however, is a patient with a severe single-vessel stenosis in the mid left arterial descending artery, for example. The next step in this case would be going to the cath lab. This will facilitate communication from cardiologists, radiologists, and cardiac imagers rendering the coronary CTA report and the decision-making process. Obviously, it's just a consideration for management decisions; the clinician will have the full clinical picture with the ECG, etc.

Table. Patients With Stable Chest Pain

CAD-RADS Classification Degree of Coronary Stenosis Further Cardiac Investigation
0 0% None
1 1%-24%(minimal) None
2 25%-49% (mild) None
3 50%-69% (moderate) Consider functional assessment
4A 70%-99% (severe) Consider angiography or functional assessment
4B Left main >50% or three-vessel disease (>70%) Angiography recommended
5 100% total occlusion Consider angiography or functional assessment

Adapted from Cury RC, et al. Cardiovasc Comput Tomogr. 2016 Jun 13. [Epub ahead of print]

Medscape: Is there a plan for rolling this out with training?

Dr Cury: Yes. The next step will be creating dedicated templates for reports to incorporate CAD-RADS and making those templates available to users. Then there will need to be a lot of education, not only for the cardiac imagers reporting coronary CTA, but also for the referring community (mainly cardiologists, emergency physicians, and primary care physicians) in order for them to understand what the classification means and how to manage the process thereafter.

If we look at the history of BI-RADS in the past 20-plus years, it was developed as a breast imaging reporting and data system. Over time, that classification evolved; there was some fine-tuning. Nowadays, every mammography report worldwide uses BI-RADS, and clinicians understand the difference between a BI-RADS 1 versus a BI-RADS 5. Our goal for CAD-RADS is the same.

Medscape: You mentioned that BI-RADS is now used worldwide. Are there any plans for you to expand CADS-RADS internationally?

Dr Cury: Absolutely. SCCT, which took the lead in developing CAD-RADS (in partnership with the other societies), is an international society. We have close to 4000 members and more than a quarter are international members. This will be disseminated internationally through the society in partnership with other societies worldwide in Europe, Asia, Latin America, and other regions of the globe.

Medscape: You describe it as a living document that's going to evolve. How will that occur? Will this be reviewed and refined periodically or as issues arise?

Dr Cury: This was based on a review of the available scientific data and expert consensus by a multisociety, multidisciplinary panel, so it's the best evidence that we have currently. Now that we have created this classification system, we are going to apply it to large registries and databases, and retrospectively to studies, in order to derive patient outcome, cost, and downstream testing for each classification. By doing that, we'll be able to refine the system. In a couple of years and as the science evolves, we will incorporate the new findings and fine-tune CAD-RADS.

Medscape: It sounds like you plan to look back at some of the studies that have been done with CTA.

Dr Cury: There are large, prospective, randomized, multicenter trials that were done with CTA both in the acute chest pain setting and in patients with stable angina. We are going to collaborate with other investigators to run CAD-RADS through those registries and large prospective trials.

We plan to derive outcome data from established trials such as PROMISE,[2] SCOT-HEART,[3] CT-STAT,[4] ACRIN-PA,[5] ROMICAT II,[6] and CT-COMPARE.[7]

Medscape: Do you envisage something equivalent to the SYNTAX score using CTA for treatment decisions?

Dr Cury: That's a great analogy. The SYNTAX score involves not only angiographic findings but also many other clinical features.

Medscape: Is there a plan to incorporate CAD-RADS into workflows and EMRs?

Dr Cury: Yes. Part of the beauty of having a standardized reporting system is that you can set up large registry databases for education, research, peer review, quality assurance, and improving quality of care. With standardized and simplified terminology, you can develop a program and collaborate with industry. This not only should work with EMR and voice-recognition software, but it could also facilitate machine learning by having e-data entries to track.

Medscape: Where can our readers find the new system? Is it available now on the SCCT site?

Dr Cury: Yes. And it will be published simultaneously in the Journal of Cardiovascular Computed Tomography,[1] the Journal of the American College of Radiology, and JACC: Cardiovascular Imaging.

Medscape: Is there anything else you want to add?

Dr Cury: This was a significant amount of work with presentations from multiple societies and multiple stakeholders. We believe that it's a very robust document, and the key will be its dissemination and implementation. There are many sites already planning to implement CAD-RADS in clinical practice, particularly those that were engaged in developing this classification and are now collecting more data for further refinement and validation. At my institution beginning July 1, every CTA report will have a CAD-RADS classification.

Disclosure: Ricardo C. Cury, MD, reported the following disclosures:
Served as a consultant for: GE Healthcare
Received research grants/research support from: GE Healthcare

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