Today, I review, link to, and excerpt from CAD-RADS™ 2.0 – 2022 Coronary Artery Disease-Reporting and Data System: An Expert Consensus Document of the Society of Cardiovascular Computed Tomography (SCCT), the American College of Cardiology (ACC), the American College of Radiology (ACR), and the North America Society of Cardiovascular Imaging (NASCI) [PubMed Abstract] [Full-Text HTML] [Full-Text PDF]. J Cardiovasc Comput Tomogr. 2022 Nov-Dec;16(6):536-557. doi: 10.1016/j.jcct.2022.07.002. Epub 2022 Jul 8.
Coronary Artery Disease Reporting and Data System (CAD-RADS) was created to standardize reporting system for patients undergoing coronary CT angiography (CCTA) and to guide possible next steps in patient management. The goal of this updated 2022 CAD-RADS 2.0 is to improve the initial reporting system for CCTA by considering new technical developments in Cardiac CT, including data from recent clinical trials and new clinical guidelines. The updated CAD-RADS classification will follow an established framework of stenosis, plaque burden, and modifiers, which will include assessment of lesion-specific ischemia using CT fractional-flow-reserve (CT-FFR) or myocardial CT perfusion (CTP), when performed. Similar to the method used in the original CAD-RADS version, the determinant for stenosis severity classification will be the most severe coronary artery luminal stenosis on a per-patient basis, ranging from CAD-RADS 0 (zero) for absence of any plaque or stenosis to CAD-RADS 5 indicating the presence of at least one totally occluded coronary artery. Given the increasing data supporting the prognostic relevance of coronary plaque burden, this document will provide various methods to estimate and report total plaque burden. The addition of P1 to P4 descriptors are used to denote increasing categories of plaque burden. The main goal of CAD-RADS, which should always be interpreted together with the impression found in the report, remains to facilitate communication of test results with referring physicians along with suggestions for subsequent patient management. In addition, CAD-RADS will continue to provide a framework of standardization that may benefit education, research, peer-review, artificial intelligence development, clinical trial design, population health and quality assurance with the ultimate goal of improving patient care.
Keywords: CAD-RADS; Coronary CTA; Coronary artery disease; Ischemia; Plaque burden; Report standardization terminology; Reporting and data system; Stenosis severity.
Declaration of competing interest ∗In accordance with SCCT policy, writing group members and reviewers are required to disclose relationships with industry; see Appendices 1 and 2 for detailed information.
Coronary CT Angiography (CCTA) has undergone significant technical advancements and clinical validation in the last decade, and several professional societies have issued guidelines, expert consensus documents, and Appropriateness Criteria for CCTA.1–11 Training physicians and technologists in image acquisition and interpretation is essential for fostering quality.12 Such training should also include an approach to standardized reporting in order to decrease variability among practitioners and ensure that test results are appropriately used in patient management decisions.
The purpose of this document is to update the first version of the CAD-RADS13 standardized classification of coronary artery disease for patients undergoing CCTA that was originally published in 2016 in order to include additional features such as plaque burden and ischemia, and to incorporate evidence from recent clinical trials as well as new clinical practice guidelines. The updated 2022 CAD-RADS 2.0 classification will follow a framework of stenosis, plaque burden and modifiers, with the option to also include ischemia evaluation by CT fractional-flow-reserve (CT-FFR) or myocardial CT perfusion (CTP), if performed. As in the original version, the most severe coronary artery luminal stenosis defined on a per-patient basis will be the central component of assessment and will provide the numeric descriptor. In addition, methods to estimate, quantify and report overall plaque burden will be provided. Collectively, the goal of these additions is intended to enhance patient management decisions following CCTA.
The main goal of CAD-RADS remains to standardize reporting of CCTA results and to facilitate communication of test results to referring physicians along with suggestions for subsequent patient management. Importantly, CAD-RADS should not be viewed as a substitute for the impression section of the report provided by the reading physician. CAD-RADS provides a complementary assessment and should always be interpreted in conjunction with the more detailed and patient-specific information found in the report and the impression, particularly because the report may provide more specific information regarding the location and extent of coronary plaque and stenosis. Furthermore, the clinical management suggestions provided by CAD-RADS should not replace clinical judgment, particularly as there are many patient-specific factors that may influence clinical management.
2 Clinical value of CAD-RADS and coronary CT angiography
More than 50 publications have further validated specific aspects of CAD-RADS since its original publication in 201614Fig. 1. The CAD-RADS classification has been shown to accurately predict major adverse cardiovascular events, defined as unstable angina, myocardial infarction, or death, in patients with stable chest pain with superior performance when compared with traditional risk factors, other risk stratification scores, the Coronary Artery Calcium Score (CAC) and the earlier SCCT coronary stenosis scoring system.15–19 CAD-RADS has also been demonstrated to correlate with the degree of stenosis measured by invasive coronary angiography (ICA) with high diagnostic accuracy.20,21 Recent publications have highlighted that adoption of CAD-RADS in clinical practice results in reduced downstream testing and cardiology referral rates in patients with non-obstructive coronary artery disease22 and has a favorable impact on medical therapy and systolic blood pressure control.23 Finally, recent studies have validated the performance of deep learning algorithms for the evaluation of CAD-RADS classification on CCTA.24
Fig. 1Timeline plots of total quarterly PubMed citations resulting from the search “CAD-RADS” [Title/Abstract] OR “CADRADS” [Title/Abstract]. The date of the search was January 25, 2021. Permission received63 Radiol Cardiothorac Imaging. 2021 Jun; 3 (3): e210016.
There has been widespread adoption of CAD-RADS in clinical practice with most sites in the United States and around the world using this classification for reporting CCTA on a routine basis. Overall, available research suggests that CAD-RADS offers a clinically useful and appropriate categorization of coronary artery disease with high diagnostic accuracy when compared with invasive angiography, with robust prognostic value and a beneficial impact on medical management.
Since the publication of the original CAD-RADS classification, several prospective trials have provided evidence supporting the clinical utility of CCTA and the relevance of CT findings among patients with suspected stable coronary artery disease. They include the PROMISE25 and SCOT-HEART26 trials, which demonstrated that CCTA is clinically useful as an alternative to functional testing (PROMISE) or in addition to standard of care (SCOT-HEART). Based on these trials and multiple registries, the prognostic value of the CAD-RADS classification has been confirmed, demonstrating that higher CAD-RADS scores were associated with increased risks of fatal and non-fatal MI.15–17
Moreover, several large randomized trials (CT-STAT, ACRIN-PA, ROMICAT II, CT-COMPARE) have compared CCTA to the current standard of care in patients with acute chest pain27–30. Complemented by real world implementation data,31–33 they consistently demonstrated the safety of discharging patients from the emergency department based on a negative CCTA, resulting in guidelines supporting the use of CCTA in low to intermediate risk patients presenting with acute chest pain to the emergency department.34
CCTA is now considered a first-line test (Class I) for use in acute and chronic coronary syndromes by the European Society of Cardiology,11 NICE guideline10 and by the new American College of Cardiology and American Heart Association Chest Pain Guideline,35 particularly in symptomatic patients with stable symptoms and intermediate or high pre-test probability of obstructive coronary artery disease, or among intermediate-risk acute chest pain patients. Moreover, there have been numerous advances in the detection and quantification, understanding of atherosclerotic plaque burden by CCTA, as well as a better understanding of the clinical implications of various CCTA findings.36
Despite the robust evidence base supporting the use of CCTA in patients with acute and stable chest pain, there is insufficient prospective randomized clinical trial data to support the optimal clinical management strategy following CCTA. Accordingly, the CAD-RADS classification is an expert consensus document. As such, the recommendations provided in this document are based on the available research data from clinical trials as well as on broad expert consensus. This includes the suggested categories for reporting and the recommendations for further patient management, which need to be interpreted in the context of other available clinical information for each individual patient.
CAD-RADS categories are based on stenosis severity and plaque burden. For the grading of stenosis severity, a classification system originally developed by the Society of Cardiovascular Computed Tomography is used (see Table 1). Table 1 also describes the terminology used to estimate the overall amount of plaque burden (P1 to P4) and the classification of ischemia into positive (I+), negative (I-) or borderline (I+/−), if a CT-based ischemia test such as, FFR-CT or myocardial CTP has been performed. Table 2 describes selected methods to categorize the overall amount of coronary plaque by CCTA. Table 3 describes examples of non-atherosclerotic causes of coronary abnormalities to be included in Modifier “E” = Exceptions. Tables 4 and 5 list the categories of the CAD-RADS reporting system for stable chest pain (Table 4) and acute chest pain (Table 5) with suggestions for further cardiac investigation and management considerations. In both settings, they range from CAD-RADS 0 (absence of atherosclerosis) to CAD-RADS 5 (presence of at least one total vessel occlusion).
Fig. 2 through 6 provide examples of different amounts of plaque burden and associated categories and terminology. Fig. 7 through 12 provide examples of CAD-RADS categories 4A, 4B, 5 and N.
