Marlene Busko

July 19, 2017

WASHINGTON, DC — The recently introduced Coronary Artery Disease-Reporting and Data System (CAD-RADS), used to standardize reporting of findings from coronary CT angiograms, was validated by classifying scans from a subset of patients with stable chest pain in the SCOT-HEART trial, and the reporting system performed well, researchers say[1].

Specifically, it "nicely stratified the patients into the five different groups, with patients with CAD-RADS 3, 4, and 5 being at particularly high risk of having subsequent events—fatal and nonfatal MI," Dr Michelle C Williams (University of Edinburgh, Scotland) told | Medscape Cardiology here at the Society of Cardiovascular Computed Tomography (SCCT) 2017 Annual Scientific Meeting.

"This really validates that the scoring system works well and is now ready for clinical use," she said.

More clinicians seem to be adopting this standardized reporting system, which also lists guideline-recommended treatments for each stenosis category. In a "nonscientific" survey of her Twitter followers, Williams commented that a third said they were using the system. 

Dr Steven D Schirm (St Anthony's Hospital, St Petersburg, FL), who does a lot of CTs for patients in the ER but was not familiar with CAD-RADS, commented: "A good standardized system for reporting is good for the physicians, the ER doctors, but also . . . the reporting radiologist, because there's too much variability built in for individual reporting. Just like mammography, I think it's good to have a standardized system."

Williams said that the system is "very easy to apply; it's just a little add-on at the end of your report." It's a fairly simple idea, but it has important implications, she added. Like any standardized reporting tool, "it clarifies how you communicate the results, and any clarification is always very beneficial, particularly when people are rushed."

She urges clinicians to look at the reference paper for CAD-RADS[2], which has examples, pictures, and practical applications, and “tells you exactly what to do."

Several other studies are under way to validate CAD-RADS, and more clinicians are using it and "including it in their final report . . . o guide clinical management of patients," outgoing SCCT president Dr Leslee J Shaw (Emory University, Atlanta, GA) commented in an email.

Five Categories Based on Worst Stenosis

CAD-RADS, based on expert consensus from representatives of multiple societies, classifies patients into five categories based on the highest grade of coronary stenosis and ists patient-management strategies recommended in the American College of Cardiology guideline for each category, including recommendations on when to consider doing invasive coronary angiography.

The document also has categories for patients with vulnerable plaque, coronary artery stents, CABG, and nondiagnostic scans.

The Scottish Computed Tomography of the Heart Trial (SCOT-HEART) in patients with suspected angina due to coronary heart disease reported that coronary CT angiography clarified the diagnosis of angina due to coronary artery disease better than standard care, which resulted in changed treatments in some patients and was associated with a trend to a reduced risk of future fatal or nonfatal MI.

Williams and colleagues validated the CAD-RADS classification system in a subset of CTA scans from SCOT-HEART.

Trained observers assessed the CT coronary angiography images from 1778 patients with stable chest pain in SCOT-HEART and classified patients using CAD-RADS.  

CAD-RADS Classification of a SCOT-HEART Subset

CAD-RADS class Coronary stenosis, % Description Patients, %
0 0 No plaque or stenosis 35
1 1–24 Minimal stenosis or plaque with no stenosis 19
2 25–49 Mild stenosis 12
3 50–69 Moderate stenosis 9
4 70–99 Severe stenosis 15
5 100 Total occlusion 10
Coronary stenosis: degree of maximal coronary stenosis, %

About a third of patients (35%) had no plaque or stenosis, and 10% had total occlusion.

In addition, 11% of patients had two features of high-risk plaque (CAD-RADS 5), 1.5% had CABG, 3.4% had a coronary artery stent, and 1.1% had a nondiagnostic CT coronary angiography scan.

Compared with patients with a CAD-RADS score of 0 (no stenosis), those with scores of 4 or 5 were more likely to undergo subsequent revascularization (49% vs 2%; P<0.001).

Over a median follow-up of 3.3 years, 31 patients (1.7%) had a fatal or nonfatal MI.

Compared with patients with a CAD-RADS score of 0, those with a score of 5 had a sevenfold increased risk of a fatal or nonfatal MI during follow-up (HR 6.89; 95% CI 1.72–27.55, P=0.006).

The increased risk of this outcome was similar for patients with a CAD-RADS score of 3 or 4. 

In contrast, there was no significant increase in fatal or nonfatal MI in patients with CAD-RADS scores of 1 or 2, or those with high-risk plaque features.

"We need to work a little bit more on how we're defining vulnerable plaque . . . but the CAD-RADS 1 to 5 is good to go," said Williams.

In addition to CAD-RADS for stable chest pain, there is also CAD-RADS for acute chest pain, with slightly different recommendations but very similar classifications, she noted.

Williams, Schirm, and Shaw had no relevant financial relationships.

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