Utility of CAD-RADS 2.0 Plaque Burden Grades and Stenosis Categories on Coronary CTA for Predicting Cardiac Events in Patients With Acute Chest Pain: A Multicenter Study

BACKGROUND. Coronary Artery Disease Reporting and Data System (CAD-RADS) 2.0 incorporated reporting of plaque burden grades in addition to stenosis categories. OBJECTIVE. The purpose of this study was to assess the usefulness of plaque burden grades and CAD-RADS categories, determined on coronary CTA by use of CAD-RADS 2.0, in predicting cardiac events in patients presenting to the emergency department (ED) with acute chest pain. METHODS. This retrospective study included patients who underwent coronary CTA after presenting to the ED with acute chest pain at one of four centers from January 2018 to December 2021. A single radiologist reviewed examinations at each center to assign a plaque burden grade by calculating a coronary artery calcium score on noncontrast images and to assign a CAD-RADS category by assessing vessel stenosis on contrast-enhanced CTA images, with both assignments made using CAD-RADS 2.0. The reviewing radiologist at each center also assessed examinations for the presence of high-risk plaque. The EMR was reviewed for cardiac events, reflecting a composite outcome of cardiac-related death, myocardial infarction, or hospitalization for unstable angina. Prognostic models were compared. RESULTS. The study included 2032 patients (1085 men and 947 women; mean age, 58.4 years). During a median follow-up of 15.2 months, 63 patients (3.1%) had cardiac events. In a multivariable Cox model adjusting for clinical variables, cardiac events showed significant independent associations with CAD-RADS 3 (HR = 7.1), CAD-RADS 4 (HR = 13.6), CAD-RADS 5 (HR = 17.6), and high-risk plaque (HR = 2.5) but not with plaque burden grades. For predicting cardiac events, the C statistic was 0.67 for a model including clinical variables; 0.74 for a model including clinical variables and plaque burden grades; 0.86 for a model including clinical variables, CAD-RADS categories, and high-risk plaque; and 0.87 for a model including clinical variables, plaque burden grades, CAD-RADS categories, and high-risk plaque. The model with clinical variables, CAD-RADS categories, and high-risk plaque but without plaque burden grades showed the highest net clinical benefit across threshold probabilities from 20% to 100%. CONCLUSION. Addition of plaque burden grades did not provide further prognostic benefit in models using CAD-RADS categories. CLINICAL IMPACT. Inclusion of an additional noncontrast acquisition for coronary artery calcium scoring within coronary CTA protocols may not improve risk stratification for patients presenting to the ED with chest pain.