Superior Risk Stratification With Coronary Computed Tomography Angiography Using a Comprehensive Atherosclerotic Risk Score

Abstract

Objectives: This study was designed to assess the prognostic value of a new comprehensive coronary computed tomography angiography (CTA) score compared with the stenosis severity component of the Coronary Artery Disease-Reporting and Data System (CAD-RADS).

Background: Current risk assessment with coronary CTA is mainly focused on maximal stenosis severity. Integration of plaque extent, location, and composition in a comprehensive model may improve risk stratification.

Methods: A total of 2,134 patients with suspected but without known CAD were included. The predictive value of the comprehensive CTA score (ranging from 0 to 42 and divided into 3 groups: 0 to 5, 6 to 20, and >20) was compared with the CAD-RADS combined into 3 groups (0% to 30%, 30% to 70% and ≥70% stenosis). Its predictive performance was internally and externally validated (using the 5-year follow-up dataset of the CONFIRM [Coronary CT Angiography Evaluation for Clinical Outcomes: An International Multicenter Registry], n = 1,971).

Results: The mean age of patients was 55 ± 13 years, mean follow-up 3.6 ± 2.8 years, and 130 events (myocardial infarction or death) occurred. The new, comprehensive CTA score showed strong and independent predictive value using the Cox proportional hazard analysis. A model including clinical variables plus comprehensive CTA score showed better discrimination of events compared with a model consisting of clinical variables plus CAD-RADS (0.768 vs. 0.742, p = 0.001). Also, the comprehensive CTA score correctly reclassified a significant proportion of patients compared with the CAD-RADS (net reclassification improvement 12.4%, p < 0.001). Good predictive accuracy was reproduced in the external validation cohort.

Conclusions: The new comprehensive CTA score provides better discrimination and reclassification of events compared with the CAD-RADS score based on stenosis severity only. The score retained similar prognostic accuracy when externally validated. Anatomic risk scores can be improved with the addition of extent, location, and compositional measures of atherosclerotic plaque. (Comprehensive CTA risk score calculator is available at: http://18.224.14.19/calcApp/).

Keywords: coronary computed tomography angiography; risk stratification; stable coronary artery disease.

Conflict of interest statement

Conflict of interest

None

Copyright © 2019 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1.. Comprehensive CTA score calculation

The new, comprehensive CTA score is calculated by addition of the individual segment scores, which are obtained by multiplication of the plaque weight factor, the stenosis weight factor and the location weight factor. For example, a patient with a right dominant system with a non-calcified plaque with >50% stenosis in the middle RCA, and a mixed plaque with

Figure 2.. Event-Free survival for the CAD-RADS and the new, comprehensive CTA score

Both classifications (0–5, 6–20, >20) were associated with increased risk for events (death and myocardial infarction) over time. CAD: coronary artery disease; CTA: computed tomography angiography.

Figure 3.. External prognostic validation (CONFIRM registry) of the new, comprehensive CTA score

Comparison of 5-years cumulative event free survival among the derivation and external validation cohort of the comprehensive CTA score showing similar discriminatory ability of the score. Abbreviations: CAD: coronary artery disease; CTA: computed tomography angiography.