Prognostic value of plaque burden assessed by coronary CT angiography in known coronary artery disease

Background: We aimed to investigate in patients with known coronary artery disease (CAD) whether plaque burden assessed by coronary computed tomography angiography (CCTA) can predict subsequent all-cause mortality (ACM). Methods: Consecutive patients with known CAD who underwent CCTA and coronary artery calcium (CAC) scans for CAD evaluation were enrolled. Known CAD was defined as history of myocardial infarction (MI) or percutaneous coronary intervention (PCI). Plaque burden was assessed by CAC (categorized as 0–100, 101–300, 301–999, ≥1000), degree of stenosis (DS) (0–24 ​%, 25–49 ​%, 50–69 ​%, and ≥70 ​%) and segmental involvement score (SIS) (≤2, 3–4, 5–7, and ≥8) on CCTA. Multivariable Cox regression analysis was used to determine the association between plaque burden and ACM. Results: 963 patients were included (age 66.1 ​± ​11.5, 72.0 ​% male) of whom 707 had PCI, 586 had MI, and 330 had both. During median follow-up of 3.0 years (interquartile range 1.0–6.5), 91 patients (9.4 ​%) died. By Kaplan-Meier analysis, higher CAC score was associated with a higher risk of ACM (p ​< ​0.001), but DS and SIS were not. In multivariable Cox regression analysis, CAC scores 301–999 (HR:3.10, 95%CI:1.23–7.80, p ​= ​0.017) and ≥1000 (HR:5.81, 95%CI:2.25–15.04, p ​< ​0.001) along with age, current smoking, and aspirin use were independently associated with increased risk of ACM, but DS and SIS were not. Conclusion: In patients with known CAD undergoing CCTA, CAC score>300 was an independent predictor of ACM. CAC may provide additional guidance for the intensity of secondary preventive treatments than the degree of residual stenosis or the number of segments with CAD.