Diffuse coronary artery disease among other atherosclerotic plaque characteristics by coronary computed tomography angiography for predicting coronary vessel-specific ischemia by fractional flow reserve

Abstract

Background and aims: Coronary computed tomography angiography (CCTA) permits effective identification of diffuse CAD and atherosclerotic plaque characteristics (APCs). We sought to examine the usefulness of diffuse CAD beyond luminal narrowing and APCs by CCTA to detect vessel-specific ischemia.

Methods: 407 vessels (n = 252 patients) from the DeFACTO diagnostic accuracy study were retrospectively analyzed for percent plaque diffuseness (PD). Percent plaque diffuseness (PD) was obtained on per-vessel level by summation of all contiguous lesion lengths and divided by total vessel length, and was logarithmically transformed (log percent PD). Additional CCTA measures of stenosis severity including minimal lumen diameter (MLD), and APCs, such as positive remodeling (PR) and low attenuation plaque (LAP), were also included. Vessel-specific ischemia was defined as fractional flow reserve (FFR) ≤0.80. Multivariable regression, discrimination by area under the receiver operating characteristic curve (AUC), and category-free net reclassification improvement (cNRI) were assessed.

Results: Backward stepwise logistic regression revealed that for every unit increase in log percent PD, there was a 58% (95% CI: 1.01-2.48, p = 0.048) rise in the odds of having an abnormal FFR, independent of stenosis severity and APCs. The AUC indicated no further improvement in discriminatory ability after adding log percent PD to the final parsimonious model of MLD, PR, and LAP (AUC difference: 0.003, 95% CI: -0.003-0.010, p = 0.33). Conversely, adding log percent PD to the base model of MLD, PR, and LAP improved cNRI by 0.21 (95% CI: 0.01-0.41, p < 0.001).

Conclusions: Accounting for diffuse CAD may help improve the accuracy of CCTA for detecting vessel-specific ischemia.

Keywords: Atherosclerotic plaque characteristics; Coronary computed tomography angiography; Diffuse coronary artery disease; Fractional flow reserve; Stenosis severity.

Fig. 1. Measurements of plaque diffuseness (PD)

(A) Multiplanar reformat of the CCTA demonstrating four individual lesions (a, b, c, and d) with proximal and distal reference in the left anterior descending artery. Percent PD was obtained by summation of all contiguous lesion lengths and divided by total vessel length of each respective coronary artery. (B, C, and D) Multiplanar reformats of the CCTA assessing percent PD in the left anterior descending arteries with 1- and 2- diseased segments (B and C), and in the right coronary artery with 3- diseased segments (D). The corresponding percent PD and fractional flow reserve values are also displayed. %PD, percent plaque diffuseness; FFR, fractional flow reserve.

Fig. 2. Discrimination by C-statistic for the presence of vessel-specific ischemia according to CCTA measures of coronary plaque

Base model included minimal lumen diameter (MLD), positive remodeling (PR), and low attenuation plaque (LAP). Comparative model included the base model as well as logarithmically transformed %PD. Area under the receiver operating characteristic curves (AUC) indicated no improvement in discriminatory ability when log percent PD was added to final parsimonious model of MLD, PR, and LAP (p =0.33). PD, plaque diffuseness.