Computed Tomography Imaging of Coronary Artery Plaque

Non-Contrast and Contrast-Enhanced Cardiac Computed Tomography Imaging in the Diagnostic and Prognostic Evaluation of Coronary Artery Disease

In recent decades, cardiac computed tomography (CT) has emerged as a powerful non-invasive tool for risk stratification, as well as the detection and characterization of coronary artery disease (CAD), which remains the main cause of morbidity and mortality in the world. Advances in technology have favored the increasing use of cardiac CT by allowing better performance with lower radiation doses. Coronary artery calcium, as assessed by non-contrast CT, is considered to be the best marker of subclinical atherosclerosis, and its use is recommended for the refinement of risk assessment in low-to-intermediate risk individuals. In addition, coronary CT angiography (CCTA) has become a gate-keeper to invasive coronary angiography (ICA) and revascularization in patients with acute chest pain by allowing the assessment not only of the extent of lumen stenosis, but also of its hemodynamic significance if combined with the measurement of fractional flow reserve or perfusion imaging. Moreover, CCTA provides a unique incremental value over functional testing and ICA by imaging the vessel wall, thus allowing the assessment of plaque burden, composition, and instability features, in addition to perivascular adipose tissue attenuation, which is a marker of vascular inflammation. There exists the potential to identify the non-obstructive lesions at high risk of progression to plaque rupture by combining all of these measures.

Serial Changes in Coronary Plaque Formation Using CT Angiography in Patients Undergoing PCSK9-Inhibitor Therapy With 1-year Follow-up

PURPOSE

Previous studies have shown positive effects of intensive low-density lipoprotein (LDL)-lowering therapy on atheroma volume using invasive intravascular ultrasound. This study describes the changes in coronary plaque composition on coronary computed tomography angiography in patients treated with proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitors.

MATERIALS AND METHODS

In this prospective study, coronary plaques were analyzed using third-generation dual-source computed tomography before and after 1 year of PCSK9-inhibitor treatment. Plaque markers included total plaque volume (TPV), calcified plaque volume (CPV), noncalcified plaque volume (NCPV), lumen volume and vessel volume (VV), minimal luminal area (MLA), minimal lumen diameter (MLD), corrected coronary opacification, eccentricity, remodeling index, and functional plaque parameters. Primary endpoint was defined as change in TPV; the secondary endpoint was TPV or CPV regression or nominal change in plaque parameters.

RESULTS

We analyzed 74 coronary plaques in 23 patients (60±9 y, 65% male). After 1 year of PCSK9-inhibitor treatment, LDL was reduced from 148 to 66 mg/dL ( P <0.0001). Significant changes were found for VV (196 to 215 mm 3 , P =0.0340), MLA (3.1 to 2.6 mm 2 , P =0.0413), and MLD (1.7 to 1.4 mm, P =0.0048). TPV, CPV, NCPV, lumen volume, and functional plaque parameters did not change significantly ( P >0.05).

CONCLUSIONS

Coronary artery plaque analysis by coronary computed tomography angiography highlights that LDL lowering therapy affects plaque composition. The primary endpoint of TPV change was not reached; however, VV, MLA, and MLD changed significantly.

Association of plaque calcification pattern and attenuation with instability features and coronary stenosis and calcification grade

BACKGROUND AND AIMS

Coronary computed tomography (CT) allows calculating coronary artery calcium score (CACS). However, other CT features might be more strongly related to plaque vulnerability and risk of future coronary events. This study investigated the association of plaque calcification pattern and attenuation with plaque instability features, coronary artery disease (CAD) grade and CACS.

METHODS

One-hundred patients with coronary stenosis associated with calcified plaques were considered for this analysis. CACS, CAD grade, calcification pattern and attenuation, features of plaque instability, and epicardial adipose tissue (EAT) thickness and attenuation were assessed with non-contrast and contrast-enhanced CT angiography.

RESULTS

Of 373 calcified plaques, 131 were responsible for the highest degree of coronary stenosis (1.31 ± 0.53 per patient). Participants were stratified according to the features of the highest-grade lesion(s) into patients with large (35%), spotty (52%) or mixed (13%) calcification pattern and tertiles of plaque calcification attenuation (using the mean value for multiple lesions). Patients with large calcification pattern or higher plaque calcification attenuation had higher stenosis and CACS grade (and EAT attenuation), but lower plaque instability score, whereas those with spotty calcification pattern or lower plaque calcification attenuation had lower stenosis and CACS grade (and EAT attenuation), but higher plaque instability score. Among the instability features, low attenuation and napkin-ring sign, but not positive remodeling, were associated with a spotty pattern and a lower calcification attenuation.

CONCLUSIONS

Both the pattern and attenuation of calcification should be considered, in addition to CACS, for risk stratification of heavily calcified high-risk patients with non-critical coronary stenosis.

Prognostic Value of Coronary Computed Tomography Angiography-derived Morphologic and Quantitative Plaque Markers Using Semiautomated Plaque Software

PURPOSE

In this study, we analyzed the prognostic value of coronary computed tomography angiography-derived morphologic and quantitative plaque markers and plaque scores for major adverse cardiovascular events (MACEs).

MATERIALS AND METHODS

We analyzed the data of patients with suspected coronary artery disease (CAD). Various plaque markers were obtained using a semiautomated software prototype or derived from the results of the software analysis. Several risk scores were calculated, and follow-up data concerning MACE were collected from all patients.

RESULTS

A total of 131 patients (65±12 y, 73% male) were included in our study. MACE occurred in 11 patients within the follow-up period of 34±25 months.CAD-Reporting and Data System score (odds ratio [OR]=11.62), SYNTAX score (SS) (OR=1.11), Leiden-risk score (OR=1.37), segment involvement score (OR=1.76), total plaque volume (OR=1.20), and percentage aggregated plaque volume (OR=1.32) were significant predictors for MACE (all P≤0.05). Moreover, the difference of the corrected coronary opacification (ΔCCO) correlated significantly with the occurrence of MACE (P<0.0001). The CAD-Reporting and Data System score, SS, and Leiden-risk score showed substantial sensitivity for predicting MACE (90.9%). The SS and Leiden-risk score displayed high specificities of 80.8% and 77.5%, respectively. These plaque markers and risk scores all provided high negative predictive value (>90%).

CONCLUSION

The coronary computed tomography angiography-derived plaque markers of segment involvement score, total plaque volume, percentage aggregated plaque volume, and ΔCCO, and the risk scores exhibited predictive value for the occurrence of MACE and can likely aid in identifying patients at risk for future cardiac events.

Cardiac CT: why, when, and how : Update 2019

PURPOSE

The aim of this study was to review established and emerging techniques of cardiac computed tomography (CT) and their clinical applications with a special emphasis on new techniques, recent trials, and guidelines.

TECHNOLOGICAL INNOVATIONS

Cardiac CT has made great strides in recent years to become an ever more robust and safe imaging technique. The improvements in spatial and temporal resolution are equally important as the substantial reduction in radiation exposure, which has been achieved through prospective ECG-triggering, low tube voltage scanning, tube current modulation, and iterative reconstruction techniques. CT-derived fractional flow reserve and CT myocardial perfusion imaging are novel, investigational techniques to assess the hemodynamic significance of coronary stenosis.

ESTABLISHED AND EMERGING INDICATIONS

In asymptomatic patients at risk for coronary artery disease, CT coronary artery calcium scoring is useful to assess cardiovascular risk and guide the intensity of risk factor modification. Coronary CT angiography is an excellent noninvasive test to rule out obstructive coronary artery disease in patients with stable chest pain. In acute chest pain with normal ECG and normal cardiac enzymes, cardiac CT can safely rule out acute coronary syndrome although its benefit and role in this indication remains controversial. Cardiac CT is the established standard for planning transcatheter aortic valve implantation and-increasingly-minimally invasive mitral valve procedures.

PRACTICAL RECOMMENDATIONS

Our review makes practical recommendations on when and how to perform cardiac CT and provides templates for structured reporting of cardiac CT examinations.

Differences in the CT findings between vulnerable plaque and culprit lesions in acute coronary syndrome

BACKGROUND

The CT finding of "vulnerable plaque" is widely regarded as similar to that of a culprit lesion in an acute coronary syndrome (ACS). However, this hypothesis may not be accurate, since "vulnerable plaques" may substantially change their morphology when they rupture to cause an ACS.

METHODS

We retrospectively evaluated coronary CT angiography data sets of 25 patients with ACS who had vulnerable (n = 10) or culprit plaques (n = 15). We analyzed CT features including positive remodeling (PR), low attenuation plaque (LAP), the napkin ring sign (NRS), degree of stenosis (normal, <50%, 50-99%, 100%), and myocardial hypoperfusion in the left ventricle.

RESULTS

There was no difference in the prevalence of PR, NRS, or LAP between vulnerable and culprit plaques. In contrast, a majority (80%, 8/10) of vulnerable plaques were associated with <50% luminal stenosis while total occlusion was identified in 47% (7/15) of culprit plaques (p = .037). In all patients with occlusion, myocardial hypoperfusion was demonstrated in the corresponding arterial territory on CT.

CONCLUSION

CT features of vulnerable and culprit plaques differ in cases with thrombotic occlusion reflecting dynamic plaque changes related to the episode of ACS.

CML/RAGE signal induces calcification cascade in diabetes

OBJECTIVE

Vascular calcification is a significant predictor of coronary heart disease events, stroke, and lower-limb amputation. Advanced glycation end-products (AGEs) play a key role in the development of vascular calcification. However, the role of Nε-carboxymethyl-lysine (CML), a major active ingredient of heterogeneous AGEs, in the development of atherosclerotic calcification in diabetic patients and the underlying mechanism remain unclear. Hence, the role and the mechanism of CML in the transmission pathway of diabetic calcification cascade were investigated in the present study.

METHODS

In vivo and in vitro investigations were performed. In study I, 45 diabetic patients hospitalized for above-knee amputation in the Department of Orthopedics, Affiliated Hospital of Jiangsu University were recruited from February 2010 to June 2015. The patients were categorized based on the severity of anterior tibial artery stenosis, which was assessed by color Doppler ultrasound, into mild stenosis (0% < stenosis < 50%, n = 15), moderate stenosis (50 ≤ stenosis < 70%, n = 15), and severe stenosis/occlusion groups (70 ≤ stenosis ≤ 100%, n = 15). In study II, the specific mechanism of CML in the transmission pathway of the diabetic calcification cascade signal was investigated in A7r5 aortic smooth muscle cells under high-lipid, apoptosis-coexisting conditions. ELISA (for serum CML concentration of patients), ultrasound (for plaque size, calcification, blood flow filling, vascular stenosis etc.), H&E staining (for plaque morphology), vonKossa staining (for qualitative analysis of calcification), calcium content assay (for quantitative analysis of calcification), and Western blot analyses of CML, receptor for advanced glycation end products (RAGE), NADPH oxidase 4, phosphorylated p38, core-binding factor α1 (cbfα1), alkaline phosphatase (ALP) and β-actin were then performed.

RESULTS

Morphological analysis revealed extensive calcification lesions in the intima and media of the anterior tibial artery. The extent and area of calcium deposition in the intima significantly increased with disease progression. Interestingly, spotty calcification was predominant in the atherosclerotic plaques of diabetic patients with amputation, and macrocalcification was almost invisible. Pearson correlation analysis revealed that serum CML level exhibited a significant positive correlation with calcium content in the arterial wall (R² = 0.6141, P < 0.0001). Semi-quantitative Western blot analysis suggested that the intensity of CML/RAGE signal increased with progression of atherosclerotic calcification in diabetic patients. In subsequent in vitro study, the related pathway was blocked by anti-RAGE antibody, NADPH oxidase inhibitor DPI, p38MAPK inhibitor SB203580, and anti-cbfa1 antibody in a step-wise manner to observe changes in calcium deposition and molecular signals. Results suggested that CML may play a key role in atherosclerotic calcification mainly through the CML/RAGE- reactive oxygen species (ROS)-p38MAPK-cbfα1-ALP pathway.

CONCLUSION

Spotty calcification was predominant in the atherosclerotic plaques of amputated diabetic patients. CML/RAGE signal may induce the calcification cascade in diabetes via ROS-p38MAPK.