Quantification of coronary low-attenuation plaque volume for long-term prediction of cardiac events and reclassification of patients

Computed tomography versus near-infrared spectroscopy for the assessment of coronary atherosclerosis

BACKGROUND

Coronary computed tomography angiography (CCTA) has been proposed as an alternative to intravascular imaging for assessing plaque pathology.

AIMS

We aimed to assess the efficacy of CCTA against near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS) in evaluating atheroma burden and composition and for guiding coronary interventions.

METHODS

Seventy patients with a chronic coronary syndrome were recruited and underwent CCTA and NIRS-IVUS. The imaging data were matched, and the estimations of lumen, vessel wall and plaque dimensions and composition of the two modalities were compared. The primary endpoint of the study was the efficacy of CCTA in detecting lipid-rich plaques identified by NIRS-IVUS. Secondary endpoints included the performance of CCTA in evaluating coronary artery pathology in the studied segments and its value in stent sizing, using NIRS-IVUS as the reference standard.

RESULTS

In total, 186 vessels were analysed. The attenuated plaque volume on CCTA had weak accuracy in detecting lipid-rich plaques (58%; p=0.029). Compared to NIRS-IVUS, CCTA underestimated the lumen volume (309.2 mm3 vs 420.4 mm3; p=0.001) and plaque dimensions (total atheroma volume 116.1 mm3 vs 292.8 mm3; p<0.001 and percentage atheroma volume 27.67% vs 41.06%; p<0.001) and overestimated the lipid component (lipid core burden index 48.6 vs 33.8; p=0.007). In the 86 lesions considered for revascularisation, CCTA underestimated the reference vessel area (8.16 mm2 vs 12.30 mm2; p<0.001) and overestimated the lesion length (23.5 mm vs 19.0 mm; p=0.029) compared to NIRS-IVUS.

CONCLUSIONS

CCTA has limited efficacy in assessing plaque composition and quantifying lumen and plaque dimensions and tissue types, which may potentially impact revascularisation planning.

Age- and Sex-Specific Nomographic CT Quantitative Plaque Data From a Large International Cohort

BACKGROUND

With growing adoption of coronary computed tomographic angiography (CTA), there is increasing evidence for and interest in the prognostic importance of atherosclerotic plaque volume. Manual tools for plaque segmentation are cumbersome, and their routine implementation in clinical practice is limited.

OBJECTIVES

The aim of this study was to develop nomographic quantitative plaque values from a large consecutive multicenter cohort using coronary CTA.

METHODS

Quantitative assessment of total atherosclerotic plaque and plaque subtype volumes was performed in patients undergoing clinically indicated coronary CTA, using an Artificial Intelligence-Enabled Quantitative Coronary Plaque Analysis tool.

RESULTS

A total of 11,808 patients were included in the analysis; their mean age was 62.7 ± 12.2 years, and 5,423 (45.9%) were women. The median total plaque volume was 223 mm3 (IQR: 29-614 mm3) and was significantly higher in male participants (360 mm3; IQR: 78-805 mm3) compared with female participants (108 mm3; IQR: 10-388 mm3) (P < 0.0001). Total plaque increased with age in both male and female patients. Younger patients exhibited a higher prevalence of noncalcified plaque. The distribution of total plaque volume and its components was reported in every decile by age group and sex.

CONCLUSIONS

The authors developed pragmatic age- and sex-stratified percentile nomograms for atherosclerotic plaque measures using findings from coronary CTA. The impact of age and sex on total plaque and its components should be considered in the risk-benefit analysis when treating patients. Artificial Intelligence-Enabled Quantitative Coronary Plaque Analysis work flows could provide context to better interpret coronary computed tomographic angiographic measures and could be integrated into clinical decision making.

CT Coronary Angiography: Technical Approach and Atherosclerotic Plaque Characterization

Coronary computed tomography angiography (CCTA) currently represents a robust imaging technique for the detection, quantification and characterization of coronary atherosclerosis. However, CCTA remains a challenging task requiring both high spatial and temporal resolution to provide motion-free images of the coronary arteries. Several CCTA features, such as low attenuation, positive remodeling, spotty calcification, napkin-ring and high pericoronary fat attenuation index have been proved as associated to high-risk plaques. This review aims to explore the role of CCTA in the characterization of high-risk atherosclerotic plaque and the recent advancements in CCTA technologies with a focus on radiomics plaque analysis.

High-quality annotations for deep learning enabled plaque analysis in SCAPIS cardiac computed tomography angiography

Background

Plaque analysis with coronary computed tomography angiography (CCTA) is a promising tool to identify high risk of future coronary events. The analysis process is time-consuming, and requires highly trained readers. Deep learning models have proved to excel at similar tasks, however, training these models requires large sets of expert-annotated training data. The aims of this study were to generate a large, high-quality annotated CCTA dataset derived from Swedish CArdioPulmonary BioImage Study (SCAPIS), report the reproducibility of the annotation core lab and describe the plaque characteristics and their association with established risk factors.

Methods and results

The coronary artery tree was manually segmented using semi-automatic software by four primary and one senior secondary reader. A randomly selected sample of 469 subjects, all with coronary plaques and stratified for cardiovascular risk using the Systematic Coronary Risk Evaluation (SCORE), were analyzed. The reproducibility study (n = 78) showed an agreement for plaque detection of 0.91 (0.84-0.97). The mean percentage difference for plaque volumes was -0.6% the mean absolute percentage difference 19.4% (CV 13.7%, ICC 0.94). There was a positive correlation between SCORE and total plaque volume (rho = 0.30, p < 0.001) and total low attenuation plaque volume (rho = 0.29, p < 0.001).

Conclusions

We have generated a CCTA dataset with high-quality plaque annotations showing good reproducibility and an expected correlation between plaque features and cardiovascular risk. The stratified data sampling has enriched high-risk plaques making the data well suited as training, validation and test data for a fully automatic analysis tool based on deep learning.

Clinical and Coronary Plaque Predictors of Atherosclerotic Nonresponse to Statin Therapy

BACKGROUND

Statins reduce the incidence of major cardiovascular events, but residual risk remains. The study examined the determinants of atherosclerotic statin nonresponse.

OBJECTIVES

This study aimed to investigate factors associated with statin nonresponse-defined atherosclerosis progression in patients treated with statins.

METHODS

The multicenter PARADIGM (Progression of AtheRosclerotic PlAque DetermIned by Computed TomoGraphic Angiography Imaging) registry included patients who underwent serial coronary computed tomography angiography ≥2 years apart, with whole-heart coronary tree quantification of vessel, lumen, and plaque, and matching of baseline and follow-up coronary segments and lesions. Patients with statin use at baseline and follow-up coronary computed tomography angiography were included. Atherosclerotic statin nonresponse was defined as an absolute increase in percent atheroma volume (PAV) of 1.0% or more per year. Furthermore, a secondary endpoint was defined by the additional requirement of progression of low-attenuation plaque or fibro-fatty plaque.

RESULTS

We included 649 patients (age 62.0 ± 9.0 years, 63.5% male) on statin therapy and 205 (31.5%) experienced atherosclerotic statin nonresponse. Age, diabetes, hypertension, and all atherosclerotic plaque features measured at baseline scan (high-risk plaque [HRP] features, calcified and noncalcified PAV, and lumen volume) were significantly different between patients with and without atherosclerotic statin nonresponse, whereas only diabetes, number of HRP features, and noncalcified and calcified PAV were independently associated with atherosclerotic statin nonresponse (odds ratio [OR]: 1.41 [95% CI: 0.95-2.11], OR: 1.15 [95% CI: 1.09-1.21], OR: 1.06 [95% CI: 1.02-1.10], OR: 1.07 [95% CI: 1.03-1.12], respectively). For the secondary endpoint (N = 125, 19.2%), only noncalcified PAV and number of HRP features were the independent determinants (OR: 1.08 [95% CI: 1.03-1.13] and OR: 1.21 [95% CI: 1.06-1.21], respectively).

CONCLUSIONS

In patients treated with statins, baseline plaque characterization by plaque burden and HRP is associated with atherosclerotic statin nonresponse. Patients with the highest plaque burden including HRP were at highest risk for plaque progression, despite statin therapy. These patients may need additional therapies for further risk reduction.

Quantified coronary total plaque volume from computed tomography angiography provides superior 10-year risk stratification

AIMS

Automated coronary total plaque volume (TPV) quantification derived from coronary computed tomographic angiography (CTA) datasets provide exact and reliable assessment of calcified and non-calcified coronary atherosclerosis burden. The aim of this analysis was to investigate the long-term predictive value of TPV.

METHODS AND RESULTS

TPV was quantified in 1577 patients undergoing coronary CTA and cardiovascular events were collected during 10.5 years (interquartile range 6.0-11.4) of follow-up. The study endpoint comprised cardiac death and acute coronary syndrome and occurred in 59 (3.7%) patients. Coronary TPV provided additive prognostic value over clinical risk assessed with the Morise Score and coronary artery disease severity (rise in C-index from 0.744 to 0.769, P = 0.03). A category-based reclassification approach combining the Morise Score and TPV revealed superior risk stratification (categorical net reclassification improvement: 0.48 with 95% CI 0.13-0.68, P < 0.001) and resulted in reclassification of 800 (51%) patients compared with the Morise Score alone. The 10-year risk for the study endpoint was 0.6% (95% CI 0-1.3) for patients classified as low risk (n = 807), 4.8% (95% CI 2.4-7.2) for patients at intermediate risk (n = 400), and 10.3% (95% CI 6.6-13.9) for patients at high risk (n = 370) using the combined reclassification approach.

CONCLUSION

Quantification of TPV from coronary CTA permits an improved 10-year cardiovascular risk stratification.

Antiretroviral therapy-treated HIV-infected adults with coronary artery disease are characterized by a distinctive regulatory T-cell signature

BACKGROUND

Despite the success of antiretroviral therapy (ART) to control viral replication, people living with HIV (PWH) have high levels of chronic systemic inflammation and immune dysregulation which drives accelerated co-morbidities including coronary artery disease (CAD). Regulatory T cells (Tregs) and ectonucleotidases CD39/CD73 are known to be athero-protective via their immunosuppressive and anti-inflammatory functions.

DESIGN

We assessed the dynamics of Treg subsets in ART-treated PWH with or without CAD vs. HIV-uninfected individuals.

METHODS

Blood specimens were obtained from 142 participants including ART-treated HIV-infected adults with (n = 43) or without CAD (n = 41), as well as HIV-uninfected controls with (n = 31) or without CAD (n = 27). CAD was determined by the presence of atherosclerotic features on computed tomography angiography of the coronary arteries performed on all study participants. Treg subsets frequencies were assessed by flow cytometry.

RESULTS

Regardless of statin treatment or ART regimen, HIV+CAD+ individuals had the highest total Treg frequencies and increased thymic generation and output of Tregs (Helios/CD31 expression), while athero-protective CD39+/CD73+ Tregs were significantly depleted in this group. Tregs from PWH had higher expression of CCR6/CXCR3 than uninfected individuals regardless of CAD, while in HIV+CAD+ individuals Tregs expressed the highest levels of CCR4, which limits their maintenance. The lowest levels of CD4+ and CD8+ T-cell immune activation has been observed in HIV+CAD+ within study groups.

CONCLUSION

ART-treated PWH with diagnosed CAD are characterized by profound alterations in populations of anti-inflammatory and athero-protective Treg subsets. These changes may contribute to atherosclerotic plaque formation and progression during chronic HIV infection in the ART era.

Hypertension attenuates the prognostic value of coronary artery calcification scoring in low-risk patients

OBJECTIVES

In outpatients with suspected ischaemic symptoms, we investigated the impact of risk factor profile on the prognostic value of coronary artery calcium scoring (CACS) and CT coronary angiography (CTCA).

METHODS

772 consecutive patients underwent CACS and CTCA; 52 patients (6.7%) with significant coronary artery lesions underwent revascularisation within 60 days and were excluded. 720 remaining patients were followed up for 38.1±17.4 months.

RESULTS

Late presentation (after 60 days) major adverse cardiovascular events (MACEs) were recorded in 27 patients (3.8%). Hypertension was strongly associated with adverse outcomes (unadjusted HR 6.5 (2.9 to 14), p<0.001), and hypertensive patients had double the prevalence of non-calcified plaque versus normotensive individuals (30.2% vs 14.3%, p<0.001). Adjusting for confounders, severe stenosis at CTCA was predictive of MACE for normotensive and hypertensive patients (HR 9.6 (2.8 to 43.1), p<0.001, and HR 6.2 (2.4 to 16.1), p<0.001, respectively). CACS alone was not predictive of MACE throughout the cohort (HR 1.001 (0.9997 to 1.001), p=0.36) and when adjusting for confounders, a cut-off of CACS>400 predicted MACE in normotensive individuals (HR 10.6 (2.41 to 49.3), p<0.001) but not in hypertensive individuals (HR 1.3 (0.5 to 3.6), p=0.56). Zero calcium score did not mitigate the risk of MACE (HR 0.84 (0.39 to 1.8), p=0.65) and 13/27 patients (48.1%) who suffered MACE had a 0 calcium score; all had hypertension.

CONCLUSIONS

In low-risk patients with stable cardiovascular symptoms, CTCA provides important additive prognostic information over CACS, and CACS (including CACS>400) underestimated cardiovascular risk in patients with hypertension. This may relate to the increased prevalence of non-calcified plaque in these individuals.

Cardiovascular risk factors and illicit drug use may have a more profound effect on coronary atherosclerosis progression in people living with HIV

OBJECTIVES

To assess whether HIV infection directly or indirectly promotes coronary artery disease (CAD) volume progression in a longitudinal study of African Americans.

METHODS

We randomly selected 300 individuals with subclinical CAD (210 male; age: 48.0 ± 7.2 years; 226 HIV infected, 174 cocaine users) from 1429 cardiovascularly asymptomatic participants of a prospective epidemiological study between May 2004 and August 2015. Individuals underwent coronary CT angiography at two time points (mean follow-up: 4.0 ± 2.3 years). We quantified noncalcified (NCP: -100-350HU), low-attenuation noncalcified (LA-NCP: -100-30HU), and calcified (CP: ≥ 351 HU) plaque volumes. Linear mixed models were used to assess the effects of HIV infection, atherosclerotic cardiovascular disease (ASCVD) risk, and years of cocaine use on plaque volumes.

RESULTS

There was no significant difference in annual progression rates between HIV-infected and HIV-uninfected regarding NCP (8.7 [IQR: 3.0-19.4] mm3/year vs. 4.9 [IQR: 1.5-18.3] mm3/year, p = 0.14), LA-NCP (0.2 [IQR: 0.0-1.6] mm3/year vs. 0.2 [IQR: 0.0-0.9] mm3/year, p = 0.07) or CP volumes (0.3 [IQR: 0.0-3.4] mm3/year vs. 0.1 [IQR: 0.0-3.2] mm3/year, p = 0.30). Multivariately, HIV infection was not associated with NCP (-6.9mm3, CI: [-32.8-19.0], p = 0.60), LA-NCP (-0.1mm3, CI: [-2.6-2.4], p = 0.92), or CP volumes (-0.3mm3, CI: [-9.3-8.6], p = 0.96). However, each percentage of ASCVD and each year of cocaine use significantly increased total, NCP, and CP volumes among HIV-infected individuals, but not among HIV-uninfected. Importantly, none of the HIV-associated medications had any effect on plaque volumes (p > 0.05 for all).

CONCLUSIONS

The more profound adverse effect of risk factors in HIV-infected individuals may explain the accelerated progression of CAD in these people, as HIV infection was not independently associated with any coronary plaque volume.

KEY POINTS

• Human immunodeficiency virus-infected individuals may have similar subclinical coronary artery disease, as the infection is not independently associated with coronary plaque volumes. • However, cardiovascular risk factors and illicit drug use may have a more profound effect on atherosclerosis progression in those with human immunodeficiency virus infection, which may explain the accelerated progression of CAD in these people. • Nevertheless, through rigorous prevention and abstinence from illicit drugs, these individuals may experience similar cardiovascular outcomes as -uninfected individuals.

Society of Cardiovascular Computed Tomography / North American Society of Cardiovascular Imaging - Expert Consensus Document on Coronary CT Imaging of Atherosclerotic Plaque

Coronary computed tomographic angiography (CCTA) provides a wealth of clinically meaningful information beyond anatomic stenosis alone, including the presence or absence of nonobstructive atherosclerosis and high-risk plaque features as precursors for incident coronary events. There is, however, no uniform agreement on how to identify and quantify these features or their use in evidence-based clinical decision-making. This statement from the Society of Cardiovascular Computed Tomography and North American Society of Cardiovascular Imaging addresses this gap and provides a comprehensive review of the available evidence on imaging of coronary atherosclerosis. In this statement, we provide standardized definitions for high-risk plaque (HRP) features and distill the evidence on the effectiveness of risk stratification into usable practice points. This statement outlines how this information should be communicated to referring physicians and patients by identifying critical elements to include in a structured CCTA report - the presence and severity of atherosclerotic plaque (descriptive statements, CAD-RADS™ categories), the segment involvement score, HRP features (e.g., low attenuation plaque, positive remodeling), and the coronary artery calcium score (when performed). Rigorous documentation of atherosclerosis on CCTA provides a vital opportunity to make recommendations for preventive care and to initiate and guide an effective care strategy for at-risk patients.

A review of serial coronary computed tomography angiography (CTA) to assess plaque progression and therapeutic effect of anti-atherosclerotic drugs

Change in coronary artery plaque on serial catheter intravascular ultrasound (IVUS) is an established technique to monitor the therapeutic effect of drugs on coronary atherosclerosis. Recent advances in coronary computed tomography angiography (CTA) now allow for non-invasive assessment of change in coronary plaque. Because coronary CTA is noninvasive, it enables clinical trials with lower-risk populations, higher retention rates, and lower costs. This review presents an overview of serial coronary CTA as a noninvasive imaging technique to gauge the therapeutic effect of anti-atherosclerotic therapies. Furthermore, it reviews the increasing use of serial CTA as an imaging endpoint in completed and ongoing clinical trials.

Effect of vessel wall segmentation on volumetric and radiomic parameters of coronary plaques with adverse characteristics

BACKGROUND

Quantitative coronary plaque parameters are increasingly being utilized as surrogate endpoints of pharmaceutical trials. However, little is known whether differences in segmentation significantly alter parameter values.

METHODS

Overall, 100 coronary plaques with adverse imaging characteristics were segmented automatically, by two experts (R₁-R₂) and three nonexperts (R₃-R₅). Low attenuation noncalcified (LANCP), noncalcified and calcified plaque volume were calculated and 4310 radiomic features were extracted. Intraclass correlation coefficient (ICC) values were calculated between the segmentations.

RESULTS

ICC values between expert readers were 0.84 [CI: 0.77-0.89] for total; 0.83 [CI: 0.76-0.88] for noncalcified; 0.96 [CI: 0.94-0.98] for calcified and 0.65 [CI: 0.51-0.75] for LANCP volumes. Comparing nonexperts' and experts' results, ICC ranged between 0.64 and 0.90 for total; 0.63-0.91 for noncalcified; 0.86-0.96 for calcified and 0.34-0.84 for LANCP volume. All readers (R₁-R₅) showed poor agreement with automatic segmentation (range: 0.00-0.27), except for calcified plaque volumes (range: 0.73-0.88). Regarding radiomic features, expert readers (R₁-R₂) achieved good reproducibility (ICC>0.80) in 88.6% (39/44) of first-order, 62.0% (424/684) of gray level co-occurrence matrix (GLCM), 75.8% (50/66) of gray level run length matrix (GLRLM) and 19.8% (696/3516) of geometrical parameters. Between experts and nonexperts, ICC ranged between: 70.5%-86.4% for first-order, 31.0%-58.3% for GLCM, 24.2%-78.8% for GLRLM and 6.2%-21.1% for geometrical features, while between all readers and automatic segmentation ICC ranged between: 25.0%-38.6%; 0.0%-0.0%; 0.0%-3.0% and 1.1%-1.4%, respectively.

CONCLUSIONS

Even among experts there is a considerable amount of disagreement in LANCP volumes. Nevertheless, expert readers have the best agreement which currently cannot be replaced with nonexperts' or automatic segmentation.

From CT to artificial intelligence for complex assessment of plaque-associated risk

The recent technological developments in the field of cardiac imaging have established coronary computed tomography angiography (CCTA) as a first-line diagnostic tool in patients with suspected coronary artery disease (CAD). CCTA offers robust information on the overall coronary circulation and luminal stenosis, also providing the ability to assess the composition, morphology, and vulnerability of atherosclerotic plaques. In addition, the perivascular adipose tissue (PVAT) has recently emerged as a marker of increased cardiovascular risk. The addition of PVAT quantification to standard CCTA imaging may provide the ability to extract information on local inflammation, for an individualized approach in coronary risk stratification. The development of image post-processing tools over the past several years allowed CCTA to provide a significant amount of data that can be incorporated into machine learning (ML) applications. ML algorithms that use radiomic features extracted from CCTA are still at an early stage. However, the recent development of artificial intelligence will probably bring major changes in the way we integrate clinical, biological, and imaging information, for a complex risk stratification and individualized therapeutic decision making in patients with CAD. This review aims to present the current evidence on the complex role of CCTA in the detection and quantification of vulnerable plaques and the associated coronary inflammation, also describing the most recent developments in the radiomics-based machine learning approach for complex assessment of plaque-associated risk.

Increased serum bile acid level is associated with high-risk coronary artery plaques in an asymptomatic population detected by coronary computed tomography angiography

Background

There are limited data on the association between serum total bile acid level and coronary plaque characteristics. This study investigated the relationship between serum total bile acid level and the severity of coronary stenosis and coronary plaque features in an asymptomatic population using coronary computed tomography angiography (CTA).

Methods

A total of 1,137 consecutive participants with no known coronary artery disease (CAD) undergoing CTA as part of a general routine health evaluation were recruited. Serum total bile acid level and clinical parameters were assayed. Coronary stenosis and high-risk plaques features (napkin-ring sign, low-attenuation plaque, spotty calcification, positive remodelling) were evaluated. Associations between serum total bile acid concentration and high-risk coronary plaques was tested through univariate and multivariate analyses.

Results

A total of 101 high-risk coronary plaques subjects and 93 controls were eligible for study inclusion. The severity of coronary artery stenosis and high-risk coronary plaques increased with serum total bile acid level quartiles (all P<0.001). The independent predictor of high-risk coronary plaques in multivariate analysis was serum total bile acid level (P<0.001). Receiver operating characteristic (ROC) confirmed that serum total bile acid concentration significantly differentiated high-risk coronary plaques [the area under the curve (AUC) =0.876; P<0.001, with a sensitivity of 87.13% and a specificity of 86.02%].

Conclusions

Higher serum total bile acid level was associated with the severity of coronary artery stenosis and high-risk coronary artery plaques detected by CTA in asymptomatic populations.