Validation of Wall Shear Stress Assessment in Non-invasive Coronary CTA versus Invasive Imaging: A Patient-Specific Computational Study.

Endothelial shear stress (ESS) identifies coronary plaques at high risk for progression and/or rupture leading to a future acute coronary syndrome. In this study an optimized methodology was developed to derive ESS, pressure drop and oscillatory shear index using computational fluid dynamics (CFD) in 3D models of coronary arteries derived from non-invasive coronary computed tomography angiography (CTA). These CTA-based ESS calculations were compared to the ESS calculations using the gold standard with fusion of invasive imaging and CTA. In 14 patients paired patient-specific CFD models based on invasive and non-invasive imaging of the left anterior descending (LAD) coronary arteries were created. Ten patients were used to optimize the methodology, and four patients to test this methodology. Time-averaged ESS (TAESS) was calculated for both coronary models applying patient-specific physiological data available at the time of imaging. For data analysis, each 3D reconstructed coronary artery was divided into 2 mm segments and each segment was subdivided into 8 arcs (45°).TAESS and other hemodynamic parameters were averaged per segment as well as per arc. Furthermore, the paired segment- and arc-averaged TAESS were categorized into patient-specific tertiles (low, medium and high). In the ten LADs, used for optimization of the methodology, we found high correlations between invasively-derived and non-invasively-derived TAESS averaged over segments (n = 263, r = 0.86) as well as arcs (n = 2104, r = 0.85, p < 0.001). The correlation was also strong in the four testing-patients with r = 0.95 (n = 117 segments, p = 0.001) and r = 0.93 (n = 936 arcs, p = 0.001).There was an overall high concordance of 78% of the three TAESS categories comparing both methodologies using the segment- and 76% for the arc-averages in the first ten patients. This concordance was lower in the four testing patients (64 and 64% in segment- and arc-averaged TAESS). Although the correlation and concordance were high for both patient groups, the absolute TAESS values averaged per segment and arc were overestimated using non-invasive vs. invasive imaging [testing patients: TAESS segment: 30.1(17.1-83.8) vs. 15.8(8.8-63.4) and TAESS arc: 29.4(16.2-74.7) vs 15.0(8.9-57.4) p < 0.001]. We showed that our methodology can accurately assess the TAESS distribution non-invasively from CTA and demonstrated a good correlation with TAESS calculated using IVUS/OCT 3D reconstructed models.

Reviewing imaging modalities for the assessment of plaque erosion.

Plaque rupture followed by intracoronary thrombus formation is recognized as the most common pathophysiological mechanism in acute coronary syndromes (ACS). The second most common underlying substrate for ACS is plaque erosion whose hallmark is thrombus formation without cap disruption. Invasive and non-invasive methods have emerged as a promising tool for evaluation of plaque features that either predict or detect plaque erosion. Optical coherence tomography (OCT), high-definition intravascular ultrasound (IVUS), near-infrared spectroscopy (NIRS), and near-infrared autofluorescence (NIRF) have been used to study plaque erosion. The detection of plaque erosion in the clinical setting, mainly facilitated by OCT, has shed light upon the complex pathophysiology underlying ACS not related to plaque rupture. Coronary computed tomography angiography (CCTA), which is to date the most commonly used non-invasive technique for coronary plaque evaluation, may also have a role in the evaluation of patients predisposed to erosion. Also, computational models enabling quantification of endothelial shear stress may pave the way to new research in coronary plaque pathophysiology. This review focuses on the recent imaging techniques for the evaluation of plaque erosion including invasive and non-invasive assessment.

Comparative differences in the atherosclerotic disease burden between the epicardial coronary arteries: quantitative plaque analysis on coronary computed tomography angiography.

AIMS: Anatomic series commonly report the extent and severity of coronary artery disease (CAD), regardless of location. The aim of this study was to evaluate differences in atherosclerotic plaque burden and composition across the major epicardial coronary arteries. METHODS AND RESULTS: A total of 1271 patients (age 60 ± 9 years; 57% men) with suspected CAD prospectively underwent coronary computed tomography angiography (CCTA). Atherosclerotic plaque volume was quantified with categorization by composition (necrotic core, fibrofatty, fibrous, and calcified) based on Hounsfield Unit density. Per-vessel measures were compared using generalized estimating equation models. On CCTA, total plaque volume was lowest in the LCx (10.0 ± 29.4 mm3), followed by the RCA (32.8 ± 82.7 mm3; P < 0.001), and LAD (58.6 ± 83.3 mm3; P < 0.001), even when correcting for vessel length or volume. The prevalence of ≥2 high-risk plaque features, such as positive remodelling or spotty calcification, occurred less in the LCx (3.8%) when compared with the LAD (21.4%) or RCA (10.9%, P < 0.001). In the LCx, the most stenotic lesion was categorized as largely calcified more often than in the RCA and LAD (55.3% vs. 39.4% vs. 32.7%; P < 0.001). Median diameter stenosis was also lowest in the LCx (16.2%) and highest in the LAD (21.3%; P < 0.001) and located more distal along the LCx when compared with the RCA and LAD (P < 0.001). CONCLUSION: Atherosclerotic plaque, irrespective of vessel volume, varied across the epicardial coronary arteries; with a significantly lower burden and different compositions in the LCx when compared with the LAD and RCA. These volumetric and compositional findings support a diverse milieu for atherosclerotic plaque development and may contribute to a varied acute coronary risk between the major epicardial coronary arteries.

Quantitative assessment of coronary plaque volume change related to triglyceride glucose index: The Progression of AtheRosclerotic PlAque DetermIned by Computed TomoGraphic Angiography IMaging (PARADIGM) registry.

BACKGROUND: The association between triglyceride glucose (TyG) index and coronary atherosclerotic change remains unclear. We aimed to evaluate the association between TyG index and coronary plaque progression (PP) using serial coronary computed tomography angiography (CCTA). METHODS: A total of 1143 subjects (aged 60.7 ± 9.3 years, 54.6% male) who underwent serial CCTA with available data on TyG index and diabetic status were analyzed from The Progression of AtheRosclerotic PlAque DetermIned by Computed TomoGraphic Angiography IMaging (PARADIGM) registry. PP was defined as plaque volume (PV) (mm3) at follow-up minus PV at index > 0. Annual change of PV (mm3/year) was defined as PV change divided by inter-scan period. Rapid PP was defined as the progression of percent atheroma volume (PV divided by vessel volume multiplied by 100) ≥ 1.0%/year. RESULTS: The median inter-scan period was 3.2 (range 2.6-4.4) years. All participants were stratified into three groups based on TyG index tertiles. The overall incidence of PP was 77.3%. Baseline total PV (group I [lowest]: 30.8 (0.0-117.7), group II: 47.2 (6.2-160.4), and group III [highest]: 57.5 (8.4-154.3); P < 0.001) and the annual change of total PV (group I: 5.7 (0.0-20.2), group II: 7.6 (0.5-23.5), and group III: 9.4 (1.4-27.7); P = 0.010) were different among all groups. The risk of PP (odds ratio [OR] 1.648; 95% confidence interval [CI] 1.167-2.327; P = 0.005) and rapid PP (OR 1.777; 95% CI 1.288-2.451; P < 0.001) was increased in group III compared to that in group I. TyG index had a positive and significant association with an increased risk of PP and rapid PP after adjusting for confounding factors. CONCLUSION: TyG index is an independent predictive marker for the progression of coronary atherosclerosis. Clinical registration ClinicalTrials.gov NCT02803411.

Uncovering social structures and informational prejudices to reduce inequity in delivery and uptake of new molecular technologies.

Advances in molecular technologies have the potential to help remedy health inequities through earlier detection and prevention; if, however, their delivery and uptake (and therefore any benefits associated with such testing) are not more carefully considered, there is a very real risk that existing inequities in access and use will be further exacerbated. We argue this risk relates to the way that information and knowledge about the technology is both acquired and shared, or not, between health practitioners and their patients.A healthcare system can be viewed as a complex social network comprising individuals with different worldviews, hierarchies, professional cultures and subcultures and personal beliefs, both for those giving and receiving care. When healthcare practitioners are not perceived as knowledge equals, they would experience informational prejudices, and the result is that knowledge dissemination across and between them would be impeded. The uptake and delivery of a new technology may be inequitable as a result. Patients would also experience informational prejudice when they are viewed as not being able to understand the information that is presented to them, and information may be withheld.Informational prejudices driven by social relations and structures have thus far been underexplored in considering (in)equitable implementation and uptake of new molecular technologies. Every healthcare interaction represents an opportunity for experiencing informational prejudice, and with it the risk of being inappropriately informed for undertaking (or offering) such screening or testing. Making knowledge acquisition and information dissemination, and experiences of informational prejudice, explicit through sociologically framed investigations would extend our understandings of (in)equity, and offer ways to affect network relationships and structures that support equity in delivery and uptake.

Baseline Predictors of Low-Density Lipoprotein Cholesterol and Systolic Blood Pressure Goal Attainment After 1 Year in the ISCHEMIA Trial.

BACKGROUND: Risk factor control is the cornerstone of managing stable ischemic heart disease but is often not achieved. Predictors of risk factor control in a randomized clinical trial have not been described. METHODS AND RESULTS: The ISCHEMIA trial (International Study of Comparative Health Effectiveness with Medical and Invasive Approaches) randomized individuals with at least moderate inducible ischemia and obstructive coronary artery disease to an initial invasive or conservative strategy in addition to optimal medical therapy. The primary aim of this analysis was to determine predictors of meeting trial goals for LDL-C (low-density lipoprotein cholesterol, goal <70 mg/dL) or systolic blood pressure (SBP, goal <140 mm Hg) at 1 year post-randomization. We included all randomized participants in the ISCHEMIA trial with baseline and 1-year LDL-C and SBP values by January 28, 2019. Among the 3984 ISCHEMIA participants (78% of 5179 randomized) with available data, 35% were at goal for LDL-C, and 65% were at goal for SBP at baseline. At 1 year, the percent at goal increased to 52% for LDL-C and 75% for SBP. Adjusted odds of 1-year LDL-C goal attainment were greater with older age (odds ratio [OR], 1.11 [95% CI, 1.03-1.20] per 10 years), lower baseline LDL-C (OR, 1.19 [95% CI, 1.17-1.22] per 10 mg/dL), high-intensity statin use (OR, 1.30 [95% CI, 1.12-1.51]), nonwhite race (OR, 1.32 [95% CI, 1.07-1.63]), and North American enrollment compared with other regions (OR, 1.32 [95% CI, 1.06-1.66]). Women were less likely than men to achieve 1-year LDL-C goal (OR, 0.68 [95% CI, 0.58-0.80]). Adjusted odds of 1-year SBP goal attainment were greater with lower baseline SBP (OR, 1.27 [95% CI, 1.22-1.33] per 10 mm Hg) and with North American enrollment (OR, 1.35 [95% CI, 1.04-1.76]). CONCLUSIONS: In ISCHEMIA, older age, male sex, high-intensity statin use, lower baseline LDL-C, and North American location predicted 1-year LDL-C goal attainment, whereas lower baseline SBP and North American location predicted 1-year SBP goal attainment. Future studies should examine the effects of sex disparities, international practice patterns, and provider behavior on risk factor control.

Longitudinal quantitative assessment of coronary plaque progression related to body mass index using serial coronary computed tomography angiography.

AIMS: This study explored the coronary plaque volume change (PVC) according to the change of percent body mass index (BMI) and categorical BMI group using serial coronary computed tomography angiography (CCTA). METHODS AND RESULTS: A total of 1568 subjects who underwent serial CCTA with available BMI at baseline (CCTA1) and follow-up (CCTA2) were included. Median inter-scan period was 3.3 (interquartile range: 2.6-4.6) years. Quantitative assessment of coronary plaque was performed at both scans. All participants were categorized into three BMI (kg/m2) groups: normal: <25.0; overweight: 25.0-29.9; and obesity: ≥30.0. During follow-up, there were no significant differences in annualized PVC according to the 5% change of BMI in all BMI groups. Among 1424 (90.8%) subjects in the same BMI group at CCTA1 and CCTA2, a significant difference in annualized (PVC) was observed among the three groups. In 144 (9.2%) subjects with the change in their BMI group at CCTA2 compared their results at CCTA1, annualized PVC was not different compared with subjects in the same BMI group during follow-up. The percent change of BMI was not significantly related to the annualized PVC after adjusting confounding factors. Male gender [odds ratio (OR): 1.38; 95% confidence interval (CI): 1.05-1.81; P = 0.022], baseline plaque volume (OR: 1.07; 95% CI: 1.05-1.09; P < 0.001), and baseline overweight or obesity (OR: 1.35; 95% CI: 1.04-1.77; P = 0.027) were independently associated with coronary plaque progression. CONCLUSION: Over the near term, longitudinal small changes in BMI were not associated with changes in coronary plaque volume although baseline BMI was. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov NCT02803411.

Longitudinal assessment of coronary plaque volume change related to glycemic status using serial coronary computed tomography angiography: A PARADIGM (Progression of AtheRosclerotic PlAque DetermIned by Computed TomoGraphic Angiography Imaging) substudy.

BACKGROUND: Data on the impact of glycemic status on coronary plaque progression have been limited. This study evaluated the association between glycemic status and coronary plaque volume change (PVC) using coronary computed tomography angiography (CCTA). METHODS: A total of 1296 subjects (61 ±â€¯9, 56.9% male) who underwent serial CCTA with available glycemic status were enrolled and analyzed from the Progression of AtheRosclerotic PlAque DetermIned by Computed TomoGraphic Angiography IMaging (PARADIGM) registry. The median inter-scan period was 3.2 (2.6-4.4) years. Quantitative assessment of coronary plaques was performed at both scans. All participants were categorized into the following groups according to glycemic status: normal, pre-diabetes (pre-DM), and diabetes mellitus (DM). RESULTS: During the follow-up, significant differences in PVC (normal: 51.3 ±â€¯83.3 mm3 vs. pre-DM: 51.0 ±â€¯84.3 mm3 vs. DM: 72.6 ±â€¯95.0 mm3; p < 0.001) and annualized PVC (normal: 14.9 ±â€¯24.9 mm3 vs. pre-DM: 15.7 ±â€¯23.8 mm3 vs. DM: 21.0 ±â€¯27.7 mm3; p = 0.001) were observed among the 3 groups. Compared with normal individuals, individuals with pre-DM showed no significant differences in the adjusted odds ratio (OR) for plaque progression (PP) (1.338, 95% confidence interval [CI] 0.967-1.853; p = 0.079). However, the adjusted OR for PP was higher in DM individuals than in normal individuals (1.635, 95% CI 1.126-2.375; p = 0.010). CONCLUSION: DM had an incremental impact on coronary PP, but pre-DM appeared to have no significant association with an increased risk of coronary PP after adjusting for confounding factors. CLINICAL TRIAL REGISTRATION: ClinicalTrials.govNCT02803411.

Quantification of Coronary Atherosclerosis in the Assessment of Coronary Artery Disease.

BACKGROUND: Diagnosis of coronary artery disease and management strategies have relied solely on the presence of diameter stenosis ≥50%. We assessed whether direct quantification of plaque burden (PB) and plaque characteristics assessed by coronary computed tomography angiography could provide additional value in terms of predicting rapid plaque progression. METHODS AND RESULTS: From a 13-center, 7-country prospective observational registry, 1345 patients (60.4±9.4 years old; 57.1% male) who underwent repeated coronary computed tomography angiography >2 years apart were enrolled. For conventional angiographic analysis, the presence of stenosis ≥50%, number of vessel involved, segment involvement score, and the presence of high-risk plaque feature were determined. For quantitative analyses, PB and annual change in PB (△PB/y) in the entire coronary tree were assessed. Clinical outcomes (cardiac death, nonfatal myocardial infarction, and coronary revascularization) were recorded. Rapid progressors, defined as a patient with ≥median value of △PB/y (0.33%/y), were older, more frequently male, and had more clinical risk factors than nonrapid progressors (all P<0.05). After risk adjustment, addition of baseline PB improved prediction of rapid progression to each angiographic assessment of coronary artery disease, and the presence of high-risk plaque further improved the predictive performance (all P<0.001). For prediction of adverse outcomes, adding both baseline PB and △PB/y showed best predictive performance (C statistics, 0.763; P<0.001). CONCLUSIONS: Direct quantification of atherosclerotic PB in addition to conventional angiographic assessment of coronary artery disease might be beneficial for improving risk stratification of coronary artery disease. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT02803411.

Implementing non-invasive prenatal testing into publicly funded antenatal screening services for Down syndrome and other conditions in Aotearoa New Zealand.

BACKGROUND: Non-invasive prenatal testing (NIPT) is a relatively new screen for congenital conditions - specifically, common fetal aneuploidies including Down Syndrome. The test is based on isolating freely circulating fragments of fetal-placental DNA that is present in the mother's blood. NIPT has a superior clinical performance compared to current screening, and has been available privately in Aotearoa New Zealand for the last 4 years. MAIN ISSUE: The proposed implementation of NIPT as a publicly funded service may widen the inequity in access to optional antenatal screening that already exists in this country. CONCLUSION: This paper discusses precautions that can be taken at the health system, organisation, and personnel levels to ensure that access to NIPT is equitable, that services are culturally responsive, and women's informed choice is promoted and protected. The adoption of NIPT into publicly funded services is an example of how genetic screening is becoming mainstreamed into health services; as such our approach may also have relevance around the introduction of other genetic and genomic screening initiatives.

Views of the obstetric profession on non-invasive prenatal testing in Aotearoa New Zealand: A national survey.

BACKGROUND: Non-invasive prenatal testing (NIPT) has been available in Aotearoa New Zealand (NZ) for approximately four years. It is likely to be introduced into the publicly funded prenatal screening service. AIM: To explore obstetrician use and views of NIPT, with consideration to its implementation into screening services for Down syndrome and other conditions. METHODS: An anonymous online survey combining Likert scales and free text was designed to assess current practice, knowledge, ethical considerations, counselling and views toward public funding of NIPT. The survey was distributed through the New Zealand members of the Royal Australian and New Zealand College of Obstetricians and Gynaecologists (n = 418) and responses collected over a two-month period in 2016. RESULTS: There were 134/418 (32.1%) respondents. Current knowledge influenced decisions to offer NIPT (70.3%, 85/121). Confidence in offering NIPT was: 'not at all' (0.8%, 1/128); 'a little' (7.03%, 9/128), 'somewhat' (16.4%, 21/128), 'quite' (40.6%, 52/128) and 'very' (35.2%, 45/128). A total of 83.5% (101/121) stated NIPT should be publicly funded and NIPT capability developed within NZ (89.1%, 106/119). More information and support on the provision of NIPT was called for. CONCLUSION: There was strong support for public funding of NIPT, and for NIPT capability to be developed in NZ. The call for more training, education and support needs to be actioned in order to facilitate the introduction of NIPT into screening services.

New screen on the block: non-invasive prenatal testing for fetal chromosomal abnormalities.

Non-invasive prenatal testing (NIPT) is a new screen for fetal chromosomal abnormalities. It is a screening test based on technology that involves the analysis of feto-placental DNA that is present in maternal blood. This DNA is then analysed for abnormalities of specific chromosomes (eg 13, 18, 21, X, Y). NIPT has a much higher screening capability for chromosomal abnormalities than current combined first trimester screening, with ~99% sensitivity for trisomy 21 (Down syndrome) and at least a 10-fold higher positive predictive value. The low false-positive rate (1-3%) is one of the most advertised advantages of NIPT. In practice, this could lead to a significant reduction in the number of false-positive tests and the need for invasive diagnostic procedures. NIPT is now suitable for singleton and twin pregnancies and can be performed from ~10 weeks in a pregnancy. NIPT is not currently publicly funded in most countries. However, the increasing availability of NIPT commercially will likely lead to an increase in demand for this as a screening option. Given the high numbers of women who visit a general practitioner (GP) in their first trimester, GPs are well-placed to also offer NIPT as a screening option. A GP's role in facilitating access to this service will likely be crucial in ensuring equity in access to this technology, and it is important to ensure that they are well supported to do so.

Anatomically correct three-dimensional coronary artery reconstruction using frequency domain optical coherence tomographic and angiographic data: head-to-head comparison with intravascular ultrasound for endothelial shear stress assessment in humans.

AIMS: To develop a methodology that permits accurate 3-dimensional (3D) reconstruction from FD-OCT and angiographic data enabling reliable evaluation of the ESS distribution, and to compare the FD-OCT-derived models against the established models based on angiography/IVUS. METHODS AND RESULTS: Fifteen patients (17 coronary arteries) who underwent angiography, FD-OCT and IVUS examination during the same procedure were studied. The FD-OCT and IVUS lumen borders were placed onto the 3D luminal centreline derived from angiographic data. Three-dimensional geometry algorithms and anatomical landmarks were used to estimate the orientation of the borders appropriately. ESS was calculated using computational fluid dynamics. In 188 corresponding consecutive 3-mm segments, FD-OCT- and IVUS-derived models were highly correlated for lumen area (r=0.96) and local ESS (r=0.89) measurements. FD-OCT-based 3D reconstructions had a high diagnostic accuracy for detecting regions exposed to proatherogenic low ESS identified on the IVUS-based 3D models, considered as the gold standard (receiver operator characteristic area under the curve: 94.9%). CONCLUSIONS: FD-OCT-based 3D coronary reconstruction provides anatomically correct models and permits reliable ESS computation. ESS assessment in combination with the superior definition of plaque characteristics by FD-OCT is expected to provide valuable insights into the effect of the haemodynamic environment on the development and destabilisation of high-risk plaques.

A new methodology for accurate 3-dimensional coronary artery reconstruction using routine intravascular ultrasound and angiographic data: implications for widespread assessment of endothelial shear stress in humans.

AIMS: To develop and validate a new methodology that allows accurate 3-dimensional (3-D) coronary artery reconstruction using standard, simple angiographic and intravascular ultrasound (IVUS) data acquired during routine catheterisation enabling reliable assessment of the endothelial shear stress (ESS) distribution. METHODS AND RESULTS: Twenty-two patients (22 arteries: 7 LAD; 7 LCx; 8 RCA) who underwent angiography and IVUS examination were included. The acquired data were used for 3-D reconstruction using a conventional method and a new methodology that utilised the luminal 3-D centreline to place the detected IVUS borders and anatomical landmarks to estimate their orientation. The local ESS distribution was assessed by computational fluid dynamics. In corresponding consecutive 3 mm segments, lumen, plaque and ESS measurements in the 3-D models derived by the centreline approach were highly correlated to those derived from the conventional method (r>0.98 for all). The centreline methodology had a 99.5% diagnostic accuracy for identifying segments exposed to low ESS and provided similar estimations to the conventional method for the association between the change in plaque burden and ESS (centreline method: slope= -1.65%/Pa, p=0.078; conventional method: slope= -1.64%/Pa, p=0.084; p =0.69 for difference between the two methodologies). CONCLUSIONS: The centreline methodology provides geometrically correct models and permits reliable ESS computation. The ability to utilise data acquired during routine coronary angiography and IVUS examination will facilitate clinical investigation of the role of local ESS patterns in the natural history of coronary atherosclerosis.

In-vivo assessment of the natural history of coronary atherosclerosis: vascular remodeling and endothelial shear stress determine the complexity of atherosclerotic disease progression.

PURPOSE OF REVIEW: Atherosclerotic disease progression is determined by localized plaque growth, which is induced by systemic and local hemodynamic factors, and the nature of the wall remodeling response. The purpose of this review is to summarize the processes underlying the heterogeneity of coronary atherosclerosis progression in relation to the local hemodynamic and arterial remodeling environment. RECENT FINDINGS: Multiple competing biological processes in the extracellular matrix define the extent of vascular remodeling and disease progression. The remodeling phenomenon is not consistent but is characterized by great phenotypical heterogeneity which reflects the complex effect of systemic, genetic and hemodynamic factors on the arterial wall response to plaque formation and progression. The exaggeration of expansive remodeling (i.e., excessive expansive remodeling) likely contributes to the transformation of an initially favorable action into an excessive course of vessel expansion, continued disease progression and plaque instability. Extremely low endothelial shear stress and excessive expansive remodeling establish a vicious cycle which leads to the formation of severe plaques with high-risk characteristics. SUMMARY: The dynamic interplay between the local hemodynamic environment and the wall remodeling behavior determines the complexity of the natural history of atherosclerosis and explains the development of localized plaque vulnerability.