Development and validation of non-invasive endothelial shear stress (ESS) estimations of coronary artery haemodynamics using computational modelling

Background

Vascular remodelling is influenced by various biomechanical forces such as endothelial shear stress (ESS) and is associated with development and progression of coronary artery disease (CAD). ESS is the parallel frictional force exerted by blood flow on the endothelial luminal surface of the arterial wall. While ESS may not be the only cause of atherosclerosis, it is postulated that low ESS creates a pro-atherogenic environment and high ESS is athero-protective. Computational fluid dynamics (CFD) is an engineering method used to analyse fluid flow and has been increasingly applied to simulate ESS in cardiovascular research. However, current CFD-derived ESS estimates have never been validated and can display significant variability between research groups.

Purpose

This study aims to provide a comparative analysis of coronary flow using in-silico modelling of coronary flow and particle image velocimetry (PIV).

Methods

A proximal left anterior descending (pLAD) coronary phantom model was constructed from a patient who had received same day cardiac computed tomography angiography (CTCA) and invasive coronary haemodynamic (Combowire XT) assessment. Patient-specific coronary flow data was applied to CFD boundary conditions and a mock circulatory loop. CFD was validated using PIV under steady flow in a 4-times-scaled model. Same plane velocity field and flow patterns (at mid-luminal of pLAD) from both in-silico and in-vivo data were compared and analysed.

Results

Mean velocity contours and magnitude were analysed from CFD and PIV. Patient specific average peak velocity obtained from invasive assessment was 0.21m/s. Patient-specific velocity average from CFD was 0.22m/s. The approximated magnitude difference is 4.7%. Both same-axial average cross-sectional velocity estimated by CFD-pLAD and PIV-pLAD are 0.087m/s. Velocity contours and flow patterns simulated in the CFD were also comparable with the PIV results.

Conclusion

Simulation data from CFD correlate well with experimental PIV results. This early data allows for a non-invasive approach to determine patient-specific coronary haemodynamics (such as velocity profiling and ESS) and form the basis of personalising cardiovascular risk. Insights from this work may aid future development of a novel tool that incorporates CFD-derived ESS estimates with patient-specific risk factors to better predict rapid CAD progression.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Cardiac Society of Australia and New Zealand Monash Institute of Medical Engineering

Ventricular arrhythmias and sudden cardiac death caused by mitral valve prolapse: should we operate and when?

Background

Several autopsy and observational studies have investigated the link between mitral valve prolapse (MVP) and sudden cardiac death (SCD) due to the well accepted yet rare occurrence of complex ventricular arrhythmia (VA) in this cohort. Few studies however have investigated whether arrhythmia burden and more importantly SCD are reduced following surgical correction of MVP.

Purpose

To investigate the impact of mitral valve surgery (MVS) (replacement or repair) on VA and SCD in patients with MVP.

Methods

A systematic review of the current literature was conducted using an electronic search of the PubMed database in October 2021. Studies were included if subjects had undergone mitral valve (MV) repair or replacement with documented rates of arrythmias/SCD pre- and post-intervention. Small patient numbers in individual reports precluded formal meta-analysis and results were reported on a per study basis.

Results

19 identified studies (10 cohort studies, nine case studies) comprised 1322 patients with a pooled mean age of 63.4 years and 38.9% were female. 748 of the 1322 patients underwent MVS: 263 MV repair, 18 MV replacement (one with leaflet and papillary muscle excision), two MV repair with Maze procedure, 177 percutaneous transcatheter MV repair, 45 annuloplasty with or without valve repair, and in 243 cases the surgical method was not specified.

Of the 10 included cohort studies, seven of the eight which investigated rates of VA post MVS concluded there was a significant reduction, while one reported the predisposition to arrythmia persisted after relieving the abnormal mechanical effects of non-ischaemic MR (75% due to MVP). One study reported a reduction in SCD post MVS. Each of the nine included case studies showed a reduction in VA post MVS. One study showed mitral annular disjunction (MAD) was independently associated with a higher risk of arrhythmic events, this link persisting with time dependent MVS although reduced compared to medical management.

Conclusions

The underlying mechanisms for VA and SCD associated with MVP are not completely understood, and guidelines for the surgical correction of MVP based on arrhythmic and SCD risk are lacking. This systematic review illustrates a possible reduction in VA following MVS. Further identification of patients at risk of SCD, and potential use of risk stratification algorithms, would allow for consideration of earlier management and appropriate use of implantable cardioverter-defibrillators (ICD) placement / MVS with an expected survival benefit.

Funding Acknowledgement

Type of funding sources: None.

Urban Roadway Runoff Is Lethal to Juvenile Coho, Steelhead, and Chinook Salmonids, But Not Congeneric Sockeye

We compared the sensitivity of closely related Pacific salmon and steelhead (Oncorhynchus spp.) to untreated urban stormwater runoff across three storm events. Juvenile coho, sockeye, steelhead, and Chinook were exposed for 24 h to untreated urban runoff and then transferred to clean water for 48 h. As anticipated from previous studies, coho were highly susceptible to runoff toxicity, with cumulative mortality rates ranging from 92%-100% across the three storms. By contrast, juvenile sockeye were unaffected (100% survival), and cumulative mortality rates were intermediate for steelhead (4%-42%) and Chinook (0%-13%). Furthermore, coho died rapidly following the onset of stormwater exposure (generally <4 h), whereas mortality in Chinook and steelhead was delayed by 1-2 days. Similar to previous findings for coho, steelhead and Chinook did not recover when transferred to clean water. Lastly, significant mortality occurred in coho even when roadway runoff was diluted by 95% in clean water. Our findings extend the urban runoff mortality syndrome in salmonids and point to a near-term need for sublethal studies in steelhead and Chinook to more precisely understand stormwater risks to threatened species recovery efforts in the western United States.

Search for Subsolar-Mass Binaries in the First Half of Advanced LIGO's and Advanced Virgo's Third Observing Run

We report on a search for compact binary coalescences where at least one binary component has a mass between 0.2  M_{⊙} and 1.0  M_{⊙} in Advanced LIGO and Advanced Virgo data collected between 1 April 2019 1500 UTC and 1 October 2019 1500 UTC. We extend our previous analyses in two main ways: we include data from the Virgo detector and we allow for more unequal mass systems, with mass ratio q≥0.1. We do not report any gravitational-wave candidates. The most significant trigger has a false alarm rate of 0.14  yr^{-1}. This implies an upper limit on the merger rate of subsolar binaries in the range [220-24200]  Gpc^{-3} yr^{-1}, depending on the chirp mass of the binary. We use this upper limit to derive astrophysical constraints on two phenomenological models that could produce subsolar-mass compact objects. One is an isotropic distribution of equal-mass primordial black holes. Using this model, we find that the fraction of dark matter in primordial black holes in the mass range 0.2  M_{⊙}<m_{PBH}<1.0  M_{⊙} is f_{PBH}≡Ω_{PBH}/Ω_{DM}≲6%. This improves existing constraints on primordial black hole abundance by a factor of ∼3. The other is a dissipative dark matter model, in which fermionic dark matter can collapse and form black holes. The upper limit on the fraction of dark matter black holes depends on the minimum mass of the black holes that can be formed: the most constraining result is obtained at M_{min}=1  M_{⊙}, where f_{DBH}≡Ω_{DBH}/Ω_{DM}≲0.003%. These are the first constraints placed on dissipative dark models by subsolar-mass analyses.

Patient experiences of shared decision-making are associated with implantable cardioverter defibrillator recipients" openness to discuss device deactivation at end-of-life

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): In Australia, this study received funding from a faculty grand by Australian University Faculty of Health Sciences Research grant. In the United States, the study was funded by a research professor award from University of Kentucky.

Background. Shared decision-making is important for ICD recipients to fully contemplate and rationally decide about ICD deactivation at end-of-life. Although discussions about device deactivation at end-of-life are recommended to be held before ICD implantation and throughout the illness trajectory, such discussions rarely occur in clinical practice.

Purpose. To identify whether ICD recipients’ experiences of end-of-life discussions with clinicians are associated with openness to discussing ICD deactivation at end-of-life.

Methods. This cross-sectional study included 293 ICD recipients living in the United States, Australia, and South Korea (mean age 59, 22.5% female, mean ICD implantation 10 years). Hierarchical logistic regression was used to determine whether patients’ experiences of shared decision-making were associated with openness to discuss device deactivation at end-of-life after controlling for relevant covariates (i.e. age, gender, ICD implantation years, ICD shock experience, general ICD experience, ICD knowledge, and concerns related to the ICD).

Results. About half of the participants (57.7%) were open to discussing ICD deactivation at end-of-life with clinicians. Almost one-quarter (23.5%) had no prior experience of discussing any end-of-life issues with clinicians. Patients’ past experiences of end-of-life discussions with clinicians were significantly associated with openness to discuss device deactivation at end-of-life (OR: 1.30) after adjusting for covariates.

Conclusion. Our results highlight that clinicians’ willingness to discuss sensitive end-of-life issues such as battery replacement and deactivation of defibrillation therapy empowers patients to actively engage in end-of-life discussions.

Association between prosthesis geometry and leaflet thrombosis following transcatheter aortic valve replacement

Introduction

Leaflet thrombosis (LT) following transcatheter aortic valve replacement (TAVR) is a recognised condition. The association between prosthesis geometry [expansion, implant depth and commissural alignment (CA)] and LT is unclear.

Methods

Patients that received intra-annular TAVR prosthesis and post-procedure computed tomography (CT) with a 320-slice scanner were included. LT, defined as at least 50% restricted leaflet motion, was assessed with a dedicated 3Mensio workstation by two experienced CT readers. Prosthesis expansion was defined as actual divided by expected prosthesis area as a percentage of expected area whilst eccentricity was [(maximum diameter − minimum diameter) / maximum diameter) × 100%], both measured at prosthesis inflow, annulus and outflow. Implant depth was the average distance between prosthesis inflow and nadir of each cusp. CA was the average angle between each native and prosthesis leaflet coaptations. Significant commissural misalignment (CMA) was defined as CA greater than 30 degrees. To exclude anticoagulation bias, similar analysis was also performed in the cohort of non-anticoagulated patients.

Results

117 patients were included; the prevalence of LT was 13.7% [13/93 cases (14.0%) of Lotus valves and 3/24 cases (12.5%) of Sapien 3 valves]. Baseline demographics (age, STS score, cardiac risk factors) and procedural characteristics (access site, post-dilation, repositioning) were similar in both groups. None of the patients with LT were discharged on anticoagulation therapy (0.0% vs 22.8%, p&lt;0.01). There were no differences in actual prosthesis area, perimeter or eccentricity at the three prosthesis levels. Patients with LT had reduced annulus expansion (89.3±9.8% vs 94.6±8.3%, p=0.02), lower implant depth (6.9±1.5mm vs 4.9±1.5mm, p&lt;0.01) and more significant CMA (81.3% vs 48.5%, p=0.02). These findings were similar in patients that were not anticoagulated (94/117 patients).

Conclusion

Patients with LT had reduced annulus expansion, lower implant depth and greater CMA. These findings were not affected by presence or absence of anticoagulation. These factors may be important considerations during procedural planning for TAVR.

Graphical abstract

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Health and Medical Research Council (NHMRC). National Heart Foundation (NHF) Australia.

Pericoronary adipose tissue attenuation (PCAT) is associated with high-risk atherosclerotic plaque and subsequent acute coronary syndrome in patients with stable coronary artery disease

Background

High-risk plaque (HRP) features detected on computed tomography coronary angiography (CTCA) are associated with subsequent development of acute coronary syndrome (ACS). Pericoronary adipose tissue attenuation (PCAT) is a novel CT-derived non-invasive marker of coronary inflammation. The association between PCAT, HRP and outcomes is unknown.

Purpose

To evaluate the association between high-risk plaque HRP characteristics, ACS and PCAT attenuation as a surrogate marker of coronary inflammation.

Methods

Patients with stable chest pain referred for CTCA between 2011 and 2013 with outcome data were included. Patients with HRP were propensity matched to patients without HRP. PCAT-RCA and PCAT-lesion were assessed using semi-automated software (AutoPlaque version 2.0). PCAT-RCA was measured around the proximal 10–50 mm of the right coronary artery (RCA). PCAT-lesion was measured around the HRP or lesion with highest-grade stenosis in patients without HRP.

Results

78 patients (67±10 years, 67% males) included 41 (52.6%) patients with HRP. Median PCAT-RCA was higher in HRP patients than non-HRP patients (−80.4 HU [IQR −86.1, −76.5] vs. −86.3 HU [IQR −92.2, −77.0], p=0.02). PCAT-Lesion was not significantly different between HRP and non-HRP patients (−78.7 HU [IQR −84.4, −73.4] vs. −82.8 HU [IQR −91.1, −75.4], p=0.16). More patients with HRP developed a subsequent ACS (24.4% vs. 5.4%, p=0.008). HRP patients who experienced an ACS demonstrated a higher PCAT-RCA (−76.6 HU [IQR −81.3, −72.4] vs. −82.6 HU [IQR −87.4, −78.0], p=0.018) and PCAT-lesion (−74.3 HU [IQR −77.1, −68.4] vs. −80.7 HU [IQR −84.8, −74.9], p=0.04) compared to those who did not experience an ACS.

Conclusion

PCAT attenuation is elevated in stable CAD patients with HRP features. Measures of periarterial inflammation were also more evident in HRP patients who develop ACS, indicating a potential contribution to vulnerability. The implications for integration of these measures in clinical practice require further investigation.

Funding Acknowledgement

Type of funding source: None

Visual spectrogram scanning paired with an observation–confirmation occupancy model improves the efficiency and accuracy of bioacoustic anuran data

Passive acoustic monitoring using autonomous recording units has improved anuran amphibian call survey data collection. A challenge associated with this approach is the time required for audio data processing. Our objective was to develop a more efficient method of processing and analyzing acoustic data through visual spectrogram scanning and the application of an observation–confirmation occupancy model. We compared detection rates between methods of standard recording listening and visually scanning spectrogram images using different spectrogram parameters. Relative to listening, we found that 1 min spectrograms in two 30 s frames yield the best time efficiency–accuracy trade-off. A standard occupancy model applied to visual scanning data underestimated occupancy estimates relative to listening data for three species and overestimated occupancy for one species. The observation–confirmation model used a subset of listening data to improve the estimates of detection probability from visual scanning and therefore reduced bias in occupancy estimates when compared with using visual scanning data alone. Overall, the combination of the visual scanning method and the observation–confirmation model allowed us to maintain the accuracy of occupancy estimates while greatly increasing the efficiency of anuran data processing. These methods are widely applicable and can increase sample size and precision for acoustic monitoring programs using autonomous recording units.

P7 The impact of coronary calcification on diagnostic performance of workstation CT derived fractional flow reserve - a multicentre experience

Background

On-site workstation based computed tomography derived fractional flow reserve (CT-FFR) is an emerging method to assess the vessel specific ischaemia in coronary artery disease (CAD). The impact of coronary calcification on its diagnostic performance is unknown.

Purpose

To evaluate the impact of coronary calcification on the diagnostic performance of reduced-order CT-FFR at detecting vessel specific ischaemia.

Methods

This is a retrospective pooled analysis of 141 patients with suspected CAD enrolled from 3 global centres who underwent CT-coronary angiography (CTA), onsite CT-FFR and invasive FFR.  Coronary calcification was assessed by Agatston score (AS). The diagnostic performance of CT-FFR (≤0.8) and CTA (≥50%) in evaluation of vessel specific ischaemia (FFR ≤ 0.8) was assessed across AS quartiles (Q1-4). A comparison of diagnostic performance of the low to mid AS (Q1 to Q3) versus high AS (Q4) was performed.

Results

Mean age and median AS was 65.8 ± 9.9 and 327.3 (interquartile range = 78.5 – 798.1). Diagnostic accuracy, sensitivity and specificity of CT-FFR for low-mid AS (0-798) and high AS (799-4019) were 77.4% vs 82.9%; 78.9% vs 94.7%; 68.8% vs 76.5% respectively with no statistical difference between the two groups.  The AUC for ischaemia of CT-FFR in low to mid AS was comparable with AUC in the high AS (0.76 [95% CI: 0.66-0.86] vs 0.84 [0.69-0.99]; P = 0.397).  The AUC for ischemia for CT-FFR in both low to mid AS and high AS was significantly higher than for CTA (0.76 [0.66-0.86] vs 0.57 [0.50-0.64]; P = 0.003 and 0.84 [0.69-0.99] vs 0.48 [0.38-0.57]; P &lt; 0.001 respectively).

Conclusion

On-site workstation CT-FFR demonstrated consistently high diagnostic performance in patients with high AS. Its diagnostic performance was superior when compared with significant stenosis assessment on CTA across all spectrum of Agatston scores.

P6187Multicentre diagnostic performance of on-site workstation CT derived fractional flow reserve

Background

On-site workstation based computed tomography derived fractional flow reserve (CT-FFR) is an emerging method to assess vessel specific ischaemia in coronary artery disease (CAD). Global data on its diagnostic performance when compared with CT coronary angiography (CTA) is limited.

Purpose

To evaluate the on-site multicentre diagnostic performance of reduced-order CT-FFR at detecting vessel specific ischaemia.

Method

This is a retrospective pooled analysis of 141 patients (204 vessels) with suspected CAD enrolled from 3 global centres who underwent CTA, onsite CT-FFR and invasive FFR. On-site CT-FFR was performed using a reduced order model on a standard desktop computer with dedicated software. The per vessel diagnostic performance of CT-FFR (≤0.8) for vessel specific ischemia (FFR≤0.8) was compared with CTA (≥50% stenosis).

Results

Mean age was 65.8±9.9, 70.7% were male. FFR significant stenosis was present in 34.3% (70/204) of vessels. Pearson correlation of CT-FFR for invasive FFR was 0.52, P<0.001. Bland Altman analysis demonstrated a mean difference of 0.06±0.15 (95% limits of agreement −0.22 to 0.35). Per vessel diagnostic accuracy, sensitivity and specificity of CT-FFR and CTA were 79.9% vs 53.5%; 78.6% vs 85.7%; 80.6% vs 35.9% respectively. Diagnostic performance as assessed by area under the receiver operator curve (AUC) for CT FFR was superior to CTA (0.82 [95% CI 0.76–0.88] vs 0.61 [0.55–0.67]; P<0.001).

Conclusion

On-site workstation CT-FFR demonstrated high per vessel diagnostic performance and was superior when compared with CTA in assessment of vessel specific ischaemia as assessed by invasive FFR in a multicentre setting.

Fear of cancer recurrence trajectory during radiation treatment and follow-up into survivorship of patients with breast cancer

BACKGROUND

Fear of cancer recurrence (FCR) has been shown to be higher in patients treated with external beam radiotherapy (RT) compared to those untreated. However, little is known about the dynamics of patient's FCR during and after RT. The aim of this study was to examine FCR levels in a longitudinal panel design with breast cancer patients receiving RT.

METHODS

Consecutive newly-diagnosed breast cancer patients (n = 94) attending a single cancer centre were invited to complete a 7-item FCR scale (FCR7) that was collected weekly by paper instrument and at a follow-up phone call 6-8 weeks after completion of RT. Descriptive statistics, and Latent Growth Curve Modelling (LGCM) were utilised to analyse the data.

RESULTS

Women who were younger, single/separated, had chemotherapy, had extra boost radiation treatment, taking Herceptin and treated by 4-field technique reported higher recurrence fear at baseline. There was strong evidence of substantial variation in the trajectory of FCR (z = - 3.54, p < .0001). The average trajectory of FCR over RT was negative (unstandardized estimate = - 0.59) and associated with FCR follow-up level (standardised estimate = 0.36, z = 3.05, p < .002), independent of baseline recurrence fears.

CONCLUSION

Patients vary in their trajectory of recurrence fears over RT which predicts FCR approximately 2 months following treatment. Review appointments by therapy radiographers presents an opportunity to intervene in FCR trajectories.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02599506 . Prospectively registered on 11th March 2015.

Emotional talk of patients with breast cancer during review appointments with therapeutic radiographers: effects on fears of cancer recurrence

Fears of cancer recurrence (FCR) in patients with breast cancer may develop during radiotherapy. Radiographer communication with their patients may influence early survivorship FCR level.

AIM

To investigate the management of emotional talk in patients with breast cancer attending their initial review appointments during radiotherapy and predict FCR at 6-8 weeks follow-up.

METHODS

A mixed-methods observational study was conducted. Patients (consecutive sample, n = 60) with breast cancer, attending a major Scottish cancer centre, had their first two review appointments with their therapeutic radiographer (TR) audio-recorded. In addition, FCR was assessed (FCR7) at baseline and at 6-8 weeks following their final radiotherapy visit. Two TRs participated. Audio files were coded by the VR-CoDES system to identify emotional cues and therapeutic radiographer (TR) responses. Linear regression models were tested for fit and to identify factors associated with follow-up FCR, i.e. patient cues, responses by TR.

RESULTS

Follow-up FCR was predicted negatively (robust estimator, p = .01) by level of patient emotional talk at the second review session. The provision of space by the TR, at the second session, to enable patients to expand their emotional utterances was also associated, but negatively (p = .01), with follow-up FCR. These effects were maintained after inclusion of covariates: age, treatment received and living conditions.

CONCLUSIONS

Patient's emotional expression and TR responses at the second review meeting predicted follow-up FCR. The study shows the effect of communication processes on this specific distress component of the patient's survivorship experience.

TRIAL REGISTRATION

NCT02599506.

Does emotional talk vary with fears of cancer recurrence trajectory? A content analysis of interactions between women with breast cancer and their therapeutic radiographers

Fears of cancer recurrence (FCR) in patients with breast cancer are hypothesised to develop over the period from diagnosis, through treatment and thereafter. A crucial point may be the contact that patients have with their therapeutic radiographer in review appointments. The study aimed to (1) describe and categorise the content of the identified emotional talk, and (2) consider the evidence for an association of content with FCR trajectory.

METHODS

A concurrent mixed methods approach was applied as part of a larger investigation (FORECAST) of breast cancer patients (n=87). Patients completed a daily diary during their radiotherapy treatment. Audio recordings were collected of review appointments. The Verona Coding Definitions of Emotional Sequences (VR-CoDES) system was used to code patient emotional cues and concerns (CCs). Purposeful sampling of the daily diary ratings identified 12 patients (30 consultations) with an increasing (n=6) or decreasing (n=6) FCR trajectory. The emotional talk of these patients at their weekly reviews was content analysed.

RESULTS

Four themes were identified from 185 CCs: Physical Symptoms, Factors External to Hospital, Treatment, and Labelling Cancer. FCR decreasing trajectory group consultations were longer (p<0.02), expressed twice as many CCs as the increasing trajectory group (p<0.001), and were more likely to refer to cancer directly (p<0.05).

CONCLUSIONS

The emotional content expressed matched features outlined in the Lee-Jones et al. (1997) FCR model, and showed evidence of avoidance in increasing FCR trajectory patients.