Acoustophoresis of monodisperse oil droplets in water: Effect of symmetry breaking and non-resonance operation on oil trapping behavior

Acoustic manipulation of particles in microchannels has recently gained much attention. Ultrasonic standing wave (USW) separation of oil droplets or particles is an established technology for microscale applications. Acoustofluidic devices are normally operated at optimized conditions, namely, resonant frequency, to minimize power consumption. It has been recently shown that symmetry breaking is needed to obtain efficient conditions for acoustic particle trapping. In this work, we study the acoustophoretic behavior of monodisperse oil droplets (silicone oil and hexadecane) in water in the microfluidic chip operating at a non-resonant frequency and an off-center placement of the transducer. Finite element-based computer simulations are further performed to investigate the influence of these conditions on the acoustic pressure distribution and oil trapping behavior. Via investigating the Gor'kov potential, we obtained an overlap between the trapping patterns obtained in experiments and simulations. We demonstrate that an off-center placement of the transducer and driving the transducer at a non-resonant frequency can still lead to predictable behavior of particles in acoustofluidics. This is relevant to applications in which the theoretical resonant frequency cannot be achieved, e.g., manipulation of biological matter within living tissues.

NECAB2 is an endosomal protein important for striatal function

Synaptic signaling depends on ATP generated by mitochondria. Dysfunctional mitochondria shift the redox balance towards a more oxidative environment. Due to extensive connectivity, the striatum is especially vulnerable to mitochondrial dysfunction. We found that neuronal calcium-binding protein 2 (NECAB2) plays a role in striatal function and mitochondrial homeostasis. NECAB2 is a predominantly endosomal striatal protein which partially colocalizes with mitochondria. This colocalization is enhanced by mild oxidative stress. Global knockout of Necab2 in the mouse results in increased superoxide levels, increased DNA oxidation and reduced levels of the antioxidant glutathione which correlates with an altered mitochondrial shape and function. Striatal mitochondria from Necab2 knockout mice are more abundant and smaller and characterized by a reduced spare capacity suggestive of intrinsic uncoupling respectively mitochondrial dysfunction. In line with this, we also found an altered stress-induced interaction of endosomes with mitochondria in Necab2 knockout striatal cultures. The predominance of dysfunctional mitochondria and the pro-oxidative redox milieu correlates with a loss of striatal synapses and behavioral changes characteristic of striatal dysfunction like reduced motivation and altered sensory gating. Together this suggests an involvement of NECAB2 in an endosomal pathway of mitochondrial stress response important for striatal function.

Rationale and design of the iCORONARY trial: improving the cost-effectiveness of coronary artery disease diagnosis

BACKGROUND

In patients with stable coronary artery disease (CAD), revascularisation decisions are based mainly on the visual grading of the severity of coronary stenosis on invasive coronary angiography (ICA). However, invasive fractional flow reserve (FFR) is the current standard to determine the haemodynamic significance of coronary stenosis. Non-invasive and less-invasive imaging techniques such as computed-tomography-derived FFR (FFR-CT) and angiography-derived FFR (QFR) combine both anatomical and functional information in complex algorithms to calculate FFR.

TRIAL DESIGN

The iCORONARY trial is a prospective, multicentre, non-inferiority randomised controlled trial (RCT) with a blinded endpoint evaluation. It investigates the costs, effects and outcomes of different diagnostic strategies to evaluate the presence of CAD and the need for revascularisation in patients with stable angina pectoris who undergo coronary computed tomography angiography. Those with a Coronary Artery Disease-Reporting and Data System (CAD-RADS) score between 0-2 and 5 will be included in a prospective registry, whereas patients with CAD-RADS 3 or 4A will be enrolled in the RCT. The RCT consists of three randomised groups: (1) FFR-CT-guided strategy, (2) QFR-guided strategy or (3) standard of care including ICA and invasive pressure measurements for all intermediate stenoses. The primary endpoint will be the occurrence of major adverse cardiac events (death, myocardial infarction and repeat revascularisation) at 1 year.

CLINICALTRIALS

gov-identifier: NCT04939207.

CONCLUSION

The iCORONARY trial will assess whether a strategy of FFR-CT or QFR is non-inferior to invasive angiography to guide the need for revascularisation in patients with stable CAD. Non-inferiority to the standard of care implies that these techniques are attractive, less-invasive alternatives to current diagnostic pathways.

Poster No. 135 Stroke risk of patients with new AF during ACS may depend on onset and duration

Background/rationale

Newly diagnosed atrial fibrillation(AF) during acute coronary syndrome(ACS) is associated with worse outcomes. In this study we evaluated the associated stroke risk of newly diagnosed AF in ACS patients according to the onset and duration of the episode.

Results

Amongst 4433 patients presenting with ACS, 439(9.9%) had newly diagnosed AF and 396(8.9%) had known AF. Of the new AF cases, 27.5% occurred post-CABG. The onset was within 24 hours of ACS presentation in 70.1% of non-CABG cases. The new AF episodes lasted longer than 24 hours in42.9% of the non-CABG cases. At discharge 54.0% of patients with new AF was treated with OAC, in contrast to 89.2% with known AF.

The incidence of ischemic stroke at one year was 1.2% in patients without AF, 1.0% with known AF, and 3.6% with new AF(P < 0.001). Within patients developing AF post-CABG, the incidence was 4/120(3.3%). Within non-CABG patients, the incidence of ischemic stroke for patients with onset within 24 hours of presentation was 0/133(0.0%) for patients with an episode lasting < 24 hours, and 6/109(5.5%) for patients with an episode lasting > 24 hours. For patients with new AF onset after 24 hours the incidence was 5/120(5.5%) for patients with an episode lasting < 24 hours, and 5/92(5.4%) for patients with an episode lasting > 24 hours.

Conclusion

Patients with newly diagnosed AF during ACS seem undertreated with OAC. The associated risk of ischemic stroke with new AF during ACS may be lower in episodes that terminate within the first 24 hours of presentation.

Prognostic impact of newly diagnosed atrial fibrillation and episode characteristics in patients with acute coronary syndrome

Background/Introduction

Newly diagnosed atrial fibrillation (AF) frequently occurs during acute coronary syndrome (ACS). In contrast to known AF, little is known about the prognostic and therapeutic implications of new AF.

Purpose

To evaluate the prognostic impact of newly diagnosed and known AF in patients with ACS. Furthermore, we evaluated the association of episode characteristics of new AF with clinical outcomes: early vs late occurrence, short vs long duration, post-CABG occurrence, and OAC treatment.

Methods

This analysis was performed within the prospective, multicentre, FORCE-ACS registry which studies ACS patients in the Netherlands. All ECGs during index ACS admission were retrospectively examined for the occurrence of AF. Patients were classified as no, new, or known AF. New AF episodes were described regarding early or late occurrence, duration of the episode, and post-CABG occurrence, and OAC prescription at discharge was evaluated. The primary outcome was MACE, a composite of death, myocardial infarction and stroke. Secondary outcomes include the separate MACE components and bleeding. Crude and adjusted outcomes were evaluated by univariable and multivariable Cox regression.

Results

3902 patients were included of which 299 (10.2%) had new and 367 (9.4%) had known AF. Major adverse cardiac events happened significantly more in both new and known AF patients than in patients without AF (22.2%, 17.4%, and 9.2%, p<0.001). Ischemic stroke occurred significantly more in new AF but not in known AF patients, compared to patients without AF (3.5% vs 0.9% vs 1.1%). After one year follow-up, a total of 234 patients (6.3%) deceased, of whom 138 in the group without AF (4.6%), and significantly more in the groups with new AF (n=59, 15.9%), and known AF (n=37, 10.8%). The timing of onset of the AF episode showed no significant association with clinical outcomes. Longer duration of the episode, however, was associated with increased MACE (HR 2.0, 95% CI 1.2–3.1) and all-cause mortality (HR 2.0, 95% CI 1.2–3.4). Episodes of new AF that occurred post-CABG were associated with less MACE (HR 0.31, 95% CI 0.14–0.67) and all-cause mortality (HR 0.20, 95% CI 0.07–0.55). No significant association between OAC treatment and MACE nor any of its separate components was found.

Conclusion

Newly diagnosed atrial fibrillation in acute coronary syndromes is associated with worse clinical outcomes than known or no atrial fibrillation. Longer episodes were associated with worse outcomes than short episodes. Post-operative new AF was associated with better outcomes than non-post-operative new AF.

Funding Acknowledgement

Type of funding sources: None.

Effects of CYP3A4*22 carrier and CYP3A5 expressor status on clinical outcome in patients treated with ticagrelor for acute coronary syndrome

Background

Current guidelines recommend using ticagrelor in patients with acute coronary syndrome. Ticagrelor is predominantly metabolized by CYP3A4 and to a lesser extent by CYP3A5. CYP3A4*22 allele and the CYP3A5 expressor status influence the metabolization of ticagrelor, increasing plasma concentration and platelet inhibition. Nevertheless, little is known about the impact of the CYP3A4*22 allele or CYP3A5 expressor status on clinical outcomes in ticagrelor treated patients.

Purpose

Our study aims to assess the effects of the CYP3A4*22 allele and CYP3A5 expressor status in patients with STEMI and treated with ticagrelor, with regards to clinical outcomes and the clinical side-effect dyspnea.

Methods

Patients from the POPular Genetics trial treated with ticagrelor were genotyped for the CYP3A4*22 and CYP3A5*3 alleles. Patients were divided into two groups based on their CYP3A4 (*22 carriers vs. *22 non carriers) and CYP3A5 status (expressor vs. non-expressors). The primary thrombotic endpoint was a composite of cardiovascular death, myocardial infarction, definite stent thrombosis and stroke. The primary bleeding outcome consisted of PLATO major and minor bleeding. The key secondary endpoint was clinically relevant dyspnea. The follow-up duration was one year.

Results

A total of 1,281 patients with ST-elevation myocardial infarction (STEMI) were used for the analyses. In the first analysis, CYP3A4*22 carriers (n=152) versus CYP3A4*22 non-carriers (n=1,129) were not found to have a significant correlation with the primary thrombotic outcome (1.3% vs. 2.5% adjusted hazard ratio 1.81 [0.43–7.62]) or the primary bleeding outcome (13.2% vs. 11.3% adjusted hazard ratio 0.93 [0.58–1.50]) (See Figure 1 and 2). CYP3A5 expressors (n=196) versus non-expressors (n=926) did not show a significant difference for the primary thrombotic outcome (2.6% versus 2.5% adjusted hazard ratio 1.03 [0.39–2.71] or the primary bleeding outcome (12.8% versus 10.9% adjusted hazard ratio 1.13 [0.73–1.76]). With respect to dyspnea, no significant difference was observed between CYP3A4*22 carriers versus CYP3A4*22 non-carriers 44.0% vs. 45.0%, risk ratio 1.04 [0.45–2.42] or CYP3A5 expressors versus CYP3A5 non-expressors 35.3% versus 47.8% risk ratio 0.60 [0.27–1.30].

Conclusions

In STEMI patients treated with ticagrelor, CYP3A4*22 carriers and CYP3A5 expressors did not affect clinical outcomes with regards to thrombotic events, bleeding rate, or the side-effect dyspnea.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The Netherlands Organization for Health Research and Development (ZonMW). The authors are solely responsible for designing and conducting this study, conducting all study analyses, and drafting and editing the manuscript and its final contents.

Diagnostic performance of coronary CTA and CT-FFR for the detection of coronary artery disease in routine TAVI work-up

Objectives

To assess the diagnostic performance of CT-FFR for the diagnosis of CAD in the work-up for TAVI.

Background

Work-up for transcatheter aortic valve implantation (TAVI) currently utilizes computed tomography (CT) to evaluate annulus diameter and peripheral vascular access, plus invasive coronary angiography (ICA) to assess significant coronary artery disease (CAD). ICA might partially be redundant with the use of Coronary CT Angiography (CCTA). Prior studies found improvement of the diagnostic accuracy of CCTA by use of CT derived fractional flow reserve (CT-FFR).

Methods

Consecutive patients with severe symptomatic aortic valve stenosis who underwent TAVI work-up between 2015–2019 were included in this cross-sectional study. All patients underwent CCTA and ICA within 3 months and diagnostic performance of both CCTA and CT-FFR were assessed using ICA as reference.

Results

Seventy-six of the 338 patients included in the analysis had ≥1 significant coronary stenosis at ICA. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy per-patient were 76.9%, 64.5%, 34.0%, 92.1% and 66.9% for CCTA and 84.6%, 88.3%, 63.2%, 96.0% and 87.6% for CT-FFR. The area under the receiver-operating characteristic-curve significantly differ between CCTA and CT-FFR (0.84 versus 0.90 p=0.02). A CT-FFR guided approach could avoid ICA in 57.1% versus 43.6% using CCTA.

Conclusions

CT-FFR significantly improves the diagnostic accuracy of CCTA without additional testing and increases the proportion of patients in whom ICA could have been safely avoided It has the potential to be integrated in the current clinical work-up for TAVI for diagnosing stable CAD requiring treatment.

Funding Acknowledgement

Type of funding sources: None.

Conservative management in a contemporary cohort of patients with acute coronary syndrome: results from the FORCE-ACS registry

Background

Contemporary real-world data on conservatively managed patients with acute coronary syndrome (ACS) is scarce.

Objective

To evaluate conservative management compared with revascularization therapy in ACS patients, focused on ischemic and bleeding outcomes at one year follow-up, and to provide insight in physician's rationale of choice for conservative management.

Methods

From January 2015 to January 2020, ACS patients were enrolled in the FORCE-ACS registry. Patients without coronary revascularization were identified and classified into three groups: 1) No coronary angiography (CAG) performed (CAG−), 2) documented obstructive coronary artery disease (CAD) with CAG (CAG+, CAD+) and 3) no obstructive CAD found with CAG (CAG+, CAD−). The first two groups were established as conservatively managed ACS patients, and were compared with those who received coronary revascularization. Survival analyses were used to assess differences in clinical endpoints and were adjusted for potential confounders using cox proportional hazard models. The primary endpoint was all-cause mortality, secondary endpoints included myocardial infarction (MI), stroke and major bleeding defined as Bleeding Academic Research Consortium (BARC) 3 or 5. Reasons for conservative management were assessed in all patients without coronary revascularization and details on antithrombotic therapy (type and duration) were explored.

Results

In 5,379 patients admitted with ACS, 93.8% underwent CAG. In total, 19.9% of patients did not receive coronary revascularization. In the non-revascularized patients, CAG was not performed in 34.8% (CAG−), documented CAD was found during CAG in 32.4% (CAG+, CAD+) and 32.7% of patients did not show obstructive CAD on CAG (CAG+, CAD−). Conservatively managed patients (14.2%) had lower survival rates compared with revascularized patients (HR 2.68; 95% CI: 1.89–3.81; p<0.0001). No significant differences were found in MI, stroke, or major bleeding between the two groups. The estimated one-year survival was the lowest in CAG− group compared to the CAG+, CAD+ group (adjusted HR 12.24; 95% CI: 4.15–36.07; p<0.001). Most frequent reasons for choosing conservative management in ACS patients included multi-comorbidity, complex coronary anatomy or a “watchful waiting” strategy. Conservatively treated patients received dual or triple antithrombotic therapy less often than the revascularized group (84.5% vs 94.6%).

Conclusion

In this contemporary ACS cohort, conservatively managed patients are at higher mortality risk than revascularized patients. This heterogeneous group of conservatively managed patients less often received guideline-recommended therapy.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Netherlands Organisation for Health, Research and Development (ZonMw)AstraZeneca

Diagnostic accuracy of on-site coronary computed tomography-derived fractional flow reserve in the diagnosis of stable coronary artery disease

PURPOSE

Invasive fractional flow reserve (FFR), the reference standard for identifying significant coronary artery disease (CAD), can be estimated non-invasively by computed tomography-derived fractional flow reserve (CT-FFR). Commercially available off-site CT-FFR showed improved diagnostic accuracy compared to coronary computed tomography angiography (CCTA) alone. However, the diagnostic performance of this lumped-parameter on-site method is unknown. The aim of this cross-sectional study was to determine the diagnostic accuracy of on-site CT-FFR in patients with suspected CAD.

METHODS

A total of 61 patients underwent CCTA and invasive coronary angiography with FFR measured in 88 vessels. Significant CAD was defined as FFR and CT-FFR below 0.80. CCTA with stenosis above 50% was regarded as significant CAD. The diagnostic performance of both CT-FFR and CCTA was assessed using invasive FFR as the reference standard.

RESULTS

Of the 88 vessels included in the analysis, 34 had an FFR of ≤ 0.80. On a per-vessel basis, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 91.2%, 81.4%, 93.6%, 75.6% and 85.2% for CT-FFR and were 94.1%, 68.5%, 94.9%, 65.3% and 78.4% for CCTA. The area under the receiver operating characteristic curve was 0.91 and 0.85 for CT-FFR and CCTA, respectively, on a per-vessel basis.

CONCLUSION

On-site non-invasive FFR derived from CCTA improves diagnostic accuracy compared to CCTA without additional testing and has the potential to be integrated in the current clinical work-up for diagnosing stable CAD.

Added value of computed tomography fractional flow reserve in the diagnosis of coronary artery disease

Multiple non-invasive tests are performed to diagnose coronary artery disease (CAD), but all are limited to either anatomical or functional assessments. Computed tomography derived Fractional Flow Reserve (CT-FFR) based on patient-specific lumped parameter models is a new test combining both characteristics simulating invasive FFR. This study aims to evaluate the added value of CT-FFR over other non-invasive tests to diagnose CAD. Patients with clinical suspicion of angina pectoris between 2010 and 2011 were included in this cross-sectional study. All underwent stress electrocardiography (X-ECG), SPECT, CT coronary angiography (CCTA) and CT-FFR. Invasive coronary angiography (ICA) and FFR were used as reference standard. Five models mimicking the clinical workflow were fitted and the area under receiver operating characteristic (AUROC) curve was used for comparison. 44% of the patients included in the analysis had a FFR of ≤ 0.80. The basic model including pre-test-likelihood and X-ECG had an AUROC of 0.79. The SPECT-strategy had an AUROC of 0.90 (p = 0.008), CCTA-strategy of 0.88 (p < 0.001), 0.93 when adding CT-FFR (p = 0.40) compared to 0.94 when combining CCTA and SPECT. This study shows adding on-site CT-FFR based on patient-specific lumped parameter models leads to an increased AUROC compared to the basic model. It improves the diagnostic work-up beyond SPECT or CCTA and is non-inferior to the combined strategy of SPECT and CCTA in the diagnosis of hemodynamically relevant CAD.

Caveolin3 Stabilizes McT1-Mediated Lactate/Proton Transport in Cardiomyocytes

[Figure: see text].

Diagnostic performance and clinical implications for enhancing a hybrid quantitative flow ratio and fractional flow reserve revascularization decision making strategy

Background

Fractional flow reserve (FFR) adoption persists low mainly due to procedural and operator related factors as well as costs. An alternative for FFR, quantitative flow ratio (QFR) achieves a high accuracy mainly outside the intermediate zone without the need for hyperemia and wire-use. Currently, no outcome trials assess the role of QFR in the guidance of revascularization. Therefore, we evaluate a QFR-FFR hybrid strategy in which FFR is measured inside of the intermediate zone.

Methods

This retrospective multi-center study included consecutive patients who underwent both invasive coronary angiography and FFR in the participating centers. QFR was calculated for all vessels in which FFR was measured. Diagnostic performance of QFR was assessed using an FFR cut-off of 0.80 as reference standard. The QFR-FFR hybrid approach was modeled using the intermediate zone of 0.77 to 0.87 assuming that lesions within the intermediate zone follow the FFR binary cutoff.

Results

In total, 381 vessels in 289 patients were analyzed. The sensitivity, specificity and accuracy on a per vessel-based analysis were 84.6%, 86.3% and 85.6% for QFR and 91.1%, 95.3% and 93.4% for the QFR-FFR hybrid approach. The diagnostic accuracy of QFR-FFR hybrid strategy with invasive FFR measurement is 93.4% and results in a FFR reduction of 56.7%.

Conclusion

QFR has a good correlation and agreement with invasive FFR and a high diagnostic accuracy. A hybrid QFR-FFR approach could extend the use of QFR and reduces the proportion of invasive FFR-measurements needed while maintaining a high accuracy.

Hybrid QFR-FFR strategy

Funding Acknowledgement

Type of funding source: None

External validation of PRECISE-DAPT score and PARIS bleeding risk score in a real-world cohort of patients with acute coronary syndrome

Background

In patients with acute coronary syndrome (ACS) shortened duration of dual antiplatelet therapy (DAPT) should be considered in those at high risk of bleeding. Risk scores may be used to assess the bleeding risk, but their predictive value remains unclear.

Purpose

To externally validate and compare the PRECISE-DAPT and the PARIS bleeding risk scores in patients with ACS.

Methods

From January 2015 to June 2018, all patients admitted with ACS were consecutively included in a single center, observational, prospective registry with follow-up of at least one year. In all patients, the PRECISE-DAPT and the PARIS risk-score were retrospectively assessed. Primary endpoint was moderate or severe bleeding defined as Bleeding Academic Research Consortium (BARC) 3 or 5 bleeding within one year after ACS. Kaplan-Meier curves showed the probabilty of bleeding during follow-up as assessed by both scores. Score discrimination using c-statistic were calculated and calibration curves were visually assessed.

Results

2,729 patients were included for analysis. 93.6% were discharged with ≥2 antithrombotic drugs. At one year follow-up, the event rate of moderate or severe bleeding was 5.5%. High bleeding risk as stratified by both risk scores was associated with higher bleeding rates. Discriminative values for BARC 3 or 5 bleeding at one year were 0.67 [95% CI 0.61–0.72] for the PRECISE-DAPT score and 0.62 [95% CI 0.57–0.68] for the PARIS bleeding score (p=0.31).

Conclusion

The PRECISE-DAPT and the PARIS bleeding scores both showed adequate discriminative performances in predicting moderate or severe bleeding in this study.

Kaplan-meier and ROC-curves

Funding Acknowledgement

Type of funding source: None

The current treatment and predictors of outcome in elderly patients with non-ST-elevation myocardial infarction in an all comers population: the POPular Age registry

Background

Elderly patients form a large and growing part of the patients presenting with non-ST-elevation myocardial infarction (NSTEMI). Choosing the optimal antithrombotic treatment in these elderly patients is more complicated because they frequently have characteristics indicating both a high ischaemic and high bleeding risk.

Purpose

We describe the treatment of elderly patients (&gt;75 years) admitted with NSTEMI, present the outcomes (major adverse cardiovascular events (MACE) and bleeding) and aim to find predictors for adverse events.

Methods

The POPular AGE registry is an investigator initiated, prospective, observational, multicentre study of patients aged 75 years or older presenting with NSTEMI. Patients were recruited between August 1st, 2016 and May 7th, 2018 at 21 sites in the Netherlands. The primary composite endpoint of MACE included cardiovascular death, non-fatal myocardial infarction and non-fatal stroke at one-year follow-up.

Results

A total of 757 patients were enrolled. During hospital stay 76% underwent coronary angiography, 34% percutaneous coronary intervention and 12% coronary artery bypass grafting (CABG). At discharge 78.6% received aspirin (non-users mostly because of the combination of oral anticoagulant and clopidogrel), 49.7% were treated with clopidogrel, 34.2% with ticagrelor and 29.6% were prescribed oral anticoagulation. Eighty-three percent of patients received dual antiplatelet therapy (DAPT) or dual therapy consisting of oral anticoagulation and at least one antiplatelet agent for a duration of 12 months. At one year, the primary outcome of cardiovascular death, myocardial infarction or stroke occurred in 12.3% of patients and major bleeding (BARC 3 or 5) occurred in 4.8% of the patients. The risk of MACE and major bleeding was highest during the first month and stayed high over time for MACE while the risk for major bleeding levelled off. Independent predictors for MACE were age, renal function, medical history of CABG, stroke and diabetes. The only independent predictor for major bleeding was haemoglobin level on admission.

Conclusion

In this all-comers registry, most elderly patients (≥75 years) with NSTEMI are treated with DAPT and undergoing coronary angiography the same way as younger NSTEMI patients from the SWEDEHEART registry. Aspirin use was lower as was the use of the more potent P2Y12 inhibitors compared to the SWEDEHEART which is very likely due to the concomitant use of oral anticoagulation in 30% of patients. The fact that ischemic risk stays constant over 1 year of follow-up, while the bleeding risk levels off after one month may suggest the need of dual antiplatelet therapy until at least one year after NSTEMI.

Funding Acknowledgement

Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): AstraZeneca

P6176Added value of computed tomography fractional flow reserve (FFRCT) in the diagnosis of coronary artery disease (CAD)

Purpose

Multiple non-invasive tests are performed as part of the standard protocol to diagnose CAD, but all are limited to either anatomical or functional assessments. FFRCT is a new non-invasive test that combines anatomical and functional characteristics based on the principles of invasive FFR. This study aims to evaluate the added value of FFRCT beyond the currently used tests.

Methods

Patients having the clinical suspicion of angina pectoris between 2010 and 2011 were included in this cross-sectional study. All underwent exercise stress electrocardiography (X-ECG), SPECT, CT coronary angiography (CCTA) and FFRCT as part of the Horoscope study. Invasive coronary angiography (ICA) and FFR were used as reference standard. Missing values were multiple imputed and five combined models mimicking the clinical workflow were fitted. The area under the receiver operating characteristic (AUROC) curve and Akaike Information Criteria (AIC) were used for comparison.

Results

89 (44%) of the 202 patients included in the analysis had a FFR of ≤0.80, while positive tests were found for X-ECG, SPECT, CCTA and FFRCT in 41%, 47%, 53% and 50% of the cases. The model including pre-test-likelihood and X-ECG had an AUROC of 0.78 (AIC: 236), which significantly increases to 0.89 by adding SPECT (AIC: 170), to 0.87 by adding CCTA (AIC: 191), to 0.92 when adding FFRCT (AIC: 155) and to 0.94 when adding CCTA and SPECT (AIC: 1 40).

ROC-curves for all diagnostic models Model 1 Model 2 Model 3 Model 4 Model 5 Basic model + SPECT + CCTA + CCTA + FFRCT +SPECT + CCTA AIC 236.0 169.8 190.8 154.5 140.1 AUC 0.78 0.89 0.87 0.92 0.94 ROC-curves for all diagnostic models and its AIC and AUC. FFRCT has an improved AUC compared to the basic model and the models including SPECT or CCTA alone, while its AIC is decreased. The model including both SPECT and CCTA has the highest AUC and the lowest AIC and seems therefore the preferable strategy.

ROC curve

Conclusion

This study shows adding FFRCT leads to an increased AUROC and a decreased AIC compared to the basic model. It therefore improves the diagnostic work-up beyond SPECT or CCTA alone in the diagnosis of CAD.

Junctophilin-2 expression rescues atrial dysfunction through polyadic junctional membrane complex biogenesis

Atrial dysfunction is highly prevalent and associated with increased severity of heart failure. While rapid excitation-contraction coupling depends on axial junctions in atrial myocytes, the molecular basis of atrial loss of function remains unclear. We identified approximately 5-fold lower junctophilin-2 levels in atrial compared with ventricular tissue in mouse and human hearts. In atrial myocytes, this resulted in subcellular expression of large junctophilin-2 clusters at axial junctions, together with highly phosphorylated ryanodine receptor (RyR2) channels. To investigate the contribution of junctophilin-2 to atrial pathology in adult hearts, we developed a cardiomyocyte-selective junctophilin-2-knockdown model with 0 mortality. Junctophilin-2 knockdown in mice disrupted atrial RyR2 clustering and contractility without hypertrophy or interstitial fibrosis. In contrast, aortic pressure overload resulted in left atrial hypertrophy with decreased junctophilin-2 and RyR2 expression, disrupted axial junctions, and atrial fibrosis. Whereas pressure overload accrued atrial dysfunction and heart failure with 40% mortality, additional junctophilin-2 knockdown greatly exacerbated atrial dysfunction with 100% mortality. Strikingly, transgenic junctophilin-2 overexpression restored atrial contractility and survival through de novo biogenesis of polyadic junctional membrane complexes maintained after pressure overload. Our data show a central role of junctophilin-2 cluster disruption in atrial hypertrophy and identify transgenic augmentation of junctophilin-2 as a disease-mitigating rationale to improve atrial dysfunction and prevent heart failure deterioration.