Spontaneous Coronary Artery Dissection in Hyperdominant Left Anterior Coronary Descending Artery

A hyperdominant left anterior descending coronary artery variation is a rare but important diagnosis because of the risk for large-territory ischemia. We describe a very rare presentation of spontaneous coronary artery dissection in the distal portion of a hyperdominant left anterior descending coronary artery. No similar cases have been described.

First Measurement of η Meson Production in Neutrino Interactions on Argon with MicroBooNE

We present a measurement of η production from neutrino interactions on argon with the MicroBooNE detector. The modeling of resonant neutrino interactions on argon is a critical aspect of the neutrino oscillation physics program being carried out by the DUNE and Short Baseline Neutrino programs. η production in neutrino interactions provides a powerful new probe of resonant interactions, complementary to pion channels, and is particularly suited to the study of higher-order resonances beyond the Δ(1232). We measure a flux-integrated cross section for neutrino-induced η production on argon of 3.22±0.84(stat)±0.86(syst) 10^{-41}  cm^{2}/nucleon. By demonstrating the successful reconstruction of the two photons resulting from η production, this analysis enables a novel calibration technique for electromagnetic showers in GeV accelerator neutrino experiments.

Impact of the COVID-19 pandemic on provision of interventional cardiology and cardiac surgery services in Australia: a review of Medicare claims data

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has significantly impacted healthcare service provision worldwide. There is limited information on changes in invasive cardiovascular services during the pandemic, particularly in Australia.

AIM

We sought to assess temporal trends on the use of interventional cardiology and cardiac surgery services before and following the COVID-19 pandemic in Australia.

METHODS

Medicare Benefits Schedule items data from the Australian Government Services Australia on outpatient and private hospital interventional cardiology procedures (coronary angiogram, percutaneous coronary intervention and transcatheter aortic valve implantation) and cardiac surgery procedures (coronary artery bypass grafting [CABG] and surgical valve replacement, repair and annuloplasty) were analysed from March 2019 to 2021. This was superimposed on monthly COVID-19 case data obtained from the Australian Department of Health and Aged Care epidemiology reports.

RESULTS

A sustained reduction in CABG (-10.1%) and surgical valve intervention (-11.1%) was appreciated from March 2019-2020 to March 2020-2021, in the first year of the COVID-19 pandemic. During this period, an overall increase (+25.9%) in the use of transcatheter aortic valve implantation was observed. Following the initial period of mandated isolation in March-April 2020, a reduction in coronary angiography (-29.1%) and percutaneous coronary intervention (-19.5%) was observed in comparison to March-April 2019; however, this was largely attenuated over time.

CONCLUSIONS

The COVID-19 pandemic has resulted in reductions in the use of interventional cardiology and cardiac surgery services, with cardiac surgery most affected. However, an increase in uptake of transcatheter aortic valve implantation has been observed during the pandemic. This may have implications for future planning and resource allocation in the aftermath of the pandemic.

Echocardiographic parameters of cardiac structure and function in the diagnosis of acute myocarditis in adult patients: A systematic review and meta-analysis

BACKGROUND

Transthoracic echocardiography (TTE) plays a key role in the initial work-up of myocarditis where the identification of pathologic structural and functional changes may assist in its diagnosis and management. The aim of this systematic review was to appraise the evidence for the utility of echocardiographic parameters of cardiac structure and function in the diagnosis of myocarditis in adult populations.

METHODS

A systematic literature search of medical databases was performed using PRISMA principles to identify all relevant studies assessing TTE parameters in adult patients with myocarditis (1995-2020; English only; PROSPERO registration CRD42021243598). Data for a range of structural and functional TTE parameters were individually extracted and those with low heterogeneity were then meta-analyzed using a random-effects model for effect size, and assessed through standardized mean difference (SMD).

RESULTS

Available data from six studies (with a pooled total of 269 myocarditis patients and 240 controls) revealed that myocarditis can be reliably differentiated from healthy controls using echocardiographic measures of left ventricular (LV) size and systolic function, in particular LV end-diastolic diameter, LV ejection fraction (LVEF) and LV global longitudinal strain (LV-GLS) (p ≤ .01 for all). LV-GLS demonstrated the highest overall effect size, followed by LVEF and LVEDD (SMD: |0.46-1.98|). Two studies also demonstrated that impairment in LV-GLS was associated with adverse cardiovascular outcomes in this population, irrespective of LVEF.

CONCLUSIONS

LV-GLS demonstrated the greatest overall effect size and therefore ability to differentiate myocarditis populations from healthy controls. GLS was also shown to be a predictor of adverse cardiovascular outcomes, in this population.

HIGHTLIGHTS

What is already known on this subject? Myocarditis is a disease process that is often a diagnosis of exclusion, as it frequently mimics other acute cardiac pathologies. Transthoracic echocardiography is traditionally the initial imaging modality used for noninvasive structural assessment in populations with myocarditis. What might this study add? This study demonstrates that left ventricular (LV) global longitudinal strain, LV ejection fraction and LV end-diastolic diameter can differentiate between myocarditis patients and healthy controls. LV-GLS demonstrated the greatest overall effect size when comparing these two populations, in comparison to the other measures. How might this impact on clinical practice? This study demonstrates that assessment of myocardial deformation indices allows for sensitive discrimination between myocarditis patients from healthy controls. Routine assessment of LV-GLS may serve as an important diagnostic tool in the acute care setting.

Search for Heavy Neutral Leptons in Electron-Positron and Neutral-Pion Final States with the MicroBooNE Detector

We present the first search for heavy neutral leptons (HNLs) decaying into νe^{+}e^{-} or νπ^{0} final states in a liquid-argon time projection chamber using data collected with the MicroBooNE detector. The data were recorded synchronously with the NuMI neutrino beam from Fermilab's main injector corresponding to a total exposure of 7.01×10^{20} protons on target. We set upper limits at the 90% confidence level on the mixing parameter |U_{μ4}|^{2} in the mass ranges 10≤m_{HNL}≤150  MeV for the νe^{+}e^{-} channel and 150≤m_{HNL}≤245  MeV for the νπ^{0} channel, assuming |U_{e4}|^{2}=|U_{τ4}|^{2}=0. These limits represent the most stringent constraints in the mass range 35 Collapse

Key Words Collapse

MESH Headings Collapse

Grants Collapse

Use of Anticoagulation for Thromboembolic Prophylaxis in Patients With Atrial High-Rate Episodes on Device Monitoring: A Narrative Review

Ischemic stroke and systemic thromboembolism are primary drivers of significant morbidity and mortality in patients with atrial fibrillation (AF). Although stroke is commonly the first index presentation of clinically silent AF, the growing use of continuous rhythm monitoring through cardiac implanted electronic devices has enabled earlier and increased detection of AF in patients who are otherwise asymptomatic before stroke development. Atrial high-rate episodes (AHREs) are atrial tachyarrhythmias frequently detected by cardiac implanted electronic devices; these events represent subclinical AF and other atrial tachyarrhythmias that can lead to stroke development and AF. Although the presence of AHREs increases the risk of developing both clinical AF and stroke compared with absence of AHREs, there has been a significant clinical variability in anticoagulation initiation in these subjects. In this narrative review, we explore the current evidence and published research surrounding the association between AHREs and stroke development in addition to the utility of anticoagulation in this population for thromboembolic prophylaxis.

The impact of body mass index on cardiac structure and function in a cohort of obese patients without traditional cardiovascular risk factors

Background

Obesity has been linked with alterations in hemodynamic, autonomic, and hormonal pathways in the body, leading to a spectrum of cardiovascular changes. We sought to evaluate the effects of obesity on structural and functional changes of the heart in the absence of cardiac disease and associated risk factors.

Methods

We identified healthy outpatients without any cardiovascular disease or risk factors from our institution's echocardiography database (2017-2020). Patients were stratified by body mass index (BMI; normal: 18.5-25 kg/m2; overweight: 25-30 kg/m2; class 1 obesity: 30-35 kg/m2; class 2 obesity: 35-40 kg/m2; class 3 obesity: >40 kg/m2). Traditional and advanced echocardiographic parameters of cardiac chamber size and function including left ventricular global longitudinal strain (LV-GLS), left atrial reservoir strain (LASr), and right ventricular free wall strain (RV-FWS) were examined. The optimal cut-off BMI for discriminating LV-GLS (>-17.5%), LASr (<23%), and RV-FWS (>-23%) impairment was calculated using ROC curves.

Results

307 patients were assessed (41.5 ± 13.3yrs; 36.5%male; LVEF 61.3 ± 4.8%). No significant differences in indexed chamber volumes or LVEF were appreciated across BMI groups (p > 0.05 for all). LV-GLS, LASr, and RV-FWS were all significant on one-way ANOVA for differences from the group mean (all p < 0.01). Jonckheere-Terpstra test confirmed a significant trend of lower absolute LV-GLS, LASr and RV-FWS values across the rising BMI groups. On ROC curve analysis, a BMI value of 29.9 kg/m2, 35.1 kg/m2, and 37.3 kg/m2 were associated with LASr (AUC: 0.75), RV-FWS (AUC: 0.72), and LV-GLS (AUC: 0.75) impairment respectively.

Conclusion

Obesity is linked with subclinical reduction of cardiac function in otherwise healthy subjects without cardiovascular risk factors, with reduction of left atrial function occurring at lower BMI, followed by the right and left ventricular function.

Characterization of Subclinical Cardiac Dysfunction by Speckle Tracking Echocardiography in Patients With Non-severe Acute-Phase Myocarditis

Subclinical changes in left ventricular (LV) function have been demonstrated in patients with acute-phase myocarditis (AM) despite normal LV ejection fraction. The impact of AM on right ventricular (RV) and left atrial (LA) function has not been well described. This study aimed to assess for subclinical chamber dysfunction by speckle tracking echocardiography and its clinical relevance in this population. Patients with a diagnosis of AM (as per the European Society of Cardiology Working Group on Myocardial and Pericardial Diseases) admitted to our institution from 2013 to 2018 were assessed. Patients with elevated serum troponin, normal coronary assessment, and normal LV ejection fraction on transthoracic echocardiogram were included. Clinical and echocardiographic parameters were compared with healthy age-, gender- and risk-factor matched controls. Global longitudinal strain assessed through speckle tracking echocardiography was performed using vendor independent software (v4.6; TomTec Arena, Munich, Germany). The final cohort consisted of 80 patients (40 AM patients and 40 controls). No significant differences in baseline clinical characteristics were observed between groups. Of the echocardiographic parameters, AM patients had lower LV-global longitudinal strain (p <0.01), lower RV free-wall strain (p = 0.02) and lower peak LA strain (p <0.01). There were no differences in traditional echocardiographic measures of LV, RV, and LA function appreciated between groups. The presence of multichamber involvement was associated with peak Troponin levels (p <0.01). In conclusion, our study demonstrates the presence of global subclinical myocardial dysfunction in patients with AM. Additionally, the presence of multichamber involvement was significantly associated with degree of myocardial necrosis.

Effectiveness of perioperative anticoagulation interruption without heparin bridging on thromboembolic events in patients with atrial fibrillation undergoing elective invasive procedures: a systematic review protocol

OBJECTIVE

This review will determine whether withholding heparin bridging is superior to bridging in patients with atrial fibrillation requiring temporary interruption of anticoagulation therapy in the perioperative period of an elective invasive procedure.

INTRODUCTION

Atrial fibrillation is the most commonly diagnosed clinical arrhythmia. It is an important cause of cardioembolic events, requiring the use of oral anticoagulation in most patients. It is unclear whether heparin bridging during temporary interruption of anticoagulants has superior outcomes compared with no bridging in the perioperative setting.

INCLUSION CRITERIA

This review will consider studies that compare adults aged 18 years or older; diagnosed with atrial fibrillation; undergoing elective invasive procedures; and who have had oral anticoagulants temporarily withheld with heparin bridging with patients without heparin bridging. Participants will be excluded if they had an alternative reason for anticoagulation or were admitted for emergency surgery. Outcomes will include arterial or venous thromboembolism (including stroke, transient ischemic attack, systemic embolism), major bleeding events, non-major bleeding events, length of hospital stay, and all-cause mortality.

METHODS

The review will follow the JBI methodology for systematic reviews of effectiveness. Databases including MEDLINE, Embase, CINAHL, and CENTRAL will be searched for randomized and non-randomized trials from inception until the present. Two independent reviewers will screen citations by title and abstract, and again at full text. Risk of bias will be assessed using the JBI critical appraisal instrument, and data will be extracted using a modified extraction tool. Results will be synthesized using a random effects meta-analysis and presented in a forest plot. Heterogeneity will be tested for using the standard χ 2 and I2 tests. Overall certainty of evidence will be evaluated using the GRADE approach.

REVIEW REGISTRATION

PROSPERO CRD42022348538.

A survey in the West Midlands of the United Kingdom of current practice in managing hypotension in lower segment caesarean section under spinal anaesthesia

BACKGROUND

Spinal anaesthesia, the most common form of anaesthesia for caesarean section, leads to sympathetic blockade and profound maternal hypotension resulting in adverse maternal and neonatal outcomes. Hypotension, nausea and vomiting remain common but until the publication of the National Institute of Health and Care Excellence (NICE) 2021 guidance, no national guideline existed on how best to manage maternal hypotension following spinal anaesthesia for caesarean section. A 2017 international consensus statement recommended prophylactic vasopressor administration to maintain a systolic blood pressure of >90% of an accurate pre-spinal value, and to avoid a drop to <80% of this value. This survey aimed to assess regional adherence to these recommendations, the presence of local guidelines for management of hypotension during caesarean section under spinal anaesthesia, and the individual clinician's treatment thresholds for maternal hypotension and tachycardia.

METHODS

The West Midlands Trainee-led Research in Anaesthesia and Intensive Care Network co-ordinated surveys of obstetric anaesthetic departments and consultant obstetric anaesthetists across 11 National Health Service Trusts in the Midlands, England.

RESULTS

One-hundred-and-two consultant obstetric anaesthetists returned the survey and 73% of sites had a policy for vasopressor use; 91% used phenylephrine as the first-line drug but a wide range of recommended delivery methods was noted and target blood pressure was only listed in 50% of policies. Significant variation existed in both vasopressor delivery methods and target blood pressures.

CONCLUSIONS

Although NICE has since recommended prophylactic phenylephrine infusion and a target blood pressure, the previous international consensus statement was not adhered to routinely.

Vessel-Specific Outcomes of Deferred Revascularization Following Negative Fractional Flow Reserve

Variations in myocardial supply area and hydrostatic pressure gradients result in greater likelihood of positive fractional flow reserve (FFR) in the left anterior descending (LAD) compared with the circumflex (Cx) and right coronary artery (RCA). However, the same FFR threshold for deferral of revascularization is applied to all arteries, without evidence that this results in equivalent outcomes. We assessed vessel-specific outcomes of deferred revascularization for the 3 major coronary arteries based on FFR > 0.8. In this retrospective study, data were obtained on consecutive patients who underwent indicated FFR assessment across 2 tertiary institutions. Patients with deferred revascularization were followed for 36 months for the primary end point of vessel-specific target lesion failure (TLF). Of 1,916 major coronary arteries (1,579 patients), the odds ratio of positive FFR was highest in the LAD (odds ratio 3.36, p <0.001). In total, 867 vessels (733 patients) with FFR > 0.8 had complete 3-year medical record follow-ups. The TLF rate for deferred vessels was 10.21%, 11.52%, and 10.96% for the LAD, Cx, and RCA respectively. In a multivariate analysis, there was no significant difference in the odds of TLF for the 0.84 (0.53 to 1.33, p = 0.459), 1.17 (0.68 to 2.01, p = 0.582), and 1.11 (0.62 to 2.00, p = 0.715) in the LAD, Cx, and RCA, respectively. In a multivariate analysis, diabetes mellitus was the only baseline characteristic significantly associated at risk of TLF (1.43 [1.01 to 2.02], p = 0.043). In conclusion, despite greater likelihood of positive FFR in the LAD, the FFR threshold for deferred revascularization resulted in equivalent outcomes in all 3 major coronary arteries, and patients with diabetes mellitus may represent a group that requires aggressive surveillance and risk factor modification after deferred revascularization.

Atrial Cardiopathy: Redefining Stroke Risk Beyond Atrial Fibrillation

Atrial fibrillation (AF) and ischemic stroke are dual epidemics in society, both associated with poor clinical outcomes, patient disability, and significant healthcare expenditure. The conditions are interrelated and share complex causal pathways. Risk stratification algorithms such as the CHADS₂ and CHA₂DS₂-VASc score offer predictive value in stroke and systemic embolism risk in the AF population, however, have limitations. Recent evidence suggests that an intrinsically prothrombotic atrial substrate may precede and promote AF and lead to thromboembolic events independent of the arrhythmia, allowing for a window of intervention before arrhythmia detection and development of ischemic stroke. Initial work has found incremental value in addition of parameters of atrial cardiopathy to traditional stroke risk stratification algorithms, however, requires evaluation with dedicated prospective randomized studies before use in real-world clinical practice. In this narrative review, we explore current evidence and literature on the use of measures of atrial cardiopathy in stroke risk stratification and management.

BARRIERS TO GUIDELINE-DIRECTED ANTICOAGULATION IN PATIENTS WITH ATRIAL FIBRILLATION NEW APPROACHES TO AN OLD PROBLEM

Optimising guideline-directed anticoagulation in atrial fibrillation remains a perennial problem despite strong evidence for improved health outcomes with use of guideline-directed anticoagulation. Efforts to improve uptake have been hampered by barriers found at the level of the physician, patient, disease and choices of therapy. Clinician judgement is often clouded by factors such as therapeutic inertia, aversion to bleeding risk and implicit bias. For patients, negative pre-conceptions of therapy, impact of therapy on day-to-day life and the nocebo effect pose significant barriers. Both groups are impacted by poor education. Utility of a single pronged approach directed towards clinicians or patients have demonstrated variable success, with the highest impact appreciated in studies employing shared decision models. Further, there is emerging evidence for use of integrated models of care, which have shown improved efficacy in improving patient outcomes, as well as use of digital platforms such as mobile app-based interventions, which can be of aid to the clinician in improving patient adherence to anticoagulation with translated improved outcomes in clinical trials. Our narrative review article aims to investigate the physician and health system, patient, as well as drug therapy and disease barriers to uptake of guideline-directed anticoagulation in treatment of non-valvular atrial fibrillation.

Temporal trends in cardiovascular care: Insights from the COVID-19 pandemic

In response to the ongoing COVID-19 pandemic, public health care measures have been implemented to limit spread of the contagion and ensure adequate healthcare resource allocation. Correlating with these measures are observed changes in the incidence and outcomes of cardiovascular conditions in the absence of COVID-19 infection. The pandemic has resulted in a reduction in acute coronary syndrome, heart failure and arrhythmia admissions but with worsened outcomes in those diagnosed with these conditions. This is concerning of an underdiagnosis of cardiovascular diseases during the pandemic. Furthermore, cardiovascular services and investigations have decreased to provide healthcare allocation to COVID-19 related services. This threatens an increasing future prevalence of cardiovascular morbidity in healthcare systems that are still adapting to the challenges of a continuing pandemic. Adaption of virtual training and patient care delivery platforms have been shown to be useful, but adequate resources allocation is needed to ensure effectiveness in vulnerable populations.

Development of process analytical tools for rapid monitoring of live virus vaccines in manufacturing

In the development of end-to-end large-scale live virus vaccine (LVV) manufacturing, process analytical technology (PAT) tools enable timely monitoring of critical process parameters (CPP) and significantly guide process development and characterization. In a commercial setting, these very same tools can enable real time monitoring of CPPs on the shop floor and inform harvest decisions, predict peak potency, and serve as surrogates for release potency assays. Here we introduce the development of four advanced PAT tools for upstream and downstream process monitoring in LVV manufacturing. The first tool explores the application of capacitance probes for real time monitoring of viable cell density in bioreactors. The second tool utilizes high content imaging to determine optimum time of infection in a microcarrier process. The third tool uses flow virometry (or nanoscale flow cytometry) to monitor total virus particle counts across upstream and downstream process steps and establishes a robust correlation to virus potency. The fourth and final tool explores the use of nucleic acid dye staining to discriminate between “good” and “damaged” virus particles and uses this strategy to also monitor virus aggregates generated sometimes during downstream processing. Collectively, these tools provide a comprehensive monitoring toolbox and represent a significantly enhanced control strategy for the manufacturing of LVVs.

Prognostic implications of traditional and non-traditional cardiovascular risk factor profiles in patients with non-valvular atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is a prevalent disease with associated mortality risk, mediated in large part through its associated cardiovascular risk factors. Standard modifiable cardiovascular risk factors (SMuRFs; hypercholesterolaemia, hypertension, diabetes and smoking) are established drivers of cardiovascular disease; however, the importance of non-traditional mediators of cardiovascular risk (NTRFs) such as chronic renal impairment, obstructive sleep apnoea and obesity is emerging. The differential impact of these risk factors on outcomes in patients with AF is not well studied.

METHODS

Consecutive patients admitted to our service between January 2013 and January 2018 with a primary diagnosis of non-valvular AF were assessed. Assessment of demographic, anthropometric, risk factor profile and pharmacotherapeutics was performed. The clinical course of these patients was followed for up to five years for the composite outcome of all-cause death and major adverse cardiovascular events.

RESULTS

Of the 1010 patients (62.29 ± 16.81 years, 51% men) included, 154 (15%) had no risk factors, 478 (47%) had only SMuRFs, 59 (6%) had only NTRFs and 319 (32%) had both SMuRFs and NTRFs. Over a mean follow-up period of 33.18 ± 21.27 months, a total of 288 patients met the composite outcome. On Cox regression, the coexistence of SMuRFs and NTRFs was an independent predictor of the composite outcome (HR 1.40; 95%CI 1.09-1.82, p = .01). Other independent predictors included age, heart failure, CHA₂ DS₂ VASc score, persistent AF and anaemia.

CONCLUSIONS

The presence of both SMuRFs and NTRFs has prognostic implications in patients with non-valvular AF.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Effect of overdispersion of lethal lesions on cell survival curves

The linear-quadratic (LQ) model is the most commonly used mechanism to predict radiobiological outcomes. It has been used extensively to describe dose-responsein vitroandin vivo. There are, however, some questions about its applicability in terms of its capacity to represent some profound mechanistic behaviour. Specifically, empirical evidence suggests that the LQ model underestimates the survival of cells at low doses while overestimating cell death at higher doses. It is believed to be driven from the usual LQ model assumption that radiogenic lesions are Poisson distributed. In this context, we use a negative binomial (NB) distribution to study the effect of overdispersion on the shapes and the possibility of reducing dose-response curvature at higher doses. We develop an overdispersion model for cell survival using the non-homologous end-joining (NHEJ) pathway double-strand break (DSB) repair mechanism to investigate the effects of the overdispersion on probabilities of repair of DSBs. The error distribution is customised to ensure that the refined overdispersion parameter depends on the mean of the distribution. The predicted cell survival responses for V79, AG and HSG cells exposed to protons, helium and carbon ions are compared with the experimental data in low and high dose regions at various linear energy transfer (LET) values. The results indicate straightening of dose-response and approaching a log-linear behaviour at higher doses. The model predictions with the measured data show that the NB modelled survival curves agree with the data following medium and high doses. Model predictions are not validated at very tiny and very high doses; the approach presented provides an analysis of mechanisms at the microscopic level. This may help improve the understanding of radiobiological responses of survival curves and resolve discrepancies between experimental and theoretical predictions of cell survival models.

Search for an Excess of Electron Neutrino Interactions in MicroBooNE Using Multiple Final-State Topologies

We present a measurement of ν_{e} interactions from the Fermilab Booster Neutrino Beam using the MicroBooNE liquid argon time projection chamber to address the nature of the excess of low energy interactions observed by the MiniBooNE Collaboration. Three independent ν_{e} searches are performed across multiple single electron final states, including an exclusive search for two-body scattering events with a single proton, a semi-inclusive search for pionless events, and a fully inclusive search for events containing all hadronic final states. With differing signal topologies, statistics, backgrounds, reconstruction algorithms, and analysis approaches, the results are found to be either consistent with or modestly lower than the nominal ν_{e} rate expectations from the Booster Neutrino Beam and no excess of ν_{e} events is observed.

The utility of cardiac magnetic resonance imaging in the diagnosis of adult patients with acute myocarditis: A systematic review and meta-analysis

BACKGROUND

The presence of myocardial late gadolinium enhancement (LGE) indicates myocyte necrosis, and assists with the diagnosis of acute myocarditis (AM). Cardiac magnetic resonance (CMR) measures other than LGE i.e. tissue characterization and myocardial structural and functional parameters, play an important diagnostic role in assessment for inflammation, as seen in AM. The aim of this systematic review was to appraise the evidence for the use of quantitative CMR measures to identify myocardial inflammation in order to diagnose of AM in adult patients.

METHODS

A systematic literature search of medical databases was performed using PRISMA principles to identify relevant CMR studies on AM in adults (2005-2020; English; PROSPERO registration CRD42020180605). Data for a range of quantitative CMR measures were extracted. Continuous variables with low heterogeneity were meta-analyzed using a random-effects model for overall effect size measured as the standard mean difference (SMD).

RESULTS

Available data from 25 studies reporting continuous quantitative 1.5 T CMR measures revealed that AM is most reliably differentiated from healthy controls using T1 mapping (SMD 1.80, p < 0.01) and T2 mapping (SMD 1.63, p < 0.01), respectively. All other measures examined including T2-weighted ratio, extracellular volume, early gadolinium enhancement ratio, right ventricular ejection fraction, and LV end-diastolic volume, mass, ejection fraction, longitudinal strain, circumferential strain, and radial strain also had discriminatory ability although with smaller standard mean difference values (|SMD| 0.32-0.96, p < 0.01 for all).

CONCLUSIONS

Meta-analysis shows that myocardial tissue characterization (T1 mapping>T2 mapping) followed by measures of left ventricular structure and function demonstrate diagnostic discriminatory ability in AM.

Diagnostic And Prognostic Value Of Left Atrial Function In Identification Of Cardioembolism And Prediction Of Outcomes In Patients With Cryptogenic Stroke

BACKGROUND

Strokes of undetermined source, commonly termed cryptogenic stroke (CS), account for a significant proportion of ischemic stroke etiology and have high rates of stroke recurrence. The heterogeneous etiology of CS makes decisions regarding treatment for such patients challenging. We sought to evaluate the diagnostic and prognostic value of left atrial (LA) function in identification of cardioembolism and prediction of outcomes in patients with CS.

METHODS

Consecutive patients admitted to our tertiary institution with ischemic stroke or transient ischemic attack (TIA) who underwent transthoracic echocardiography were recruited with comprehensive evaluation of LA metrics including LA strain. Ischemic strokes / TIAs were classified as non-cardioembolic, cryptogenic and cardioembolic. A total of 709 patients (66.0±15.1 years, 55% male) were recruited. 291 patients had CS, 189 had non-cardioembolic stroke and 229 had cardioembolic stroke. Patients with CS were followed for 20.0±13.8 months for recurrent ischemic stroke / TIA.

RESULTS

Receiver-operating characteristic curves showed LA reservoir (LASr) and contractile (LASct) strains to be strong discriminators of cardioembolic strokes and log rank tests showed both measures to be significantly associated with the distribution of time to recurrent ischemic stroke / TIA in patients with CS. Multivariable hazards models showed LASr and LASct to be independent predictors of recurrent ischemic stroke / TIA in CS patients in addition to eGFR and active smoking.

CONCLUSIONS

LASr and LASct were strong discriminators of cardioembolic stroke and independently predicted recurrent ischemic stroke / TIA in patients with CS. Use of LA strain may improve risk stratification and decision-making in patients with CS, with particular regards to prolonged ambulatory heart rhythm monitoring and/or empiric anticoagulation.

First Measurement of Energy-Dependent Inclusive Muon Neutrino Charged-Current Cross Sections on Argon with the MicroBooNE Detector

We report a measurement of the energy-dependent total charged-current cross section σ(E_{ν}) for inclusive muon neutrinos scattering on argon, as well as measurements of flux-averaged differential cross sections as a function of muon energy and hadronic energy transfer (ν). Data corresponding to 5.3×10^{19} protons on target of exposure were collected using the MicroBooNE liquid argon time projection chamber located in the Fermilab booster neutrino beam with a mean neutrino energy of approximately 0.8 GeV. The mapping between the true neutrino energy E_{ν} and reconstructed neutrino energy E_{ν}^{rec} and between the energy transfer ν and reconstructed hadronic energy E_{had}^{rec} are validated by comparing the data and Monte Carlo (MC) predictions. In particular, the modeling of the missing hadronic energy and its associated uncertainties are verified by a new method that compares the E_{had}^{rec} distributions between data and a MC prediction after constraining the reconstructed muon kinematic distributions, energy, and polar angle to those of data. The success of this validation gives confidence that the missing energy in the MicroBooNE detector is well modeled and underpins first-time measurements of both the total cross section σ(E_{ν}) and the differential cross section dσ/dν on argon.

Search for Neutrino-Induced Neutral-Current Δ Radiative Decay in MicroBooNE and a First Test of the MiniBooNE Low Energy Excess under a Single-Photon Hypothesis

We report results from a search for neutrino-induced neutral current (NC) resonant Δ(1232) baryon production followed by Δ radiative decay, with a ⟨0.8⟩  GeV neutrino beam. Data corresponding to MicroBooNE's first three years of operations (6.80×10^{20} protons on target) are used to select single-photon events with one or zero protons and without charged leptons in the final state (1γ1p and 1γ0p, respectively). The background is constrained via an in situ high-purity measurement of NC π^{0} events, made possible via dedicated 2γ1p and 2γ0p selections. A total of 16 and 153 events are observed for the 1γ1p and 1γ0p selections, respectively, compared to a constrained background prediction of 20.5±3.65(syst) and 145.1±13.8(syst) events. The data lead to a bound on an anomalous enhancement of the normalization of NC Δ radiative decay of less than 2.3 times the predicted nominal rate for this process at the 90% confidence level (C.L.). The measurement disfavors a candidate photon interpretation of the MiniBooNE low-energy excess as a factor of 3.18 times the nominal NC Δ radiative decay rate at the 94.8% C.L., in favor of the nominal prediction, and represents a greater than 50-fold improvement over the world's best limit on single-photon production in NC interactions in the sub-GeV neutrino energy range.

The role of echocardiography in the diagnosis of adult patients with myocarditis: a systematic review and meta-analysis

Funding Acknowledgements

Type of funding sources: None.

Background

Transthoracic echocardiography (TTE) plays a key diagnostic role in the initial work-up of patients presenting with myocarditis. Its utility in myocarditis is for identification of structural and functional changes, which may assist with diagnosis, surveillance and prognostication.

Purpose

The purpose of this systematic review and meta-analysis was to appraise the evidence associated with the use of echocardiography for the diagnosis of myocarditis in adults.

Methods

A systematic literature search of medical databases including Pubmed, Ovid Online, EMBASE, Web of Science, Cochrane Central Register of Controlled Trials, Scopus, ProQuest, Science Direct and grey literature was performed using PRISMA principles to identify all relevant TTE studies on myocarditis in adult patients (1995-2020; English only; PROSPERO registration CRD42021243598). Data for a range of TTE parameters were individually extracted and then meta-analysed using a random-effects model for overall effect size through standard mean difference (SMD).

Results

Of the 13 relevant studies, 6 were included and revealed that myocarditis can be reliably differentiated from healthy controls, both in the acute and sub-acute phase by left ventricular (LV) global longitudinal strain, and less so by LV ejection fraction and LV end-diastolic volume (p &lt; 0.05 for all). See Table. LV-GLS demonstrated the strongest ability to discriminate myocarditis patients from healthy controls when compared to standard two-dimensional measures of LV size and function (p &lt; 0.05).

Conclusions

LV-GLS demonstrated the best discriminatory ability for differentiation of myocarditis from adult healthy controls. Further research is required to characterize the utility of these quantitative parameters in the diagnostic work-up of these patients. Abstract Figure.

Embolic Stroke of Undetermined Source: Approaches in Risk Stratification for Cardioembolism

Ischemic stroke is a leading cause of morbidity and mortality worldwide. Embolic stroke of undetermined source has been recently proposed to categorize nonlacunar ischemic strokes without confirmed etiology after adequate investigation with a likely embolic stroke mechanism. A strategy of empirical anticoagulation for embolic stroke of undetermined source patients is attractive but may only be beneficial in a select subset of patients. Strategies which would help identify the subset of embolic stroke of undetermined source patients most likely to have cardioembolic origin of stroke, and hence benefit from anticoagulation, are needed. This article will review current evidence which may be useful in the development of a risk stratification approach based on arrhythmia monitoring, cardiac imaging, and clinical risk stratification. This approach may be beneficial in clinical practice in improving patient outcomes and reducing stroke recurrence in this population; however, further work is required with active trials underway.

Unilateral diaphragmatic paresis following supracostal post-percutaneous nephrolithotomy

Unilateral acquired diaphragmatic paresis is a known complication of thoracic surgeries. Direct mechanical injury to the phrenic nerve during surgery results in this complication. However its occurrence post-percutaneous nephrolithotomy (PCNL) has not been described. We report a 43-year-old man who underwent prone PCNL for endourological management of left complete staghorn calculus. Access via the 10^th left intercostal space, under fluoroscopy, was carried out to remove the calculus. Post-operative, the routine chest radiograph revealed left hemidiaphragmatic blunting. Computerized tomography of the chest confirmed left hemidiaphragmatic elevation, suggesting unilateral diaphragmatic paresis. He did not have any respiratory symptoms, was managed conservatively with chest physiotherapy and incentive spirometry and responded extremely well. The absence of reported cases of diaphragmatic paresis post PCNL lends to a dearth in knowledge regarding recognition and management. This case report aims to acquaint urologists with this rare complication associated with supracostal PCNL and provide a rational management plan.

Patterns of left ventricular recovery in patients with heart failure with mid-range ejection fraction

Background

Heart failure with mid-range ejection fraction (HFmEF) represents a new classification of heart failure with intermediate clinical characteristics to those with HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF). A proportion of HFmEF is attributed to atrio-ventricular dyssynchrony from atrial fibrillation (AF) as opposed to a primary cardiomyopathy with intrinsic cardiac myocyte dysfunction.

Purpose

We aim to compare the rate of left ventricular ejection fraction (LVEF) recovery in those with AF-mediated cardiomyopathy compared to those with primary myocyte dysfunction.

Methods

Consecutive patients with stable non-ischaemic cardiomyopathy with LVEF 40–49% on transthoracic echocardiography (TTE) were recruited from our institution's heart failure clinic and followed for 18 months. Patients with ischaemic, valvular or congenital heart disease, incomplete follow-up or poor quality TTE images were excluded. Eligible patients were separated into two groups: AF-mediated (n=44); and primary myocyte dysfunction (n=116).

Results

A total of 160 patients (62.1±16.4 years, 62% men) were included. There was no significant difference in age (p=0.06) and gender (p=0.59). Comorbid AF was higher in those with AF-mediated HFmEF (100 vs 28.4%; p&lt;0.01), otherwise no significant differences in clinical history was found between groups. AF-mediated HFmEF had lower rates of cardiac-specific beta-blocker use (15.9 vs 47.4%; p&lt;0.01). Baseline TTE showed similar LVEF and LV global longitudinal strain. On log-rank analysis there was no significant difference in all-cause death (p=0.75), or HF-related hospitalisation (p=0.14), however, higher rates of LVEF recovery were observed in the AF-mediated HFmEF group (p&lt;0.01). See figure 1.

Conclusion

There were higher rates of LVEF recovery in those with AF-mediated HFmEF compared to those with a primary myocardial disorder despite lower rates of cardiac-specific beta-blocker use. This did not translate to improvements in intermediate-term survival or HF related hospitalisation. These findings provide insight into the natural history of the disorder and its clinical phenotype.

Funding Acknowledgement

Type of funding sources: None. Figure 1. Rate of LVEF Recovery

LV-GLS is a predictor of all-cause death and cardiovascular MACE events in patients with neuro-immunological disorders

Background

Neuro-immunological disorders encompass several disease states, including multiple sclerosis (MS), autoimmune encephalitis (AE) and myasthenia gravis (MG). These autoimmune conditions are mediated via pro-inflammatory cytokines, and there is growing evidence to suggest cardiovascular involvement within these inflammatory states. Left ventricular global longitudinal strain (LV-GLS) is proposed to be a more sensitive measure of LV systolic function when compared to standard two-dimensional measures such as LV ejection fraction (LVEF).

Purpose

The purpose of this study was to assess for subclinical cardiac dysfunction in a cohort of patients with neuro-immunological disorders and correlate this with the development of outcomes on follow-up.

Methods

Consecutive patients with MS, AE and MG admitted to our institution during 2013–2020 were assessed (n=102). Patients without pre-existing cardiovascular disease, LVEF &lt;50% or lack of comprehensive transthoracic echocardiography during their index admission were included (n=55). This group was compared to age- and gender-matched controls (n=55) LV-GLS was measured offline using vendor-independent software (TomTec Arena, Germany v4.6) by two cardiologists blinded to the patient group or outcomes. These patients were followed for up for the composite outcome of all-cause death and major adverse cardiovascular events (MACE).

Results

A total of 55 patients (31 MS, 14 AE and 10 MG) were age- and gender- matched to 55 controls. There was no significant difference in baseline demographic characteristics or cardiovascular risk factors between groups. Patients with neuro-immunological disorders demonstrated impaired LV-GLS (−17.6±3.5 vs −20.8±1.9; p&lt;0.01) when compared to healthy controls, despite an LVEF within the normal range (60.9±7.7 vs 64.1±5.7; p=0.02) in both groups. There were a total of 9 (16.4%) outcomes during a mean follow-up of 41.0±33.0 months. LV-GLS was the only significant echocardiographic predictor of all-cause death and MACE events (p=0.013) on multi-variate analysis.

Conclusions

Our results suggest that patients with neuro-immunological disorders have subclinical LV dysfunction as assessed by LV-GLS which has prognostic capacity in this population. Further larger studies are required to further characterize this phenomenon.

Funding Acknowledgement

Type of funding sources: None.

Patients with rare autoimmune inflammatory disorders demonstrate sub-clinical left ventricular dysfunction

Background

ANCA-associated Vasculitis (AAV) and inflammatory myositis (IM) are rare inflammatory autoimmune disorders mediated via pro-inflammatory cytokines and result in a systemic inflammatory state with multi-organ involvement. There is growing evidence to suggest cardiovascular involvement within these inflammatory states. Left ventricular global longitudinal strain (LV-GLS) is proposed to be a more sensitive measure of LV systolic function when compared to standard two-dimensional measures such as LV ejection fraction (LVEF).

Purpose

The purpose of this study was to assess for subclinical cardiac dysfunction in these cohorts when compared to controls.

Methods

Consecutive patients with AAV (n=56) and IM (n=68) admitted to our institution during 2013–2021 were assessed. Patients with pre-existing cardiovascular disease, significant renal impairment (eGFR &lt;30mL/min/1.73m2), LVEF &lt;50% or lack of comprehensive transthoracic echocardiography during admission were excluded (n=72). LV-GLS was measured offline using vendor-independent software (TomTec Arena, Germany v4.6).

Results

A total of 52 patients (22 AAV and 30 IM) were age- and gender-matched to 52 controls. In comparison of the two study populations (AAV and IM), patients with AAV had higher rates of renal impairment (p=0.02) but lower rates of interstitial lung disease when compared to IM (p=0.02). There were no differences between the two groups in terms of cardiovascular risk factors, demographics or other laboratory investigations (p&gt;0.05 for all). In comparison to the control population, patients with AAV and IM had higher indexed LV mass and a lower TAPSE, respectively, when compared to controls. These cohorts also demonstrated impaired LV-GLS (−17.7±2.6 vs −20.6±2.4; p&lt;0.01) when compared to healthy controls, despite no differences in LVEF (62.6±7.8 vs 61.8±5.4; p=0.56) between both groups.

Conclusions

Our results suggest that patients with autoimmune inflammatory disorders demonstrate subclinical LV dysfunction which is likely secondary to a chronic inflammatory state.

Funding Acknowledgement

Type of funding sources: None.

Search for a Higgs Portal Scalar Decaying to Electron-Positron Pairs in the MicroBooNE Detector

We present a search for the decays of a neutral scalar boson produced by kaons decaying at rest, in the context of the Higgs portal model, using the MicroBooNE detector. We analyze data triggered in time with the Fermilab NuMI neutrino beam spill, with an exposure of 1.93×10^{20} protons on target. We look for monoenergetic scalars that come from the direction of the NuMI hadron absorber, at a distance of 100 m from the detector, and decay to electron-positron pairs. We observe one candidate event, with a standard model background prediction of 1.9±0.8. We set an upper limit on the scalar-Higgs mixing angle of θ<(3.3-4.6)×10^{-4} at the 95% confidence level for scalar boson masses in the range (100-200)  MeV/c^{2}. We exclude, at the 95% confidence level, the remaining model parameters required to explain the central value of a possible excess of K_{L}^{0}→π^{0}νν[over ¯] decays reported by the KOTO collaboration. We also provide a model-independent limit on a new boson X produced in K→πX decays and decaying to e^{+}e^{-}.

Cosmic Ray Background Removal With Deep Neural Networks in SBND

In liquid argon time projection chambers exposed to neutrino beams and running on or near surface levels, cosmic muons, and other cosmic particles are incident on the detectors while a single neutrino-induced event is being recorded. In practice, this means that data from surface liquid argon time projection chambers will be dominated by cosmic particles, both as a source of event triggers and as the majority of the particle count in true neutrino-triggered events. In this work, we demonstrate a novel application of deep learning techniques to remove these background particles by applying deep learning on full detector images from the SBND detector, the near detector in the Fermilab Short-Baseline Neutrino Program. We use this technique to identify, on a pixel-by-pixel level, whether recorded activity originated from cosmic particles or neutrino interactions.

Association of Left Atrial Metrics with Atrial Fibrillation Rehospitalization and Adverse Cardiovascular Outcomes in Patients with Nonvalvular Atrial Fibrillation following Index Hospitalization

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice, with significant clinical and economic burdens, largely driven by adverse cardiovascular outcomes and AF-related hospitalization. Left atrial (LA) parameters have been shown to have prognostic value in cardiovascular disease states. We sought to evaluate the prognostic value of measures of LA size and function, as measured through LA volume index and LA emptying fraction (LAEF), respectively, for AF rehospitalization and long-term adverse outcomes in patients with nonvalvular AF following index hospitalization.

METHODS

In this retrospective study, 594 consecutive patients (mean age, 67.8 ± 13.6 years, 53% men) admitted to a tertiary referral center with nonvalvular AF were assessed. Patients who underwent transthoracic echocardiography during their index admission and had complete follow-up data were included and followed for a mean period of 33.18 ± 21.27 months for the primary outcome of AF rehospitalization. The secondary outcome was a composite of all-cause death and major adverse cardiovascular events.

RESULTS

The primary outcome occurred in 250 (42%) patients, and the secondary outcome occurred in 219 (37%) patients. On multivariable regression analysis, LAEF had an independent association with AF rehospitalization (hazard ratio [HR] = 0.967; 95% CI, 0.953-0.982; P < .01), and time-dependent receiver operating characteristic curves demonstrated LAEF to have strong diagnostic accuracy in predicting early and intermediate AF rehospitalization. Both LA volume index (HR = 1.014; 95% CI, 1.003-1.026; P = .01) and LAEF (HR = 0.982; 95% CI, 0.970-0.993; P < .01) were associated with all-cause death and major adverse cardiovascular events.

CONCLUSIONS

Adverse LA remodeling, as reflected through LA enlargement and reduced LA mechanical function, is associated with AF rehospitalization and long-term adverse cardiovascular outcomes in hospitalized patients with nonvalvular AF.

167 The Experience and Outcomes of Elective Urgent and Cancer Surgery in A District General Hospital in The United Kingdom During Covid-19 Pandemic

Background

Many urgent and elective surgeries were postponed to cope with the Coronavirus disease (COVID-19) pandemic, with latest data found a substantial postoperative mortality risk (25·6%, 18.9%) after emergency and elective surgery, respectively.

Our institution was one of the first trust to offer essential elective surgery using a “COVID-free” designated site during the start of the pandemic.

The aim of this study is to analyse the clinical outcomes of patients who underwent essential elective procedures during the virus outbreak in the UK.

Method

Retrospective analysis of outcomes all patients who had undergone urgent elective and cancer surgery, from 30th March 2020 to 21st May 2020, using an implemented “Super Green Pathway”.

The primary endpoints were 30 days mortality and COVID related morbidities, and the secondary endpoints were surgical related complications and oncological outcomes.

Results

92 patients (Male:45%; Female:55%) across 5 surgical specialties were identified. There was no record of mortality in our cohort. Only 1 patient was tested positive for SARS-CoV-2, 18 days after the initial operation without any pulmonary complications.

Conclusions

It is possible to mitigate the high mortality risk of postoperative complications associated with COVID-19, with no delay to essential surgeries for cancer patients, thus delivering safe practice during the pandemic.

Integrated Care in Atrial Fibrillation: A Road Map to the Future

Atrial fibrillation (AF) is the most commonly encountered arrhythmia in clinical practice with an epidemiological coupling appreciated with advancing age, cardiometabolic risk factors, and structural heart disease. This has resulted in a significant public health burden over the years, evident through increasing rates of hospitalization and AF-related clinical encounters. The resultant gap in health care outcomes is largely twinned with suboptimal rates of anticoagulation prescription and adherence, deficits in symptom identification and management, and insufficient comorbid cardiovascular risk factor investigation and modification. In view of these shortfalls in care, the establishment of integrated chronic care models serves as a road map to best clinical practice. The expansion of integrated chronic care programs, which include multidisciplinary team care, nurse-led AF clinics, and use of telemedicine, are expected to improve AF-related outcomes in the coming years. This review will delve into current gaps in AF care and the role of integrated chronic care models in bridging fragmentations in its management.