Prevalence of coronary artery disease and coronary microvascular dysfunction in heart failure with preserved ejection fraction

Background Heart failure (HF) is a major cause of morbidity and mortality worldwide. HF with preserved ejection fraction (HFpEF) now accounts for around half of the HF population. To date, no treatments for HFpEF have proven effect and outcomes have not improved in recent decades. The heterogeneity of the HFpEF population and the failure of randomised controlled trials (RCTs) to demonstrate effective therapies has led to attempts to identify sub-phenotypes of HFpEF which may respond to targeted therapies. Recent studies suggest that epicardial coronary artery disease (CAD) and coronary microvascular dysfunction (CMD) may play an important role in a substantial group of patients with HFpEF. A novel paradigm has been proposed suggesting that endothelium-dependent CMD may play a key role in the unifying pathophysiology of HFpEF. I performed a systematic review of the literature describing the prevalence of epicardial CAD and CMD in HFpEF populations. Most studies were retrospective observational and population-based studies with inconsistent definitions of HF, preserved left ventricular ejection fraction (LVEF) and CAD. Studies which documented CAD angiographically were almost exclusively performed in highly-selected convenience cohorts. Consequently, prevalence estimates of CAD in HFpEF varied considerably between studies. Similarly, studies assessing CMD in HFpEF reported inconsistent results due to variable definitions of CMD and methods of assessing coronary microvascular function. Therefore, the prevalence of epicardial CAD and CMD have not been prospectively and systematically studied in an unselected HFpEF population. Aims The main aims of this study were to determine the prevalence of obstructive epicardial CAD, CMD and previous myocardial infarction (MI) in an unselected cohort of patients hospitalised with HFpEF using reference standard invasive investigations. Methods This was a prospective, multicentre, observational study of patients hospitalised with HFpEF. All patients recruited had a confirmed diagnosis of HFpEF according to the 2016 European Society of Cardiology (ESC) HF guidelines. Participants underwent invasive coronary angiography with guidewire-based assessment of coronary flow reserve (CFR) and the index of microcirculatory resistance (IMR), followed by vasoreactivity testing with intra-coronary acetylcholine. This allowed the comprehensive assessment of epicardial and microvascular structure and function to determine the prevalence of CAD, CMD and coronary endothelial dysfunction in the cohort. Adenosine perfusion cardiac magnetic resonance (CMR) imaging was also performed to assess the burden of myocardial infarction (MI), diffuse fibrosis and inducible ischaemia in the study population. Patients were followed up by electronic medical record linkage for a minimum of 12 months. Results Of 2285 near-consecutive patients hospitalised with suspected HF, 628 were confirmed to have a diagnosis of HFpEF, and 106 HFpEF patients met the inclusion criteria and agreed to participate in the study. A total of 83 participants underwent invasive coronary angiography or CMR. Seventy-five participants underwent invasive coronary angiography, 62 had guidewire-based coronary physiology testing, and 41 underwent vasoreactivity testing. Fifty-two participants underwent CMR and 44 had both invasive coronary angiography and CMR. Twenty-three patients did not proceed to the study investigations, predominantly due to a decline in health, functional status or renal function making proceeding with the study investigations inappropriate or unsafe. In this unselected hospitalised HFpEF cohort, the prevalence of obstructive epicardial CAD on invasive assessment was 51% (95% confidence interval [CI] 39-62%); half of patients with obstructive epicardial disease had no clinical history of CAD. On invasive coronary physiological testing, 41 patients (66% [95% CI 53-77%]) had endothelium-independent CMD, and 10 (24% [95% CI 13-40%]) had endothelium-dependent CMD. Overall, 91% of participants had evidence of macrovascular and/or microvascular CAD. Of those who underwent CMR, 27% (95% CI 16-41%) had evidence of previous MI and 32% (95% CI 19-48%) had inducible ischaemia. Over half of patients with CMR-proven MI had no history of clinically apparent MI. Over a median follow-up period of 18 months, study participants with obstructive epicardial CAD had significantly more hospitalisations (for any cause, a cardiovascular cause or HF) than those without obstructive CAD. There was no significant difference in outcomes between those with or without endothelium-independent or -dependent CMD. Conclusion Both epicardial CAD and CMD are common in the HFpEF population, and there is a high prevalence of clinically unrecognised obstructive epicardial CAD and previous MI. Patients with obstructive epicardial CAD had significantly more hospitalisations than those without obstructive disease. Treatments for epicardial CAD (e.g. coronary revascularisation) might improve quality of life and reduce hospitalisations in HFpEF patients with CAD. Although it has been hypothesised that CMD in HFpEF is the result of endothelial dysfunction, it appears to be predominantly due to endothelium-independent mechanisms. This may have important implications for future treatments directed at CMD in patients with HFpEF

Association is not causation: treatment effects cannot be estimated from observational data in heart failure

Aims: Treatment ‘effects’ are often inferred from non-randomized and observational studies. These studies have inherent biases and limitations, which may make therapeutic inferences based on their results unreliable. We compared the conflicting findings of these studies to those of prospective randomized controlled trials (RCTs) in relation to pharmacological treatments for heart failure (HF). Methods and results: We searched Medline and Embase to identify studies of the association between non-randomized drug therapy and all-cause mortality in patients with HF until 31 December 2017. The treatments of interest were: angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, mineralocorticoid receptor antagonists (MRAs), statins, and digoxin. We compared the findings of these observational studies with those of relevant RCTs. We identified 92 publications, reporting 94 non-randomized studies, describing 158 estimates of the ‘effect’ of the six treatments of interest on all-cause mortality, i.e. some studies examined more than one treatment and/or HF phenotype. These six treatments had been tested in 25 RCTs. For example, two pivotal RCTs showed that MRAs reduced mortality in patients with HF with reduced ejection fraction. However, only one of 12 non-randomized studies found that MRAs were of benefit, with 10 finding a neutral effect, and one a harmful effect. Conclusion: This comprehensive comparison of studies of non-randomized data with the findings of RCTs in HF shows that it is not possible to make reliable therapeutic inferences from observational associations. While trials undoubtedly leave gaps in evidence and enrol selected participants, they clearly remain the best guide to the treatment of patients

One Minute Tips: Take Two! Student Perceptions of Videos Used for Information Literacy Instruction

Digital learning objects are all the rage, but what does the YouTube generation think? We will discuss student perceptions of videos used for information literacy instruction and methods for incorporating short videos into assessable learning activities

Multi-Epoch Matrix Factorization Mechanisms for Private Machine Learning

We introduce new differentially private (DP) mechanisms for gradient-based machine learning (ML) with multiple passes (epochs) over a dataset, substantially improving the achievable privacy-utility-computation tradeoffs. We formalize the problem of DP mechanisms for adaptive streams with multiple participations and introduce a non-trivial extension of online matrix factorization DP mechanisms to our setting. This includes establishing the necessary theory for sensitivity calculations and efficient computation of optimal matrices. For some applications like $>\!\! 10,000$ SGD steps, applying these optimal techniques becomes computationally expensive. We thus design an efficient Fourier-transform-based mechanism with only a minor utility loss. Extensive empirical evaluation on both example-level DP for image classification and user-level DP for language modeling demonstrate substantial improvements over all previous methods, including the widely-used DP-SGD . Though our primary application is to ML, our main DP results are applicable to arbitrary linear queries and hence may have much broader applicability.Comment: 9 pages main-text, 3 figures. 40 pages with 13 figures tota

Recycled culture: the significance of intertextuality in twenty-first century musical theatre

The twenty-first century musical is dominated by high-profile adaptations and the recycling of popular texts in a wider trend Graham Allen terms ‘cultural regurgitation’. From Wicked (2003) and Billy Elliot the Musical (2005) to Jersey Boys (2005) and The Book of Mormon (2011), the commercial musical stage is a prominent site of high-profile intertextuality in that it draws from ‘innumerable centres of culture’ to fuel an evening’s entertainment. Given the proliferation of such intertextuality, however, this trend has received little critical attention beyond the detailing of these musicals as ‘safe-bet’ entertainments which attract an audience through the recycling of familiar elements. The primary aim of this thesis is therefore to fill an important gap within existing scholarship by investigating how intertextual references function and operate within contemporary musical theatre. In differentiating the various styles of intertextual reference evidenced within the form, this thesis argues that most twenty-first century musicals either adapt a specific text, capitalise on nostalgia, fashion a bricolage of references or metatheatricalise perceptions of musical theatre as an art form. In doing so, it put forwards the claim that musical theatre invites intertextuality as a diverse layering of textual elements in and of itself. Not only is musical theatre an inherently intertextual form, but it ultimately requires intertextuality to reflect the recycled nature of popular culture more broadly

The emerging burden of heart failure in adults with congenital heart disease

Ntiloudi et al. confirm the high burden of failure-related morbidity and mortality in adults with CHD. However, the pathways leading to heart failure in ACHD are heterogeneous and often poorly understood. Most importantly, there is a need for more randomized trials. Trials investigating effects on symptoms and surrogate measures of disease need not be large. However, much larger trials are required to investigate the effects of treatment on disease progression and prognosis, requiring collaborations at national and international levels, as is already the case for other forms of heart failure

(Amplified) Banded Matrix Factorization: A unified approach to private training

Matrix factorization (MF) mechanisms for differential privacy (DP) have substantially improved the state-of-the-art in privacy-utility-computation tradeoffs for ML applications in a variety of scenarios, but in both the centralized and federated settings there remain instances where either MF cannot be easily applied, or other algorithms provide better tradeoffs (typically, as $\epsilon$ becomes small). In this work, we show how MF can subsume prior state-of-the-art algorithms in both federated and centralized training settings, across all privacy budgets. The key technique throughout is the construction of MF mechanisms with banded matrices (lower-triangular matrices with at most $\hat{b}$ nonzero bands including the main diagonal). For cross-device federated learning (FL), this enables multiple-participations with a relaxed device participation schema compatible with practical FL infrastructure (as demonstrated by a production deployment). In the centralized setting, we prove that banded matrices enjoy the same privacy amplification results as the ubiquitous DP-SGD algorithm, but can provide strictly better performance in most scenarios -- this lets us always at least match DP-SGD, and often outperform it.Comment: 34 pages, 13 figure

Aminophobanes:hydrolytic stability, tautomerism and application in Cr-catalysed ethene oligomerisation

The bicyclic aminophobanes have significantly different chemistry from their acyclic analogues Cy2PNHR′.</p