South Asian ethnicity is associated with a lower prevalence of atrial fibrillation despite greater prevalence of established risk factors: a population-based study in Bradford Metropolitan District

Aims: Previous studies indicate that South Asians (SAs) may have a reduced risk of developing atrial fibrillation (AF) despite having a higher prevalence of traditional cardiovascular risk factors. This observational study was designed to explore the relative differences between SAs and Whites in a well-defined, multi-ethnic population with careful consideration of traditional cardiovascular risk factors that are thought to contribute to the development of AF. Methods and results: Anonymized data from 417 575 adults were sourced from primary care records within Bradford Metropolitan District, UK. Atrial fibrillation diagnosis was indicated by the presence on the AF Quality Outcomes Framework register. Self-reported ethnicity was mapped to census ethnic codes. The age-standardized prevalence rates of AF were calculated for comparison between the White and SA populations; our study sample presented relative proportions of 2.39 and 0.4%. Multivariable logistic regression analysis was performed to estimate the odds of developing AF given SA ethnicity. Adjustment for age, sex, and established risk factors found a 71% reduction in odds of AF in SAs when compared with Whites [odds ratio (OR): 0.29, 95% confidence interval (CI): 0.26–0.32]. When stratified by ethnicity, analyses revealed significantly different odds of AF for patients with diabetes; diabetes was not associated with the development of AF in the SA population (0.81, 95% CI: 0.63–1.05). Conclusion: This study, in a multi-ethnic population, presents ethnicity as a predictor of AF in which prevalence is significantly lower in SAs when compared with Whites. This is despite SAs having a higher frequency of established risk factors for the development of AF, such as ischaemic heart disease, heart failure, hypertension, and type 2 diabetes. These findings are consistent with previous literature and add weight to the need for further investigation, although this is the first study to investigate the differential associations of individual risk factors with development of AF

Early Repolarization Syndrome; Mechanistic Theories and Clinical Correlates

The early repolarization (ER) pattern on the 12-lead electrocardiogram is characterized by J point elevation in the inferior and/or lateral leads. The ER pattern is associated with an increased risk of ventricular arrhythmias and sudden cardiac death (SCD). Based on studies in animal models and genetic studies, it has been proposed that J point elevation in ER is a manifestation of augmented dispersion of repolarization which creates a substrate for ventricular arrhythmia. A competing theory regarding early repolarization syndrome (ERS) proposes that the syndrome arises as a consequence of abnormal depolarization. In recent years, multiple clinical studies have described the characteristics of ER patients with VF in more detail. The majority of these studies have provided evidence to support basic science observations. However, not all clinical observations correlate with basic science findings. This review will provide an overview of basic science and genetic research in ER and correlate basic science evidence with the clinical phenotype

Self-terminating re-entrant cardiac arrhythmias: quantitative characterization

Atrial and ventricular tachyarrhythmia are often sustained by re-entrant propagation, and explained by deterministic models. A quantitative, stochastic description of self-termination provides an alternative to the current paradigm for re-entrant tachyarrhythmia - that of triggers and a substrate, modelled by parametrically heterogeneous deterministic partial differential equations. Atrial and ventricular data was from recordings obtained during routine clinical monitoring and treatment, either noninvasively or invasively. Atrial and ventricular tachycardia are characterised by their initiation times and durations, re-presented as instantaneous rates, whose means estimate transition probabilities/s for onset and termination. These estimated probabilities range from 10(-9) to 10(-1)/s

the path to silicon-singlet fission heterojunction devices

Singlet exciton fission is an exciton multiplication process that occurs in certain organic materials, converting the energy of single highly-energetic photons into pairs of triplet excitons. This could be used to boost the conversion efficiency of crystalline silicon solar cells by creating photocurrent from energy that is usually lost to thermalisation. An appealing method of implementing singlet fission with crystalline silicon is to incorporate singlet fission media directly into a crystalline silicon device. To this end, we developed a solar cell that pairs the electron-selective contact of a high-efficiency silicon heterojunction cell with an organic singlet fission material, tetracene, and a PEDOT:PSS hole extraction layer. Tetracene and n-type crystalline silicon meet in a direct organic–inorganic heterojunction. In this concept the tetracene layer selectively absorbs blue-green light, generating triplet pairs that can dissociate or resonantly transfer at the organo-silicon interface, while lower-energy light is transmitted to the silicon absorber. UV photoemission measurements of the organic–inorganic interface showed an energy level alignment conducive to selective hole extraction from silicon by the organic layer. This was borne out by current–voltage measurements of devices subsequently produced. In these devices, the silicon substrate remained well-passivated beneath the tetracene thin film. Light absorption in the tetracene layer created a net reduction in current for the solar cell, but optical modelling of the external quantum efficiency spectrum suggested a small photocurrent contribution from the layer. This is a promising first result for the direct heterojunction approach to singlet fission on crystalline silicon

Perspectives on the modern management of non-valvular atrial fi brillation

Atrial fi brillation is the most common clinical arrhythmia. The mainstay in the prevention of atrial fi brillation related stroke is oral anticoagulation. The 2 most important aspects in the management of patients with atrial fi brillation, is therefore risk stratifi cation for stroke and risk assessment for bleeding. Assessment of risk factors is in fact a dynamic process. In appropriate patients, novel anticoagulants are safe and better tolerated, and may be considered as an alternative to warfarin. In patients who are truly intolerant of, or where an absolute contra-indication to anticoagulationexists, occlusion of the left atrial appendage may be considered. Patients are to be carefully counselled with regards this therapy as currently, questions surrounding its safety and long-term effi ciency remain unanswered. This is an area of on-going research and further evidenceis awaited. Catheter ablation of atrial fi brillation is a highly effective therapy to achieve freedom of recurrent arrhythmia and relief from symptomatic atrial fi brillation. Recent systematic reviews demonstrate a low incidence of periprocedural complications with regards catheter ablation of atrial fi brillation, with acute complication rates having decreased signifi cantly in recent years. This may be attributed to increasing experience andimproved catheter technology

Introducing Lived Experience Workers Into a Pregnancy Child Protection Intervention: Parent and Staff Experiences

Pregnancy Family Conferencing is a program to support families with identified child protection risks during the perinatal period. Parents are often cautious about engagement due to mistrust of services and fear of having their babies removed if they discuss their difficulties. Subsequently, the inclusion of lived experience parent supporter roles was piloted to support families with engagement. Little is known about lived experience workers in child protection services and thus this qualitative study explored the experiences and perspectives of families, parent supporters and professionals, and of implementing parent supporter roles into the pregnancy family conferencing program. Inductive thematic analysis identified benefits of lived experience inclusion in child protection processes for parents, families, staff, and services, and highlighted that introducing lived experience positions into systems requires significant reflection, structures, and flexibility to ensure wellbeing and sustainability for those working in the roles. Recommendations are made for other child protection or social work services introducing lived experience roles. The inclusion of lived experience workers into child protection services has enormous potential for improving the experiences of people accessing services, enacting the values of social work, and balancing the inherent power dynamics embedded in practice. However, in introducing such roles into existing systems, there is a role for social workers and other practitioners in advocating for, and leading, the structural changes required to ensure the sustainability of positions and wellbeing of people working in these roles

Tuning Singlet Fission in Homoconjugated Pi-Bridge-Pi Dimers

We have designed a series of pentacene dimers separated by homoconjugated or non-conjugated bridges that exhibit fast and efficient intramolecular singlet exciton fission (iSF). These materials are distinctive among reported iSF compounds because they exist in the unexplored regime of close spatial proximity but weak electronic coupling between the singlet exciton and triplet pair states. Using transient absorption spectroscopy to investigate photophysics in these molecules, we find that homoconjugated dimers display desirable excited state dynamics, with significantly reduced recombination rates as compared to conjugated dimers with similar singlet fission rates. In addition, unlike conjugated dimers, the time constants for singlet fission are relatively insensitive to the interplanar angle between chromophores, since rotation about σ bonds negligibly affects the orbital overlap within the π-bonding network. In the non-conjugated dimer, where the iSF occurs with a time constant > 10 ns, comparable to the fluorescence lifetime, we used electron spin resonance spectroscopy to unequivocally establish the formation of triplet-triplet multiexcitons and uncoupled triplet exciton through singlet fission. Together, these studies enable us to articulate the role of the conjugation motif in iSF

Phase entrainment of induced ventricular fibrillation: A human feasibility and proof of concept study

Cardioversion and defibrillation by a single high energy shock applied by myocardial or body surface electrodes is painful, causes long term tissue damage, and is associated with worsening long term outcomes, but is almost always required for treatment of ventricular fibrillation . As a initial step towards developing methods that can terminate ventricular arrhythmias painlessly, we aim to determine if pacing stimuli at a rate of 5/s applied via an implantable cardiac defibrillator (ICD) can modify human ventricular fibrillation. In 8 patients undergoing defibrillation testing of a new/exchanged intracardiac defibrillator, five seconds of pacing at five stimuli per second was applied during the 10-20 seconds of induced ventricular fibrillation before the defibrillation shock was automatically applied, and the cardiac electrograms recorded and analyzed. The high frequency pacing did not entrain the ventricular fibrillation, but altered the dominant frequency in all 8 patients, and modulated the phase computed via the Hilbert Transform, in four of the patients. In this pilot study we demonstrate that high frequency pacing applied via ICD electrodes during VF can alter the dominant frequency and modulate the probability density of the phase of the electrogram of the ventricular fibrillation