1,721,008 research outputs found
The role of high sensitivity troponin outside the context of acute coronary syndromes
No full textIschaemic heart disease remains the leading cause of mortality worldwide and, whilst there has been progress in reducing this, mainly due to smoking cessation, there are concerns that the obesity epidemic may negate this progress. Chest pain is a key presenting complaint for patients with ischaemic heart disease but it is also seen in a range of other conditions. Given that chest pain accounts for around 6% of emergency department presentations, healthcare systems need an efficient algorithm for managing these patients quickly. The use of biomarkers has become a central component in the diagnosis of myocardial infarction as defined by international guidelines. High sensitivity cardiac troponin (hs-cTn) is now considered the biomarker of choice and, as such, is widely used across a range of different healthcare systems.Cardiac troponin (cTn) is a key component of the calcium-mediated contractile apparatus found within cardiac myocytes and is released upon injury to the myocardium. There are three isoforms of cTn, two of which have been found to be specific to the myocardium and, as such, these assays became embedded in routine practice. There was, however, one important limitation in their use; in order to reach adequate levels of sensitivity, a sample was needed at 10-12 hours after the onset of chest pain. This had significant resource implications for healthcare systems, and this became a driver for the development of high sensitivity cTn (hs-cTn) assays which now haveexcellent performance within three hours of chest pain. Whilst this has proven highly beneficial to many aspects of clinical care, especially the ability to rule out a heart attack very early, the increased sensitivity of the assays, combined with increased usage, has resulted in concentrations above the manufacturer’s upper limit of normal (ULN) being frequently detected across a range of presentations not traditionally associated with acute myocardial infarction (AMI). The result has been uncertainty, and some inaccuracy, about the interpretation of these results in clinical practice. Excitingly, however, there are emerging data to suggest that the hs-cTn concentration, outside the context of myocardial infarction, may act as a biomarker of prognosis.In view of this, the aim of my thesis was to assess whether there was an association between hs-cTn concentration and mortality outside the context of AMI in several patient populations. The first two chapters of this thesis follow on from the original CHARIOT study (which was performed by my predecessor, Dr Mark Mariathas). In the first chapter I demonstrate that elevated hs-cTnI concentrations are frequently seen on presentation to the emergency department and, whilst these are associated with the severity of illness, they are also independent predictors of short term mortality. In the second chapter, I demonstrate that hs-cTnI concentrations are independently associated with one year mortality (both cardiovascular and non-cardiovascular) across a complete, consecutive hospital cohort of 20,000 patients (inpatients, outpatients and those in the emergency department) regardless of whether there was a clinical indication for the test. Finally, in a population of patients in critical care I show that the hs-cTnI concentration is associated with illness severity but is also independently associated with critical care mortality. Furthermore, that hs-cTnI concentration on admission to critical care performs as well as previously validated prognostic scores in discriminating critical care mortality.In summary, this thesis demonstrates that hs-cTnI concentration is associated with both short and medium term outcomes across a range of populations. Further research is now required to assess whether any medical intervention can alter the risk in those patients identified by hs-cTn as having adverse prognosis. The potential clinical value of the concept that hs-cTn is a general biomarker for prognosis is far reaching: it would represent a novel application for the assay outside the context of its use to rule out AMI
Is the true clinical value of high-sensitivity troponins as a biomarker of risk? The concept that detection of high-sensitivity troponin ‘never means nothing’
No full textIntroductionHigh-sensitivity troponin (hs-cTn) assays are central to the diagnosis of myocardial infarction (MI). Their increased sensitivity has facilitated rapid pathways for the exclusion of MI. However, hs-cTn is now more readily detectable in patients without symptoms typical of MI, in whom a degree of myocardial injury is assumed. Recently, the practice of using the 99th centile of hs-cTn as a working ‘upper reference limit’ has been challenged. There is increasing evidence that hs-cTn may provide useful prognostic information, regardless of any suspicion of MI, and as such these assays may have potential as a general biomarker for mortality. This raises the concept that detection of hs-cTn ‘never means nothing.’Areas coveredIn this review, we will evaluate the evidence for the use of hs-cTn assays outside their common clinical indication to rule out or diagnose acute MI.Expert opinionThe data presented suggest that hs-cTn testing may in the future have a generalized role as a biomarker of mortality risk and may be used less as a test for ruling in acute MI, but will remain a frontline test to exclude that diagnosis in ED. Further, the data suggest that the detection of hs-cTn ‘never means nothing.
Atheroma or ischemia: which is more important for managing patients with stable chest pain?
No full textIn the evaluation and management of patients with stable chest pain/chronic coronary syndrome, cardiologists need to be able to weigh up the relative merits of managing these patients using either optimal therapy alone or optimal therapy plus revascularization. These decisions rely on an understanding of both the presence and the degree of coronary atheroma and myocardial ischemia, and the impact that these have on patients' symptoms and their prognosis. In this review the authors examine the relative impact of the anatomical and physiological assessment of patients with chronic coronary syndrome and how it can be used to achieve optimal and tailored therapy.</p
Cardiogenic shock due to acute severe ischemic mitral regurgitation.
No full textThe reduction in patients presenting with ST-elevation myocardial infarction (STEMI) during the COVID19 crisis could have resulted from fears about developing COVID-19 infection in hospital. Patients who delay presenting with STEMI are more likely to develop mechanical complications, including acute ischemic mitral regurgitation (MR). We present a 69-year-old women with an inferior STEMI and cardiogenic shock due to acute ischemic MR who delayed presenting to hospital due to the fear of COVID-19. Early identification of this mechanical complication using transthoracic echocardiography in the Emergency Department enabled the team to target her optimisation. Ultimately these patients require urgent surgery to repair the mitral valve and revascularize the myocardium but they are often too unwell to undergo surgery and even when it is feasible the outcomes are poor
Fractional flow reserve derived from coronary computed tomography: where are we now and where are we heading?
No full textComputed tomography coronary angiography is emerging as the preferred diagnostic tool for patients with chest pain. Additional knowledge of the extent and distribution of myocardial ischemia enables tailored patient management. Computed tomography-derived fractional flow reserve (FFRCT) employs computed tomography coronary angiography raw data processed via complex computational fluid dynamics and produces a surrogate of the invasive fractional flow reserve (FFR) thus delivering anatomical and physiological assessment in a single test. FFRCT has been extensively validated against invasive FFR and observational clinical studies have consistently demonstrated its utility as gatekeeper to invasive angiography while also reducing downstream clinical events and costs. Novel workstation-based models of estimating FFR are now being tested. Ongoing and future research results will define their role in clinical practice.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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