69 research outputs found
The assessment of the coronary microcirculation using the index of microvascular resistance in patients with ischaemic heart disease
No full text© 2013 Dr. Jamie J. W. LaylandDespite improvements in medical therapy, ischaemic heart disease (IHD) remains a significant cause of morbidity and mortality in western societies. The link between epicardial stenosis and myocardial ischaemia is well documented, yet improvements in outcome have come from a focus on myocardial perfusion rather than just restoration of epicardial flow. Myocardial perfusion is comprised of collateral flow; epicardial flow and microcirculatory flow yet the key regulator of this process is the coronary microcirculation. Thus focusing on the coronary microcirculation may provide a further pathway for improving outcomes in patients with ischaemic heart disease. However, factors affecting the coronary microcirculation, in particular the effect of percutaneous coronary intervention, have not extensively studied. Furthermore, the role of the coronary microcirculation in defining key relationships in coronary physiology is also unresolved.
There are a variety of methods that can be utilized to assess the coronary microcirculation both invasive and non-invasive. Each method has its own potential advantages and disadvantages but invasive methods would seem intuitively more useful amongst patients presenting to the catheter laboratory. The Index of Microvascular Resistance (IMR) is a novel invasive technique that has been extensively validated in both in-vivo and in-vitro models.
The principle aim of this thesis is to use the index of microvascular resistance to examine the coronary microcirculation in patients with ischaemic heart disease. Specifically I will examine the predictors of IMR and the influence of the collateral circulation on IMR in patients with stable angina. I will also examine the predictors of microcirculatory dysfunction following PCI and look at factors both clinical and biochemical, effecting IMR measured following PCI. I will also use IMR to define controversial relationships in coronary physiology. Specifically I will examine the relationship between coronary flow reserve and fractional flow reserve and also the ability of the microcirculation to vasodilate in patients with NSTEMI.
A variety of patients with IHD were recruited into the study. 80 patients with stable angina, 50 patients with NSTEMI and 40 patients with STEMI were included in the analysis. Coronary Physiological measurements were taken pre and following PCI in the culprit vessel and where possible, in an angiographically normal reference vessel. Bloods were taken at the time of the procedure and sequentially every 6 to 12 hours up to 24 hours following percutaneous coronary stenting.
In summary, the main findings of this thesis are:
i) Epicardial Stenosis does not increase microvascular resistance when collateral flow is accounted for.
ii) The resting status of the coronary microcirculation is a key predictor of post PCI coronary microvascular function.
iii) The resting status of the coronary microcirculation is an independent predictor of periprocedural myocardial infarction. Specifically localized impairment of the coronary microcirculation as determined by the relative pre IMR ratio was a predictor of periprocedural myocardial infarction.
iv) The ability of the coronary microcirculation to vasodilate is preserved in selected patients with NSTEMI. This property is directly correlated with the baseline level of IMR and myocardial injury and suggests that the use of diagnostic tests that rely on hyperemia may be suitable for use in selected patients with NSTEMI.
v) The discordance between fractional and coronary flow reserve is not explained by variations in microvascular resistance.
The findings of this PhD are novel and have implications for the prediction of myocardial injury caused by percutaneous coronary intervention (PCI). Specifically that targeting a high IMR prior to stenting may allow for further improvements in outcome in elective PCI. I have also clearly shown (in the largest studied cohort to date) that the measurement of collateral flow is mandated when calculating microvascular resistance to avoid overestimation. Furthermore, that maximal hyperemia is possible in high acuity patients with non-ST segment myocardial infarction, potentially allowing the use of diagnostic tests such as fractional flow reserve that rely on an intact microcirculation. This may have far reaching clinical implications but warrants confirmation in a large prospective, randomised study
Letter by Layland et al Regarding Article, “Validation of Intravascular Ultrasound–Derived Parameters With Fractional Flow Reserve for Assessment of Coronary Stenosis Severity”
No full textEmerging evidence for the use of colchicine for secondary prevention of coronary heart disease
No full textCardiovascular disease imposes a major burden on Australians and the Australian health care system. Due to campaigns to reduce smoking and the widespread use of effective lipid-lowering therapy, there has been a significant decline in the death rate from cardiovascular disease over several decades.1 However, nearly 600 000 patients are hospitalised each year with cardiovascular disease, at a cost to the community of over $4 billion in 2018 – 19.1 Patients with coronary heart disease face an ongoing risk of cardiovascular events even when their lipid-lowering and antithrombotic therapy is optimal. Thus, to reduce morbidity in these patients, there is a need for doctors to employ additional therapies that are effective, safe, readily available and cost-efficient for this purpose. In the past decade, increasing evidence has accrued suggesting that there are cardiovascular benefits associated with adding colchicine 0.5 mg daily to lipid-lowering and antithrombotic therapy for secondary prevention of coronary heart disease.Stefan M Nidorf, Jamie Layland, Philip C Robinson, Sanjay Patel, Peter J Psaltis, Peter L Thompso
Utility and safety of invasive (fractional flow reserve) and non-invasive (cardiac magnetic resonance imaging) diagnostic tests in patients with NSTEMI
No full textA prospective randomised controlled clinical trial of treatment decisions informed by invasive functional testing of coronary artery disease severity compared with standard angiography-guided management was implemented in 350 patients with a recent non-ST elevation myocardial infarction (NSTEMI) admitted to 6 hospitals in the National Health Service. The main aims of this study were to examine the utility of both invasive fractional flow reserve (FFR) and non-invasive cardiac magnetic resonance imaging (MRI) amongst patients with a recent diagnosis of NSTEMI. In summary, the findings of this thesis are: (1) the use of FFR combined with intravenous adenosine was feasible and safe amongst patients with NSTEMI and has clinical utility; (2) there was discordance between the visual, angiographic estimation of lesion significance and FFR; (3). The use of FFR led to changes in treatment strategy and an increase in prescription of medical therapy in the short term compared with an angiographically guided strategy; (4) in the incidence of major adverse cardiac events (MACE) at 12 months follow up was similar in the two groups. Cardiac MRI was used in a subset of patients enrolled in two hospitals in the West of Scotland. T1 and T2 mapping methods were used to delineate territories of acute myocardial injury. T1 and T2 mapping were superior when compared with conventional T2-weighted dark blood imaging for estimation of the ischaemic area-at-risk (AAR) with less artifact in NSTEMI. There was poor correlation between the angiographic AAR and MRI methods of AAR estimation in patients with NSTEMI. FFR had a high accuracy at predicting inducible perfusion defects demonstrated on stress perfusion MRI.
This thesis describes the largest randomized trial published to date specifically looking at the clinical utility of FFR in the NSTEMI population. We have provided evidence of the diagnostic and clinical utility of FFR in this group of patients and provide evidence to inform larger studies. This thesis also describes the largest ever MRI cohort, including with myocardial stress perfusion assessments, specifically looking at the NSTEMI population. We have demonstrated the diagnostic accuracy of FFR to predict reversible ischaemia as referenced to a non-invasive gold standard with MRI. This thesis has also shown the futility of using dark blood oedema imaging amongst all comer NSTEMI patients when compared to novel T1 and T2 mapping methods
Safety of guidewire-based measurement of fractional flow reserve and the index of microvascular resistance using intravenous adenosine in patients with acute or recent myocardial infarction
No full textAimsCoronary guidewire-based diagnostic assessments with hyperemia may cause iatrogenic complications. We assessed the safety of guidewire-based measurement of coronary physiology using intravenous adenosine in patients with an acute coronary syndrome.MethodsWe prospectively enrolled invasively managed STEMI and NSTEMI patients in two simultaneously conducted studies in 6 centers (NCT01764334; NCT02072850). All of the participants underwent a diagnostic coronary guidewire study using intravenous adenosine (140 ?g/kg/min) infusion for 1–2 min. The patients were prospectively assessed for the occurrence of serious adverse events (SAEs) and symptoms and invasively measured hemodynamics were also recorded.Results648 patients (n = 298 STEMI patients in 1 hospital; mean time to reperfusion 253 min; n = 350 NSTEMI in 6 hospitals; median time to angiography from index chest pain episode 3 (2, 5) days) were included between March 2011 and May 2013. Two NSTEMI patients (0.03% overall) experienced a coronary dissection related to the guidewire. No guidewire dissections occurred in the STEMI patients. Chest symptoms were reported in the majority (86%) of patient's symptoms during the adenosine infusion. No serious adverse events occurred during infusion of adenosine and all of the symptoms resolved after the infusion ceased.ConclusionsIn this multicenter analysis, guidewire-based measurement of FFR and IMR using intravenous adenosine was safe in patients following STEMI or NSTEMI. Self-limiting symptoms were common but not associated with serious adverse events. Finally, coronary dissection in STEMI and NSTEMI patients was noted to be a rare phenomenon
Fractional flow reserve vs angiography in non-ST- elevation myocardial infarction: long-term results of the FAMOUS-NSTEMI trial
No full textLGBTQ+ Youth Identity Disclosure Processes: A Systematic Review
No full textThis article was originally published in Adolescent Research Review. The version of record is available at: https://doi.org/10.1007/s40894-024-00243-1.
© The Author(s) 2024.
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
This research was featured in UDaily on 10/10/2024 at: https://www.udel.edu/udaily/2024/october/mousavi-layland-disclosure-LGBTQ-national-coming-out-day/Disclosure, as a complex social process, profoundly influences the well-being of LGBTQ + youth. This study, guided by the disclosure process model, systematically reviews and synthesizes LGBTQ + youth disclosure literature, considering it as a developmental, multi-component process across various contexts. After screening 5,433 articles, 29 studies were identified, focusing on identity-disclosure processes among LGBTQ + youth aged 26 or younger. These studies were scrutinized for disclosure process components, individual and contextual factors shaping disclosure, and potential bias. Findings reveal a predominant focus on avoidance goals (e.g., fear of rejection, LGBTQ + stigma) rather than approach goals (e.g., seeking belonging, authenticity) in studies examining the disclosure decision-making process. Reactions to disclosures were often mixed, initially leaning negative but evolving positively over time. Mental health emerged as the most studied outcome of disclosure. Additionally, disclosure processes were shaped by disclosure recipients, social context, and cultural beliefs. In conclusion, research on LGBTQ + youth disclosure is advancing and evolving, with increasing attention to disclosure goals and outcomes. Rather than viewing disclosure as a singular event, this review underscores LGBTQ + youth identity disclosure as a complex, developmental process extending over time and across diverse contexts
Many shades of grey:Seeking the optimal medical therapy of acute coronary syndrome in older people
No full textIschaemic heart disease is the leading cause of death worldwide. Age is the strongest risk factor, yet older patients are consistently underrepresented in clinical trials. With an ageing population, knowledge of the evidence base for the treatment of older patients with acute coronary syndrome (ACS) is crucial. As people age, their responses to medications change, and they may become more susceptible to adverse effects of cardiovascular medications. Management of ACS in older people may be further complicated by the presence of comorbidities, polypharmacy and frailty. Treatment decisions need to be individualised, with consideration of patient preferences, functional and cognitive status and life expectancy. This review aims to summarise the current data for the management of older patients with ACS, with a focus on pharmacological treatment.</p
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