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Darrel Francis

Christopher A Rajkumar, Sukhjinder S Nijjer, Graham D Cole, Rasha Al-Lamee, Darrel P Francis
No abstract text is available yet for this article.
March 2018: Circulation. Cardiovascular Quality and Outcomes
Habib Rehman Khan, Ines Kralj-Hans, Shouvik Haldar, Toufan Bahrami, Jonathan Clague, Anthony De Souza, Darrel Francis, Wajid Hussain, Julian Jarman, David Gareth Jones, Neeraj Mediratta, Raad Mohiaddin, Tushar Salukhe, Simon Jones, Joanne Lord, Caroline Murphy, Joanna Kelly, Vias Markides, Dhiraj Gupta, Tom Wong
BACKGROUND: Atrial fibrillation is the commonest arrhythmia which raises the risk of heart failure, thromboembolic stroke, morbidity and death. Pharmacological treatments of this condition are focused on heart rate control, rhythm control and reduction in risk of stroke. Selective ablation of cardiac tissues resulting in isolation of areas causing atrial fibrillation is another treatment strategy which can be delivered by two minimally invasive interventions: percutaneous catheter ablation and thoracoscopic surgical ablation...
February 20, 2018: Trials
Yousif Ahmad, Ozan Demir, Christopher Rajkumar, James P Howard, Matthew Shun-Shin, Christopher Cook, Ricardo Petraco, Richard Jabbour, Ahran Arnold, Angela Frame, Nilesh Sutaria, Ben Ariff, Gajen Kanaganayagam, Darrel Francis, Jamil Mayet, Ghada Mikhail, Iqbal Malik, Sayan Sen
Objective: International guidelines recommend the use of dual antiplatelet therapy (DAPT) after transcatheter aortic valve implantation (TAVI). The recommended duration of DAPT varies between guidelines. In this two-part study, we (1) performed a structured survey of 45 TAVI centres from around the world to determine if there is consensus among clinicians regarding antiplatelet therapy after TAVI; and then (2) performed a systematic review of all suitable studies (randomised controlled trials (RCTs) and registries) to determine if aspirin monotherapy can be used instead of DAPT...
2018: Open Heart
Ricardo Petraco, Hakim-Moulay Dehbi, James P Howard, Matthew J Shun-Shin, Sayan Sen, Sukhjinder S Nijjer, Jamil Mayet, Justin E Davies, Darrel P Francis
Background: Diagnostic accuracy is widely accepted by researchers and clinicians as an optimal expression of a test's performance. The aim of this study was to evaluate the effects of disease severity distribution on values of diagnostic accuracy as well as propose a sample-independent methodology to calculate and display accuracy of diagnostic tests. Methods and findings: We evaluated the diagnostic relationship between two hypothetical methods to measure serum cholesterol (Cholrapid and Cholgold) by generating samples with statistical software and (1) keeping the numerical relationship between methods unchanged and (2) changing the distribution of cholesterol values...
2018: Open Heart
Stefania Sacchi, Niti M Dhutia, Matthew J Shun-Shin, Massoud Zolgharni, Nilesh Sutaria, Darrel P Francis, Graham D Cole
Aims: Measurements with superior reproducibility are useful clinically and research purposes. Previous reproducibility studies of Doppler assessment of aortic stenosis (AS) have compared only a pair of observers and have not explored the mechanism by which disagreement between operators occurs. Using custom-designed software which stored operators' traces, we investigated the reproducibility of peak and velocity time integral (VTI) measurements across a much larger group of operators and explored the mechanisms by which disagreement arose...
January 15, 2018: European Heart Journal Cardiovascular Imaging
Rasha Al-Lamee, Darrel P Francis
No abstract text is available yet for this article.
December 8, 2017: EuroIntervention
Vasileios F Panoulas, Darrel P Francis, Neil Ruparelia, Iqbal S Malik, Andrew Chukwuemeka, Sayan Sen, Jonathan Anderson, Petros Nihoyannopoulos, Nilesh Sutaria, Edward L Hannan, Zaza Samadashvili, Paola D'Errigo, Gerhard Schymik, Roxana Mehran, Alaide Chieffo, Azeem Latib, Patrizia Presbitero, Julinda Mehilli, Anna Sonia Petronio, Marie-Claude Morice, Corrado Tamburino, Hans G H Thyregod, Martin Leon, Antonio Colombo, Ghada W Mikhail
Transcatheter aortic valve implantation (TAVI) for severe aortic stenosis (AS) is the first area of interventional cardiology where women are treated as often as men. In this analysis of the gender specific results of randomised controlled trials (RCTs) comparing TAVI with surgical aortic valve replacement (SAVR) we aimed to determine whether gender affects the survival comparison between TAVI and SAVR. We identified all RCTs comparing TAVI versus SAVR for severe AS and reporting 1 and/or 2year survival. Summary odds ratios (ORs) were obtained using a random-effects model...
January 1, 2018: International Journal of Cardiology
Rasha Al-Lamee, David Thompson, Hakim-Moulay Dehbi, Sayan Sen, Kare Tang, John Davies, Thomas Keeble, Michael Mielewczik, Raffi Kaprielian, Iqbal S Malik, Sukhjinder S Nijjer, Ricardo Petraco, Christopher Cook, Yousif Ahmad, James Howard, Christopher Baker, Andrew Sharp, Robert Gerber, Suneel Talwar, Ravi Assomull, Jamil Mayet, Roland Wensel, David Collier, Matthew Shun-Shin, Simon A Thom, Justin E Davies, Darrel P Francis
BACKGROUND: Symptomatic relief is the primary goal of percutaneous coronary intervention (PCI) in stable angina and is commonly observed clinically. However, there is no evidence from blinded, placebo-controlled randomised trials to show its efficacy. METHODS: ORBITA is a blinded, multicentre randomised trial of PCI versus a placebo procedure for angina relief that was done at five study sites in the UK. We enrolled patients with severe (≥70%) single-vessel stenoses...
November 1, 2017: Lancet
Kevin M W Leong, Fu Siong Ng, Caroline Roney, Christopher Cantwell, Matthew J Shun-Shin, Nicholas W F Linton, Zachary I Whinnett, David C Lefroy, D Wyn Davies, Sian E Harding, Phang Boon Lim, Darrel Francis, Nicholas S Peters, Amanda M Varnava, Prapa Kanagaratnam
BACKGROUND: Models of cardiac arrhythmogenesis predict that nonuniformity in repolarization and/or depolarization promotes ventricular fibrillation and is modulated by autonomic tone, but this is difficult to evaluate in patients. We hypothesize that such spatial heterogeneities would be detected by noninvasive ECG imaging (ECGi) in sudden cardiac death (SCD) survivors with structurally normal hearts under physiological stress. METHODS: ECGi was applied to 11 SCD survivors, 10 low-risk Brugada syndrome patients (BrS), and 10 controls undergoing exercise treadmill testing...
January 2018: Journal of Cardiovascular Electrophysiology
Markus B Sikkel, Darrel P Francis, James Howard, Fabiana Gordon, Christina Rowlands, Nicholas S Peters, Alexander R Lyon, Sian E Harding, Kenneth T MacLeod
Aims: It is generally accepted that post-MI heart failure (HF) changes a variety of aspects of sarcoplasmic reticular Ca2+ fluxes but for some aspects there is disagreement over whether there is an increase or decrease. The commonest statistical approach is to treat data collected from each cell as independent, even though they are really clustered with multiple likely similar cells from each heart. In this study, we test whether this statistical assumption of independence can lead the investigator to draw conclusions that would be considered erroneous if the analysis handled clustering with specific statistical techniques (hierarchical tests)...
December 1, 2017: Cardiovascular Research
Darrell R Lewis, Marianne O Price, Matthew T Feng, Francis W Price
PURPOSE: To describe the recurrence of granular corneal dystrophy type 1 (GCD1) after penetrating keratoplasty (PKP), anterior lamellar keratoplasty (ALK), deep anterior lamellar keratoplasty (DALK), and phototherapeutic keratectomy (PTK) in a single population. The time required to achieve best-corrected visual acuity (BCVA) after each intervention was also analyzed. METHODS: Retrospective review of all patients with GCD1 from a single center between 1989 and 2016...
October 2017: Cornea
Edoardo Gronda, Darrel Francis, Faiez Zannad, Christian Hamm, Josep Brugada, Emilio Vanoli
: Chronic heart failure is a common clinical condition characterized by persistent excessive sympathetic nervous system activation. The derangement of the sympathetic activity has relevant implications for disease progression and patient survival. Aiming to positively impact patient outcome, autonomic nervous system modulatory therapies have been developed and tested in animal and clinical studies. As a general gross assumption, direct vagal stimulation and baroreflex activation are considered equivalent. This assumption does not take into account the fact that direct cervical vagal nerve stimulation involves activation of both afferent and efferent fibers innervating not only the heart, but the entire visceral system, leading to undesired responses to and from this compartment...
September 2017: Journal of Cardiovascular Medicine
Matthew J Shun-Shin, Darrel P Francis
No abstract text is available yet for this article.
June 23, 2017: BMJ: British Medical Journal
Sameer Zaman, Saman S Zaman, Timothy Scholtes, Matthew J Shun-Shin, Carla M Plymen, Darrel P Francis, Graham D Cole
AIMS: The prescription of optimal medical therapy for heart failure is often delayed despite compelling evidence of a reduction in mortality. We calculated the absolute risk resulting from delayed prescription of therapy. For comparison, we established the threshold applied by clinicians when discussing the risk for death associated with an intervention, and the threshold used in official patient information leaflets. METHODS AND RESULTS: We undertook a meta-analysis of randomized controlled trials to calculate the excess mortality caused by deferral of medical therapy for 1 year...
November 2017: European Journal of Heart Failure
Massoud Zolgharni, Madalina Negoita, Niti M Dhutia, Michael Mielewczik, Karikaran Manoharan, S M Afzal Sohaib, Judith A Finegold, Stefania Sacchi, Graham D Cole, Darrel P Francis
BACKGROUND: Correctly selecting the end-diastolic and end-systolic frames on a 2D echocardiogram is important and challenging, for both human experts and automated algorithms. Manual selection is time-consuming and subject to uncertainty, and may affect the results obtained, especially for advanced measurements such as myocardial strain. METHODS AND RESULTS: We developed and evaluated algorithms which can automatically extract global and regional cardiac velocity, and identify end-diastolic and end-systolic frames...
June 1, 2017: Echocardiography
Christopher M Cook, Ricardo Petraco, Matthew J Shun-Shin, Yousif Ahmad, Sukhjinder Nijjer, Rasha Al-Lamee, Yuetsu Kikuta, Yasutsugu Shiono, Jamil Mayet, Darrel P Francis, Sayan Sen, Justin E Davies
Importance: Computed tomography-derived fractional flow reserve (FFR-CT) is a novel, noninvasive test for myocardial ischemia. Clinicians using FFR-CT must be able to interpret individual FFR-CT results to determine subsequent patient care. Objective: To provide clinicians a means of interpreting individual FFR-CT results with respect to the range of invasive FFRs that this interpretation might likely represent. Evidence Review: We performed a systematic review in accordance with guidelines from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses...
July 1, 2017: JAMA Cardiology
Alex A T Bui, John Darrell Van Horn
Through the increasing availability of more efficient data collection procedures, biomedical scientists are now confronting ever larger sets of data, often finding themselves struggling to process and interpret what they have gathered. This, while still more data continues to accumulate. This torrent of biomedical information necessitates creative thinking about how the data are being generated, how they might be best managed, analyzed, and eventually how they can be transformed into further scientific understanding for improving patient care...
May 2017: Journal of Biomedical Informatics
Matthew J Shun-Shin, Sean L Zheng, Graham D Cole, James P Howard, Zachary I Whinnett, Darrel P Francis
Aims: Primary prevention implantable cardioverter defibrillators (ICDs) are established therapy for reducing mortality in patients with left ventricular systolic dysfunction and ischaemic heart disease (IHD). However, their efficacy in patients without IHD has been controversial. We undertook a meta-analysis of the totality of the evidence. Methods and results: We systematically identified all RCTs comparing ICD vs. no ICD in primary prevention. Eligible RCTs were those that recruited patients with left ventricular dysfunction, reported all-cause mortality, and presented their results stratified by the presence of IHD (or recruited only those with or without)...
June 7, 2017: European Heart Journal
Niti M Dhutia, Massoud Zolgharni, Michael Mielewczik, Madalina Negoita, Stefania Sacchi, Karikaran Manoharan, Darrel P Francis, Graham D Cole
Current guidelines for measuring cardiac function by tissue Doppler recommend using multiple beats, but this has a time cost for human operators. We present an open-source, vendor-independent, drag-and-drop software capable of automating the measurement process. A database of ~8000 tissue Doppler beats (48 patients) from the septal and lateral annuli were analyzed by three expert echocardiographers. We developed an intensity- and gradient-based automated algorithm to measure tissue Doppler velocities. We tested its performance against manual measurements from the expert human operators...
August 2017: International Journal of Cardiovascular Imaging
Wilfred Ngwa, Francis Boateng, Rajiv Kumar, Darrell J Irvine, Silvia Formenti, Twalib Ngoma, Carsten Herskind, Marlon R Veldwijk, Georg Lars Hildenbrand, Michael Hausmann, Frederik Wenz, Juergen Hesser
Radiation therapy (RT) is a crucial component of cancer care, used in the treatment of over 50% of cancer patients. Patients undergoing image guided RT or brachytherapy routinely have inert RT biomaterials implanted into their tumors. The single function of these RT biomaterials is to ensure geometric accuracy during treatment. Recent studies have proposed that the inert biomaterials could be upgraded to "smart" RT biomaterials, designed to do more than 1 function. Such smart biomaterials include next-generation fiducial markers, brachytherapy spacers, and balloon applicators, designed to respond to stimuli and perform additional desirable functions like controlled delivery of therapy-enhancing payloads directly into the tumor subvolume while minimizing normal tissue toxicities...
March 1, 2017: International Journal of Radiation Oncology, Biology, Physics
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