Publications by authors named "Niall G Keenan"

Importance: Development of myocardial fibrosis in patients with aortic stenosis precedes left ventricular decompensation and is associated with an adverse long-term prognosis.

Objective: To investigate whether early valve intervention reduced the incidence of all-cause death or unplanned aortic stenosis-related hospitalization in asymptomatic patients with severe aortic stenosis and myocardial fibrosis.

Design, Setting, And Participants: This prospective, randomized, open-label, masked end point trial was conducted between August 2017 and October 2022 at 24 cardiac centers across the UK and Australia.

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Heart and circulatory diseases affect more than seven million people in the UK. Non-invasive cardiac imaging is a critical element of contemporary cardiology practice. Progressive improvements in technology over the last 20 years have increased diagnostic accuracy in all modalities and led to the incorporation of non-invasive imaging into many standard cardiac clinical care pathways.

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Objectives: To examine service provision in cardiovascular magnetic resonance (CMR) in the UK. Equitable access to diagnostic imaging is important in healthcare. CMR is widely available in the UK, but there may be regional variations.

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Article Synopsis
  • - A 49-year-old female experienced acute chest pain and was found to have multiple blood clots leading to several complications, including heart attacks and strokes, with a history of sickle cell trait.
  • - Cardiac imaging revealed an abnormality where the right superior vena cava (RSVC) connected to the left atrium, creating a small right-to-left shunt, and a persistent left SVC draining into the right atrium.
  • - The patient’s condition is attributed to repeated paradoxical emboli linked to her unusual venous structure and a tendency to form blood clots due to her sickle cell trait.
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Background: Dobutamine stress echocardiography is widely used to test for ischemia in patients with stable coronary artery disease. In this analysis, we studied the ability of the prerandomization stress echocardiography score to predict the placebo-controlled efficacy of percutaneous coronary intervention (PCI) within the ORBITA trial (Objective Randomised Blinded Investigation With Optimal Medical Therapy of Angioplasty in Stable Angina).

Methods: One hundred eighty-three patients underwent dobutamine stress echocardiography before randomization.

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Background: There are no data on how fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are associated with the placebo-controlled efficacy of percutaneous coronary intervention (PCI) in stable single-vessel coronary artery disease.

Methods: We report the association between prerandomization invasive physiology within ORBITA (Objective Randomised Blinded Investigation With Optimal Medical Therapy of Angioplasty in Stable Angina), a placebo-controlled trial of patients who have stable angina with angiographically severe single-vessel coronary disease clinically eligible for PCI. Patients underwent prerandomization research FFR and iFR assessment.

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Background: Cardiac phenotypes, such as left ventricular (LV) mass, demonstrate high heritability although most genes associated with these complex traits remain unidentified. Genome-wide association studies (GWAS) have relied on conventional 2D cardiovascular magnetic resonance (CMR) as the gold-standard for phenotyping. However this technique is insensitive to the regional variations in wall thickness which are often associated with left ventricular hypertrophy and require large cohorts to reach significance.

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Computed tomography coronary angiography (CTCA) is widely accepted in the evaluation of patients with stable chest pain. Its use in patients with unstable chest pain is more controversial. CTCA can be performed alone or with a computed tomography pulmonary angiogram and aortogram as a 'triple rule-out' scan.

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Obesity is a major risk factor for cardiometabolic disease, but the effect of body composition on vascular aging and arterial stiffness remains uncertain. We investigated relationships among body composition, blood pressure, age, and aortic pulse wave velocity in healthy individuals. Pulse wave velocity in the thoracic aorta, an indicator of central arterial stiffness, was measured in 221 volunteers (range, 18-72 years; mean, 40.

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Background: No previous study has looked for an association between aortic dilatation and the clinical sequelae of patent foramen ovale (PFO), although a possible relationship has been identified in case reports.

Aim: To compare aortic dimensions in patients with symptomatic PFO and healthy controls.

Methods: Forty-seven patients were identified who presented with cryptogenic cerebrovascular accident (CVA) assessed as most likely secondary to PFO (confirmed by contrast study), were aged less than 50 years and underwent percutaneous PFO closure.

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Aims: Patients with acute myocardial infarction (AMI) represent a high-risk population in which screening for abdominal aortic aneurysm (AAA) is recommended but only occasionally performed. Transthoracic echocardiography (TTE) may offer the unique opportunity to evaluate the cardiac function and to screen for AAA during the same examination. We aimed to evaluate the feasibility of AAA screening at bedside using a portable cardiac ultrasound (US) echo machine and to determine the prevalence of AAA in population with AMI.

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In patients with mitral stenosis (MS) in sinus rhythm (SR), guidelines recommend anticoagulation if the left atrium is enlarged based on diameter measurements. We sought to compare the association of left atrial (LA) diameter and LA volume with markers of thromboembolic risk (peak LA appendage emptying velocity [LAAv] and LA spontaneous contrast density) measured during transesophageal echocardiography in 152 patients with moderate to severe MS. High thromboembolic risk was defined by a peak LAAv < 25 cm/s and/or dense spontaneous contrast.

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Objectives: This study aimed to characterize myocardial infarction after percutaneous coronary intervention (PCI) based on cardiac marker elevation as recommended by the new universal definition and on the detection of late gadolinium enhancement (LGE) by cardiovascular magnetic resonance (CMR). It is also assessed whether baseline inflammatory biomarkers are higher in patients developing myocardial injury.

Background: Cardiovascular magnetic resonance accurately assesses infarct size.

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This paper presents a novel approach to shape extraction and interpretation in 4-D cardiac magnetic resonance imaging data. Statistical modeling of spatiotemporal interlandmark relationships is performed to enable the decomposition of global shape constraints and subsequently of the image analysis tasks. The introduced descriptors furthermore provide invariance to similarity transformations and thus eliminate pose estimation errors in the presence of image artifacts or geometrical inconsistencies.

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We present the case of a 42-year-old man who underwent tissue mitral valve replacement for symptomatic mitral stenosis. Post-operative course was unremarkable but three-dimensional transoesophageal echocardiography clearly indicated that one cusp had very restricted motion with incomplete opening and premature closure. The cause of this early single cusp failure is unclear.

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Purpose: To validate cardiovascular magnetic resonance (CMR) arterial wall volume measurement using whole arterial specimens ex vivo.

Materials And Methods: Twenty cadaveric carotid arteries (from 10 patients) were fixed in formaldehyde and imaged with a clinical T1-weighted 2D CMR sequence and, for imaging validation, with a high-resolution 3D sequence. Histological validation was performed by sectioning the arteries and microscopically determining area and volume.

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Background: Multi-contrast weighted cardiovascular magnetic resonance (CMR) allows detailed plaque characterisation and assessment of plaque vulnerability. The aim of this preliminary study was to show the potential of Ultra-short Echo Time (UTE) subtraction MR in detecting calcification.

Methods: 14 ex-vivo human carotid arteries were scanned using CMR and CT, prior to histological slide preparation.

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Purpose: To calculate the sample size for a theoretical pulmonary arterial hypertension (PAH) randomized controlled trial (RCT) by using cardiovascular magnetic resonance (CMR) imaging to determine the repeatability of measures between two scans.

Materials And Methods: Two same-day examinations from 10 PAH patients were analyzed manually and semiautomatically. Study size was calculated from the standard deviation (SD) of repeatability.

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Objective: This study was undertaken to evaluate the value of cardiovascular magnetic resonance (CMR) in the assessment of patients with Takayasu arteritis (TA).

Methods: Sixteen patients with TA and 2 populations comprising 110 normal volunteers were prospectively recruited. All patients with TA underwent a CMR protocol including measurement of carotid artery wall volume, assessment of left ventricular (LV) volumes and function, and late gadolinium enhancement for the detection of myocardial scarring.

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Background: There is recent evidence suggesting that rosiglitazone increases death from cardiovascular causes. We investigated the direct effect of this drug on atheroma using 3D carotid cardiovascular magnetic resonance.

Results: A randomized, placebo-controlled, double-blind study was performed to evaluate the effect of rosiglitazone treatment on carotid atherosclerosis in subjects with type 2 diabetes and coexisting vascular disease or hypertension.

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