Publications by authors named "David W Muller"

Article Synopsis
  • Patients with mitral regurgitation (MR) and significant mitral annular calcification (MAC) face limited treatment options, making transcatheter mitral valve replacement (TMVR) an interesting area of study.
  • The research involved 279 patients, revealing that those with MAC had higher rates of post-procedural bleeding and renal failure but similar overall survival rates and functional improvement compared to those without MAC.
  • The findings suggest that while TMVR can be performed in MAC patients, it comes with increased complications, highlighting the need for more research on tailored TMVR devices for this group.
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Pulmonary hypertension (PH) is a common and prognostically important complication of mitral regurgitation (MR). Mean pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR) are traditionally used to diagnose PH, however these indices measure static rather than pulsatile load, leading to an incomplete representation of pulmonary vascular load on the right ventricle (RV). Pulmonary arterial compliance (PAC) is one method for quantifying pulsatile load, and is both a stronger predictor of prognosis in left heart failure, as well as a more sensitive measure of early pulmonary vascular dysfunction than PVR.

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Background: Transcatheter mitral valve replacement (TMVR) is a therapeutic option for patients with severe mitral regurgitation (MR) who are ineligible for conventional surgery. There are limited data on the outcomes of large patient cohorts treated with TMVR.

Aims: This study aimed to investigate the outcomes and predictors of mortality for patients treated with transapical TMVR.

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Background: Transcatheter mitral valve replacement (TMVR) using dedicated devices is an alternative therapy for high-risk patients with symptomatic mitral regurgitation (MR).

Aims: This study aimed to assess the 2-year outcomes and predictors of mortality in patients undergoing TMVR from the multicentre CHOICE-MI Registry.

Methods: The CHOICE-MI Registry included consecutive patients with symptomatic MR treated with 11 different dedicated TMVR devices at 31 international centres.

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Transcatheter mitral valve repair with the MitraClip, a catheter-based percutaneous edge-to-edge repair technique to correct mitral regurgitation (MR), has been demonstrated in Western studies to be an effective and safe MR treatment strategy. However, randomised clinical trial data on its use in Asian-Pacific patients is limited. Hence, the Asian Pacific Society of Cardiology convened an expert panel to review the available literature on MitraClip and to develop consensus recommendations to guide clinicians in the region.

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Background: Spontaneous coronary artery dissection (SCAD) occurs when an epicardial coronary artery is narrowed or occluded by an intramural hematoma. SCAD mainly affects women and is associated with pregnancy and systemic arteriopathies, particularly fibromuscular dysplasia. Variants in several genes, such as those causing connective tissue disorders, have been implicated; however, the genetic architecture is poorly understood.

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The burden of cardiovascular disease in women is being increasingly appreciated. Nevertheless, both clinicians and the general public are largely unaware that cardiovascular disease is the leading cause of death worldwide in women in all countries and that outcomes after a heart attack are worse for women than men. Of note, certain types of cardiovascular disease have a predilection for women, including spontaneous coronary artery dissection (SCAD) and fibromuscular dysplasia (FMD).

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Paravalvular leak can complicate transcatheter aortic valve replacement with important prognostic implications. Correction of defects requires complex planning and execution. Multiple or irregular lesions, calcified annulus, and high sealing skirts on self-expandable devices are especially challenging.

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Spontaneous coronary artery dissection (SCAD) is a non-atherosclerotic form of coronary artery disease of unknown cause that predominantly affects women (>90%; mean age 44-55 years) and can be fatal. The finding of familial clustering, including the concordant involvement of monozygotic twins, and its association with the PHACTR1/EDN1 genetic locus, indicate a genetic predisposition to its pathophysiology. A human induced pluripotent stem cell line (hiPSC) was generated from a patient who had survived an episode of SCAD.

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Contrast-induced encephalopathy (CIE) is an acute and reversible neurological disturbance associated with the intra-arterial administration of iodinated contrast medium during cardiac catheterisation. It may manifest with encephalopathy, motor and sensory disturbances; vision disturbances, including cortical blindness, ophthalmoplegia, aphasia; and seizures. Disruption of the blood-brain barrier and direct neuronal toxicity are believed to be implicated in the pathophysiology of the syndrome.

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Objectives: To describe the epidemiology, pathophysiology, clinical presentation, and management of contrast-induced encephalopathy (CIE) following cardiac catheterization.

Background: CIE is an acute, reversible neurological disturbance directly attributable to the intra-arterial administration of iodinated contrast medium.

Methods: The PubMed database was searched and all cases in the literature were retrieved and reviewed.

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Background: Spontaneous coronary artery dissection (SCAD) is an uncommon but serious condition presenting as an acute coronary syndrome (ACS) or cardiac arrest. The pathophysiology and outcomes are poorly understood. We investigated the characteristics and outcomes of patients presenting with SCAD.

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Dual antiplatelet therapy with aspirin and clopidogrel is commonly used to prevent recurrent ischemic events in patients with cardiovascular disease. Whilst their effects on platelet reactivity are well documented, it is unclear, however, whether antiplatelet therapy inhibits platelet extracellular vesicle (EV) release. The aim of this study was to investigate the effects of antiplatelet therapy on platelet EV formation and procoagulant activity.

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Chronic thromboembolic pulmonary hypertension (CTEPH) occurs as a consequence of a series of events that includes arterial obstruction by embolic material, secondary in situ thrombosis, cytokine activation and inflammation, and small vessel angiopathy. Medical therapies have a limited efficacy. Only the guanylate cyclase stimulator, riociguat, is approved for this condition.

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Background: Technological advancements in newer-generation catheterisation laboratories may reduce patient and occupational radiation exposure.

Methods: We compared fluoroscopy time and dose-area product (DAP) between a Philips Allura X-PER FD20 and Siemens Artis Zeego Hybrid systems for 47 single-vessel percutaneous coronary interventions (PCI) and 35 transcatheter aortic valve implantations (21 Corevalve, 14 Edwards Sapien TAVI) using the FD20, versus 30 PCI and 28 TAVI (15 Corevalve, 13 Sapien) with the Zeego over a 24-month period.

Results: Multivariate analysis revealed that, adjusting for patient weight and fluoroscopy time, DAP (median, interquartile range) was 26% lower for PCI with the Zeego than the FD20 [55.

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Objectives: The objective of this study is to describe and compare the use of the MitraClip therapy in mitral regurgitation (MR) patients with degenerative MR (DMR) and functional MR (FMR).

Introduction: Percutaneous edge-to-edge repair of severe MR using the MitraClip device is approved for use in the USA for high risk DMR while European guidelines include its use in FMR patients as well.

Methods: The MitraClip in the Asia-Pacific Registry (MARS) is a multicenter retrospective registry, involving eight sites in five Asia-Pacific countries.

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Transcatheter aortic valve implantation (TAVI) in patients with bicuspid aortic valve disease is associated with higher rates of paravalvular aortic regurgitation, which may require subsequent surgical correction. We report a case of successful late surgical CoreValve explantation 1,389 days after TAVI in a patient with bicuspid aortic valve stenosis and McArdle's disease who developed severe paravalvular aortic regurgitation. We confirm that neoendothelialization and incorporation of the nitinol cage into the aortic wall had occurred at nearly 4 years postimplantation, although explantation with careful endarterectomy could still be performed without requiring simultaneous aortic root replacement.

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Transcatheter aortic valve replacement with either the balloon-expandable Edwards SAPIEN XT valve, or the self-expandable CoreValve prosthesis has become the established therapeutic modality for severe aortic valve stenosis in patients who are not deemed suitable for surgical intervention due to excessively high operative risk. Native aortic valve regurgitation, defined as primary aortic incompetence not associated with aortic stenosis or failed valve replacement, on the other hand, is still considered a relative contraindication for transcatheter aortic valve therapies, because of the absence of annular or leaflet calcification required for secure anchoring of the transcatheter heart valve. In addition, severe aortic regurgitation often coexists with aortic root or ascending aorta dilatation, the treatment of which mandates operative intervention.

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Background: Although numerous studies have reported the safety and effectiveness of transcatheter aortic valve implantation (TAVI), integration of this therapy into standard of care varies widely by region. We evaluated mid-term follow-up in 540 patients with severe symptomatic AS at high risk of surgical AV replacement, enrolled in the ongoing Medtronic CoreValve Australia-New Zealand Study.

Methods: Between August 2008 and July 2013, 10 centres in Australia/New Zealand enrolled 540 patients, which includes initial use of the CoreValve System for all investigators.

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Mitral regurgitation is the most common valve abnormality worldwide and its prevalence is expected to increase in the future due to aging of the population. Percutaneous mitral valve repair therapies may offer an opportunity to treat severe MR in the elderly or other high-risk groups who would otherwise be ineligible for surgery. The MitraClip system uses edge-to-edge coaptation of the mitral leaflets to create a double-orifice valve and reduce MR.

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