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Dive into the research topics where D. Walters is active.

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Featured researches published by D. Walters.


Journal of the American College of Cardiology | 2014

Transcatheter aortic valve replacement for severe symptomatic aortic stenosis using a repositionable valve system: 30-day primary endpoint results from the REPRISE II study.

Ian T. Meredith Am; D. Walters; Nicolas Dumonteil; Stephen G. Worthley; Didier Tchetche; Ganesh Manoharan; Daniel J. Blackman; Gilles Rioufol; David Hildick-Smith; Robert Whitbourn; Thierry Lefèvre; Rüdiger Lange; Ralf Müller; Simon Redwood; Dominic J. Allocco; Keith D. Dawkins

BACKGROUND Transcatheter aortic valve replacement provides results comparable to those of surgery in patients at high surgical risk, but complications can impact long-term outcomes. The Lotus valve, designed to improve upon earlier devices, is fully repositionable and retrievable, with a unique seal to minimize paravalvular regurgitation (PVR). OBJECTIVES The prospective, single-arm, multicenter REPRISE II study (REpositionable Percutaneous Replacement of Stenotic Aortic Valve Through Implantation of Lotus Valve System: Evaluation of Safety and Performance) evaluated the transcatheter valve system for treatment of severe symptomatic calcific aortic valve stenosis. METHODS Patients (n = 120; aortic annulus 19 to 27 mm) considered by a multidisciplinary heart team to be at high surgical risk received the valve transfemorally. The primary device performance endpoint, 30-day mean pressure gradient, was assessed by an independent echocardiographic core laboratory and compared with a pre-specified performance goal. The primary safety endpoint was 30-day mortality. Secondary endpoints included safety/effectiveness metrics per Valve Academic Research Consortium criteria. RESULTS Mean age was 84.4 years, 57% of the patients were female, and 76% were New York Heart Association functional class III/IV. Mean aortic valve area was 0.7 ± 0.2 cm(2). The valve was successfully implanted in all patients, with no cases of valve embolization, ectopic valve deployment, or additional valve implantation. All repositioning (n = 26) and retrieval (n = 6) attempts were successful; 34 patients (28.6%) received a permanent pacemaker. The primary device performance endpoint was met, because the mean gradient improved from 46.4 ± 15.0 mm Hg to 11.5 ± 5.2 mm Hg. At 30 days, the mortality rate was 4.2%, and the rate of disabling stroke was 1.7%; 1 (1.0%) patient had moderate PVR, whereas none had severe PVR. CONCLUSIONS REPRISE II demonstrates the safety and effectiveness of the Lotus valve in patients with severe aortic stenosis who are at high surgical risk. The valve could be positioned successfully with minimal PVR. (REPRISE II: REpositionable Percutaneous Replacement of Stenotic Aortic Valve Through Implantation of Lotus™ Valve System - Evaluation of Safety and Performance; NCT01627691).


Jacc-cardiovascular Interventions | 2009

Clinical and angiographic results with the next-generation resolute stent system A prospective, multicenter, first-in-human trial

Ian T. Meredith; Stephen G. Worthley; Robert Whitbourn; D. Walters; Dougal McClean; M. Horrigan; Jeffrey J. Popma; Donald E. Cutlip; Ann DePaoli; Manuela Negoita; Peter J. Fitzgerald; Resolute Trial Investigators

OBJECTIVES The RESOLUTE trial examined the safety and efficacy of a next-generation zotarolimus-eluting coronary stent, Resolute (Medtronic CardioVascular Inc., Santa Rosa, California). BACKGROUND Revascularization benefits associated with current drug-eluting stents are often diminished in the presence of complex coronary lesions and in certain patient cohorts. Resolute uses a new proprietary polymer coating that extends the duration of drug delivery to match the longer healing duration often experienced in more complex cases. METHODS The RESOLUTE trial was a prospective, nonrandomized, multicenter study of the Resolute stent in 139 patients with de novo coronary lesions with reference vessel diameters > or =2.5 and < or =3.5 mm and lesion length > or =14 and < or =27 mm. The primary end point was 9-month in-stent late lumen loss by quantitative coronary angiography. Secondary end points included major adverse cardiac events (MACE) at 30 days, 6, 9, and 12 months; acute device, lesion, and procedure success; and 9-month target vessel failure (TVF), target lesion revascularization (TLR), stent thrombosis, neointimal hyperplastic (NIH) volume, and percent NIH volume obstruction. RESULTS The 9-month in-stent late lumen loss was 0.22 +/- 0.27 mm. Cumulative MACE were 4.3%, 4.3%, 7.2%, and 8.7% at 30 days, 6, 9, and 12 months, respectively. Acute lesion, procedure, and device success rates were 100.0%, 95.7%, and 99.3%, respectively. At 9 months, TLR was 0.0%, TVF was 6.5%, stent thrombosis was 0.0%, NIH volume was 6.55 +/- 7.83 mm(3), and percent NIH volume obstruction was 3.73 +/- 4.05%. CONCLUSIONS In this feasibility study, the Resolute stent demonstrated low in-stent late lumen loss, minimal neointimal hyperplastic ingrowth, low TLR, no stent thrombosis, and acceptable TVF and MACE. (The RESOLUTE Clinical Trial; NCT00248079).


The New England Journal of Medicine | 2017

Use of the Instantaneous Wave-free Ratio or Fractional Flow Reserve in PCI

Justin E. Davies; Sayan Sen; Hakim-Moulay Dehbi; Rasha Al-Lamee; Ricardo Petraco; Sukhjinder Nijjer; Ravinay Bhindi; Sam J. Lehman; D. Walters; James Sapontis; Luc Janssens; Christiaan J. Vrints; Ahmed Khashaba; Mika Laine; Eric Van Belle; Florian Krackhardt; Waldemar Bojara; Olaf Going; Tobias Härle; Ciro Indolfi; Giampaolo Niccoli; Flavo Ribichini; Nobuhiro Tanaka; Hiroyoshi Yokoi; Hiroaki Takashima; Yuetsu Kikuta; Andrejs Erglis; Hugo Vinhas; Pedro Canas Silva; Sérgio B. Baptista

Background Coronary revascularization guided by fractional flow reserve (FFR) is associated with better patient outcomes after the procedure than revascularization guided by angiography alone. It is unknown whether the instantaneous wave‐free ratio (iFR), an alternative measure that does not require the administration of adenosine, will offer benefits similar to those of FFR. Methods We randomly assigned 2492 patients with coronary artery disease, in a 1:1 ratio, to undergo either iFR‐guided or FFR‐guided coronary revascularization. The primary end point was the 1‐year risk of major adverse cardiac events, which were a composite of death from any cause, nonfatal myocardial infarction, or unplanned revascularization. The trial was designed to show the noninferiority of iFR to FFR, with a margin of 3.4 percentage points for the difference in risk. Results At 1 year, the primary end point had occurred in 78 of 1148 patients (6.8%) in the iFR group and in 83 of 1182 patients (7.0%) in the FFR group (difference in risk, ‐0.2 percentage points; 95% confidence interval [CI], ‐2.3 to 1.8; P<0.001 for noninferiority; hazard ratio, 0.95; 95% CI, 0.68 to 1.33; P=0.78). The risk of each component of the primary end point and of death from cardiovascular or noncardiovascular causes did not differ significantly between the groups. The number of patients who had adverse procedural symptoms and clinical signs was significantly lower in the iFR group than in the FFR group (39 patients [3.1%] vs. 385 patients [30.8%], P<0.001), and the median procedural time was significantly shorter (40.5 minutes vs. 45.0 minutes, P=0.001). Conclusions Coronary revascularization guided by iFR was noninferior to revascularization guided by FFR with respect to the risk of major adverse cardiac events at 1 year. The rate of adverse procedural signs and symptoms was lower and the procedural time was shorter with iFR than with FFR. (Funded by Philips Volcano; DEFINE‐FLAIR ClinicalTrials.gov number, NCT02053038.)


Heart | 2014

Smartphone-based home care model improved use of cardiac rehabilitation in postmyocardial infarction patients: results from a randomised controlled trial

Marlien Varnfield; Mohanraj Karunanithi; Chi-Keung Lee; Enone Honeyman; Desre Arnold; Hang Ding; Catherine Smith; D. Walters

Objective Cardiac rehabilitation (CR) is pivotal in preventing recurring events of myocardial infarction (MI). This study aims to investigate the effect of a smartphone-based home service delivery (Care Assessment Platform) of CR (CAP-CR) on CR use and health outcomes compared with a traditional, centre-based programme (TCR) in post-MI patients. Methods In this unblinded randomised controlled trial, post-MI patients were randomised to TCR (n=60; 55.7±10.4 years) and CAP-CR (n=60; 55.5±9.6 years) for a 6-week CR and 6-month self-maintenance period. CAP-CR, delivered in participants’ homes, included health and exercise monitoring, motivational and educational material delivery, and weekly mentoring consultations. CAP-CR uptake, adherence and completion rates were compared with TCR using intention-to-treat analyses. Changes in clinical outcomes (modifiable lifestyle factors, biomedical risk factors and health-related quality of life) across baseline, 6 weeks and 6 months were compared within, and between, groups using linear mixed model regression. Results CAP-CR had significantly higher uptake (80% vs 62%), adherence (94% vs 68%) and completion (80% vs 47%) rates than TCR (p<0.05). Both groups showed significant improvements in 6-minute walk test from baseline to 6 weeks (TCR: 537±86–584±99 m; CAP-CR: 510±77–570±80 m), which was maintained at 6 months. CAP-CR showed slight weight reduction (89±20–88±21 kg) and also demonstrated significant improvements in emotional state (K10: median (IQR) 14.6 (13.4–16.0) to 12.6 (11.5–13.8)), and quality of life (EQ5D-Index: median (IQR) 0.84 (0.8–0.9) to 0.92 (0.9–1.0)) at 6 weeks. Conclusions This smartphone-based home care CR programme improved post-MI CR uptake, adherence and completion. The home-based CR programme was as effective in improving physiological and psychological health outcomes as traditional CR. CAP-CR is a viable option towards optimising use of CR services. Trial registration number ANZCTR12609000251224.


Circulation | 2010

Part 9: Acute Coronary Syndromes 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations

Robert E. O'Connor; Leo Bossaert; Hans Richard Arntz; Steven C. Brooks; Deborah B. Diercks; Gilson Feitosa-Filho; Jerry P. Nolan; Terry L. Vanden Hoek; D. Walters; Aaron Wong; Michelle Welsford; Karen Woolfrey

Note From the Writing Group: Throughout this article, the reader will notice combinations of superscripted letters and numbers (eg, “Chest Pain Observation Units”). These callouts are hyperlinked to evidence-based worksheets, which were used in the development of this article. An appendix of worksheets, applicable to this article, is located at the end of the text. The worksheets are available in PDF format and are open access.


Resuscitation | 2014

Cardiac catheterization is associated with superior outcomes for survivors of out of hospital cardiac arrest: review and meta-analysis.

A. Camuglia; Varinder K. Randhawa; Shahar Lavi; D. Walters

AIMS Survivors of out-of-hospital cardiac arrest (OHCA) have a high rate of morbidity and mortality. Invasive cardiac assessment with coronary angiography offers the potential for improving outcomes by facilitating early revascularization. The aim of the present study was to review the published data on early coronary angiography for survivors of OHCA, and its impact on survival and neurological outcomes. METHODS Medline, Embase and PubMed were searched with a structured search query. The primary outcome was in-hospital (or if not available, 30 day or 6 month) survival. Rates of survival with good neurological outcome were a secondary endpoint. The time period of the search was from 1 January 1980 to 1 January 2014. Data was pooled with means and 95% CI interval calculated. Meta-analysis of the main outcomes was performed using a weighted random effects model. RESULTS Following review of all identified records, 105 relevant full text articles were retrieved. Fifty had adequate outcome information stratified by the use of coronary angiography for analysis. In studies where a control group was available for comparison, the overall survival in the acute angiography group was 58.8% versus 30.9% in the control group (Odds ratio 2.77, 95% CI 2.06-3.72). Survival with good neurological outcome (as per the Utstein framework) in the early angiography group was 58% versus 35.8% in the control group (Odds ratio 2.20, 95% CI 1.46-3.32). CONCLUSIONS Early coronary angiography in patients following OHCA is associated with improved outcome and better survival.


International Journal of Cardiology | 2014

Diagnostic performance and cost of CT angiography versus stress ECG — A randomized prospective study of suspected acute coronary syndrome chest pain in the emergency department (CT-COMPARE) ☆ ☆☆

C. Hamilton-Craig; Allison Fifoot; Mark Hansen; M. Pincus; Jonathan Chan; D. Walters; Kelley R. Branch

BACKGROUND Coronary CT angiography (CCTA) has high sensitivity, with 3 recent randomized trials favorably comparing CCTA to standard-of-care. Comparison to exercise stress ECG (ExECG), the most available and least expensive standard-of-care worldwide, has not been systematically tested. METHODS CT-COMPARE was a randomized, single-center trial of low-intermediate risk chest pain subjects undergoing CCTA or ExECG after the first negative troponin. From March 2010 to April 2011, 562 patients randomized to either dual-source CCTA (n=322) or ExECG (n=240). Primary endpoints were diagnostic performance for ACS, and hospital cost at 30 days. Secondary endpoints were time-to-discharge, admission rates, and downstream resource utilization. RESULTS ACS occurred in 24 (4%) patients. ExECG had 213 negative studies and 27 (26%) positive studies for ACS with sensitivity of 83% [95% CI: 36, 99.6%], specificity of 91% [CI: 86, 94%], and ROC AUC of 0.87 [CI: 0.70, 1]. CCTA (>50% stenosis considered positive) had 288 negative studies and 18/35 (51%) positive studies with a sensitivity of 100% [CI: 81.5, 100], specificity of 94% [CI: 91.2, 96.7%], and ROC of 0.97 [CI: 0.92, 1.0; p=0.2]. Despite CCTA having higher odds of downstream testing (OR 2.0), 30 day per-patient cost was significantly lower for CCTA (


Circulation | 2014

Characterization of Neurological Injury in Transcatheter Aortic Valve Implantation How Clear Is the Picture

Jonathon P. Fanning; D. Walters; D. Platts; Eamonn Eeles; Judith Bellapart; John F. Fraser

2193 vs


Eurointervention | 2010

Long-term clinical outcomes with the next-generation Resolute Stent System: a report of the two-year follow-up from the RESOLUTE clinical trial.

Ian T. Meredith; Stephen G. Worthley; Robert Whitbourn; D. Walters; Dougal McClean; John Ormiston; M. Horrigan; Gerard T. Wilkins; Randall Hendriks; Philip Matsis; David W.M. Muller; Donald E. Cutlip

2704, p<0.001). Length of stay for CCTA was significantly reduced (13.5h [95% CI: 11.2-15.7], ExECG 19.7h [95% CI: 17.4-22.1], p<0.0005), which drove the reduction in cost. No patient had post-discharge cardiovascular events at 30 days. CONCLUSIONS CCTA had improved diagnostic performance compared to ExECG, combined with 35% relative reduction in length-of-stay, and 20% reduction in hospital costs. These data lend further evidence that CCTA is useful as a first line assessment in emergency department chest pain.


Circulation-heart Failure | 2016

One-year outcomes after transcatheter insertion of an interatrial shunt device for the management of heart failure with preserved ejection fraction

David M. Kaye; Gerd Hasenfuß; Petr Neuzil; Martijn Post; Robert N. Doughty; Jean Noel Trochu; Adam Kolodziej; Ralf Westenfeld; Martin Penicka; Mark Rosenberg; A. Walton; David W.M. Muller; D. Walters; Jörg Hausleiter; Philip Raake; Mark C. Petrie; Martin Bergmann; Guillaume Jondeau; Ted Feldman; Dirk J. van Veldhuisen; Piotr Ponikowski; Frank E. Silvestry; Dan Burkhoff; Christopher S. Hayward

The application of transcatheter aortic valve implantation (TAVI) to high-surgical-risk and inoperable patients with severe aortic stenosis (AS) is gaining widespread acceptance with a burgeoning supportive evidence base.1 The benefits associated with the application of this technique, however, are mitigated by the occurrence of major, disabling stroke with associated increased mortality and early-reduced quality of life.2 Despite this, the risk/benefit ratio has been considered acceptable in appropriately selected patients given the outcomes of alternate management options in these high-risk and inoperable populations.3,4 The incidence of cerebrovascular events (CVEs) subsequent to TAVI exceeds that after any other cardiac intervention or valve surgery, most notably in the acute periprocedural period, diminishing over the subsequent 2 months.5 This elevated early risk reflects the increased incidence of ischemic stroke thought secondary to particulate emboli dislodged by the procedure itself or as a result of thromboembolism.6 In fact, cerebral embolism is a universal finding associated with these procedures.7 Most events, however, are subclinical or silent, with clinically apparent CVEs representing but the tip-of-the-iceberg. As a result of the difficulty ascertaining these subclinical events, the true association between TAVI and neurological injury is unknown and the harm potentially underestimated. This article aims to comprehensively review neurological injury in TAVI, with an emphasis on cerebrovascular disease. Evidence and current concepts regarding pathophysiological mechanisms, risk factors, and prognostic implications will be discussed and risk reduction strategies explored. CVEs post-TAVI are classified based on clinical severity as illustrated in Figure 1. Incomplete reporting and variable definitions of clinically apparent events and disregard of subclinical events have limited the true evaluation of CVEs associated with TAVI. Consequently, in 2011 the Valve Academic Research Consortium published a consensus report on standardized end point definitions, including stroke, which were expanded and refined in …

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Dive into the D. Walters's collaboration.

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K. Poon

University of Queensland

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A. Incani

University of Queensland

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M. Savage

Thomas Jefferson University Hospital

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D. Murdoch

University of Queensland

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J. Crowhurst

University of Queensland

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C. Raffel

University of Queensland

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G. Scalia

University of Queensland

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D. Burstow

University of Queensland

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