Publications by authors named "Kenneth Knecht"

Angiotensin receptor neprilysin inhibitor is the standard of care for systolic heart failure in adults. In addition, its use in adults with failing systemic right ventricles and diastolic heart failure is promising. This study reports our experience with this drug for protein-losing enteropathy secondary to Fontan failure in pediatrics.

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Background: The aims of the study were to assess the performance of a clinically available cell-free DNA (cfDNA) assay in a large cohort of pediatric and adult heart transplant recipients and to evaluate performance at specific cut points in detection of rejection.

Methods: Observational, non-interventional, prospective study enrolled pediatric and adult heart transplant recipients from seven centers. Biopsy-associated plasma samples were used for cfDNA measurements.

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Mid-aortic syndrome is a rare condition characterised by segmental narrowing of the thoracoabdominal aorta. Here, we demonstrate a case of mid-aortic syndrome in a 30-month-old female who was diagnosed via transesophageal echocardiography after presenting with dilated cardiomyopathy and severe heart failure requiring placement of a left ventricular assist device.

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Objectives: Donor-specific cell-free DNA shows promise as a noninvasive marker for allograft rejection, but as yet has not been validated in both adult and pediatric recipients. The study objective was to validate donor fraction cell-free DNA as a noninvasive test to assess for risk of acute cellular rejection and antibody-mediated rejection after heart transplantation in pediatric and adult recipients.

Methods: Pediatric and adult heart transplant recipients were enrolled from 7 participating sites and followed for 12 months or more with plasma samples collected immediately before all endomyocardial biopsies.

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Background Children with Down syndrome (DS) have a high risk of cardiac disease that may prompt consideration for heart transplantation (HTx). However, transplantation in patients with DS is rarely reported. This project aimed to collect and describe waitlist and post- HTx outcomes in children with DS.

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Background: Clinical rejection (CR) defined as decision to treat clinically suspected rejection with change in immunotherapy based on clinical presentation with or without diagnostic biopsy findings is an important part of care in heart transplantation. We sought to assess the utility of donor fraction cell-free DNA (DF cfDNA) in CR and the utility of serial DF cfDNA in CR patients in predicting outcomes of clinical interest.

Methods: Patients with heart transplantation were enrolled in two sequential, multi-center, prospective observational studies.

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Abnormal dystrophin production due to mutations in the dystrophin gene causes Duchenne Muscular Dystrophy (DMD). Cases demonstrate considerable genetic and disease progression variability. It is unclear if specific gene mutations are prognostic of outcomes in this population.

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Background: Echocardiographic markers of ACR are essential for early recognition and management. The literature's primary focus has been on the LV with little attention given to the RV. This study aimed to investigate echocardiographic right ventricular indices in the detection of ACR and to evaluate their utility as prognostic indicators of graft integrity.

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Background: There is wide variability in the timing of heart transplant (HTx) after pediatric VAD implant. While some centers wait months before listing for HTx, others accept donor heart offers within days of VAD surgery. We sought to determine if HTx within 30 days versus ≥ 30 after VAD impacts post-HTx outcomes.

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Background: Cell-free DNA is an emerging biomarker. While donor fraction may detect graft events in heart transplant recipients, the prognostic value of total nuclear cell-free DNA (ncfDNA) itself is largely unexplored.

Objective: Explore the relationship between ncfDNA and clinical events in heart transplant recipients.

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Aim: To describe the clinical and hemodynamic characteristics of Fontan failure in children listed for heart transplant.

Methods: In a nested study of the Pediatric Heart Transplant Society, 16 centers contributed information on Fontan patients listed for heart transplant between 2005and 2013. Patients were classified into four mutually exclusive phenotypes: Fontan with abnormal lymphatics (FAL), Fontan with reduced systolic function (FRF), Fontan with preserved systolic function (FPF), and Fontan with "normal" hearts (FNH).

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Infection by SARS-CoV-2 has led to disease referred to as coronavirus disease 2019 which, in children has been described as of multisystem inflammatory syndrome in children. Our experience demonstrates 2 distinct presentations of this syndrome which have different clinical courses and may have differing long-term outcomes.

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Background: Heart transplantation has become standard of care for pediatric patients with either end-stage heart failure or inoperable congenital heart defects. Despite increasing surgical complexity and overall volume, however, annual transplant rates remain largely unchanged. Data demonstrating pediatric donor heart refusal rates of 50% suggest optimizing donor utilization is critical.

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Duchenne muscular dystrophy (DMD) is characterized by myocardial fibrosis and left ventricular (LV) dysfunction. Implantable cardioverter defibrillator (ICD) use has not been characterized in this population but is considered for symptomatic patients with severe LV dysfunction (SLVD) receiving guideline-directed medical therapy (GDMT). We evaluated ICD utilization and efficacy in patients with DMD.

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The number of potential pediatric heart transplant recipients continues to exceed the number of donors, and consequently the waitlist mortality remains significant. Despite this, around 40% of all donated organs are not used and are discarded. This document (62 authors from 53 institutions in 17 countries) evaluates factors responsible for discarding donor hearts and makes recommendations regarding donor heart acceptance.

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As survival and neuromuscular function in Duchenne muscular dystrophy (DMD) have improved with glucocorticoid (GC) therapy and ventilatory support, cardiac deaths are increasing. Little is known about risk factors for cardiac and non-cardiac causes of death in DMD. A multi-center retrospective cohort study of 408 males with DMD, followed from January 1, 2005 to December 31, 2015, was conducted to identify risk factors for death.

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Background: Endomyocardial biopsy (EMB) is the current standard for rejection surveillance in heart transplant recipients. The quantification of donor-specific cell-free DNA (cfDNA) may be an appropriate biomarker for non-invasive rejection surveillance. A multicenter prospective blinded study (DNA-Based Transplant Rejection Test, DTRT) investigated the value of donor fraction (DF), defined as the ratio of cfDNA specific to the transplanted organ to the total amount of cfDNA present in a blood sample.

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Background: As survival and neuromuscular function in Duchenne Muscular Dystrophy (DMD) improve with glucocorticoid therapy and respiratory advances, the proportion of cardiac deaths is increasing. Little is known about the use and outcomes of advanced heart failure (HF) therapies in this population.

Methods: A retrospective cohort study of 436 males with DMD was performed, from January 1, 2005-January 1, 2018, with the primary outcome being use of advanced HF therapies including: implantable cardioverter defibrillator (ICD), left ventricular assist device (LVAD), and heart transplantation (HTX).

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The objective of this study was to describe a cohort of patients with clinical myocarditis and normal left ventricular (LV) systolic function on admission. A retrospective chart review at seven tertiary pediatric hospitals identified patients aged < 19 years admitted with an ICD-9 code of myocarditis between 2008 and 2012. Patients were excluded if admission LV systolic ejection fraction was < 50%, fractional shortening (FS) was < 28% or if the admitting or consulting cardiologist did not suspect myocarditis.

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The objective of this study was to describe a contemporary cohort of pediatric patients hospitalized for clinically suspected myocarditis. A retrospective chart review was performed at seven tertiary pediatric hospitals. Electronic medical records were searched between 2008 and 2012 for patients ≤18 years admitted with an ICD-9 code consistent with myocarditis.

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Our aim is to determine (a) the effect of changes in pre-transplant management and era of listing on survival of children listed for HTx and (b) risk factors for death while waiting. This retrospective study included all children listed between 1/1993 and 12/2009 at our center. Survival was determined using survival analysis and competing outcomes modeling.

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Background: Although used routinely, the pleiotropic benefits of statins remain understudied in children after heart transplantation. We hypothesized that statin therapy would reduce the incidence of rejection, cardiac allograft vasculopathy (CAV) and post-transplant lymphoproliferative disease (PTLD).

Methods: This study was a retrospective review of 964 pediatric (ages 5 to 18 years) heart transplant recipients in the multicenter Pediatric Heart Transplant Study registry from 2001 to 2012.

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