A case for genetic testing: Arrhythmogenic cardiomyopathy presenting as myocarditis.

Arrhythmogenic cardiomyopathy (ACM) is an inherited cardiomyopathy associated with fibrofatty tissue replacement of the ventricular tissue. The disease can cause ventricular dysfunction and arrhythmias and can increase the risk of sudden cardiac death. This cardiomyopathy can have variable clinical presentations, especially in the pediatric and young adult populations. In this report, we describe the case of an 18-year-old female with myocarditis as the initial presentation of ACM. She presented following a resuscitated cardiac arrest due to ventricular arrhythmia. On arrival, myocardial edema and delayed gadolinium enhancement were present on cardiac magnetic resonance imaging, with no ventricular changes observed, making the diagnosis consistent with myocarditis. Genetic testing revealed a pathogenic mutation in the desmoplakin gene consistent with ACM. Given the unconventional initial presentation of this patient's disease, early consideration of genetic testing may be beneficial to aid in the early diagnosis and management of ACM in young patients.

Waitlist Outcomes for Pediatric Heart Transplantation in the Current Era: An Analysis of the Pediatric Heart Transplant Society Database.

BACKGROUND: Waitlist mortality (WM) remains elevated in pediatric heart transplantation. Allocation policy is a potential tool to help improve WM. This study aims to identify patients at highest risk for WM to potentially inform future allocation policy changes. METHODS: The Pediatric Heart Transplant Society database was queried for patients <18 years of age indicated for heart transplantation between January 1, 2010 to December 31, 2021. Waitlist mortality was defined as death while awaiting transplant or removal from the waitlist due to clinical deterioration. Because WM is low after the first year, analysis was limited to the first 12 months on the heart transplant list. Kaplan-Meier analysis and log-rank testing was conducted to compare unadjusted survival between groups. Cox proportional hazard models were created to determine risk factors for WM. Subgroup analysis was performed for status 1A patients based on body surface area (BSA) at time of listing, cardiac diagnosis, and presence of mechanical circulatory support. RESULTS: In total 5974 children met study criteria of which 3928 were status 1A, 1012 were status 1B, 963 were listed status 2, and 65 were listed status 7. Because of the significant burden of WM experienced by 1A patients, further analysis was performed in only patients indicated as 1A. Within that group of patients, those with smaller size and lower eGFR had higher WM, whereas those patients without congenital heart disease or support from a ventricular assist device (VAD) at time of listing had decreased WM. In the smallest size cohort, cardiac diagnoses other than dilated cardiomyopathy were risk factors for WM. Previous cardiac surgery was a risk factor in the 0.3 to 0.7 m2 and >0.7 m2 BSA groups. VAD support was associated with lower WM other than in the single ventricle cohort, where VAD was associated with higher WM. Extracorporeal membrane oxygenation and mechanical ventilation were associated with increased risk of WM in all cohorts. CONCLUSIONS: There is significant variability in WM among status-1A patients. Potential refinements to current allocation system should factor in the increased WM risk we identified in patients supported by extracorporeal membrane oxygenation or mechanical ventilation, single ventricle congenital heart disease on VAD support and small children with congenital heart disease, restrictive cardiomyopathy, or hypertrophic cardiomyopathy.

DQB1 antigen matching improves rejection-free survival in pediatric heart transplant recipients.

BACKGROUND: Presence of donor-specific antibodies (DSAs), particularly to class II antigens, remains a major challenge in pediatric heart transplantation. Donor-recipient human leukocyte antigen (HLA) matching is a potential strategy to mitigate poor outcomes associated with DSAs. We evaluated the hypothesis that antigen mismatching at the DQB1 locus is associated with worse rejection-free survival. METHODS: Data were collected from Scientific Registry of Transplant Recipients for all pediatric heart transplant recipients 2010-2021. Only transplants with complete HLA typing at the DQB1 locus for recipient and donor were included. Primary outcome was rejection-free graft survival through 5 years. RESULTS: Of 5,115 children, 4,135 had complete DQB1 typing and were included. Of those, 503 (12%) had 0 DQB1 donor-recipient mismatches, 2,203 (53%) had 1, and 1,429 (35%) had 2. Rejection-free survival through 5 years trended higher for children with 0 DQB1 mismatches (68%), compared to those with 1 (62%) or 2 (63%) mismatches (pairwise p = 0.08 for both). In multivariable analysis, 0 DQB1 mismatches remained significantly associated with improved rejection-free graft survival compared to 2 mismatches, while 1 DQB1 mismatch was not. Subgroup analysis showed the strongest effect in non-Hispanic Black children and those undergoing retransplant. CONCLUSIONS: Matching at the DQB1 locus is associated with improved rejection-free survival after pediatric heart transplant, particularly in Black children, and those undergoing retransplant. Assessing high-resolution donor typing at the time of allocation may further corroborate and refine this association. DQB1 matching may improve long-term outcomes in children stabilized either with optimal pharmacotherapy or supported with durable devices able to await ideal donors.

Successful implementation of telehealth visits in the paediatric heart failure and heart transplant population.

The Advanced Cardiac Therapies Improving Outcomes Network (ACTION) and Pediatric Heart Transplant Society (PHTS) convened a working group at the beginning of 2020 during the COVID-19 pandemic, with the aim of using telehealth as an alternative medium to provide quality care to a high-acuity paediatric population receiving advanced cardiac therapies. An algorithm was developed to determine appropriateness, educational handouts were developed for both patients and providers, and post-visit surveys were collected. Telehealth was found to be a viable modality for health care delivery in the paediatric heart failure and transplant population and has promising application in the continuity of follow-up, medication titration, and patient education/counselling domains.

Urinary biomarkers associated with acute kidney injury in pediatric mechanical circulatory support patients.

BACKGROUND: In patients requiring mechanical circulatory support (MCS), the incidence of acute kidney injury (AKI) is between 37 and 63%. In this study, we performed an exploratory analysis evaluating the relationship of multiple urine biomarkers with AKI development in pediatric MCS patients. METHODS: This is a single center retrospective study in a pediatric cohort receiving MCS from August 2014 to November 2020. We measured 14 urine biomarkers of kidney injury on day 1 following MCS initiation and analyzed their association with development of AKI in the first 7 days of MCS initiation. RESULTS: Sixty patients met inclusion criteria. Patients with AKI were more likely to be supported by venoarterial extracorporeal membrane oxygenation (65% vs. 8.3%, p < 0.001), compared to the no AKI group and less likely to have ventricular assist devices (10% vs. 50%, p < 0.001). There was a significant increase in the median urine albumin and urine osteoactivin in the AKI group, compared to the no AKI group (p = 0.020 and p = 0.018, respectively). When normalized to urine creatinine (UCr), an increased log osteoactivin/UCr was associated with higher odds of AKI development (OR: 2.05; 95% CI: 1.07, 4.44; p = 0.028), and higher log epidermal growth factor (EGF)/UCr (OR: 0.41; 95% CI: 0.15, 0.96) was associated with decreased odds of AKI. CONCLUSIONS: Early increase in urine osteoactivin is associated with AKI development within 7 days of MCS initiation in pediatric patients. Contrary, an increased urine EGF is associated with kidney protection. A higher resolution version of the Graphical abstract is available as Supplementary information.

Assessing Donor-Recipient Size Mismatch in Pediatric Heart Transplantation: Lessons Learned From Over 7,500 Transplants.

BACKGROUND: To date, no studies have identified an optimal metric to match donor-recipient (D-R) pairs in pediatric heart transplantation (HT). OBJECTIVES: This study sought to identify size mismatch metrics that predicted graft survival post-HT. METHODS: D-R pairs undergoing HT in Pediatric Heart Transplant Society database from 1993 to 2021 were included. Effects of size mismatch by height, weight, body mass index, body surface area, predicted heart mass, and total cardiac volume (TCV) on 1- and 5-year graft survival and morbidity outcomes (rejection and cardiac allograft vasculopathy) were evaluated. Cox models with stepwise selection identified size metrics that independently predicted graft survival. RESULTS: Of 7,715 D-R pairs, 36.0% were well matched (D-R ratio: -20% to +20%) by weight, 39.0% by predicted heart mass, 50.0% by body surface area, 57.0% by body mass index, 71.0% by height, and 93.0% by TCV. Of all size metrics, only D-R mismatch by height and TCV predicted graft survival at 1 and 5 years. Effects of D-R size mismatch on graft survival were nonlinear. At both 1 and 5 years post-HT, D-R undersizing and oversizing by height led to increased graft loss, with graft loss observed more frequently with undersizing. Moderately undersized donors by height (D-R ratio: <-30%) frequently experienced rejection post-HT (P < 0.001). Assessing D-R size matching by TCV, minimal donor undersizing was protective, while oversizing up to 25% was not associated with increased graft loss. CONCLUSIONS: In pediatric HT, D-R appear most optimally matched using TCV. Only D-R size mismatch by TCV and height independently predicts graft survival. Standardizing size matching across centers may reduce donor discard.

Novel uses for implanted haemodynamic monitoring in adults with subaortic right ventricles.

BACKGROUND: Pulmonary hypertension (PH) is a common complication in patients with complete dextro-transposition of the great arteries (TGA) after atrial switch (D-TGA/AS) and congenitally corrected TGA (ccTGA). In this population with subaortic right ventricles (sRVs), echocardiography is a poor screening tool for PH; implantable invasive haemodynamic monitoring (IHM) could be used for this purpose, but data are limited. The aim of this study is to report on novel uses of IHM in patients with sRV. METHODS: This retrospective study describes the uses of IHM, impact of IHM on heart failure hospitalisation (HFH) and device-related complications in adults with sRV from a single centre (2015-2022). RESULTS: IHM was placed in 18 patients with sRV (median age 43 (range 30-54) years, 8 female, 16 with D-TGA/AS, 2 with ccTGA); 16 had moderate or severe sRV systolic dysfunction, 13 had PH on catheterisation. IHM was used for (1) Medical therapy titration, (2) Medical management after ventricular assist device in patients with transplant-limiting PH and (3) Serial monitoring of pulmonary artery pressures without repeat catheterisations to help identify the optimal time for heart transplant referral. In follow-up (median 23 months), HFHs/year were similar to the year prior to IHM (median 0 (IQR 0-1.0) before vs 0 (0-0.8) after, p=0.984). Device migration occurred in one, without long-term sequelae. CONCLUSIONS: Uses of IHM in patients with sRV are described which may minimise the need for serial catheterisations in a population where PH is prevalent. HFHs were low overall but not impacted by IHM. One device-related complication occurred without long-term consequence.

Cardiac magnetic resonance assessment of acute rejection and cardiac allograft vasculopathy in pediatric heart transplant.

BACKGROUND: In pediatric heart transplant (PHT), cardiac catheterization with endomyocardial biopsy (EMB) is standard for diagnosing acute rejection (AR) and cardiac allograft vasculopathy (CAV) but is costly and invasive. OBJECTIVES: To evaluate the ability of cardiac magnetic resonance (CMR) to noninvasively identify differences in PHT patients with AR and CAV. METHODS: Patients were enrolled at three children's hospitals. Data were collected from surveillance EMB or EMB for-cause AR. Patients were excluded if they had concurrent diagnoses of AR and CAV, CMR obtained >7days from AR diagnosis, they had EMB negative AR, or could not undergo contrasted, unsedated CMR. Kruskal-Wallis test was used to compare groups: (1) No AR or CAV (Healthy), (2) AR, (3) CAV. Wilcoxon rank-sum test was used for pairwise comparisons. RESULTS: Fifty-nine patients met inclusion criteria (median age 17years [IQR 15-19]) 10 (17%) with AR, and 11 (19%) with CAV. AR subjects had worse left ventricular ejection fraction compared to Healthy patients (p = 0.001). Global circumferential strain (GCS) was worse in AR (p = 0.054) and CAV (p = 0.019), compared to Healthy patients. ECV, native T1, and T2 z-scores were elevated in patients with AR. CONCLUSIONS: CMR was able to identify differences between CAV and AR. CAV subjects had normal global function but abnormal GCS which may suggest subclinical dysfunction. AR patients have abnormal function and tissue characteristics consistent with edema (elevated ECV, native T1 and T2 z-scores). Characterization of CMR patterns is critical for the development of noninvasive biomarkers for PHT and may decrease dependence on EMB.

An in vitro comparison of intra-operative isohemagglutinin and human leukocyte antigen removal techniques in pediatric heart transplantation.

BACKGROUND: Highly sensitized pediatric patients awaiting heart transplantation experience longer wait times and thus higher waitlist mortality. Similarly, children less than 2 years of age have increased waitlist times and mortality when compared to their older peers. To improve the likelihood of successful transplantation in these patients, various strategies have been utilized, including peri-operative plasmapheresis. However, limited data exists comparing plasmapheresis techniques for antibody reduction. This study's aim was to compare the in vitro magnitude of isohemagglutinin titers (IT) and human leukocyte antigen (HLA) antibody removal and the time required between membrane-based plasmapheresis (MP) and centrifuge-based plasmapheresis (CP) incorporated into the extracorporeal (EC) circuit. METHODS: Two MP (Prismaflex) and two CP (Spectra Optia, Terumo BCT) circuits were incorporated into four separate EC circuits primed with high titer, highly sensitized type O donor whole blood. Assays were performed to determine baseline IT and anti-HLA antibodies and then at 30-minute increments until completion of the run (two plasma volume exchanges) at two hours. RESULTS: There was a decrease in anti-A and anti-B IgM and IgG titers with both MP and CP. Mean anti-A and anti-B titer reduction was by 4.625 titers (93.7% change) and 4.375 titers (93.8% change) using MP and CP, respectively. At 2 h of apheresis, CP reduced 62.5% of all ITs to ≤ 1:4, while MP reduced 50% of ITs to ≤ 1:4. Additionally, reduction of anti-HLA class II antibody to mean fluorescence intensity (MFI) <3000 was achieved with both MP and CP. At 2 h of apheresis, CP reduced MFI by 2-3.5 fold and MP reduced MFI by 1.7-2.5 fold. Both demonstrated similar hemolytic and thrombotic profiles. CONCLUSIONS: In this in vitro plasmapheresis model of IT and anti-HLA antibody reduction, both MP and CP incorporated into the EC circuit can be used quickly and effectively to reduce circulating antibodies. While CP may have some greater efficiency, further study is necessary to verify this in vivo.

Initial Counseling Prior to Palliation for Hypoplastic Left Heart Syndrome: 2021 vs 2011.

We sought to examine current practices and changes in practice regarding initial counseling for families of patients with hypoplastic left heart syndrome (HLHS) given the evolution of options and outcomes over time. Counseling (Norwood with Blalock-Taussig-Thomas shunt (NW-BTT), NW with right ventricle to pulmonary artery conduit (NW-RVPA), hybrid palliation, heart transplantation, or non-intervention/hospice (NI)) for patients with HLHS were queried via questionnaire of pediatric care professionals in 2021 and compared to identical questionnaire from 2011. Of 322 respondents in 2021 (39% female), 299 respondents were cardiologists (92.9%), 17cardiothoracic surgeons (5.3%), and 6 were nurse practitioners (1.9%). Respondents were largely from North America (96.9%). In 2021, NW-RVPA procedure was the preferred palliation for standard risk HLHS patient (61%) and was preferred across all US regions (p < 0.001). NI was offered as an option by 71.4% of respondents for standard risk patients and was the predominant strategy for patients with end-organ dysfunction, chromosomal abnormality, and prematurity (52%, 44%, and 45%, respectively). The hybrid procedure was preferred for low birth-weight infants (51%). In comparison to the identical 2011 questionnaire (n = 200), the NW-RVPA was endorsed more in 2021 (61% vs 52%, p = 0.04). For low birth-weight infants, hybrid procedure was more recommended than in 2011 (51% vs 21%, p < 0.001). The NW-RVPA operation is the most recommended strategy throughout the US for infants with HLHS. The hybrid procedure for low birth-weight infants is increasingly recommended. NI continues to be offered even in standard risk patients with HLHS.

Racial and socioeconomic disparities in status exceptions for pediatric heart transplant candidates under the current U.S. Pediatric Heart Allocation Policy.

BACKGROUND: The 2016 revision of the US Pediatric Heart Allocation Policy developed stringent rules for priority status creating impetus for clinicians to seek status exceptions. We hypothesized there may be differential status exceptions based on race and socioeconomic status (SES) contributing to disparities in waitlist outcomes. METHODS: The Scientific Registry for Transplant Recipients was queried for children listed for heart transplant from 2012 to 2020. Waitlist status & mortality with regards to race and neighborhood SES were stratified by listing before (Era 1) or after (Era 2) the policy change. RESULTS: The use of both 1A and 1B exceptions (E) increased in Era 2. In Era 1, there was no association between patient race or neighborhood SES on use of 1A(E) or 1B(E) when controlling for age and diagnosis. In Era 2, neither race nor neighborhood SES were associated with 1A(E), but both were associated with 1B(E): non-Hispanic (NH) Black children and those from low- and middle-SES neighborhoods were significantly less likely to be listed 1B(E). In Era 1, there were no significant differences in waitlist mortality based on race at any waitlist status; in Era 2, NH Black children had higher waitlist mortality when initially listed 1B or 2. CONCLUSIONS: Since the 2016 policy change, racial disparities in waitlist mortality have worsened among children initially listed with lower priority status. Unequal use of 1B exceptions, which lower waitlist mortality, may explain some of these disparities. Recently implemented standardized pediatric exception guidance has the potential to improve equity.

Evidence-Based Guidelines for Acute Stabilization and Management of Neonates with Persistent Pulmonary Hypertension of the Newborn.

Persistent pulmonary hypertension of the newborn, or PPHN, represents a challenging condition associated with high morbidity and mortality. Management is complicated by complex pathophysiology and limited neonatal specific evidence-based literature, leading to a lack of universal contemporary clinical guidelines for the care of these patients. To address this need and to provide consistent high-quality clinical care for this challenging population in our neonatal intensive care unit, we sought to develop a comprehensive clinical guideline for the acute stabilization and management of neonates with PPHN. Utilizing cross-disciplinary expertise and incorporating an extensive literature search to guide best practice, we present an approachable, pragmatic, and clinically relevant guide for the bedside management of acute PPHN. KEY POINTS: · PPHN is associated with several unique diagnoses; the associated pathophysiology is different for each unique diagnosis.. · PPHN is a challenging, dynamic, and labile process for which optimal care requires frequent reassessment.. · Key management goals are adequate tissue oxygen delivery, avoiding harm..

Surgical outcomes of infective endocarditis in pediatrics: Moving the needle to a contemporary, multidisciplinary approach.

BACKGROUND: Infective endocarditis (IE) is an uncommon disease in children that, when present, is accompanied by significant morbidity and mortality. The presence of congenital heart disease often complicates management. The aim of the present study is to describe the characteristics and outcomes of children undergoing surgery for IE. METHODS: A retrospective chart review from 2004 to 2020 was conducted to identify consecutive patients younger than age 20 years with IE undergoing surgery. RESULTS: A total of 94 patients with IE were identified, of whom 47 underwent surgery at a median age of 16.7 years. Thirty-one patients (65.95%) had congenital heart disease. Vegetation and embolic phenomena occurred in 41 and 29 patients (87.23% and 61.7%), respectively, with the brain as most common location (57.1%). Native valve involvement had a greater tendency to embolize (P < .001). Staphylococcus spp was the most common organism (49%). The mitral valve was the most affected (31.9%). Seven (14.9%) patients had multivalvar involvement and valve replacement was the most common procedure performed (37 patients; 78.7%). There were 3 operative deaths (6.4%). Median length of hospital stay was 21 days. Risk factors for prolonged hospital stay were time to surgery in days (P < .001) and native valvar involvement (P = .05). Five patients (10.6%) had postoperative recurrent IE. Survival at 1 and 5 years was 93.6% and 89.4%, respectively. CONCLUSIONS: Children with IE can undergo surgery with acceptable results. The morbidity, but not mortality, is driven by embolic complications. Staphylococcus spp and native valve involvement are significant risk factors. VIDEO ABSTRACT.

Fontan-associated liver disease after heart transplant.

BACKGROUND: Fontan associated liver disease (FALD) potentially impacts Fontan patients undergoing heart transplant. This multi-center study sought to identify pre-transplant risk factors and characterize any post-transplant liver recovery in those patients undergoing heart-alone transplant. METHODS: Review of Fontan patients at 12 pediatric institutions who underwent heart transplant between 2001-2019. Radiologists reviewed pre and post-transplant liver imaging for fibrosis. Laboratory, pathology and endoscopy studies were reviewed. RESULTS: 156 patients underwent transplant due to decreased ventricular function (49%), protein losing enteropathy (31%) or plastic bronchitis (10%); median age at transplant was 13.6 years (interquartile range IQR 7.8, 17.2) with a median of 9.3 years (IQR 3.2, 13.4) between the Fontan operation and transplant. Few patients had pre-transplant endoscopy (18%), and liver biopsy (19%). There were 31 deaths (20%). The median time from transplant to death was 0.5 years (95% Confidence Interval CI 0.0, 3.6). The five-year survival was 73% (95% CI 64%, 83%). Deaths were related to cardiac causes in 68% (21/31) and infection in 6 (19%). A pre-transplant elevation in bilirubin was a predictor of death. Higher platelet levels were protective. Immediate post-transplant elevations in creatinine, AST, ALT, and INR were predictive of death. Advanced liver fibrosis identified on ultrasound, computed tomography, or magnetic resonance imaging was not predictive of death. Liver imaging suggested some improvement in liver congestion post-transplant. CONCLUSIONS: Elevated bilirubin, but not fibrosis on liver imaging, was associated with post-heart transplant mortality in Fontan patients in this multicenter retrospective study. Additionally, heart transplant may alter the progression of FALD.

Initial multicenter experience with ventricular assist devices in children and young adults with muscular dystrophy: An ACTION registry analysis.

PURPOSE: Cardiac disease results in significant morbidity and mortality in patients with muscular dystrophy (MD). Single centers have reported their ventricular assist device (VAD) experience in specific MDs and in limited numbers. This study sought to describe the outcomes associated with VAD therapy in an unselected population across multiple centers. METHODS: We examined outcomes of patients with MD and dilated cardiomyopathy implanted with a VAD at Advanced Cardiac Therapies Improving Outcomes Network (ACTION) centers from 9/2012 to 9/2020. RESULTS: A total of 19 VADs were implanted in 18 patients across 12 sites. The majority of patients had dystrophinopathy (66%) and the median age at implant was 17.2 years (range 11.7-29.5). Eleven patients were non-ambulatory (61%) and 6 (33%) were on respiratory support pre-VAD. Five (28%) patients were implanted as a bridge to transplant, 4 of whom survived to transplant. Of 13 patients implanted as bridge to decision or destination therapy, 77% were alive at 1 year and 69% at 2 years. The overall frequencies of positive outcome (transplanted or alive on device) at 1 year and 2 years were 84% and 78%, respectively. Two patients suffered a stroke, 2 developed sepsis, 1 required tracheostomy, and 1 experienced severe right heart failure requiring right-sided VAD. CONCLUSIONS: This study demonstrates the potential utility of VAD therapies in patients with muscular dystrophy. Further research is needed to further improve outcomes and better determine which patients may benefit most from VAD therapy in terms of survival and quality of life.

Worsening racial disparity in waitlist mortality for pediatric heart transplant candidates since the 2016 Pediatric Heart Allocation Policy revision.

BACKGROUND: The US Pediatric Heart Allocation Policy (PHAP) was revised in March 2016, with the goal of reducing waitlist mortality. We evaluated the hypothesis that these changes, which increased status exceptions, have worsened racial disparities in waitlist outcomes. METHODS: Children in the Pediatric Heart Transplant Study database listed for first heart transplant from January 2012 - June 2020 were included and stratified by listing before (Era 1) or after (Era 2) the PHAP revision. RESULTS: A total of 4,089 children were listed during the study period. Compared with white children (n = 2648), non-white children (n = 1441) were more likely to have an underlying diagnosis of cardiomyopathy in both eras. Waitlist mortality was similar in white and non-white children in Era 1, but comparatively worse for non-white children in Era 2. In multivariable analysis controlling for diagnosis, age, and severity markers, non-white children had a significantly higher waitlist mortality only in Era 2 (Era 1: sHR 1.22 [95%CI 0.90 - 1.66] vs. Era 2: sHR 1.57 [95%CI 1.17 - 2.10]). CONCLUSIONS: Widening racial disparities in waitlist mortality may be an unintended consequence of the 2016 PHAP revision. Additional analyses may inform the degree to which this policy vs. unrelated changes in care differentially contribute to these disparities.

Clinical approach to antibody-mediated rejection from the pediatric heart transplant society.

OBJECTIVE: This document is designed to outline the definition, pathogenesis, diagnostic modalities and therapeutic measures to treat antibody-mediated rejection in children postheart transplant METHODS: Literature review was conducted by a Pediatric Heart Transplant Society (PHTS) working group to identify existing pediatric and adult studies on antibody-mediated rejection (AMR). In addition, the centers participating in PHTS were asked to submit their approach to diagnosis and management of pediatric AMR. This document synthesizes information gathered from both these sources to highlight a practical approach to diagnosing and managing a child with AMR postheart transplant. This document may not represent the practice at all centers in the PHTS and serves as a starting point to understand an approach to this clinical scenario.

Clinical approach to acute cellular rejection from the pediatric heart transplant society.

BACKGROUND: Early detection of cardiac allograft rejection is crucial for post-transplant graft survival. Despite the progress made in immunosuppression strategies, acute cellular rejection remains a serious complication during and after the first post-transplant year, and there is a continued lack of consensus regarding its treatment, especially in pediatric transplant patients. METHODS: An open request was placed via the listserv to the membership of the Pediatric Heart Transplant Society (PHTS). Along with a broad literature search, numerous institutional protocols were pooled, analyzed and consolidated. A clinical approach document was generated highlighting areas of consensus and practice variation. RESULTS: The clinical approach document divides cellular rejection by International Society for Heart and Lung Transplantation grades and provides management strategies for each, including persistent cellular rejection. CONCLUSIONS: Cellular rejection treatment can be tailored to the clinical status, graft function, and the grade of cellular rejection. A case of mild and asymptomatic rejection may not require treatment, whereas a higher-grade rejection or rejection with graft dysfunction or hemodynamic compromise may require aggressive intravenous therapies, changes to maintenance immunosuppression therapy and augmented surveillance.

Cardiorespiratory management of Duchenne muscular dystrophy: emerging therapies, neuromuscular genetics, and new clinical challenges.

The life-limiting complications of Duchenne muscular dystrophy (DMD) include loss of lung function and progressive cardiomyopathy; when patients are treated with assisted ventilation, cardiac function becomes the main determinant of survival. Therapy for DMD is changing rapidly, with the emergence of new genetic and molecular therapeutic options, the proliferation of which has fostered the perception that DMD is a potentially curable disease. However, data for respiratory and cardiac outcomes are scarce and available evidence is not uniformly positive. Patients who share a dystrophin (DMD) genotype can have highly divergent cardiorespiratory phenotypes; genetic modifiers of DMD gene expression are a probable cause of respiratory and cardiac phenotypic variability and discordance. In this Personal View, we provide an overview of new and emerging DMD therapies, highlighting the limitations of current research and considering strategies to incorporate cardiorespiratory assessments into clinical trials. We explore how genetic modifiers could be used to predict cardiorespiratory natural history and how manipulation of such modifiers might represent a promising therapeutic strategy. Finally, we examine the changing role of respiratory physicians, cardiologists, and intensive care clinicians on the frontline of a challenging new clinical landscape.

The evolution of pediatric heart retransplantation over three decades: An analysis from the PHTS.

BACKGROUND: Retransplantation is rare and associated with worse survival and more morbidity. The study aim is to describe an updated cohort of pediatric retransplants, determine if there has been an era effect on outcomes, and understand if identified trends are explained by changes in patient selection. METHODS: Pediatric Heart Transplant Society database analysis of retransplantation patients <18 years of age (Era 1: 1993-2001, Era 2: 2002-2010, Era 3: 2011-2018). Multivariate analysis identified risk factors for graft loss. Multiphase parametric hazard modeling was used to depict era and risk factor effect. RESULTS: Survival was lower (p < .0001) for retransplant (n = 222) compared to primary transplant (n = 6548) (median 9.3 vs 20.2 years). Median survival increased from Era 1 to 2 (4.8 vs 9.3 years; p < .0001) with no incremental change in Era 3. Era 2 and 3 retransplants had a longer inter-transplant interval (p < .0001), were less frequently for early graft failure (p = .0004) or acute rejection (p = .007), more frequently from a ventricular assist device (p = .0014), and less frequently from extracorporeal membrane oxygenation (p = .0024). Predictors of graft loss included Era 1 (HR 10.55, p = .001), congenital heart disease (HR 4.42, p = .01), inter-transplant interval <1 year (HR 5.34, p = .002), and mechanical support (ventricular assist device HR 7.47, p = .0042; extracorporeal membrane oxygenation HR 10.09, p < .0001). For each 1-year increase in inter-transplant interval, graft loss risk decreased by 1.15 (p = .0002). Retransplantation was associated with more rejection, infection, and allograft vasculopathy. CONCLUSIONS: Graft survival has improved in pediatric retransplants making it a viable option in select patients. Retransplantation should be avoided in the setting of early graft failure especially requiring mechanical support.