Decline in rejection in the first year after pediatric cardiac transplantation: a multi-institutional study

Prevalence and Impact of Recurrent Rejection on Pediatric Heart Transplant Recipients: A PHTS Multi-Institutional Analysis

BACKGROUND

Studies evaluating the prevalence and impact of recurrent rejection (RR) in pediatric heart transplant (HT) are sparse.

OBJECTIVES

The purpose of this study was to describe prevalence and impact of RR on cardiac allograft vasculopathy (CAV) and graft loss after pediatric HT.

METHODS

Data on HT from January 1, 2000, to June 30, 2020, in the Pediatric Heart Transplant Society database were included. Freedom from RR (≥2 rejection episodes) was compared by era (early: 2000-2009; current: 2010-2020). Outcomes for children experiencing RR were compared with those experiencing 0 or 1 rejection episodes and by type of RR (antibody-mediated rejection [AMR], acute cellular rejection [ACR], mixed [ACR/AMR]).

RESULTS

Of 6,342 HT recipients, 1,035 (17%) experienced RR. In the current era, pediatric HT recipients were less likely to experience RR (P < 0.001). Freedom from CAV was similar for those experiencing RR to those experiencing 0 or 1 episode (96.6% vs 95.3% vs 96.6%); and similar regardless of the type of RR (AMR, ACR, or mixed) (65.5% vs 82.9% vs 100%) (P > 0.05). Freedom from graft loss was significantly lower for those experiencing RR to those experiencing 0 or 1 episode (56.3% vs 72.3% vs 82.3%) and lower for those experiencing recurrent mixed rejection or recurrent AMR compared with those experiencing recurrent ACR (65.3% vs 50% vs 81.8%). Black children experiencing RR subsequently had lower freedom from CAV and graft loss than White children (P < 0.05 for all).

CONCLUSIONS

Although prevalence of RR has decreased, children experiencing RR are at greatly increased risk for losing their graft, particularly those who have recurrent mixed or antibody-mediated rejection.

The potential of autologous regulatory T cell (Treg) therapy to prevent Cardiac Allograft Vasculopathy (CAV) in paediatric heart transplant recipients

Paediatric heart transplant is an established treatment for end stage heart failure in children, however patients have to commit to lifelong medical surveillance and adhere to daily immunosuppressants to minimise the risk of rejection. Compliance with immunosuppressants can be burdensome with their toxic side effects and need for frequent blood monitoring especially in children. Though the incidence of early rejection episodes has significantly improved overtime, the long-term allograft health and survival is determined by Cardiac Allograft Vasculopathy (CAV) which affects a vast number of post-transplant patients. Once CAV has set in, there is no medical or surgical treatment to reverse it and graft survival is significantly compromised across all age groups. Current treatment strategies include novel immunosuppressant agents and drugs to lower blood lipid levels to address the underlying immunological pathophysiology and to manage traditional cardiac risk factors. Translational researchers are seeking novel immunological approaches that can lead to permanent acceptance of the allograft such as using regulatory T cell (Tregs) immunotherapy. Clinical trials in the setting of graft versus host disease, autoimmunity and kidney and liver transplantation using Tregs have shown the feasibility and safety of this strategy. This review will summarise current knowledge of the latest clinical therapies for CAV and pre-clinical evidence in support of Treg therapy for CAV. We will also discuss the different Treg sources and the considerations of translating this into a feasible immunotherapy in clinical practice in the paediatric population.

Pathology of explanted pediatric hearts: An 11-year study. Population characteristics and implications for outcomes

BACKGROUND

As more pediatric patients become candidates for heart transplantation (HT), understanding pathological predictors of outcome and the accuracy of the pretransplantation evaluation are important to optimize utilization of scarce donor organs and improve outcomes. The authors aimed to investigate explanted heart specimens to identify pathologic predictors that may affect cardiac allograft survival after HT.

METHODS

Explanted pediatric hearts obtained over an 11-year period were analyzed to understand the patient demographics, indications for transplant, and the clinical-pathological factors.

RESULTS

In this study, 149 explanted hearts, 46% congenital heart defects (CHD), were studied. CHD patients were younger and mean pulmonary artery pressure and resistance were significantly lower than in cardiomyopathy patients. Twenty-one died or underwent retransplantation (14.1%). Survival was significantly higher in the cardiomyopathy group at all follow-up intervals. There were more deaths and the 1-, 5- and 7-year survival was lower in patients ≤10 years of age at HT. Early rejection was significantly higher in CHD patients exposed to homograft tissue, but not late rejection. Mortality/retransplantation rate was significantly higher and allograft survival lower in CHD hearts with excessive fibrosis of one or both ventricles. Anatomic diagnosis at pathologic examination differed from the clinical diagnosis in eight cases.

CONCLUSIONS

Survival was better for the cardiomyopathy group and patients >10 years at HT. Prior homograft use was associated with a higher prevalence of early rejection. Ventricular fibrosis (of explant) was a strong predictor of outcome in the CHD group. We presented several pathologic findings in explanted pediatric hearts.

mTor-inhibition within the first days after pediatric heart transplantation is a potentially safe option to prevent cardiac allograft vasculopathy

BACKGROUND

Immunosuppression after heart transplantation (HTX) with mammalian target of rapamycin (mTOR) inhibitors serves as a prophylaxis against rejection and to treat coronary vascular injury. However, there is little data on the early, preventive use of everolimus after pediatric HTX.

METHODS

Retrospective study of 61 pediatric HTX patients (48 cardiomyopathy and 13 congenital heart disease), 28 females, median age 10.1 (range 0.1-17.9) years transplanted between 2008 and 2020. We analyzed survival, rejection, renal function, occurrence of lymphoproliferative disorder, and allograft vasculopathy together with adverse effects of early everolimus therapy combined with low-dose calcineurin inhibitors.

RESULTS

Everolimus therapy was started at a median 3.9 (1-14) days after HTX. Median follow-up was 4.3 (range 0.5-11.8) years, cumulative 184 patient years. The estimated 1- and 5-year survival probability was 89% (CI 82%:98%) and 87% (CI 78%:97%). Four patients developed rejection (6.6%) (maximum 2R ISHLT criteria). No patient suffered from chronic renal failure. Three patients (4.9%) developed post-transplant lymphoproliferative disorder. Five patients suffered relevant wound-healing disorders after transplantation, four of them carrying relevant risk factors before HTX (mechanical circulatory support (n = 3), delayed chest closure after HTX (n = 3)). No recipient developed cardiac allograft vasculopathy.

CONCLUSION

Initiating everolimus within the first 14 days after HTX seems to be well tolerated, enabling a low incidence of rejection, post-transplant lymphoproliferative disorders, renal failure, and reveals no evidence of cardiac allograft vasculopathy as well as good overall survival in pediatric heart transplant recipients.

Pediatric heart transplantation: Looking forward after five decades of learning

Heart transplantation has become the standard of care for pediatric patients with end-stage heart disease throughout the world. Since the first transplant was performed in 1967, the number of transplants has grown dramatically with 13 449 pediatric heart transplants being reported to The International Society of Heart and Lung Transplant (ISHLT) between January 1992 and June 30, 2018. Outcomes have consistently improved over the last few decades, specifically short-term outcomes. Most recent survival data demonstrate that recipients who survive to 1-year post-transplant have excellent long-term survival with more than 60% of those who were transplanted as infants being alive 25 years later. Nonetheless, the rates of graft loss beyond the first year have remained relatively constant over time; driven primarily by our poor understanding and lack of treatments for chronic allograft vasculopathy (CAV). Acute rejection, CAV, graft failure, and infection continue to be the major causes of death within the first 5 years post-transplant. In addition, renal dysfunction, malignancy, and the need for re-transplantation remain as significant issues that require close follow-up. Looking forward, key challenges include improving donor utilization rates (including donation after cardiac death (DCD) and the use of ex vivo perfusion devices), the development of non-invasive biomarkers for rejection, efforts to mitigate the long-term effects of immunosuppression, and prevention of CAV. It is not possible to cover the entire evolution of pediatric heart transplantation over the last five decades, but in this review, we hope to touch on key observations, lessons learned, and practice changes that have advanced the field, as well as glance ahead to the next decade.

Three decades of collaboration through the Pediatric Heart Transplant Society Registry: A journey through registry data with a highlight on children with single ventricle anatomy

BACKGROUND

The Pediatric Heart Transplant Society (PHTS) Registry was founded 30 years ago as a collaborative effort among like-minded providers of this novel life-saving technique for children with end-stage heart failure. In the intervening decades, the data from the Registry have provided invaluable knowledge to the field of pediatric heart transplantation. This report of the PHTS Registry provides a comprehensive look at the data, highlighting both the longevity of the registry and one unique aspect of the PHTS registry, allowing for exploration into children with single ventricle anatomy.

METHODS

The PHTS database was queried from January 1, 1993 to December 31, 2019 to include pediatric (age < 18 years) patients listed for HT. For our analysis, we primarily analyzed patients by era. The early era was defined as children listed for HT from January 1, 1993 to December 31, 2004; middle era January 1, 2005 to December 31, 2009; and recent era January 1, 2010 to December 31, 2019. Outcomes after listing and transplant, including mortality and morbidities, are presented as unadjusted for risk, but compared across eras.

RESULTS

Since 1993, 11 995 children were listed for heart transplant and entered into the PHTS Registry with 9755 listed during the study period. The majority of listings occurred within the most recent era. Waitlist survival improved over the decades as did posttransplant survival. Other notable changes over time include fewer patients experiencing allograft rejection or infection after transplant. Waitlist and posttransplant survival have changed dramatically in patients with single ventricle physiology and significantly differ by stage of single ventricle palliation.

SUMMARY

Key points from this PHTS Registry summary and focus on patients with single ventricle congenital heart disease in particular, include the changing landscape of candidates and recipients awaiting heart transplant. There is clear improvement in waitlist and transplant outcomes for children with both cardiomyopathy and congenital heart disease alike.

Establishing a nationwide pediatric heart transplantation program with mid-term results comparable to worldwide data - The Czech experience

BACKGROUND

Heart transplantation (HTx) is an established therapeutic option for children with end-stage heart failure. Comprehensive pediatric nationwide HTx program was introduced in 2014 in the Czech Republic. The aim of this study was to evaluate its mid-term characteristics and outcomes and to compare them with international data.

METHODS

Retrospective observational study, including all patients who underwent HTx from June 2014 till December 2022. Data from the institutional database were used for descriptive statistics and survival analyses.

RESULTS

A total of 30 HTx were performed in 29 patients with congenital heart disease (CHD, N = 15, single ventricular physiology in 10 patients) and cardiomyopathy (CMP, N = 14). Ten patients were bridged to HTx by durable left ventricular assist devices (LVADs) for a mean duration of 104 (SD 89) days. There was one early and one late death during median follow-up of 3.3 (IQR 1.3-6.1) years. Survival probability at 5 years after HTx was 93%. Two patients underwent re-transplantation (one of them in an adult center). Significant rejection-free survival at 1, 3, and 6 years after HTx was 76%, 63%, and 63%, respectively.

CONCLUSIONS

The introduced pediatric HTx program reflects the complexity of the treated population, with half of the patients having complex CHD and one-third being bridged to HTx by LVADs. Mid-term results are comparable to worldwide data. The data confirm the possibility of establishing a successful nationwide pediatric HTx program in a relatively small population country with well-developed pediatric cardiovascular care and other transplantation programs.

Heart Transplantation in Children With Down Syndrome

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.

Methods and Results

This is a retrospective case series of children with DS listed for HTx. Pediatric HTx centers were identified by their participation in 2 international registries with centers reporting HTx in a patient with DS providing detailed demographic, medical, surgical, and posttransplant outcome data for analysis. A total of 26 patients with DS were listed for HTx from 1992 to 2020 (median age, 8.5 years; 46% male). High‐risk or failed repair of congenital heart disease was the most common indication for transplant (N=18, 69%). A total of 23 (88%) patients survived to transplant. All transplanted patients survived to hospital discharge with a median posttransplant length of stay of 22 days. At a median posttransplant follow‐up of 2.8 years, 20 (87%) patients were alive, 2 (9%) developed posttransplant lymphoproliferative disorder, and 8 (35%) were hospitalized for infection within the first year. Waitlist and posttransplant outcomes were similar in patients with and without DS (P=non‐significant for all).

Conclusions

Waitlist and post‐HTx outcomes in children with DS selected for transplant listing are comparable to pediatric HTx recipients overall. Given acceptable outcomes, the presence of DS alone should not be considered an absolute contraindication to HTx.

Rejection surveillance in pediatric heart transplant recipients: Critical reflection on the role of frequent and long-term routine surveillance endomyocardial biopsies and comprehensive review of non-invasive rejection screening tools

BACKGROUND

Despite significant medical advances in the field of pediatric heart transplantation (HT), acute rejection remains an important cause of morbidity and mortality. Endomyocardial biopsy (EMB) remains the gold-standard method for diagnosing rejection but is an invasive, expensive, and stressful process. Given the potential adverse consequences of rejection, routine post-transplant rejection surveillance protocols incorporating EMB are widely employed to detect asymptomatic rejection. Each center employs their own specific routine rejection surveillance protocol, with no consensus on the optimal approach and with high inter-center variability. The utility of high-frequency and long-term routine surveillance biopsies (RSB) in pediatric HT has been called into question.

METHODS

Sources for this comprehensive review were primarily identified through searches in biomedical databases including MEDLINE and Embase.

RESULTS

The available literature suggests that the diagnostic yield of RSB is low beyond the first year post-HT and that a reduction in RSB intensity from high-frequency to low-frequency can be done safely with no impact on early and mid-term survival. Though there are emerging non-invasive methods of detecting asymptomatic rejection, the evidence is not yet strong enough for any test to replace EMB.

CONCLUSION

Overall, pediatric HT centers in North America should likely be doing fewer RSB than are currently performed. Risk factors for rejection should be considered when designing the optimal rejection surveillance strategy. Noninvasive testing including emerging biomarkers may have a complementary role to aid in safely reducing the need for RSB.

Emergency Department Management of Pediatric Heart Transplant Recipients: Unique Immunologic and Hemodynamic Challenges

BACKGROUND

Since the first heart transplant in 1967, there has been significant progress in this field of cardiac transplantation. Approximately 600 pediatric heart transplants are performed every year worldwide. With the increasing number of pediatric heart transplant patients, and given the few tertiary care pediatric transplant centers, adult and pediatric emergency department (ED) providers are increasingly engaged in the care of pediatric heart transplant recipients in the ED.

OBJECTIVE

The aim of this article is to review common ED scenarios pertinent to the pediatric heart transplant patients.

DISCUSSION

There are complications unique to this population, such as rejection, opportunistic infections, and medication side effects, that require special considerations, and it is helpful for the emergency medicine (EM) provider to have knowledge about them.

CONCLUSIONS

The unique immunological challenges in these patients, including rejection and medication side effects and opportunistic infections, make this population fragile, and the knowledge of these challenges is helpful for EM providers.

Practice variation in the diagnosis of acute rejection among pediatric heart transplant centers: An analysis of the pediatric heart transplant society (PHTS) registry

BACKGROUND

Freedom from rejection in pediatric heart transplant recipients is highly variable across centers. This study aimed to assess the center variation in methods used to diagnose rejection in the first-year post-transplant and determine the impact of this variation on patient outcomes.

METHODS

The PHTS registry was queried for all rejection episodes in the first-year post-transplant (2010-2019). The primary method for rejection diagnosis was determined for each event as surveillance biopsy, echo diagnosis, or clinical. The percentage of first-year rejection events diagnosed by surveillance biopsy was used to approximate the surveillance strategy across centers. Methods of rejection diagnosis were described and patient outcomes were assessed based on surveillance biopsy utilization among centers.

RESULTS

A total of 3985 patients from 56 centers were included. Of this group, 873 (22%) developed rejection within the first-year post-transplant. Surveillance biopsy was the most common method of rejection diagnosis (71.7%), but practices were highly variable across centers. The majority (73.6%) of first rejection events occurred within 3-months of transplantation. Diagnosis modality in the first-year was not independently associated with freedom from rejection, freedom from rejection with hemodynamic compromise, or overall graft survival.

CONCLUSIONS

Rejection in the first-year after pediatric heart transplant occurs in 22% of patients and most commonly in the first 3 months post-transplant. Significant variation exists across centers in the methods used to diagnose rejection in pediatric heart transplant recipients, however, these variable strategies are not independently associated with freedom from rejection, rejection with hemodynamic compromise, or overall graft survival.

Impact of induction strategy change on first-year rejection in pediatric heart transplantation at a single center-From postoperative basiliximab to either postoperative anti-thymocyte globulin or preoperative basiliximab

BACKGROUND

Our pediatric heart transplant center transitioned from post-bypass basiliximab (BAS) induction to either anti-thymocyte globulin (ATG) or pre-bypass BAS. The purpose of this study was to compare first-year rejection rates before and after this change.

METHODS

A single-center retrospective analysis was conducted of pediatric heart transplant recipients from 2010 to 2019. Primary outcome was first-year rejection. Bivariate analysis, Kaplan-Meier curves, and multivariable regression were performed across eras.

RESULTS

Forty-three early era patients (55%) received post-bypass BAS, and 35 late era patients (45%) received pre-bypass BAS (n = 17) or ATG (n = 18). First-year rejection decreased in the late era (31% vs 53%, p = .05). This finding was more pronounced after excluding infants (38% vs 73%, p = .006). Late era was associated with a decreased likelihood of rejection (all cohort OR 0.19, 95% CI 0.05-0.66; infants excluded OR 0.17, 95% CI 0.04-0.61). No differences in post-transplant lymphoproliferative disease, donor-specific antibody, or infection were observed.

CONCLUSIONS

Fewer late era patients receiving ATG or pre-bypass BAS induction had first-year rejection compared to the early era patients receiving standard post-bypass BAS induction. This programmatic shift in induction strategy was readily achievable and potentially effective in reducing first-year rejection.

The impact of psychiatric disorders on outcomes following heart transplantation in children

Psychiatric disorders are common in pediatric HTx recipients. However, the impact of psychiatric comorbidities on patient outcomes is unknown. We aimed to assess the impact of disorders of adjustment, depression, and anxiety on HTx outcomes in children; hypothesizing that the presence of psychiatric disorders during or preceding HTx would negatively impact outcomes. All pediatric HTx recipients ≥8 years of age who survived to hospital discharge were identified from a novel linkage between the PHIS and SRTR databases (2002-2016). Psychiatric disorders were identified using ICD codes during or preceding the HTx admission. Post-transplant graft survival, freedom from readmission, and freedom from rejection were analyzed using the Kaplan-Meier method. Multivariable Cox proportional hazard models were used to adjust for covariates. A total of 1192 patients were included, of which 133 (11.2%) had depression, 197 (16.5%) had anxiety, and 218 (18.3%) had adjustment disorders. The presence of depression was independently associated with higher rates of readmission (60.9% vs 54.1% at 6 months) (AHR 1.63, 95% CI 1.22-2.18, P = .001) and inferior graft survival (70.2% vs 83.4% at 5 years) (AHR 1.62, 95% CI 1.14-2.3, P = .007). Anxiety was independently associated with higher rates of readmission (60.4% vs 53.9% at 6 months) (AHR 1.46, 95% CI 1.09-1.94, P = .01). Anxiety and depression in the pretransplant period are independently associated with outcomes following HTx in children. Evaluation and management of psychiatric comorbidities represents an important component of care in this vulnerable population.

Surveillance for cardiac allograft vasculopathy: Practice variations among 50 pediatric heart transplant centers

BACKGROUND

Coronary allograft vasculopathy (CAV) is a leading cause of mortality after heart transplantation (HT) in children. Variation in CAV screening practices may impact detection rates and patient outcomes.

METHODS

Among 50 Pediatric Heart Transplant Society (PHTS) sites from 2001 to 2016, coronary evaluations were classified as angiography or non-invasive testing, and angiograms were designated as routine or symptom based. CAV detection rates stratified by routine vs symptom-based angiograms were calculated. Freedom from CAV and mortality after CAV diagnosis, stratified by study indication, were calculated.

RESULTS

A total of 3,442 children had 13,768 coronary evaluations; of these, 97% (n = 13,012) were for routine surveillance, and only 3% (n = 333) were for cause. Over the study period, CAV was detected in 472 patients (14%). Whereas 58% (n = 29) of PHTS sites evaluate by angiography alone, 42% reported supplementing with a non-invasive test, although only 423 non-invasive studies were reported. Angiographic detection of CAV was higher for symptom-based testing than for routine testing (29% vs 4%, p < 0.0001), although routine testing identified a majority of cases (88%; n = 414). The 10-year freedom from CAV was 77% overall. Once CAV is detected, 5-year graft survival was 58%, with lower survival for patients diagnosed after symptoms angiogram than after routine angiogram (30% vs 62%; p < 0.0001).

CONCLUSIONS

Development of a robust model for CAV risk should allow low-risk patients to undergo less frequent invasive angiography without adverse impact on CAV detection rates or outcomes.

Quantitative cardiac magnetic resonance T2 imaging offers ability to non-invasively predict acute allograft rejection in children

BACKGROUND

Monitoring for acute allograft rejection improves outcomes after cardiac transplantation. Endomyocardial biopsy is the gold standard test defining rejection, but carries risk and has limitations. Cardiac magnetic resonance T2 mapping may be able to predict rejection in adults, but has not been studied in children. Our aim was to evaluate T2 mapping in identifying paediatric cardiac transplant patients with acute rejection.

METHODS

Eleven paediatric transplant patients presenting 18 times were prospectively enrolled for non-contrast cardiac magnetic resonance at 1.5 T followed by endomyocardial biopsy. Imaging included volumetry, flow, and T2 mapping. Regions of interest were manually selected on the T2 maps using the middle-third technique in the left ventricular septal and lateral wall in a short-axis and four-chamber slice. Mean and maximum T2 values were compared with Student's t-tests analysis.

RESULTS

Five cases of acute rejection were identified in three patients, including two cases of grade 2R on biopsy and three cases of negative biopsy treated for clinical symptoms attributed to rejection (new arrhythmia, decreased exercise capacity). A monotonic trend between increasing T2 values and higher biopsy grades was observed: grade 0R T2 53.4 ± 3 ms, grade 1R T2 54.5 ms ± 3 ms, grade 2R T2 61.3 ± 1 ms. The five rejection cases had significantly higher mean T2 values compared to cases without rejection (58.3 ± 4 ms versus 53 ± 2 ms, p = 0.001).

CONCLUSIONS

Cardiac magnetic resonance with quantitative T2 mapping may offer a non-invasive method for screening paediatric cardiac transplant patients for acute allograft rejection. More data are needed to understand the relationship between T2 and rejection in children.

Review of the discard and/or refusal rate of offered donor hearts to pediatric waitlisted candidates

We aimed to review current literature on the discard rate of donor hearts offered to pediatric recipients and assess geographical differences. Consequences and ways to reduce the discard rate are discussed. A systemic review on published literature on pediatric transplantation published in English since 2010 was undertaken. Additionally, a survey was sent to international OPOs with the goal of incorporating responses from around the world providing a more global picture. Based on the literature review and survey, there is a remarkably wide range of discard and/or refusal for pediatric hearts offered for transplant, ranging between 18% and 57% with great geographic variation. The data suggest that that the overall refusal rate may have decreased over the last decade. Reasons for organ discard were difficult to identify from the available data. Although the refusal rate of pediatric donor hearts seems to be lower compared to that reported in adults, it is still as high as 57% with geographic variation.

Correlation of gene expression profiling score, cardiac hemodynamics and echocardiographic parameters in asymptomatic, rejection-free pediatric heart transplant recipients

OBJECTIVES

To correlate gene expression profiling scores obtained by AlloMap^® with cardiac hemodynamics, cardiac allograft vasculopathy (CAV), and echocardiographic parameters in asymptomatic, rejection-free pediatric heart transplant (HT) recipients.

METHODS

Single-institution retrospective study of 210 AlloMap scores obtained concomitantly with cardiac catheterization and echocardiogram from 55 children during follow-up after cardiac transplantation.

RESULTS

The median age at HT was 5.1 years (range, 0.9-14.1), with 29 males and 26 females. AlloMap scores were high in <2 years vs ≥2 years of age at the time of HT (P = .001), and trending higher with time after HT (R²  = .04, P = .004). There was no significant difference in scores between ACR grades 0 and 1R or CAV. There was mild to modest correlation of AlloMap scores with the mean right atrial pressure (P = .002), and pulmonary capillary wedge pressure (P = .02), but no correlation was found with LV SF% (P = .3), LV EF% (P = .5), or RV FAC % (P = .8).

CONCLUSIONS

Our study provides preliminary data that the AlloMap score must be studied carefully before it can be used in children, particularly in those under 2 years of age. Monitoring of serial scores for each patient could potentially reflect changes in allograft performance that may determine indications for catheterization and biopsy which needs to be validated in future studies.

Use of the terminal complement inhibitor eculizumab in paediatric heart transplant recipients

Antibody-mediated rejection is a major clinical challenge that limits graft survival. Various modalities of treatment have been reported in small studies in paediatric heart recipients. A novel approach is to use complement-inhibiting agents, such as eculizumab, which inhibits cleavage of C5 to C5a thereby limiting the formation of membrane attack complex and terminal complement-mediated injury of tissue-bound antibodies. This medical modality of treatment has theoretical advantages but the collective experience in its use in the solid organ transplant community remains small. We add to this experience by combining 14 cases from 6 paediatric heart centres in this descriptive study.

Paediatric heart transplantation: an update

Heart transplantation is a standard treatment for selected paediatric patients with end-stage heart disease. With improvement in surgical techniques, organ procurement and preservation strategies, immunosuppressive drugs, and more sophisticated monitoring strategies, survival following transplantation has increased over time. However, rejection, infection, renal failure, post-transplant lymphoproliferative disease and post-transplant cardiac allograft vasculopathy still preclude long-term survival. Therefore, continued multidisciplinary scientific efforts are needed for future gains. This review focuses on the current status, outcomes and ongoing challenges including patient selection, indications and contraindications, national and international survivals, post-transplant complications and quality of life.

Early outcomes for low-risk pediatric heart transplant recipients and steroid avoidance: A multicenter cohort study (Clinical Trials in Organ Transplantation in Children - CTOTC-04)

BACKGROUND

Immunosuppression strategies have changed over time in pediatric heart transplantation. Thus, comorbidity profiles may have evolved. Clinical Trials in Organ Transplantation in Children-04 is a multicenter, prospective, cohort study assessing the impact of pre-transplant sensitization on outcomes after pediatric heart transplantation. This sub-study reports 1-year outcomes among recipients without pre-transplant donor-specific antibodies (DSAs).

METHODS

We recruited consecutive candidates (<21 years) at 8 centers. Sensitization status was determined by a core laboratory. Immunosuppression was standardized as follows: Thymoglobulin induction with tacrolimus and/or mycophenolate mofetil maintenance. Steroids were not used beyond 1 week. Rejection surveillance was by serial biopsy.

RESULTS

There were 240 transplants. Subjects for this sub-study (n = 186) were non-sensitized (n = 108) or had no DSAs (n = 78). Median age was 6 years, 48.4% were male, and 38.2% had congenital heart disease. Patient survival was 94.5% (95% confidence interval, 90.1-97.0%). Freedom from any type of rejection was 67.5%. Risk factors for rejection were older age at transplant and presence of non-DSAs pre-transplant. Freedom from infection requiring hospitalization/intravenous anti-microbials was 75.4%. Freedom from rehospitalization was 40.3%. New-onset diabetes mellitus and post-transplant lymphoproliferative disorder (PTLD) occurred in 1.6% and 1.1% of subjects, respectively. There was no decline in renal function over the first year. Corticosteroids were used in 14.5% at 1 year.

CONCLUSIONS

Pediatric heart transplantation recipients without DSAs at transplant and managed with a steroid avoidance regimen have excellent short-term survival and a low risk of first-year diabetes mellitus and PTLD. Rehospitalization remains common. These contemporary observations allow for improved caregiver and/or patient counseling and provide the necessary outcomes data to help design future randomized controlled trials.

Temporal changes in left ventricular strain with the development of rejection in paediatric heart transplant recipients

INTRODUCTION

Myocardial strain measurements are increasingly used to detect complications following heart transplantation. However, the temporal association of these changes with allograft rejection is not well defined. The aim of this study was to describe the evolution of strain measurements prior to the diagnosis of rejection in paediatric heart transplant recipients.

METHODS

All paediatric heart transplant recipients (2004-2015) with at least one episode of acute rejection were identified. Longitudinal and circumferential strain measurements were assessed at the time of rejection and retrospectively on all echocardiograms until the most recent negative biopsy. Smoothing technique (LOESS) was used to visualise the changes of each variable over time and estimate the time preceding rejection at which alterations are first detectable.

RESULTS

A total of 58 rejection episodes were included from 37 unique patients. In the presence of rejection, there were decrements from baseline in global longitudinal strain (-18.2 versus -14.1), global circumferential strain (-24.1 versus -19.6), longitudinal strain rate (-1 versus -0.8), circumferential strain rate (-1.3 versus -1.1), peak longitudinal early diastolic strain rate (1.3 versus 1), and peak circumferential early diastolic strain rate (1.5 versus 1.3) (p<0.01 for all). The earliest detectable changes occurred 45 days prior to rejection with simultaneous alterations in myocardial strain and ejection fraction.

CONCLUSIONS

Changes in graft function can be detected non-invasively prior to the diagnosis of rejection. However, changes in strain occur concurrently with a decline in ejection fraction. Strain measurements aid in the non-invasive detection of rejection, but may not facilitate earlier diagnosis compared to more traditional measures of ventricular function.

Outcomes of low-intensity biopsy surveillance for rejection in paediatric cardiac transplantation

BACKGROUND

Significant inter-centre variability in the intensity of endomyocardial biopsy surveillance for rejection following paediatric cardiac transplantation has been reported. Our aim was to determine if low-intensity biopsy surveillance with two scheduled biopsies in the first year would produce outcomes similar to published registry outcomes.

METHODS

A retrospective study of paediatric recipients transplanted between 2008 and 2014 using a low-intensity biopsy protocol consisting of two surveillance biopsies at 3 and 12-13 months in the first post-transplant year, then annually thereafter. Additional biopsies were performed based on echocardiographic and clinical surveillance. Excluded were recipients that were re-transplanted or multi-organ transplanted or were followed at another institution.

RESULTS

A total of 81 recipients in the first 13 months after transplant underwent an average of 2 (SD ± 1.3) biopsies, 24 ± 6.8 echocardiograms, and 17 ± 4.4 clinic visits per recipient. During the 13-month period, 19 recipients had 24 treated rejection episodes, with the first at an average of 2.8 months post-transplant. The 3-, 12-, 36-, and 60-month conditional on discharge graft survival were 100%, 98.8%, 98.8%, and 90.4%, respectively, comparable to reported figures in major paediatric registries. At a mean follow-up of 4.7 ± 2.1 years, four patients (4.9%) developed cardiac allograft vasculopathy, three (3.7%) developed a malignancy, and seven (8.6%) suffered graft loss.

CONCLUSION

Rejection surveillance with a low-intensity biopsy protocol demonstrated similar intermediate-term outcomes and safety measures as international registries up to 5 years post-transplant.

Pediatric heart transplantation: long-term outcomes

Pediatric heart transplant has become the standard of care for end-stage heart disease in children throughout the world. The number of transplants has grown dramatically since the first transplant was performed, and over the last two decades, outcomes have consistently improved with progression in knowledge enhancing the clinical course and outcomes of these patients. Short-term outcomes in the most recent era have been excellent resulting in a renewed focus towards medium- and long-term outcomes. This article will review the most up-to-date literature on overall heart transplantation outcomes and specific long-term outcomes including rejection, cardiac allograft vasculopathy, graft failure, infection, renal dysfunction, malignancy, and the need for re-transplantation. The article also explores the post-transplantation outcomes of special populations, including Fontan patients, ABO-incompatible recipients, sensitized recipients, extracorporeal membrane oxygenation, and ventricular assist devices. The article concludes with a look at transition from pediatric to adult care and medication adherence, which are becoming major issues related to long-term outcomes as post-transplant survival increases.

Sensitization in Heart Transplantation: Emerging Knowledge: A Scientific Statement From the American Heart Association

Sensitization, defined as the presence of circulating antibodies, presents challenges for heart transplant recipients and physicians. When present, sensitization can limit a transplantation candidate’s access to organs, prolong wait time, and, in some cases, exclude the candidate from heart transplantation altogether. The management of sensitization is not yet standardized, and current therapies have not yielded consistent results. Although current strategies involve antibody suppression and removal with intravenous immunoglobulin, plasmapheresis, and antibody therapy, newer strategies with more specific targets are being investigated.

Protective action of bone marrow mesenchymal stem cells in immune tolerance of allogeneic heart transplantation by regulating CD45RB+ dendritic cells

BACKGROUND

Bone marrow-derived mesenchymal stem cells (BMSCs) could exert a potent immunosuppressive effect and therefore may have a therapeutic potential in T-cell-dependent pathologies. We aimed to examine the effects of BMSCs on immune tolerance of allogeneic heart transplantation and the involvement of CD45RB⁺ dendritic cells (DCs).

METHODS

Bone marrow-derived DCs and BMSCs were co-cultured, with CD45RB expression on the surface of DCs measured by flow cytometry. qRT-PCR and Western blotting were used to detect mRNA and protein levels. Cytometric bead array was performed to determine the serum level of IL-10. Survival time of transplanted heart and expression of CD4⁺ , CD8⁺ , IL-2, IL-4, IL-10, IFN-γ were determined. Immunofluorescence assay was employed to determine intensity of C3d and C4d.

RESULTS

DCs co-cultured with BMSCs showed increased CD45RB and Foxp3 levels. CD45RB⁺ DCs co-cultured with T-cells CD4⁺ displayed increased T-cell CD4⁺ Foxp3 ratio and IL-10 than DCs. Both of them extended survival time of transplanted heart, decreased histopathological classification and score, intensity of C3d, C4d, proportion of CD4⁺ , expression levels of IL-2 and IFN-γ, and increased the CD4⁺ Foxp3 ratio and levels of IL-4 and IL-10. CD45RB⁺ DCs achieved better protective effects than DCs.

CONCLUSION

BMSCs increased the expression of CD45RB in the bone marrow-derived DCs, thereby strengthening immunosuppression capacity of T cells and immune tolerance of allogeneic heart transplantation.

Current state of pediatric cardiac transplantation

Pediatric heart transplantation is standard of care for children with end-stage heart failure. The diverse age range, diagnoses, and practice variations continue to challenge the development of evidence-based practices and new technologies. Outcomes in the most recent era are excellent, especially with the more widespread use of ventricular assist devices (VADs). Waitlist mortality remains high and knowledge of risk factors for death while waiting and following transplantation contributes to decision-making around transplant candidacy and timing of listing. The biggest gap impacting both waitlist and overall survival remains mechanical support options for infants and patients with single ventricle physiology. Though acute rejection has decreased progressively, both diagnosis and management of antibody-mediated rejection has become increasingly challenging and complex, as has the ability to understand the implication of anti-HLA antibodies detected both pre- and post-transplantation-including when and how to intervene. Trends in immunosuppression protocols include more use of induction therapy and steroid avoidance or withdrawal protocols. Common long-term morbidities include renal insufficiency, which can be mitigated with surveillance and renal-sparing strategies, and infections. Functional outcomes are excellent, but significant psychosocial challenges exist in relation to neurodevelopment, non-adherence, and transition from child-centered to adult-centered care. Cardiac allograft vasculopathy (CAV) remains a barrier to long-term survival, though it is more apparent that objective evidence of an impact on the allograft is important with regards to impact on outcomes. Retransplantation is rare in pediatric heart transplant recipients. Pediatric heart transplantation continues to evolve in order to address the challenges of the diverse group of patients that reach end-stage heart failure during childhood.

Pediatric Heart Failure: A Practical Guide to Diagnosis and Management

Pediatric heart failure represents an important cause of morbidity and mortality in childhood. Currently, there are well-established guidelines for the management of heart failure in the adult population, but an equivalent consensus in children is lacking. In the clinical setting, ensuring an accurate diagnosis and defining etiology is essential to optimal treatment. Diuretics and angiotensin-converting enzyme inhibition are the first-line therapies, whereas beta-blockers and devices for electric therapy are less used in children than in adults. In the end-stage disease, heart transplantation is the best choice of treatment, while a left ventricular assist device can be used as a bridge to transplantation (due to the difficulties in finding organ donors), recovery (in the case of myocarditis), or destination therapy (for patients with systemic disease).

Reducing Fluoroscopic Radiation Exposure During Endomyocardial Biopsy in Pediatric Transplant Recipients

Endomyocardial biopsy (EMB) with fluoroscopy is used for rejection surveillance in pediatric heart transplantation. Lowering frame rate may reduce radiation, but decreases temporal resolution and image quality. We undertook a quality initiative reducing frame rate from 10 frames per second (FPS) to 5 FPS. To assess whether lowering frame rate can reduce radiation exposure without compromising safety, data on EMBs from 9/2009 to 4/2013 without angiography or intervention were reviewed. Effective dose was calculated from dose area product (DAP) and fluoroscopy time. Complications were reviewed. Independent t test compared pre- and post-data and a general linear model were used to control for confounders. Paired t test of most proximate data was used for pts with EMB before and after our change. Eighty-six patients had 543 EMB. After adjusting for weight, attending, and presence of a fellow, the lower FPS group had a 60.3% reduction in DAP (p < 0.0001) and 53.8% drop in effective dose (p < 0.0001). Fluoroscopy time did not differ. Twenty-eight pts had EMBs both before and after the FPS change. Pair-wise analysis of this group demonstrated a 33% reduction in DAP (p < 0.05) and 37% drop in effective dose (p < 0.01), without difference in fluoroscopy time. No patient had an increase in TR > 1 grade by ECHO. There were no deaths or perforations. Lowering the frame rate reduces radiation exposure by >50% without compromising safety. Efforts to further minimize radiation exposure of this vulnerable population should be considered.

Alemtuzumab (Campath-1H) therapy for refractory rejections in pediatric heart transplant recipients

Despite substantial improvements in survival after pediatric heart transplantation, refractory rejection remains a major cause of morbidity and mortality. We have utilized ALE (Campath-1H) in six consecutive patients with refractory rejection. These rejection episodes persisted despite conventional treatment, which included intravenous methylprednisolone, rituximab, immunoglobulin G, and antithymocyte globulin. In our series, after ALE therapy, LV SF increased from 22%±5% to 33%±5% (P=.01). However, in our series, ALE therapy neither led to persistent LV function recovery nor could it prevent subsequent antibody-mediated rejection.

Impact of age on incidence and prevalence of moderate-to-severe cellular rejection detected by routine surveillance biopsy in pediatric heart transplantation

BACKGROUND

The effect of age at transplant on rejection detected by routine surveillance biopsy (RSB) in pediatric heart transplant (HT) recipients is unknown. We hypothesized there would be low diagnostic yield and decreased prevalence of rejection detected on RSB in infants (age <1 year) when compared with children (age 1 to 9 years) and adolescents (age 10 to 18 years).

METHODS

We utilized Pediatric Heart Transplant Study (PHTS) data from 2010 to 2013 to analyze moderate-to-severe (ISHLT Grade 2R/3R) cellular rejection (MSR) detected only on RSB (RSBMSR).

RESULTS

RSB detected 280 of 343 (81.6%) episodes of MSR. RSBMSR was detected in all age groups even >5 years after HT. Infant RSBMSR had a greater proportion (p = 0.0025) occurring >5 years after HT (39.2 vs 18.4 vs 10.8%) and a lower proportion (p = 0.0009) occurring in the first year after HT (25.5 vs 60.6 vs 51.7%) compared with children and adolescents, respectively. Freedom from RSBMSR was 87 ± 7% in infants, 76 ± 6% in children and 73 ± 7% in adolescents 4 years after HT. In 1-year survivors who had RSBMSR in the first year after HT, the risk of RSBMSR occurring in Years 2 to 4 was significantly (p < 0.0001) greater than patients without RSBMSR in the first year (hazard ratio 21.28, 95% confidence interval 10.87 to 41.66), regardless of recipient age.

CONCLUSIONS

RSBMSR exists in all age groups after pediatric HT with long-term follow-up. The prevalence in infant recipients is highest >5 years after HT. Those with RSBMSR in the first year after HT are at a high risk for recurrent rejection regardless of age at HT.

Heart Transplantation-The Pediatric Cardiac Critical Care Perspective

OBJECTIVES

Although there have been tremendous advancements in the care of severe pediatric cardiovascular disease, heart transplantation remains the standard therapy for end-stage heart disease in children. As such, these patients comprise an important and often complex subset of patients in the ICU. The purpose of this article is to review the causes and management of allograft dysfunction and the medications used in the transplant population.

DATA SOURCES

MEDLINE, PubMed, and Cochrane Database of systemic reviews.

CONCLUSIONS

Pediatric heart transplant recipients represent a complex group of patients that frequently require critical care. Their immunosuppressive medications, while being vital to maintenance of allograft function, are associated with significant short- and long-term complications. Graft dysfunction can occur from a variety of etiologies at different times following transplantation and remains a major limitation to long-term posttransplant survival.

Validation of a Simple Score to Determine Risk of Early Rejection After Pediatric Heart Transplantation

OBJECTIVES

This study aimed to develop a reliable and feasible score to assess the risk of rejection in pediatric heart transplantation recipients during the first post-transplant year.

BACKGROUND

The first post-transplant year is the most likely time for rejection to occur in pediatric heart transplantation. Rejection during this period is associated with worse outcomes.

METHODS

The United Network for Organ Sharing database was queried for pediatric patients (age <18 years) who underwent isolated orthotopic heart transplantation from January 1, 2000 to December 31, 2012. Transplantations were divided into a derivation cohort (n = 2,686) and a validation (n = 509) cohort. The validation cohort was randomly selected from 20% of transplantations from 2005 to 2012. Covariates found to be associated with rejection (p < 0.2) were included in the initial multivariable logistic regression model. The final model was derived by including only variables independently associated with rejection. A risk score was then developed using relative magnitudes of the covariates' odds ratio. The score was then tested in the validation cohort.

RESULTS

A 9-point risk score using 3 variables (age, cardiac diagnosis, and panel reactive antibody) was developed. Mean score in the derivation and validation cohorts were 4.5 ± 2.6 and 4.8 ± 2.7, respectively. A higher score was associated with an increased rate of rejection (score = 0, 10.6% in the validation cohort vs. score = 9, 40%; p < 0.01). In weighted regression analysis, the model-predicted risk of rejection correlated closely with the actual rates of rejection in the validation cohort (R(2) = 0.86; p < 0.01).

CONCLUSIONS

The rejection score is accurate in determining the risk of early rejection in pediatric heart transplantation recipients. The score has the potential to be used in clinical practice to aid in determining the immunosuppressant regimen and the frequency of rejection surveillance in the first post-transplant year.

Pediatric Heart Transplantation: Report from a Single Center in China

BACKGROUND

Although heart transplantation (HTx) has become a standard therapy for end-stage heart diseases, experience with pediatric HTx is limited in China. In this article, we will try to provide the experience with indications, complications, perioperative management, immunosuppressive therapy, and survival for pediatric HTx based on our clinical work.

METHODS

This is a retrospective chart review of the pediatric patients undergoing HTx at Department of Cardiovascular Surgery of Union Hospital from September 2008 to December 2014. We summarized the indications, surgical variables, postoperative complications, and survival for these patients.

RESULTS

Nineteen pediatric patients presented for HTx at Union Hospital of Tongji Medical College, of whom 10 were male. The age at the time of transplantation ranged from 3 months to 18 years (median 15 years). Patient weight ranged from 5.2 kg to 57.0 kg (median 38.0 kg). Pretransplant diagnosis included cardiomyopathy (14 cases), complex congenital heart disease (3 cases), and tumor (2 cases). All recipients received ABO-compatible donor hearts. Postoperative complications occurred in 12 patients, including cardiac dysfunction, arrhythmia, pulmonary infection, renal dysfunction, and rejection. Two of them experienced cardiac failure and required extracorporeal membrane oxygenation. The immunosuppression regimen was comprised of prednisone, a calcineurin inhibitor, and mycophenolate. All patients recovered with New York Heart Association (NYHA) Class I-II cardiac function and were discharged. Only one patient suffered sudden death 19 months after transplantation.

CONCLUSION

Orthotopic HTx is a promising therapeutic option with satisfying survival for the pediatric population in China with end-stage heart disease.

Late outcome after paediatric heart transplantation in Finland

OBJECTIVES

We studied the long-term survival and rejection episodes of paediatric heart transplant recipients.

METHODS

We included all paediatric patients (≤18 years) who underwent heart transplantation during 1991-2014 in Finland. Data were obtained retrospectively from a paediatric cardiac surgery database. Patient status was received from the Finnish population registry. All patients underwent yearly routine postoperative endomyocardial biopsies and coronary angiographies.

RESULTS

Between 1991 and 2014, 68 heart transplantations were performed. The early mortality (<30 days after surgery) rate was 10% and follow-up coverage was 100%. The 10- and 15-year survival rates for all patients were 68% (95% confidence internal, CI, 56-80%) and 65% (95% CI 53-78%), respectively, including early mortality. The 1-year survival rate was 100% when excluding early operative mortality. Indications for heart transplantation were cardiomyopathy in 57% and cardiac malformations in 43% of patients, with similar long-term survival between the groups. During 23 years of follow-up, 43 patients (70%) had at least one rejection episode and 17 patients (29%) at least a grade 1 coronary artery vasculopathy finding. Patients with early rejection episodes (<3 months) had a higher incidence of late rejection episodes (P = 0.025). Older age at operation was a significant risk factor for the development of coronary artery vasculopathy (hazard ratio 1.1, 95% CI 1.0-1.3, P = 0.012).

CONCLUSIONS

First-year survival was excellent. Asymptomatic rejection episodes were common among patients. Early rejection episodes are a risk factor for late rejection episodes and show a trend towards an increased risk of late death. Coronary artery vasculopathy remains a major challenge for late graft survival.

Elevated ST2 Distinguishes Incidences of Pediatric Heart and Small Bowel Transplant Rejection

Elevated serum soluble (s) suppressor of tumorigenicity-2 is observed during cardiovascular and inflammatory bowel diseases. To ascertain whether modulated ST2 levels signify heart (HTx) or small bowel transplant (SBTx) rejection, we quantified sST2 in serially obtained pediatric HTx (n = 41) and SBTx recipient (n = 18) sera. At times of biopsy-diagnosed HTx rejection (cellular and/or antibody-mediated), serum sST2 was elevated compared to rejection-free time points (1714 ± 329 vs. 546.5 ± 141.6 pg/mL; p = 0.0002). SBTx recipients also displayed increased serum sST2 during incidences of rejection (7536 ± 1561 vs. 2662 ± 543.8 pg/mL; p = 0.0347). Receiver operator characteristic (ROC) analysis showed that serum sST2 > 600 pg/mL could discriminate time points of HTx rejection and nonrejection (area under the curve [AUC] = 0.724 ± 0.053; p = 0.0003). ROC analysis of SBTx measures revealed a similar discriminative capacity (AUC = 0.6921 ± 0.0820; p = 0.0349). Quantitative evaluation of both HTx and SBTx biopsies revealed that rejection significantly increased allograft ST2 expression. Pathway and Network Analysis of biopsy data pinpointed ST2 in the dominant pathway modulated by rejection and predicted tumor necrosis factor-α and IL-1β as upstream activators. In total, our data indicate that alloimmune-associated pro-inflammatory cytokines increase ST2 during rejection. They also demonstrate that routine serum sST2 quantification, potentially combined with other biomarkers, should be investigated further to aid in the noninvasive diagnosis of rejection.

Clinical Issues and Controversies in Heart Failure and Transplantation

Heart failure is a common problem among children admitted in the intensive care unit and is associated with significant morbidity and mortality. As such, the 2014 meeting of the Pediatric Cardiac Intensive Care Society included a session on Clinical Controversies in Heart Failure and Transplantation. This review contains the summaries of the podium presentations of this session and will cover some of the challenging aspects of caring for these patients including medical and mechanical support, fluid overload states, high-risk populations including those after heart transplantation, and end-of-life considerations.

The use of circulating donor specific antibody to predict biopsy diagnosis of antibody-mediated rejection and to provide prognostic value after heart transplantation in children

BACKGROUND

Antibody-mediated rejection (AMR) is a significant cause of mortality after heart transplantation (HT). Although the presence of donor specific antibody (DSA) is a risk factor for developing AMR, serial DSA testing is not widely performed. We aimed to investigate the predictive values and prognostic implications of circulating DSA using endomyocardial biopsy as the gold standard for AMR diagnosis in pediatric recipients of HT.

METHODS

We performed a retrospective study in pediatric recipients of HT followed during the period 2009-2013 with at least 1 biopsy paired with DSA testing. Positive DSA was defined at mean fluorescent intensity (MFI) ≥2,000 using single antigen bead testing. Statistical analyses included 2 × 2 contingency tables, receiver operating characteristic analysis for optimal MFI cutoffs, Spearman correlation of MFI strength to AMR grade, and Kaplan-Meier analysis of event-free survival.

RESULTS

Of 66 children included, 27 (41%) had ≥1 DSA positive test. DSA testing had a sensitivity of 92.6%, specificity of 62.2%, positive predictive value of 24.0%, and negative predictive value of 98.5% for biopsy diagnosis of AMR at our institution. There was a statistically significant correlation between higher MFI and higher AMR grade. Patients with positive DSA and AMR had similar survival early after DSA detection but trended toward lower cardiovascular event-free survival later compared with patients without DSA and a negative biopsy.

CONCLUSIONS

The results of DSA testing in this cohort showed excellent sensitivity and negative predictive value for biopsy-diagnosed AMR, suggesting that DSA testing may aid in the non-invasive prediction of AMR absence in HT. The correlation of DSA MFI strength with higher AMR biopsy grade and the trend toward differences in longer term cardiovascular outcomes provide evidence for routine DSA monitoring after pediatric HT.

Variation in the use of surveillance endomyocardial biopsy among pediatric heart transplant centers over time

EMB is widely utilized for graft surveillance after HTx; however, there is significant variation in the frequency of surveillance EMB use during the first year post-HTx. The aim of this study was to assess changes in the utilization of surveillance EMB over time among member institutions of PHTS. A survey of PHTS centers assessing the frequency of surveillance EMB use during the first year post-HTx was conducted in 2006. The same survey was repeated in 2014 to assess changes in practice over time. The number of EMB in infants ranged from 0 to 9 and in adolescents 0 to 16. The number of EMB decreased or remained unchanged in the majority of centers. Fewer EMB are performed in infants compared to adolescents and this practice did not change over time. There was a significant decrease in surveillance EMB use in adolescents (p = 0.012). International centers perform significantly fewer EMB in adolescents when compared to centers within the United States (p = 0.006). There continues to be significant variation in the utilization of surveillance EMB, with a shift toward less reliance on EMB for adolescents in the current era. Further research is necessary to determine the optimal frequency of invasive monitoring that reduces costs without compromising outcomes.

More lessons learned from the Pediatric Heart Transplant Study

Paediatric heart transplantation has evolved over the last 3 decades. The research group, Pediatric Heart Transplant Study, has been in step with that evolution over the nearly 20 years of its existence by utilising its registry to contribute a wealth of clinical research to the field. The highlights of its studies will be presented in this review.