Early predictors of survival to and after heart transplantation in children with dilated cardiomyopathy

Heart transplantation for pediatric patients with malignant arrhythmias: Indications and Outcomes

BACKGROUND

Arrhythmias can lead to cardiac arrest (CA) and heart failure. When intractable, heart transplant (HTX) can become the only viable treatment. This rare, high-risk cohort has not been reported as a distinct group.

OBJECTIVE

Characterize the outcomes of pediatric patients listed for HTX with the primary indication being malignant arrhythmia (MA).

METHODS

Using the Pediatric Heart Transplant Society prospective registry, we identified all patients <18 years-old listed between 2014-2022. MA as the listing indication was categorized into primary tachy-arrhythmia (PT), inherited arrhythmia (IA), congenital heart disease (CHD) and cardiomyopathy (CM) with secondary arrhythmia. Demographic, listing and transplant data were analyzed.

RESULTS

Among 4630 patients listed and 3317 transplanted, MA was the indication in 63 (1.4%) and 49 (1.5%), respectively. MA patients were categorized as PT in 11, IA in 4, CHD in 6 and CM in 42. When compared to the non-MA cohort, patients listed for MA were older (mean (SD) age 10.6 (6.2) vs. 6.1 (6.2) years, p<0.01), more likely to present with a CA (43% vs. 11%, p<0.01), and less likely to be in the intensive care unit (40% vs. 58%, p<0.01) or on inotropes (30% vs. 60%, p<0.01) at listing. Outcomes including waitlist mortality, transplantation, post-transplant survival and freedom from rejection were comparable to the non-MA cohort.

CONCLUSION

Patients with MA constitute a small proportion of those listed for HTX in childhood. CM was the most common category, while IA and PT were rare. Their waitlist mortality and post-transplant outcomes were comparable to the non-MA cohort.

Pediatric dilated cardiomyopathy: a review of current clinical approaches and pathogenesis

Pediatric dilated cardiomyopathy (DCM) is a rare, yet life-threatening cardiovascular condition characterized by systolic dysfunction with biventricular dilatation and reduced myocardial contractility. Therapeutic options are limited with nearly 40% of children undergoing heart transplant or death within 2 years of diagnosis. Pediatric patients are currently diagnosed based on correlating the clinical picture with echocardiographic findings. Patient age, etiology of disease, and parameters of cardiac function significantly impact prognosis. Treatments for pediatric DCM aim to ameliorate symptoms, reduce progression of disease, and prevent life-threatening arrhythmias. Many therapeutic agents with known efficacy in adults lack the same evidence in children. Unlike adult DCM, the pathogenesis of pediatric DCM is not well understood as approximately two thirds of cases are classified as idiopathic disease. Children experience unique gene expression changes and molecular pathway activation in response to DCM. Studies have pointed to a significant genetic component in pediatric DCM, with variants in genes related to sarcomere and cytoskeleton structure implicated. In this regard, pediatric DCM can be considered pediatric manifestations of inherited cardiomyopathy syndromes. Yet exciting recent studies in infantile DCM suggest that this subset has a distinct etiology involving defective postnatal cardiac maturation, such as the failure of programmed centrosome breakdown in cardiomyocytes. Improved knowledge of pathogenesis is central to developing child-specific treatment approaches. This review aims to discuss the established biological pathogenesis of pediatric DCM, current clinical guidelines, and promising therapeutic avenues, highlighting differences from adult disease. The overarching goal is to unravel the complexities surrounding this condition to facilitate the advancement of novel therapeutic interventions and improve prognosis and overall quality of life for pediatric patients affected by DCM.

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.

A parental communication assessment initiative in the paediatric cardiovascular ICU

OBJECTIVE

Challenges to communication between families and care providers of paediatric patients in intensive care units (ICU) include variability of communication preferences, mismatched goals of care, and difficulties carrying forward family preferences from provider to provider. Our objectives were to develop and test an assessment tool that queries parents of children requiring cardiac intensive care about their communication preferences and to determine if this tool facilitates patient-centred care and improves families' ICU experience.

DESIGN

In this quality improvement initiative, a novel tool was developed, the Parental Communication Assessment (PCA), which asked parents with children hospitalised in the cardiac ICU about their communication preferences. Participants were prospectively randomised to the intervention group, which received the PCA, or to standard care. All participants completed a follow-up survey evaluating satisfaction with communication.

MAIN RESULTS

One hundred thirteen participants enrolled and 56 were randomised to the intervention group. Participants who received the PCA preferred detail-oriented communication over big picture. Most parents understood the daily discussions on rounds (64%) and felt comfortable expressing concerns (68%). Eighty-six percent reported the PCA was worthwhile. Parents were generally satisfied with communication. However, an important proportion felt unprepared for difficult decisions or setbacks, inadequately included or supported in decision-making, and that they lacked control over their child's care. There were no significant differences between the intervention and control groups in their communication satisfaction results.

CONCLUSIONS

Parents with children hospitalised in the paediatric ICU demonstrated diverse communication preferences. Most participants felt overall satisfied with communication, but individualising communication with patients' families according to their preferences may improve their experience.

Risk factors for 1-year allograft loss in pediatric heart transplant patients using machine learning: An analysis of the pediatric heart transplant society database

BACKGROUND

Pediatric heart transplant patients are at greatest risk of allograft loss in the first year. We assessed whether machine learning could improve 1-year risk assessment using the Pediatric Heart Transplant Society database.

METHODS

Patients transplanted from 2010 to 2019 were included. The primary outcome was 1-year graft loss free survival. We developed a prediction model using cross-validation, by comparing Cox regression, gradient boosting, and random forests. The modeling strategy with the best discrimination and calibration was applied to fit a final prediction model. We used Shapley additive explanation (SHAP) values to perform variable selection and to estimate effect sizes and importance of individual variables when interpreting the final prediction model.

RESULTS

Cumulative incidence of graft loss or mortality was 7.6%. Random forests had favorable discrimination and calibration compared to Cox proportional hazards with a C-statistic (95% confidence interval [CI]) of 0.74 (0.72, 0.76) versus 0.71 (0.69, 0.73), and closer alignment between predicted and observed risk. SHAP values computed using the final prediction model indicated that the diagnosis of congenital heart disease (CHD) increased 1 year predicted risk of graft loss by 1.7 (i.e., from 7.6% to 9.3%), need for mechanical circulatory support increased predicted risk by 2, and single ventricle CHD increased predicted risk by 1.9. These three predictors, respectively, were also estimated to be the most important among the 15 predictors in the final model.

CONCLUSIONS

Risk prediction models used to facilitate patient selection for pediatric heart transplant can be improved without loss of interpretability using machine learning.

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) in Cardiovascular Disease: A Comprehensive Clinical Review on Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM) is one of the most important causes of heart failure in developed and developing countries. Currently, most medical interventions in the treatment of DCM are mainly focused on mitigating the progression of the disease and controlling the symptoms. The vast majority of patients who survive till the late stages of the disease require cardiac transplantation; this is exactly why we need novel therapeutic interventions and hopefully treatments that can reverse the clinical cardiac deterioration in patients with DCM. Clustered regularly interspaced short palindromic repeats (CRISPR) technology is a novel therapeutic intervention with such capacity; it can help us edit the genome of patients with genetic etiology for DCM and potentially cure them permanently. This review provides an overview of studies investigating CRISPR-based gene editing in DCM, including the use of CRISPR in DCM disease models, phenotypic screening, and genotype-specific precision therapies. The review discusses the outcomes of these studies and highlights the potential benefits of CRISPR in developing novel genotype-agnostic therapeutic strategies for the genetic causes of DCM. The databases we used to extract relevant literature include PubMed, Google Scholar, and Cochrane Central. We used the Medical Subject Heading (MeSH) strategy for our literature search in PubMed and relevant search keywords for other databases. We screened all the relevant articles from inception till February 22, 2023. We retained 74 research articles after carefully reviewing each of them. We concluded that CRISPR gene editing has shown promise in developing precise and genotype-specific therapeutic strategies for DCM, but there are challenges and limitations, such as delivering CRISPR-Cas9 to human cardiomyocytes and the potential for unintended gene targeting. This study represents a turning point in our understanding of the mechanisms underlying DCM and paves the way for further investigation into the application of genomic editing for identifying novel therapeutic targets. This study can also act as a potential framework for novel therapeutic interventions in other genetic cardiovascular diseases.

Waitlist and post-transplant outcomes for children with myocarditis listed for heart transplantation over 3 decades

BACKGROUND

There is limited and conflicting information on waitlist and transplant outcomes for children with myocarditis.

METHODS

Retrospective review included children with myocarditis and dilated cardiomyopathy (DCM) listed for HT from January 01, 1993 to December 31, 2019 in the Pediatric Heart Transplant Society database. Clinical characteristics, waitlist and post-HT outcomes (graft loss, rejection, cardiac allograft vasculopathy, infection and malignancy) for children listed from early (1993-2008) and current era (2009-2019) with myocarditis were evaluated and compared to those with DCM.

RESULTS

Of 9755 children listed, 322 (3.3%) had myocarditis and 3178 (32.6%) DCM. Compared to DCM, children with myocarditis in the early and the current era were significantly more likely to be listed at higher urgency; be in intensive care unit; on mechanical ventilation; extracorporeal membrane oxygenation and ventricular assist device (p < 0.05 for all). While unadjusted analysis revealed lower transplant rates and higher waitlist mortality for children with myocarditis, in multivariable analysis, myocarditis was not a risk factor for waitlist mortality. Myocarditis, however, was a significant risk factor for early phase post-HT graft loss (HR 2.46; p = 0.003). Waitlist and post-HT survival for children with myocarditis were similar for those listed and transplanted in the early era to those listed and transplanted in the current era (p > 0.05 for both).

CONCLUSIONS

Children with myocarditis have a higher acuity of illness at listing and at HT and have inferior post-HT survival compared to children with DCM. Outcomes for children with myocarditis have not improved over the 3 decades and efforts are needed to improve outcomes for this cohort.

Findings and Outcome of Transcatheter Right Ventricular Endomyocardial Biopsy and Hemodynamic Assessment in Children with Suspected Myocarditis or Cardiomyopathy

OBJECTIVE

The study objective is assessing findings and outcome in children with suspected cardiomyopathy (CMP) or myocarditis undergoing cardiac catheterization with transcatheter right ventricular endomyocardial biopsy (RV-EMB).

METHODS

All consecutive children undergoing cardiac catheterization with RV-EMB for suspected CMP/myocarditis between 2002-2021 were analysed regarding clinical presentation, cardiac biomarkers, periprocedural management, hemodynamic, histological/immunohistological findings, and outcome.

RESULTS

Eighty-five RV-EMBs were performed in 81 patients at a median age of 6.8 (IQR 9.9) years and a bodyweight of 20 (32.2) kg. Histological/immunohistological findings of RV-EMB revealed dilated CMP in 10 (12%), chronic myocarditis in 28 (33%), healing myocarditis in 5 (6%), acute myocarditis in 9 (11%), other heart muscle diseases in 23 (27%) (7 restrictive CMP, 5 hypertrophic CMP, 4 toxic/anthracycline-induced CMP, 4 endocardfibroelastosis, 1 arrhythmogenic right ventricular CMP, 1 laminin CMP, 1 haemangioma), no conclusive histology in 7 (8%), and normal histology in 3 (4%) patients. Median LVEDP was 17 mmHg (IQR 9), LAP 15 mmHg (10), and PVR 1.83 (1.87) Wood Units/m². There were 3 major complications (3%), all patients recovered without any sequelae. At follow-up (median 1153, IQR 1799 days) 47 (59%) patients were alive, 11 (13%) dead, 15 (18%) underwent cardiac transplantation, and 8 (9%) were lost to follow-up. Death/cardiac transplantation occurred within 3 years from RV-EMB. All patients with an acute myocarditis survived. NT-pro-BNP, echo parameters, and invasive hemodynamics correlate independently with death/cardiac transplant.

CONCLUSION

Hemodynamic invasive data and morphological findings in RV-EMB complete clinical diagnosis in children with suspected CMP/myocarditis and provide important information for further clinical management.

Addressing Chemotherapy-Induced Peripheral Neuropathy Using Multi-Frequency Vibrometry and Patient-Reported Outcomes

(1) The study evaluated correlations between multi-frequency vibrometry (MF-V) and the measure of chemotherapy-induced peripheral neuropathy developed by the European Organization for the Research and Treatment of Cancer (CIPN18). (2) Patients with cancer scheduled to undergo treatment with capecitabine and oxaliplatin (CAPOX) or carboplatin and paclitaxel (Carbo-Tax) were recruited in a prospective, observational study with MF-V and the CIPN18 from baseline to one year after end of treatment. (3) The study recruited 31 evaluable patients. All MF-V measurements correlated significantly with the CIPN18 scores (r = 0.25−0.48, p > 0.003), with a low frequency (32 Hz) from metatarsals showing the best correlation coefficients (0.059 Z-score per CIPN18 point change, r = 0.48, CI-95 = [0.32; 0.60], p > 0.0001). The largest change in MF-V scores from baseline was seen in low-frequency VPTs taken from metatarsals at 8 Hz three months after end of treatment (from −0.26, CI-95 [−0.85, 0.38] to 1.15, CI-95 [0.53, 1.84]) for patients treated with oxaliplatin and at 32 Hz one year after end of treatment (from 0.09, CI-95 [−0.56, 0.77] to 0.88, CI-95 [0.34, 1.47]) for patients treated with paclitaxel. (4) Low-frequency vibration perception thresholds (8 and 32 Hz) correlated better with CIPN18 scores than high-frequency ones (128 and 250 Hz). If validated, this finding will advance CIPN pathophysiological understanding and inform the development of assessment methods.

Endomyocardial Biopsy in Pediatric Myocarditis and Dilated Cardiomyopathy: A Tool in Search for a Role

Endomyocardial biopsy (EMB) is a well-known diagnostic tool for the investigation and treatment of myocardial diseases and remains the gold standard for the diagnosis of myocarditis. Due to its invasiveness, with a complication rate ranging from 1 to 15%, its role in the diagnostic work-up of pediatric heart failure is not well established. The aim of this review is to define the role of EMB as diagnostic technique in the work up of children presenting with severe left ventricular dysfunction with the support of our center experience.

Orthotopic Heart Transplantation in a Child with Single Ventricle after Pneumonectomy

We report a 6-year-old with single ventricle physiology secondary to tricuspid atresia who had cardiorespiratory failure who was not a candidate for further single ventricle palliation. The patient underwent planned staged left pneumonectomy for recurrent pneumonias secondary to bronchomalacia followed by orthotopic heart transplantation. This aggressive approach improved the patient candidacy for heart transplantation by removing the source of recurrent infection and respiratory failure (left lung).

Cost-effectiveness of implantable ventricular assist devices in older children with stable, inotrope-dependent dilated cardiomyopathy

BACKGROUND

In a stable, inotrope-dependent pediatric patient with dilated cardiomyopathy, we evaluated the cost-effectiveness of continuous-flow VAD implantation compared to a watchful waiting approach using chronic inotropic therapy.

METHODS

We used a state-transition model to estimate the costs and outcomes of 14-year-old (INTERMACS profile 3) patients receiving either VAD or watchful waiting. We measured benefits in terms of lifetime QALYs gained. Model inputs were taken from the literature. We calculated the ICER, or the cost per additional QALY gained, of VADs and performed multiple sensitivity analyses to test how our assumptions influenced the results.

RESULTS

Compared to watchful waiting, VADs produce 0.97 more QALYs for an additional $156 639, leading to an ICER of $162 123 per QALY gained from a healthcare perspective. VADs have 17% chance of being cost-effective given a cost-effectiveness threshold of $100 000 per QALY gained. Sensitivity analyses suggest that VADs can be cost-effective if the costs of implantation decrease or if hospitalization costs or mortality among watchful waiting patients is higher.

CONCLUSIONS

As a bridge to transplant, VADs provide a health benefit to children who develop stable, inotrope-dependent heart failure, but immediate implantation is not yet a cost-effective strategy compared to watchful waiting based on commonly used cost-effectiveness thresholds. Early VAD support can be cost-effective in sicker patients and if device implantation is cheaper. In complex conditions such as pediatric heart failure, cost-effectiveness should be just one of many factors that inform clinical decision-making.

Racial Disparities in Hospital Mortality Among Pediatric Cardiomyopathy and Myocarditis Patients

Racially disparate health outcomes exist for a multitude of populations and illnesses. It is unknown how race and ethnicity impact mortality for children with cardiomyopathy or myocarditis. This retrospective cross-sectional study employed the Kids' Inpatient Database to analyze 34,617 hospital admissions for patients ≤ 18 years old with cardiomyopathy, myocarditis, or both, without concomitant congenital heart disease. Multivariate logistic regression models investigated the impact of race/ethnicity on in-hospital mortality adjusting for age, calendar year, sex, insurance type, diagnostic category, treatment at a pediatric hospital, and non-cardiac organ dysfunction. African American race and Hispanic ethnicity were independent risk factors for mortality (African American: odds ratio (OR) 1.25, 95% confidence interval (CI) 1.01-1.53 and Hispanic: OR 1.29, 95% CI 1.03-1.60). African American race was also found to be significantly associated with the use of extracorporeal membrane oxygenation (ECMO), mortality while on ECMO, and cardiac arrest. Adjusting the regression model for ECMO and arrest attenuated the impact of African American race on mortality, suggesting that these variables may indeed play a role in explaining the impact of race on mortality for African American patients with myocardial disease. Hispanic ethnicity remained associated with higher risk of mortality despite controlling for all mechanical circulatory support and transplant (OR 1.30, 95% CI 1.04-1.63). Children of racial and ethnic minorities hospitalized with cardiomyopathy or myocarditis are more likely to die than their white counterparts, a trend that may be due at least in part to in-hospital differences in care or response to therapy.

Longitudinal Prediction of Transplant-Free Survival by Echocardiography in Pediatric Dilated Cardiomyopathy

BACKGROUND

The prognostic significance of serial echocardiography and its rate of change in children with dilated cardiomyopathy (DCM) is incompletely defined.

METHODS

We retrospectively analysed up to 4 serial echocardiograms. Associations between mortality/transplant and echocardiographic parameters over time and between outcomes and the rate of change of echocardiographic parameters were analysed. Estimation of patient-specific intercepts and slopes was done using linear regression models.

RESULTS

Fifty-seven DCM children were studied (50% male; median age, 0.6 year; average follow-up, 2.1 ± 2.4 years). The median time to transplant or death was 2.0 years. Increased left ventricular (LV) diastolic (LVEDD) and systolic (LVESD) dimensions and myocardial performance index (MPI) were associated with increased mortality and transplant risk. Increased LV ejection fraction, mitral E-deceleration time, right ventricular (RV) fractional area change, and tricuspid annular plane systolic excursion were associated with reduced mortality and transplant risk. Transplant/mortality likelihood increased by 41.6% and 19.8% for each unit increase in LVEDD and LVESD z scores, respectively (LVEDD: hazard ratio [HR], 1.416; 95% confidence interval [CI], 1.285-1.560; P < 0.001; LVESD: HR, 1.198; 95% CI, 1.147-1.251; P < 0.001). A higher monthly change in LVESD z score increased transplant/mortality likelihood by 85.6% (HR, 1.856; 95% CI, 1.572-2.191; P = 0.015). Greater changes in mitral E/e' (HR, 0.707; 95% CI, 0.636-0.786; P < 0.001) and RV MPI (HR, 0.412; 95% CI, 0.277-0.613; P < 0.001) were associated with reduced mortality and transplant risk.

CONCLUSIONS

LV and RV systolic and diastolic dimensions and function over time and their rate of change are associated with risk for transplant and mortality in childhood DCM. Serial changes in these parameters may be useful to predict clinical outcomes.

Detection of parvovirus B19 and human herpesvirus 6 in pediatric dilated cardiomyopathy: Impact after heart transplantation

Objectives:

The aim of this study is to evaluate HHV-6 and PVB19 infection using polymerase chain reaction (PCR) and immunofluorescent assay (IFA) in the myocardium of pediatric patients with dilated cardiomyopathy (DCM) and the impact of viral persistence in the cardiac allograft after heart transplantation (HT).

Methods:

Multiplex droplet digital PCR was used to analyze the prevalence of viral sequences in myocardial samples from 48 pediatric DCM patients and 10 control subjects. Of the 48 DCM patients, 44 underwent HT. After HT, consecutive endomyocardial biopsy (EMB) samples were analyzed for the presence of PVB19 and HHV-6 antigens using IFA and the patients were evaluated for rejections, coronary vasculopathy, and graft loss.

Results:

Of the 48 DCM patients, 14 had positive viral PCR results in explanted/autopsy hearts. Among them, PVB19 was found in 8/48, HHV6 in 4/48, both PVB19 and HHV6 in 1/48, and enterovirus in one, but no adenovirus was found. The EMB samples obtained after HT were positive for PVB19 and HHV-6 in 7/44 and 3/44 cases, respectively. Viral presence in both the explanted heart and the cardiac allograft was demonstrated in 4 patients, 3 of whom were positive for PVB19, and one of whom was positive for HHV-6 pretransplant. Coronary vasculopathy and graft loss were more common in patients with PVB19-positive myocardial tissues versus those who were PVB19-negative.

Conclusions:

There is an association between PVB19 and HHV-6 infection and DCM in children. The study suggests the persistence of PVB19 and HHV-6 in the host can lead to subsequent viral reactivation in the transplanted heart, even in those recipients who do not have active myocarditis. PVB19 in the cardiac allograft tended toward higher adverse post-HT events.

Aetiology and 30-Year Long-Term Outcome of Children with Cardiomyopathy Necessitating Heart Transplantation

Studies assessing the long-term outcome after heart transplantation HTX in patients with cardiomyopathy (CM) in the paediatric age range are rare. The aim of this study was to determine the survival rate of children with CM undergoing HTX and to analyse how aetiology of cardiomyopathy influenced morbidity and mortality. We retrospectively analysed the medical records of children; who were transplanted in our centre between June 1988 and October 2019. 236 heart transplantations were performed since 1988 (9 re-transplants). 98 of 227 patients (43.2%) were transplanted because of CM. Survival rates were 93% after 1; 84% after 10 and 75% after 30 years. Overall; the aetiology of CM could be clearly identified in 37 subjects (37.7%). This rate increased up to 66.6% (12/19) by applying a comprehensive diagnostic workup since 2016. The survival rate was lower (p < 0.05) and neurocognitive deficits were more frequent (p = 0.001) in subjects with systemic diseases than in individuals with cardiac-specific conditions. These data indicate that the long-term survival rate of children with CM after HTX in experienced centers is high. A comprehensive diagnostic workup allows unraveling the basic defect in the majority of patients with CM undergoing HTX. Aetiology of CM affects morbidity and mortality in subjects necessitating HTX.

Diagnosis, Evaluation, and Treatment of Myocarditis in Children

Myocarditis in the pediatric population can be a challenging diagnosis to make and often requires utilization of multiple diagnostic modalities. The cause is often due to a viral infection with activation of the innate and acquired immune response with either recovery or disease progression. Laboratory testing often includes inflammatory markers, cardiac troponin levels, and natriuretic peptides. Noninvasive testing should include electrocardiogram, echocardiogram, and possibly an MRI. Treatment of myocarditis remains controversial with most providers using immune modulators with intravenous immunoglobulin and corticosteroids.

Early Acute Graft Rejection in a Heart Transplanted Child with Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM) is the most common type of cardiomyopathy in children. Heart transplantation is considered standard therapy in dilated cardiomyopathy with end-stage heart failure. We present a case of a 15-year-old patient diagnosed with DCM in the neonatal period, who underwent heart transplantation for end-stage heart failure. Despite the use of induction therapy, the endomyocardial biopsy performed at two weeks post-transplant revealed mixed moderate cellular (2R) and humoral (pAMR2) allograft rejection. Aggressive rejection treatment was initiated with good outcome. Besides endomyocardial biopsy, advanced echocardiography can also be a valuable noninvasive tool for rejection assessment.

A Systematic Review for Variables to Be Collected in a Transplant Database for Improving Risk Prediction

BACKGROUND

This systematic review was commissioned to identify new variables associated with transplant outcomes that are not currently collected by the Organ Procurement and Transplantation Network (OPTN).

METHODS

We identified 81 unique studies including 1 193 410 patients with median follow-up of 36 months posttransplant, reporting 108 unique risk factors.

RESULTS

Most risk factors (104) were recipient related; few (4) were donor related. Most risk factors were judged to be practical and feasible to routinely collect. Relative association measures were small to moderate for most risk factors (ranging between 1.0 and 2.0). The strongest relative association measure for a heart transplant outcome with a risk factor was 8.6 (recipient with the previous Fontan operation), for a kidney transplant 2.8 (sickle cell nephropathy as primary cause of end-stage renal disease), for a liver transplant 14.3 (recipient serum ferritin >500 µg/L), and for a lung transplant 6.3 (Burkholderia cepacia complex infection for 1 y or less). OPTN may consider some of these 108 variables for future collection to enhance transplant research and clinical care.

CONCLUSIONS

Evidence-based approaches can be used to determine variables collected in databases and registries. Several candidate variables have been identified for OPTN.

Outcome for children following admission to hospital with a first episode of heart failure, due to heart muscle disease, in the ventricular assist device (VAD) era

AIMS

Most reports on the outcome of children who present with heart failure, due to heart muscle disease, are from an era when ventricular assist devices were not available. This study provides outcome data for the current era where prolonged circulatory support can be considered for most children.

METHODS & RESULTS

Data was retrieved on 100 consecutive children, who presented between 2010 - 2016, with a first diagnosis of unexplained heart failure. Hospital outcome was classified as either death, transplantation, recovery of function or persistent heart failure. Median age at presentation was 24 months and 58% were < 5 years old. Hospital mortality was 12% and 59% received a heart transplant. Most, 79%, of the transplants were carried out on patients with a device. Recovery of function was observed in 18% and 10% stabilised on oral therapy. Eighty-four percent of the deaths occurred in the <5 year old group. Shorter duration of support was associated with survival (34 days in survivors versus 106 in non-survivors, p = 0.01) and 72% were on an assist device at time of death.

CONCLUSION

Heart failure in children who require referral to a transplant unit is a serious illness with a high chance of either transplantation or death. Modifications in assist devices will be required to improve safety, especially for children < 5 years old where the donor wait may be prolonged. The identification of children who may recover function requires further study.

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.

Circulating Long Non-coding RNA ENST00000507296 Is a Prognostic Indicator in Patients with Dilated Cardiomyopathy

Background: Long non-coding RNAs (lncRNAs) participate in the pathogenesis of cardiovascular diseases. However, whether circulating lncRNAs serve as dilated cardiomyopathy (DCM) biomarkers remains unclear. Methods: Totally, 266 controls and 818 patients were enrolled. First, microarray-based circulating lncRNA profiling was performed in 10 normal controls and 10 patients with DCM. Second, the top 20 differentially expressed lncRNAs were validated by real-time qPCR in 64 controls and 64 DCM patients. Moreover, lncRNA sequencing was performed in three human heart-derived cell types, and the correlation between circulating lncRNA levels and the severity of heart failure was evaluated in the validated population. The validated two lncRNAs were assessed in 198 DCM patients and 198 matched controls. Finally, the sensitivity and specificity of circulating lncRNA expression in DCM diagnosis were evaluated using receiver-operating characteristic curve analysis, while Cox regression and Kaplan-Meier curve analysis were further performed in 552 DCM patients. Results: Eight candidate lncRNA biomarkers were obtained after microarray screening and real-time PCR validation. Among them, five were validated in the second cohort. However, only the levels of circulating lncRNA ENST00000507296 and ENST00000532365 were significantly correlated with the cardiac function, as well as detectable in at least one of the human heart-derived cell types by lncRNA-seq. Importantly, low circulating ENST00000507296 level was associated with high event-free survival in patients with DCM. Conclusions: Circulating lncRNA ENST00000507296 was a prognostic biomarker in patients with DCM.

Potential for and timing of recovery in children with dilated cardiomyopathy

OBJECTIVE

Understanding the clinical course and time-frame for recovery is helpful to guide management and counselling following a diagnosis of Dilated Cardiomyopathy (DCM). We aimed to document outcomes and time to recovery for a cohort of patients with a dilated cardiomyopathy phenotype.

METHODS

An observational cohort methodology was used to collect retrospective data from the departmental database for those identified with DCM. Data relating to mode of presentation, echocardiographic parameters, clinical management and outcome were collated and analysed. Predictors and time-scale for recovery were investigated and reported.

RESULTS

209 new referrals were included within the time frame. 82 children median age 1.0years (IQR 3.4) required intensive care (ICU) and their survival without death or transplant was 51% to one year and 45% to five years. 127 children presented to the pediatric heart failure clinic. Excluding 58 with neuromuscular disease, median age was 4.1years (IQR 11.3) & survival without death or transplant 85% to 1year and 50% to 5years. NT-proBNP normalized in survivors before echocardiographic parameters. Predictors of recovery included younger age, female sex and smaller left ventricular end diastolic Z score on echocardiogram at presentation.

CONCLUSION

Transplant-free survival to one year is significantly better for patients presenting to clinic, but longer-term survival is better amongst those presenting to ICU due to a late attrition in those with less severe heart failure at presentation. Falling NT-proBNP is the earliest marker of recovery. Recovery of cardiac function remains possible up to three years from presentation.

Sca-1+ cardiac fibroblasts promote development of heart failure

The causative effect of GM-CSF produced by cardiac fibroblasts to development of heart failure has not been shown. We identified the pathological GM-CSF-producing cardiac fibroblast subset and the specific deletion of IL-17A signaling to these cells attenuated cardiac inflammation and heart failure. We describe here the CD45^- CD31^- CD29⁺ mEF-SK4⁺ PDGFRα⁺ Sca-1⁺ periostin⁺ (Sca-1⁺ ) cardiac fibroblast subset as the main GM-CSF producer in both experimental autoimmune myocarditis and myocardial infarction mouse models. Specific ablation of IL-17A signaling to Sca-1⁺ periostin⁺ cardiac fibroblasts (Postn^Cre Il17ra^fl/fl ) protected mice from post-infarct heart failure and death. Moreover, Postn^Cre Il17ra^fl/fl mice had significantly fewer GM-CSF-producing Sca-1⁺ cardiac fibroblasts and inflammatory Ly6C^hi monocytes in the heart. Sca-1⁺ cardiac fibroblasts were not only potent GM-CSF producers, but also exhibited plasticity and switched their cytokine production profiles depending on local microenvironments. Moreover, we also found GM-CSF-positive cardiac fibroblasts in cardiac biopsy samples from heart failure patients of myocarditis or ischemic origin. Thus, this is the first identification of a pathological GM-CSF-producing cardiac fibroblast subset in human and mice hearts with myocarditis and ischemic cardiomyopathy. Sca-1⁺ cardiac fibroblasts direct the type of immune cells infiltrating the heart during cardiac inflammation and drive the development of heart failure.

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.

The Influence of Race and Common Genetic Variations on Outcomes After Pediatric Heart Transplantation

Significant racial disparity remains in the incidence of unfavorable outcomes following heart transplantation. We sought to determine which pediatric posttransplantation outcomes differ by race and whether these can be explained by recipient demographic, clinical, and genetic attributes. Data were collected for 80 black and 450 nonblack pediatric recipients transplanted at 1 of 6 centers between 1993 and 2008. Genotyping was performed for 20 candidate genes. Average follow-up was 6.25 years. Unadjusted 5-year rates for death (p = 0.001), graft loss (p = 0.015), acute rejection with severe hemodynamic compromise (p = 0.001), late rejection (p = 0.005), and late rejection with hemodynamic compromise (p = 0.004) were significantly higher among blacks compared with nonblacks. Black recipients were more likely to be older at the time of transplantation (p < 0.001), suffer from cardiomyopathy (p = 0.004), and have public insurance (p < 0.001), and were less likely to undergo induction therapy (p = 0.0039). In multivariate regression models adjusting for age, sex, cardiac diagnosis, insurance status, and genetic variations, black race remained a significant risk factor for all the above outcomes. These clinical and genetic variables explained only 8-19% of the excess risk observed for black recipients. We have confirmed racial differences in survival, graft loss, and several rejection outcomes following heart transplantation in children, which could not be fully explained by differences in recipient attributes.

Eosinophil-derived IL-4 drives progression of myocarditis to inflammatory dilated cardiomyopathy

Diny et al. report a pathogenic role for eosinophils in autoimmune myocarditis and dilated cardiomyopathy. Eosinophils are required for progression of myocarditis to dilated cardiomyopathy and drive severe disease when present in large numbers. Activated cardiac eosinophils mediate this process through IL-4.

Inflammatory dilated cardiomyopathy (DCMi) is a major cause of heart failure in children and young adults. DCMi develops in up to 30% of myocarditis patients, but the mechanisms involved in disease progression are poorly understood. Patients with eosinophilia frequently develop cardiomyopathies. In this study, we used the experimental autoimmune myocarditis (EAM) model to determine the role of eosinophils in myocarditis and DCMi. Eosinophils were dispensable for myocarditis induction but were required for progression to DCMi. Eosinophil-deficient ΔdblGATA1 mice, in contrast to WT mice, showed no signs of heart failure by echocardiography. Induction of EAM in hypereosinophilic IL-5Tg mice resulted in eosinophilic myocarditis with severe ventricular and atrial inflammation, which progressed to severe DCMi. This was not a direct effect of IL-5, as IL-5TgΔdblGATA1 mice were protected from DCMi, whereas IL-5^−/− mice exhibited DCMi comparable with WT mice. Eosinophils drove progression to DCMi through their production of IL-4. Our experiments showed eosinophils were the major IL-4–expressing cell type in the heart during EAM, IL-4^−/− mice were protected from DCMi like ΔdblGATA1 mice, and eosinophil-specific IL-4 deletion resulted in improved heart function. In conclusion, eosinophils drive progression of myocarditis to DCMi, cause severe DCMi when present in large numbers, and mediate this process through IL-4.

Is Myocarditis an Independent Risk Factor for Post-Transplant Mortality in Pediatric Heart Transplant Recipients?

BACKGROUND

Previous studies suggest that children with myocarditis who receive heart transplantation (HT) may be at higher risk of post-transplant mortality compared with children who are transplanted for idiopathic dilated cardiomyopathy. We hypothesized that these differences are because of more severe heart failure at HT in children with myocarditis.

METHODS AND RESULTS

We identified 221 children with myocarditis and 1583 with idiopathic dilated cardiomyopathy who were <18 years old and listed for HT in the United States between July 2004 and December 2013 using the Organ Procurement and Transplant Network database. We compared baseline characteristics at listing and at HT and used Cox models to determine whether myocarditis is independently associated with wait-list mortality (or becoming too sick to transplant) or post-transplant graft loss (death/re-HT). Children with myocarditis were more likely to be listed while on assisted ventilation, mechanical circulatory support and with renal dysfunction. Overall, 137 children with myocarditis and 1249 with idiopathic dilated cardiomyopathy received HT. In unadjusted analysis, children with myocarditis were at higher risk of wait-list mortality (hazard ratio 2.1; 95% confidence interval 1.5-3.0) and showed a trend toward increased risk of post-transplant graft loss (hazard ratio 1.4; 95% confidence interval 1.0-2.2). However, in adjusted analysis, myocarditis was not associated with wait-list mortality (hazard ratio 1.3, 95% confidence interval 0.9-1.9) or post-transplant graft loss (hazard ratio 1.3, 95% confidence interval 0.9-2.0).

CONCLUSIONS

Among children listed for HT, those with myocarditis have more severe heart failure than children with idiopathic dilated cardiomyopathy. After adjustment for severity of illness, myocarditis does not confer additional risk for wait-list or post-transplant mortality.

Risk factors for specific causes of death following pediatric heart transplant: An analysis of the registry of the International Society of Heart and Lung Transplantation

We sought to determine temporal changes in COD and identify COD-specific risk factors in pediatric primary HTx recipients. Using the ISHLT registry, time-dependent hazard of death after pediatric HTx, stratified by COD, was analyzed by multiphasic parametric hazard modeling with multivariable regression models for risk factor analysis. The proportion of pediatric HTx deaths from each of cardiovascular cause, allograft vasculopathy, and malignancy increased over time, while all other COD decreased post-HTx. Pre-HTx ECMO was associated with increased risk of death from graft failure (HR 2.43; p < 0.001), infection (HR 2.85; p < 0.001), and MOF (HR 2.22; p = 0.001), while post-HTx ECMO was associated with death from cerebrovascular events/bleed (HR 2.55; p = 0.001). CHD was associated with deaths due to pulmonary causes (HR 1.78; p = 0.007) or infection (HR 1.72; p < 0.001). Non-adherence was a significant risk factor for all cardiac COD, notably graft failure (HR 1.66; p = 0.001) and rejection (HR 1.89; p < 0.001). Risk factors related to specific COD are varied across different temporal phases post-HTx. Increased understanding of these factors will assist in risk stratification, guide anticipatory clinical decisions, and potentially improve patient survival.

Lessons learned from the Pediatric Cardiomyopathy Registry (PCMR) Study Group

Cardiomyopathy is a rare disorder of the heart muscle, affecting 1.13 cases per 100,000 children, from birth to 18 years of age. Cardiomyopathy is the leading cause of heart transplantation in children over the age of 1. The Pediatric Cardiomyopathy Registry funded in 1994 by the National Heart, Lung, and Blood Institute was established to examine the epidemiology of the disease in children below 18 years of age. More than 3500 children across the United States and Canada have been enrolled in the Pediatric Cardiomyopathy Registry, which has followed-up these patients until death, heart transplantation, or loss to follow-up. The Pediatric Cardiomyopathy Registry has provided the most in-depth illustration of this disease regarding its aetiology, clinical course, associated risk factors, and patient outcomes. Data from the registry have helped in guiding the clinical management of cardiomyopathy in children under 18 years of age; however, questions still remain regarding the most clinically effective diagnostic and treatment approaches for these patients. Future directions of the registry include the use of next-generation whole-exome sequencing and cardiac biomarkers to identify aetiology-specific treatments and improve diagnostic strategies. This article provides a brief synopsis of the work carried out by the Pediatric Cardiomyopathy Registry since its inception, including the current knowledge on the aetiologies, outcomes, and treatments of cardiomyopathy in children.

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.

Extracorporeal Membrane Oxygenation as a Bridge to Pediatric Heart Transplantation: Effect on Post-Listing and Post-Transplantation Outcomes

BACKGROUND

Current organ allocation algorithms direct hearts to the sickest recipients to mitigate death while waiting. This may result in lower post-transplant (Tx) survival for high-risk candidates mandating close examination to determine the appropriateness of different technologies as a bridge to Tx.

METHODS AND RESULTS

We analyzed all patients (<18 years old) from the Pediatric Heart Transplant Study (PHTS) database listed for heart Tx (1993-2013) to determine the effect of extracorporeal membrane oxygenation (ECMO) support at the time of listing and the time of Tx on waitlist mortality and post-Tx outcomes. Eight percent of patients were listed on ECMO, and within 12 months, 49% had undergone Tx, 35% were deceased, and 16% were alive waiting. Survival at 12 months after listing (censored at Tx) was worse in patients on ECMO at listing (50%) compared with ventricular assist device at listing (76%) or not on ECMO or ventricular assist device at listing (76%; P<0.0001). Two hundred three (5%) patients underwent Tx from ECMO; 135 (67%) had been on ECMO since listing, and 67 (33%) had deteriorated to ECMO support while waiting. Survival after Tx was worse in patients who underwent Tx from ECMO (3 years: 64%) versus on ventricular assist device at Tx (3 years: 84%) or not on ECMO/ventricular assist device at Tx (3 years: 85%; P<0.0001). Patients transplanted from ECMO at age <1 year had the worst survival.

CONCLUSIONS

Pediatric patients requiring ECMO support before heart Tx have poor outcomes. Prioritization of donor hearts to children waitlisted on ECMO warrants careful consideration because of ECMO's high pre- and post-Tx mortality.

Evaluation of the diagnostic work-up in children with myocarditis and idiopathic dilated cardiomyopathy

The underlying etiology of dilated cardiomyopathy (DCM) in children varies, 14-22% is secondary to myocarditis, and the majority remains idiopathic. Etiology has prognostic value; however, 'a clinical diagnosis of myocarditis' has been frequently used because the gold standard [endomyocardial biopsy (EMB)] is often not performed. Therefore, a consistent diagnostic approach and interpretation is needed. In this multicenter study, we evaluated the diagnostic approach and interpretation of the viral results in children with myocarditis and idiopathic DCM. We included 150 children with DCM, of whom 103 were assigned the diagnosis myocarditis (n = 21) or idiopathic DCM (n = 82) by the attending physician. Viral tests were performed in 97/103 patients, in only 34% (n = 35) some of the tests were positive. Of those patients, we evaluated the probability of the assigned diagnosis using the viral test results. We classified viral test results as reflecting definite or probable myocarditis in 14 children and possible or unlikely myocarditis in 21 children. Based on this classification, 23% of patients were misclassified. We found that in children with DCM, the diagnostic approach varied and the interpretation was mainly based on viral results. Since a 'clinical diagnosis of myocarditis' has been frequently used in daily practice because of the lack of EMB results, a uniform protocol is needed. We propose to use viral test results in several steps (blood PCR, serology, PCR and/or cultures of the gastro-intestinal and respiratory tract, and EMB results) to estimate the probability of myocarditis.

Circulating microRNA as a biomarker for recovery in pediatric dilated cardiomyopathy

BACKGROUND

MicroRNAs (miRNAs) are short regulatory RNAs that control gene expression through interacting with the 3'UTR of target messenger RNAs. The purpose of this study was to determine if circulating miRNAs are useful biomarkers of outcome in children with dilated cardiomyopathy (DCM).

METHODS

An array for 754 miRNAs and real time polymerase chain reaction confirmation of select miRNAs were performed. Serum from 55 children <18 years old with DCM was analyzed. Samples were drawn from all patients with DCM when undergoing heart transplant evaluation and/or at the time of transplantation. Patients with DCM were categorized based on when their blood was drawn (Pre-Transplant or Transplant) and outcome (Transplant/died or Recovered).

RESULTS

Two miRNAs were significantly up-regulated (hsa-miR-155 and hsa-miR-636) and 2 miRNAs were down-regulated (hsa-miR-646 and hsa-miR-639) in patients with DCM who were transplanted or died compared with patients with DCM who recovered their ventricular function. Receiver operator curves, performed for differences in any 1 of these 4 differentially regulated miRNAs in patients who were transplanted or died compared with patients who recovered, resulted in an area under the receiver operating characteristic curve of 0.875 for the Pre-Transplant blood draw time point and an area under the receiver operating characteristic curve of 0.93 for the day of Transplant time point.

CONCLUSIONS

We identified specific miRNAs that are differentially regulated between children with DCM who need a transplant compared with children with DCM who recover. A unique biomarker signature of miRNAs that are specific to children with DCM who have the potential to recover would be valuable in risk stratification of this challenging patient population.

Predicting graft loss by 1 year in pediatric heart transplantation candidates: an analysis of the Pediatric Heart Transplant Study database

BACKGROUND

Pediatric data on the impact of pre-heart transplantation (HTx) risk factors on early post-HTx outcomes remain inconclusive. Thus, among patients with previous congenital heart disease or cardiomyopathy, disease-specific risk models for graft loss were developed with the use pre-HTx recipient and donor characteristics.

METHODS AND RESULTS

Patients enrolled in the Pediatric Heart Transplant Study (PHTS) from 1996 to 2006 were stratified by pre-HTx diagnosis into cardiomyopathy and congenital heart disease cohorts. Logistic regression identified independent, pre-HTx risk factors. Risk models were constructed for 1-year post-HTx graft loss. Donor factors were added for model refinement. The models were validated with the use of patients transplanted from 2007 to 2009. Risk factors for graft loss were identified in patients with cardiomyopathy (n=896) and congenital heart disease (n=965). For cardiomyopathy, independent risk factors were earlier year of transplantation, nonwhite race, female sex, diagnosis other than dilated cardiomyopathy, higher blood urea nitrogen, and panel reactive antibody >10%. The recipient characteristic risk model had good accuracy in the validation cohort, with predicted versus actual survival of 97.5% versus 95.3% (C statistic, 0.73). For patients with congenital heart disease, independent risk factors were nonwhite race, history of Fontan, ventilator dependence, higher blood urea nitrogen, panel reactive antibody >10%, and lower body surface area. The risk model was less accurate, with 86.6% predicted versus 92.4% actual survival, in the validation cohort (C statistic, 0.63). Donor characteristics did not enhance model precision.

CONCLUSIONS

Risk factors for 1-year post-HTx graft loss differ on the basis of pre-HTx cardiac diagnosis. Modeling effectively stratifies the risk of graft loss in patients with cardiomyopathy and may be an adjunctive tool in allocation policies and center performance metrics.

Pediatric heart transplantation-indications and outcomes in the current era

Pediatric heart transplantation (HTx) remains an important treatment option in the care of children with end-stage heart disease, whether it is secondary to cardiomyopathy or congenital heart disease (CHD). As surgical outcomes for CHD have improved, the indications for pediatric HTx have had to be dynamic, not only for children with CHD but also for the growing population of adults with CHD. As the field of pediatric HTx has evolved, the outcomes for children undergoing HTx have improved. This is undoubtedly due to the continued research efforts of both single-center studies, as well as research collaboratives such as the International Society for Heart and Lung Transplantation (ISHLT) and the Pediatric Heart Transplant Study (PHTS) group. Research collaboratives are increasingly important in pediatric HTx as single center studies for a limited patient population may not elicit strong enough evidence for practice evolution. Similarly, complications that limit the long term graft survival may occur in a minority of patients thus pooled experience is essential. This review focuses on the indications and outcomes for pediatric HTx, with a special emphasis on studies generated by these research collaboratives.

Pediatric heart transplantation-indications and outcomes in the current era

Pediatric heart transplantation (HTx) remains an important treatment option in the care of children with end-stage heart disease, whether it is secondary to cardiomyopathy or congenital heart disease (CHD). As surgical outcomes for CHD have improved, the indications for pediatric HTx have had to be dynamic, not only for children with CHD but also for the growing population of adults with CHD. As the field of pediatric HTx has evolved, the outcomes for children undergoing HTx have improved. This is undoubtedly due to the continued research efforts of both single-center studies, as well as research collaboratives such as the International Society for Heart and Lung Transplantation (ISHLT) and the Pediatric Heart Transplant Study (PHTS) group. Research collaboratives are increasingly important in pediatric HTx as single center studies for a limited patient population may not elicit strong enough evidence for practice evolution. Similarly, complications that limit the long term graft survival may occur in a minority of patients thus pooled experience is essential. This review focuses on the indications and outcomes for pediatric HTx, with a special emphasis on studies generated by these research collaboratives.

Creation of a quantitative score to predict the need for mechanical support in children awaiting heart transplant

BACKGROUND

Due to the availability of new devices, the use of ventricular assist devices (VADs) in children has been increasing; however, patient selection and optimal timing of device implantation in this population remains uncertain.

METHODS

A retrospective review of the United Network for Organ Sharing dataset identified 5,200 listings without mechanical circulatory support (MCS) for isolated pediatric heart transplant, 1995 to 2012. Patients were randomly divided into a derivation and validation cohort. A multivariable logistic regression model predicting the likelihood of death or need for MCS within 60 days was built using the derivation cohort and tested in the validation cohort. A simplified score (PedsMCS score) was developed and evaluated for accuracy.

RESULTS

The predictive model consisted of variables present at listing (age, albumin level, creatinine clearance, serum bilirubin, mechanical ventilation, and inotropic support). It had good predictive ability (C statistic 0.7304) within the validation cohort. The simplified PedsMCS score was also predictive (C statistic 0.7217) and there was a strong correlation between predicted and expected outcomes (r=0.91, p<0.0001). Patients with PedsMCS score 16 or greater had a significantly higher risk of death or MCS within 2 months (36.6%) than those with low scores (<6) (1.5%, p<0.0001). A single point increase in PedsMCS score was associated with a 16.7% increase in the risk of death or MCS with 2 months (p<0.0001).

CONCLUSIONS

We have developed and validated a simplified score to predict the need for MCS based on risk factors present at listing. This will provide more accurate prognostication in children awaiting heart transplant, and may improve patient selection.

Heart transplantation in pediatric cardiomyopathies

Cardiomyopathies represent an uncommon but serious cause of heart disease in the pediatric population and can be categorized as dilated, hypertrophic, restrictive and left ventricular non-compaction. Each of these subtypes has multiple potential genetic etiologies in addition to possible non-genetic causes. Many patients with cardiomyopathies can benefit from transplantation, although there is not insignificant morbidity and mortality for those patients. Outcomes both prior to and following transplantation depend on the underlying etiology, the amount of support needed prior to transplantation and the illness severity of the patient prior to transplantation. Mechanical circulatory support is frequently used to bridge patients to transplantation, and newer technologies are currently in development.

Cardiac fibroblasts mediate IL-17A-driven inflammatory dilated cardiomyopathy

IL-17A stimulates cardiac fibroblasts to produce inflammatory mediators critical for the recruitment and differentiation of myeloid cells during inflammatory dilated cardiomyopathy.

Inflammatory dilated cardiomyopathy (DCMi) is a major cause of heart failure in individuals below the age of 40. We recently reported that IL-17A is required for the development of DCMi. We show a novel pathway connecting IL-17A, cardiac fibroblasts (CFs), GM-CSF, and heart-infiltrating myeloid cells with the pathogenesis of DCMi. Il17ra^−/− mice were protected from DCMi, and this was associated with significantly diminished neutrophil and Ly6Chi monocyte/macrophage (MO/MΦ) cardiac infiltrates. Depletion of Ly6Chi MO/MΦ also protected mice from DCMi. Mechanistically, IL-17A stimulated CFs to produce key chemokines and cytokines that are critical downstream effectors in the recruitment and differentiation of myeloid cells. Moreover, IL-17A directs Ly6Chi MO/MΦ in trans toward a more proinflammatory phenotype via CF-derived GM-CSF. Collectively, this IL-17A–fibroblast–GM-CSF–MO/MΦ axis could provide a novel target for the treatment of DCMi and related inflammatory cardiac diseases.

Adolescent age and heart transplantation outcomes in myocarditis or congenital heart disease

BACKGROUND

Adolescents often fare poorly after heart transplantation. However, whether the effect of age varies according to the etiology of heart failure is unknown. We tested the hypothesis that age-related heart transplantation outcomes are different in patients with myocarditis and congenital heart disease (CHD).

METHODS

A retrospective analysis of the United Network of Organ Sharing database was performed for patients with myocarditis (n = 709) and CHD (n = 1,631) undergoing heart transplantation from 1987 to 2011. The effect of age on graft survival was assessed. Age was categorized as children (6-12 years), adolescents (13-18 years), younger adults (19-30 years), and older adults (31-50 years).

RESULTS

For myocarditis, the median graft survival for adolescents was 6.9 years (95% confidence interval [CI], 5.6-9.6), which was significantly lower than other age groups (children: 14.1 [95% CI, 9.8-10.9] years, p = 0.004; younger adults: 11.8 [95% CI, 8.3-15.2] years, p = 0.172; older adults: 12.0 years [95% CI, 10.0-14.3 years], p = 0.033). For CHD, the median graft survival for adolescents was 7.4 years (95% CI, 6.8-8.6), which was not significantly different from other age groups (children: 9.0 [95% CI, 7.9-11.0] years, p = 0.737; younger adults: 11.2 [95% CI, 8.6-13.3] years, p = 0.744; older adults: 11.6 [95% CI, 9.2-15.3] years, p = 0.608). Multivariable analysis showed adolescent age was independently associated with worse graft survival for patients with myocarditis but not for CHD.

CONCLUSIONS

Adolescents with myocarditis have significantly worse graft survival after heart transplantation, but adolescents with CHD have similar outcomes to other patients with CHD. Further study is needed to improve outcomes in this vulnerable population.

Severity of mitral regurgitation predicts risk of death or cardiac transplantation in children with idiopathic dilated cardiomyopathy

Clinical outcomes among children with idiopathic dilated cardiomyopathy (IDC) are diverse, which makes the decision as to when a patient should be listed for a cardiac transplantation challenging. This study aimed to determine echocardiographic and clinical variables that can help clinicians identify those at highest risk for death or cardiac transplantation. The study was a single-center, retrospective chart review of children with IDC. Patients younger than 18 years with a diagnosis of IDC, as defined by a left ventricular end-diastolic dimension (LVEDD) z-score higher than 2, and fractional shortening of less than 28 % on the initial echocardiogram, were included in the study. Echocardiographic parameters including mitral regurgitation (MR) grade and certain clinical parameters at the time of presentation were assessed. A follow-up echocardiogram was similarly studied. The study included 49 children with IDC. Those who died or underwent cardiac transplantation were grouped as "nonsurvivors" (n = 26). The remaining children who either completely recovered or experienced chronic dilated cardiomyopathy were grouped as "survivors" (n = 23). The median age overall was 1.25 years (range 0.1-17 years). The follow-up echocardiograms of the survivors showed significant improvement in left ventricle size, systolic function, left atrial volume, and MR grade, whereas these parameters did not change in the nonsurvivor group. The use of inotropic medications at initial presentation was an independent predictor of death or cardiac transplantation (p < 0.05). The presence of moderate to severe MR at diagnosis also was predictive of a worse outcome.

Role of endomyocardial biopsy for children presenting with acute systolic heart failure

Myocarditis, an inflammatory disease of the heart, frequently results from viral infections, postviral immune-mediated responses, or both. It is a common cause of acute-onset systolic heart failure in children. Endomyocardial biopsy (EMB) remains the gold standard for the diagnosis of myocarditis. However, EMB is not performed for most myocarditis cases involving children in the United States. Clinical scenarios in which EMB results added unique prognostic data and guidance to therapy have been defined recently. This review outlines the role of EMB in the diagnosis and management of myocarditis for children presenting with acute-onset systolic heart failure.