Evaluating threshold for donor fraction cell-free DNA using clinically available assay for rejection in pediatric and adult heart transplantation

BACKGROUND

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

METHODS

Observational, non-interventional, prospective study enrolled pediatric and adult heart transplant recipients from seven centers. Biopsy-associated plasma samples were used for cfDNA measurements. Pre-determined cut points were tested for analytic performance.

RESULTS

A total of 487 samples from 160 subjects were used for the analysis. There were significant differences for df-cfDNA values between rejection [0.21% (IQR 0.12-0.69)] and healthy samples [0.05% (IQR 0.01-0.14), p < .0001]. The pediatric rejection group had a median df-cfDNA value of 0.93% (IQR 0.28-2.84) compared to 0.09% (IQR 0.04-0.23) for healthy samples, p = .005. Overall negative predictive value was 0.94 while it was 0.99 for pediatric patients. Cut points of 0.13% and 0.15% were tested for various types of rejection profiles and were appropriate to rule out rejection.

CONCLUSION

The study suggests that pediatric patients with rejection show higher levels of circulating df-cfDNA compared to adults and supports the specific cut points for clinical use in pediatric and adult patients with overall acceptable performance.

School age and adolescent heart failure following the Norwood procedure

BACKGROUND

Heart failure results in significant morbidity and mortality for young children with hypoplastic left heart syndrome (HLHS) following the Norwood procedure. The trajectory in later childhood is not well described.

METHODS

We studied the outcome into adolescence of participants enrolled in the Single Ventricle Reconstruction trial who underwent the Fontan procedure or survived to 6 years without having undergone Fontan procedure. The primary outcome was heart failure events, defined as heart transplant listing or death attributable to heart failure. Symptomatic heart failure for participants surviving 10 or more years was also assessed utilizing the Pediatric Quality of Life Inventory (PedsQL).

RESULTS

Of the 345 participants who underwent a Fontan operation or survived to 6 years without Fontan, 25 (7.2%) had a heart failure event before the age of 12 years. Among these, 21 were listed for heart transplant, and 4 died from heart failure. Nineteen participants underwent heart transplant, all of whom survived to age 12 years. Factors associated with a heart failure event included longer Norwood hospital length of stay, aortic atresia, and no Fontan operation by age 6 years. Assessment of heart failure symptoms at 12 years of age revealed that 24 (12.2%) of 196 PedsQL respondents "often" or "almost always" had difficulty walking more than one block.

CONCLUSIONS

Heart failure events occur in over 5% of children with palliated HLHS between preschool age and adolescence. Outcomes for children listed for transplant are excellent. However, a substantial portion of palliated HLHS children have significant symptoms of heart failure at 12 years of age.

Validation of donor fraction cell-free DNA with biopsy-proven cardiac allograft rejection in children and adults

OBJECTIVES

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

METHODS

Pediatric and adult heart transplant recipients were enrolled from 7 participating sites and followed for 12 months or more with plasma samples collected immediately before all endomyocardial biopsies. Donor fraction cell-free DNA was extracted, and quantitative genotyping was performed. Blinded donor fraction cell-free DNA and clinical data were analyzed and compared with a previously determined threshold of 0.14%. Sensitivity, specificity, negative predictive value, positive predictive value, and receiver operating characteristic curves were calculated.

RESULTS

A total of 987 samples from 144 subjects were collected. After applying predefined clinical and technical exclusions, 745 samples from 130 subjects produced 54 rejection samples associated with the composite outcome of acute cellular rejection grade 2R or greater and pathologic antibody-mediated rejection 2 or greater and 323 healthy samples. For all participants, donor fraction cell-free DNA at a threshold of 0.14% had a sensitivity of 67%, a specificity of 79%, a positive predictive value of 34%, and a negative predictive value of 94% with an area under the curve of 0.78 for detecting rejection. When analyzed independently, these results held true for both pediatric and adult cohorts at the same threshold of 0.14% (negative predictive value 92% and 95%, respectively).

CONCLUSIONS

Donor fraction cell-free DNA at a threshold of 0.14% can be used to assess for risk of rejection after heart transplantation in both pediatric and adult patients with excellent negative predictive value.

Considerations for Advanced Heart Failure Consultation in Individuals With Fontan Circulation: Recommendations From ACTION

Individuals with Fontan circulation are at risk of late mortality from both cardiac and noncardiac causes. Despite the known risk of mortality, referral indications for advanced heart failure care vary between centers, and many individuals die from Fontan circulation-related complications either after late consideration for advanced heart failure therapies or having never seen a heart failure specialist. There is a critical need for guidelines to direct appropriately timed referral for advanced heart failure consultation. The Advanced Cardiac Therapies Improving Outcomes Network (ACTION) Fontan Committee has developed recommended thresholds for advanced heart failure referral to guide primary cardiologists. These recommendations are divided into 4 categories of clinical Fontan circulatory dysfunction including (1) cardiac/systemic ventricular dysfunction, (2) Fontan pathway dysfunction, (3) lymphatic dysfunction, and (4) extracardiac dysfunction.

Clinical Variables Associated with Pre-Fontan Aortopulmonary Collateral Burden

Aortopulmonary collaterals (APCs) develop universally, but to varying degrees, in patients with single ventricle congenital heart disease (CHD). Despite their ubiquitous presence, APCs remain poorly understood. We sought to evaluate the association between APC burden and common non-invasive clinical variables. We conducted a single center, retrospective study of patients with single ventricle CHD and previous Glenn palliation who underwent pre-Fontan cardiac magnetic resonance (CMR) imaging from 3/2018 to 3/2021. CMR was used to quantify APC flow, which was normalized to aortic (APC/QAo) and pulmonary vein (APC/QPV) blood flow. Univariate, multivariable, and classification and regression tree (CART) analyses were done to investigate the potential relationship between CMR-quantified APC burden and clinical variables. A total of 29 patients were included, all of whom had increased APC flow (APC/QAo: 26.9, [22.0, 39.1]%; APC/QPV: 39.4 [33.3, 46.9]%), but to varying degrees (APC/QAo: range 11.9-44.4%; APC/QPV: range 17.7-60.0%). Pulmonary artery size (Nakata index, at pre-Fontan CMR) was the only variable associated with APC flow on multivariable analysis (APC/QAo: p = 0.020, R2 = 0.19; APC/QPV: p = 0.0006, R2 = 0.36) and was the most important variable associated with APC burden identified by CART analysis (size inversely related to APC flow). APC flow is universally increased but highly variable in patients with single ventricle CHD and Glenn circulation. Small branch pulmonary artery size is a key factor associated with increased APC burden; however, the pathogenesis of APCs is likely multifactorial. Further research is needed to better understand APC pathogenesis, including predisposing and mitigating factors.

Relationship between donor fraction cell-free DNA and clinical rejection in heart transplantation

BACKGROUND

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

METHODS

Patients with heart transplantation were enrolled in two sequential, multi-center, prospective observational studies. Blood samples were collected for surveillance or clinical events. Clinicians were blinded to the results of DF cfDNA.

RESULTS

A total of 835 samples from 269 subjects (57% pediatric) were included for this analysis, including 28 samples associated with CR were analyzed. Median DF cfDNA was 0.43 (IQR 0.15, 1.36)% for CR and 0.10 (IQR 0.07, 0.16)% for healthy controls (p < .0001). At cutoff value of 0.13%, the area under curve (AUC) was 0.82, sensitivity of 0.86, specificity of 0.67, and negative predictive value of 0.99. There was serial decline in DF cfDNA post-therapy, however, those with cardiovascular events (cardiac arrest, need for mechanical support or death) showed significantly higher levels of DF cfDNA on Day 0 (2.11 vs 0.31%) and Day 14 (0.51 vs 0.22%) compared to those who did not have such an event (p < .0001).

CONCLUSION

DF cfDNA has excellent agreement with clinical rejection and, importantly, serial measurement of DF cfDNA predict clinically significant outcomes post treatment for rejection in these patients.

Increase in nuclear cell-free DNA is associated with major adverse events in adult and pediatric heart transplant recipients

BACKGROUND

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

OBJECTIVE

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

METHODS

We conducted a multi-center prospective study to investigate the value of cell-free DNA in non-invasive monitoring following heart transplantation. Over 4000 blood samples were collected from 388 heart transplant patients. Total ncfDNA and donor fraction were quantified. Generalized linear models with maximum likelihood estimation for repeated measures with subjects as clusters were used to explore the relationship of ncfDNA and major adverse events. Receiver operating characteristic curves were used to help choose cutpoints.

RESULTS

A ncfDNA threshold (50 ng/ml) was identified that was associated with increased risk of major adverse events. NcfDNA was elevated in patients who suffered cardiac arrest, required mechanical circulatory support or died post heart transplantation as well as in patients undergoing treatment for infection.

CONCLUSIONS

Elevated ncfDNA correlates with risk for major adverse events in adult and pediatric heart transplant recipients and may indicate a need for enhanced surveillance after transplant.

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.

Innominate Vein Turn-down Procedure for Failing Fontan Circulation

After the Fontan, systemic venous hypertension induces pathophysiologic changes in the lymphatic system that can result in complications of pleural effusion, ascites, plastic bronchitis, and protein losing enteropathy. Advances in medical therapy and novel interventional approaches have not substantially improved the poor prognosis of these complications. A more physiological approach has been developed by decompression of the thoracic duct to the lower pressure common atrium with a concomitant increase of preload. Diverting the innominate vein to the common atrium increases the transport capacity of the thoracic duct, which in most patients enters the circulation at the left subclavian-jugular vein junction. Contrary to the fenestrated Fontan circulation, in which the thoracic duct is drained into the high pressure Fontan circulation, turn down of the innominate vein to the common atrium effectively decompresses the thoracic duct to the lower pressure system with "diastolic suctioning" of lymph. Innominate vein turn-down may be considered for medical-refractory post-Fontan lymphatic complications of persistent chylothorax, plastic bronchitis, and protein losing enteropathy. Prophylactic innominate vein turn-down may also be considered at time of the Fontan operation for patients that are higher risk for lymphatic complications.

Diazoxide-associated pulmonary hypertension in a patient with noncompaction cardiomyopathy

Development of pulmonary hypertension after initiation of diazoxide for the treatment of neonatal hyperinsulinemic hypoglycemia is a rare, but previously described association. Risk factors for development of diazoxide-associated pulmonary hypertension include lower gestational age and congenital heart disease. This novel case report describes an infant with noncompaction cardiomyopathy who developed pulmonary hypertension shortly after initiation of diazoxide for hyperinsulinemic hypoglycemia which resolved upon cessation of the drug. This case highlights the benefit of having pre-treatment knowledge of underlying cardiac anatomy and makes a case for routine echocardiographic screening for neonates initiating diazoxide treatment.

Educational and learning morbidity in pediatric heart transplant recipients: A pediatric heart transplant society study

Educational development is an important component of quality of life for children with heart transplant. Aims include determining prevalence of and risk factors for modified education placement in a large representative sample of pediatric heart transplant recipients. Participants included 1495 patients (age 6-18 years) from the PHTS database. Data on education placement and clinical predictors were collected at listing and at 1 and 3 years post-transplant. At listing, 88% of patients were in typical education placement, while 12% were in modified education. Males (P = .02), those with CHD (P < .0001), those with non-private insurance (P < .0001), and those with longer hospital stay (P = .001) were more likely to be in a modified education placement at time of listing. Age, race, listing status, mechanical support, and waitlist time were not significantly associated with placement. The prevalence of typical education placement was similar (87% at 1-year and 86% at 3-year) post-transplant. Predictors of modified education placement at 3-year follow-up included placement at listing (OR = 12.9 [95% CI 7.6-21.9], P < .0001), non-private insurance (OR = 2.0 [95% CI 1.3-3.2], P = .001), CHD (OR = 1.8 [95% CI 1.1-2.7, P = .01), history of post-transplant infection (OR = 1.9 [95% CI 1.2-2.9, P = .007), and number of post-transplant infections (OR = 1.3 [95% CI 1.1-1.5, P = .002). Among pediatric heart transplant recipients, males, those with non-private insurance, those with CHD, and those who experience post-transplant infections are at greatest risk for modified academic placement, which persists for several years post-transplant and deserves targeted intervention.

Marijuana in pediatric and adult congenital heart disease heart transplant listing: A survey of provider practices and attitudes

Despite increasing legalization and use of marijuana, there is no consensus among pediatric heart transplant institutions or providers regarding users' eligibility for cardiac transplant. We sent a survey to pediatric and ACHD transplant providers (physicians, surgeons, transplant coordinators, and pharmacists) assessing their current institution's policies and their personal opinions about marijuana use in patients being considered for heart transplantation. Of the respondents, 84% practice in the United States and Canada. Most providers (80%) care for both pediatric and ACHD patients. Respondents included cardiologists (77%) and surgeons (11%), with the remaining being coordinators and pharmacists. Most providers (73%) reported their institution had no policy regarding marijuana use in heart transplant candidates. Only 20% of respondents' institutions consider mode of consumption, with 87% and 53% approving of oral and transdermal routes, respectively, and only 7% approving of vaporized or smoked routes. While 73% of providers would consider illegal marijuana use an absolute/relative contraindication to heart transplant listing, the number decreases to 57% for legal recreational users and 21% for legal medical users. Most providers personally believe marijuana to be physically and mentally/emotionally harmful to pediatric patients (67% and 72%, respectively). Many institutions lack a policy regarding marijuana use in pediatric and ACHD heart transplant candidates, and there is considerable disagreement among providers on the best practice. With increasing legalization and use of marijuana, each institution will have to address this issue thoughtfully to continue to provide high-quality, consistent, and equitable care for pediatric and ACHD heart transplant candidates.

Early changes in cell-free DNA levels in newly transplanted heart transplant patients

Heart transplantation is a well-established therapy for end-stage heart failure in children and young adults. The highest risk of graft loss occurs in the first 60 days post-transplant. Donor fraction of cell-free DNA is a highly sensitive marker of graft injury. Changes in cell-free DNA levels have not previously been studied in depth in patients early after heart transplant. A prospective study was conducted among heart transplant recipients at a single pediatric heart center. Blood samples were collected from children and young adult transplant patients at three time points within 10 days of transplantation. DF and total cell-free DNA levels were measured using a targeted method (myTAI_HEART ). In 17 patients with serial post-transplant samples, DF peaks in the first 2 days after transplant (3.5%, [1.9-10]%) and then declines toward baseline (0.27%, [0.19-0.52]%) by 6-9 days. There were 4 deaths in the first year among the 10 patients with complete sample sets, and 3 out of 4 who died had a late rise or blunted decline in donor fraction. Patients who died trended toward an elevated total cell-free DNA at 1 week (41.5, [34-65] vs 13.6, [6.2-22] P = .07). Donor fraction peaks early after heart transplant and then declines toward baseline. Patients without sustained decline in donor fraction and/or elevated total cell-free DNA at 1 week may have worse outcomes.

Donor fraction cell-free DNA and rejection in adult and pediatric heart transplantation

BACKGROUND

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

METHODS

A total of 241 heart transplant patients were recruited from 7 centers. Age at transplant ranged from 8 days to 73 years, with 146 subjects <18 years and 95 ≥18 years. All the patients were followed for at least 1 year, with blood samples drawn at routine and for-cause biopsies. A total of 624 biopsy-paired samples were included for analysis through a commercially available cfDNA assay (myTAI_HEART, TAI Diagnostics Inc.). A blinded analysis of repeated measures compared the outcomes using receiver operating characteristic (ROC) curves. All primary clinical end-points were monitored at 100%. All analysis and conclusions were reviewed by both an independent external oversight committee and the National Institutes of Health-mandated DTRT steering committee.

RESULTS

DF in acute cellular rejection (ACR) 1R/2R (n = 15) was higher than ACR 0R (n = 42) (p = 0.02); DF in antibody-mediated rejection pAMR1 (n = 8) and pAMR2 (n = 12) (p = 0.05) were higher than pAMR0 (n = 466) (p = 0.04 and p = 0.05 respectively). An optimal DF threshold was determined by the use of an ROC analysis, which ruled out the presence of either ACR or antibody-mediated rejection.

CONCLUSIONS

The cell-free DNA DF holds promise as a non-invasive diagnostic test to rule out acute rejection in both adult and pediatric heart transplant populations.

Arteriovenous fistula creation for hypoxia after single ventricle palliation: A single-institution experience and literature review

BACKGROUND

Hypoxia is a common and sometimes severe morbidity of single ventricle congenital heart disease (CHD). Creation of an arteriovenous fistula (AVF) is occasionally performed for patients after superior or total cavopulmonary connection (SCPC or TCPC) in an attempt to improve oxygen saturations. Despite previous reports, AVF creation is a rare palliation with inadequately defined benefits and risks. We sought to determine changes in peripheral oxygen saturation (SpO₂ ) and risk of adverse event after AVF creation in children with single ventricle CHD at our institution.

METHODS

We conducted a retrospective chart review of patients with a history of single ventricle palliation and history of surgical AVF creation who were seen at our tertiary care center from 1996 to 2017.

RESULTS

A total of seven patients were included in our study. SpO₂ for the overall cohort did not significantly increase after AVF creation (pre-AVF 79.1 ± 6.9%, post-AVF 82.7 ± 6.0% [P = .23]). SpO₂ trended up for large shunts (>5 mm) (pre-AVF 75.0 ± 7.6%, post-AVF 84.0 ± 5.3% [P = .25]). SpO₂ did not improve for small shunts (≤5 mm) (pre-AVF 82.3 ± 6.5%, post-AVF 81.0 ± 8.5% [P = .50]). The 12-month overall and transplant-free survival were 85.7% and 71.4%, respectively. Freedom from AVF-related complication (cephalic edema, thrombotic occlusion) was 51.4% at 12 months.

CONCLUSION

Palliative AVF creation for patients with single ventricle CHD and hypoxia does not universally improve SpO₂ and is prone to early complications. Despite a lack of durable benefit and known risks, AVF creation remains a reasonable palliation for a subset of patients after SCPC who are not candidates for TCPC, or potentially as a bridge to heart transplantation.

Brain death interval and relationship to outcomes of pediatric cardiac transplantation

BACKGROUND

We sought to analyze brain death interval and outcomes of pediatric cardiac transplantation using national registry data.

METHODS

We retrospectively evaluated a pediatric cohort from the UNOS registry from 2005 to 2014. We restricted the donor cohort to those with a primary central nervous system event as the cause of hospitalization. Brain death interval (BDI) was defined as the time between hospital admission and organ procurement. Primary outcomes were recipient and graft survival time. Logistical regression modeling was used for multivariable analysis.

RESULTS

The donor cohort included 2565 cases. Multivariable analysis demonstrated no relationship between BDI and recipient or graft survival time. For patient survival time, the lowest HR was 0.94 (0.63-1.39), P = 0.531; for graft survival time, the lowest HR was 0.89 (0.53-1.49), P = 0.563. We obtained similar results using a non-restricted donor cohort.

CONCLUSIONS

There was no clear relationship between BDI and recipient or graft survival after pediatric cardiac transplantation.

Outcomes of children with congenital heart disease implanted with ventricular assist devices: An analysis of the Pediatric Interagency Registry for Mechanical Circulatory Support (Pedimacs)

BACKGROUND

The reported ventricular assist device (VAD) experience in the pediatric congenital heart disease (CHD) population is limited. We sought to describe contemporary use and outcomes of VADs in children with CHD and compare these outcomes to those of non-CHD children.

METHODS

Patients enrolled in the Pediatric Interagency Registry for Mechanical Circulatory Support (Pedimacs) between September 19, 2012 through June 30, 2017 were included. CHD was classified as biventricular vs single ventricle (Stages 1, 2, or 3). Outcomes were compared between groups and multivariable analysis was used to identify factors associated with mortality on the device.

RESULTS

Among the 471 patients enrolled, 108 (24%) had CHD (45 biventricular and 63 single ventricle). CHD patients were younger (5.7 ± 5.7 years vs 9.8 ± 6.5 years; p < 0.0001) and smaller (0.8 ± 0.5 m² vs 1.2 ± 0.7 m²; p < 0.0001) compared with non-CHD patients. CHD patients were more likely to receive a paracorporeal continuous-flow VAD (36.1% vs 12.9%; p < 0.0001) and less likely to receive an implantable continuous-flow VAD (27.8% vs 55.0%; p < 0.0001) compared with non-CHD patients. After 6 months on a VAD, CHD patients had higher mortality (36.4% vs 12.1%) and a lower transplantation rate (29.1% vs 59.9%) than non-CHD patients (p < 0.0001). In the multivariable analysis, CHD was the factor most strongly associated with mortality on VAD (hazard ratio [HR] = 2.9; p < 0.0001), whereas the factors implantable continuous-flow device and high-volume center were protective (HR = 0.3, p < 0.0001, and HR = 0.6, respectively; p = 0.02).

CONCLUSIONS

VAD use in children with CHD is associated with increased mortality and decreased transplant rates compared to children without CHD. For the subgroup of children with CHD who received implantable continuous-flow VADs, survival rates were higher and comparable to those of children without CHD. Increased experience correlated with better survival in pediatric VADs.

Current Topics and Controversies in Pediatric Heart Transplantation: Proceedings of the Pediatric Heart Transplantation Summit 2017

In October 2017, a pediatric heart transplant summit was held in Seattle-the first of its kind internationally-which focused solely upon controversies in pediatric end-stage heart failure management and pediatric heart transplantation. We selected five of the most popular and contentious topics and asked the speakers to provide a position paper. Worldwide, the vast majority of programs perform only a handful of pediatric heart transplants a year. Because of this, these "orphan" areas of investigation provide an opportunity for us as a community to aggregate our collective knowledge, which may represent the only viable way that we might sort through these complex and controversial issues in the field. We hope this represents the first of many such conferences and that this initial selection of papers encourages us to begin this collaborative process.

Changes in renal function after left ventricular assist device placement in pediatric patients: A Pedimacs analysis

BACKGROUND

Renal dysfunction (RD) is prevalent among pediatric patients with advanced heart failure. Data are limited regarding changes in renal function after left ventricular assist device (LVAD) placement in this population.

METHODS

Pediatric LVAD recipients enrolled in the Pediatric Interagency Registry for Mechanical Circulatory Support (Pedimacs) between September 19, 2012 and June 30, 2016 were included. Longitudinal changes in renal function were analyzed for the entire cohort as well as subgroups stratified by patient and device characteristics. Logistic regression was used to attempt to identify factors associated with lack of improvement in renal function after LVAD placement. Post-LVAD outcomes were assessed using the Kaplan‒Meier method.

RESULTS

Data from 247 patients from 39 centers were analyzed. Baseline RD (estimated glomerular filtration rate [eGFR] <90 ml/min/1.73 m²) was present in 150 (61%) patients. Overall, eGFR improved post-LVAD, peaking at 1 month post-implant. There was an inverse relationship between baseline eGFR and the degree of improvement at 1 month. Degree of improvement in eGFR at 1 month was not impacted by device type, age, Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profile, or diagnosis. Failure to normalize renal function at 1 week was correlated with persistent RD at 1 month. Post-implant outcomes did not differ among patients stratified by pre-implant renal function.

CONCLUSIONS

Renal function improves post-LVAD placement in pediatric patients regardless of age, diagnosis, illness severity, or device type, with improvement most pronounced in patients with baseline RD. Identifying patients with irreversible renal dysfunction before LVAD placement remains difficult. Pre-LVAD renal function does not appear to impact survival to transplant.

Haemodynamic profiles of children with end-stage heart failure

Aims

To evaluate associations between haemodynamic profiles and symptoms, end-organ function and outcome in children listed for heart transplantation.

Methods and results

Children <18 years listed for heart transplant between 1993 and 2013 with cardiac catheterization data [pulmonary capillary wedge pressure (PCWP), right atrial pressure (RAP), and cardiac index (CI)] in the Pediatric Heart Transplant Study database were included. Outcomes were New York Heart Association (NYHA)/Ross classification, renal and hepatic dysfunction, and death or clinical deterioration while on waitlist. Among 1059 children analysed, median age was 6.9 years and 46% had dilated cardiomyopathy. Overall, 58% had congestion (PCWP >15 mmHg), 28% had severe congestion (PCWP >22 mmHg), and 22% low cardiac output (CI < 2.2 L/min/m2). Twenty-one per cent met the primary outcome of death (9%) or clinical deterioration (12%). In multivariable analysis, worse NYHA/Ross classification was associated with increased PCWP [odds ratio (OR) 1.03, 95% confidence interval (95% CI) 1.01-1.07, P = 0.01], renal dysfunction with increased RAP (OR 1.04, 95% CI 1.01-1.08, P = 0.007), and hepatic dysfunction with both increased PCWP (OR 1.03, 95% CI 1.01-1.06, P < 0.001) and increased RAP (OR 1.09, 95% CI 1.06-1.12, P < 0.001). There were no associations with low output. Death or clinical deterioration was associated with severe congestion (OR 1.6, 95% CI 1.2-2.2, P = 0.002), but not with CI alone. However, children with both low output and severe congestion were at highest risk (OR 1.9, 95% CI 1.1-3.5, P = 0.03).

Conclusion

Congestion is more common than low cardiac output in children with end-stage heart failure and correlates with NYHA/Ross classification and end-organ dysfunction. Children with both congestion and low output have the highest risk of death or clinical deterioration.

Pompe disease treatment with twice a week high dose alglucoside alfa in a patient with severe dilated cardiomyopathy

There is limited information regarding ideal dosage of alglucoside alfa in patients with Infantile Onset Pompe Disease (IOPD). The U.S. Food and Drug Administration approved alglucoside alfa at dosing of 20 mg/kg every other week, but there are small studies and case reports suggesting that dosing higher than this leads to improved ventilator free survival and development without adverse events. We review the clinical course and short term clinical outcomes one year following late diagnosis of IOPD in a 3 month old who presented severely affected and was treated with 40 mg/kg twice a week for 21 infusions until six months of age then transitioned to 40 mg/kg/week. The patient responded well to 40 mg/kg twice a week treatment without adverse reactions and significant clinical improvement.

Heart failure after the Norwood procedure: An analysis of the Single Ventricle Reconstruction Trial

BACKGROUND

Heart failure results in significant morbidity and mortality in young children with hypoplastic left heart syndrome (HLHS) after the Norwood procedure.

METHODS

We studied subjects enrolled in the prospective Single Ventricle Reconstruction (SVR) Trial who survived to hospital discharge after a Norwood operation and were followed up to age 6 years. The primary outcome was heart failure, defined as heart transplant listing after Norwood hospitalization, death attributable to heart failure, or symptomatic heart failure (New York Heart Association [NYHA] Class IV). Multivariate modeling was undertaken using Cox regression methodology to determine variables associated with heart failure.

RESULTS

Of the 461 subjects discharged home following a Norwood procedure, 66 (14.3%) met the criteria for heart failure. Among these, 15 died from heart failure, 39 were listed for transplant (22 had a transplant, 12 died after listing, and 5 were alive and not yet transplanted), and 12 had NYHA Class IV heart failure but were never listed. The median age at heart failure identification was 1.28 (interquartile range 0.30 to 4.69) years. Factors associated with early heart failure included post-Norwood lower fractional area change, need for extracorporeal membrane oxygenation, non-Hispanic ethnicity, Norwood perfusion type, and total support time (p < 0.05).

CONCLUSIONS

By 6 years of age, heart failure developed in nearly 15% of children after the Norwood procedure. Although transplant listing was common, many patients died from heart failure before receiving a transplant or without being listed. Shunt type did not impact the risk of developing heart failure.

Total Artificial Heart Using Bilateral Paracorporeal Pulsatile Ventricular Assist Devices in an 8.2-kg Child

We present a case report illustrating a novel method of placing a total artificial heart in a small child.

HeartWare Ventricular Assist Device Implantation in Patients With Fontan Physiology

We aim to describe the clinical course of a series of patients with hypoplastic left heart syndrome and refractory systolic heart failure supported with a HeartWare ventricular assist device (HVAD) following Fontan palliation. This is a retrospective review of three consecutive patients supported with a HVAD following Fontan palliation through February 2016. Data include patient characteristics, operative variables, postimplantation hemodynamic/device parameters, event outcomes, and duration of HVAD support. Patient ages were 11.7, 13.5, and 17.5 years, respectively, at the time of HVAD implant. The duration of HVAD support was 148, 272, and 271 days, respectively, of which 86, 222, and 211 were outpatient days. Inflow cannula position was the morphologic right ventricle with depth adjustment and manipulation of the tricuspid subvalvar apparatus to ensure good inflow. Echocardiographic, hemodynamic, and noninvasive oximetric monitoring resulted in high RPM settings for all patients. Despite various complications, all patients were successfully transplanted and discharged home alive. We present three patients bridged to transplantation using the HVAD following Fontan palliation. We demonstrate potential for durable support with transition to outpatient care while awaiting heart transplantation in a subset of patients status post Fontan surgery.

Eosinophilic esophagitis in children following cardiac transplantation: association with post-transplant lymphoproliferative disorder and other transplant outcomes

Although cardiac transplantation is life-saving, morbidities from immunosuppression are significant. EoE is a complication of calcineurin inhibitors following liver transplant causing feeding intolerance, weight loss, vomiting, and dysphagia. There are limited reports of EoE following heart transplantation. We performed a retrospective single-center review of pediatric cardiac transplant patients from 2000 to 2010. A case-control analysis of patients with and without EoE was performed evaluating heart transplantation outcomes such as rates of rejection, CAV, PTLD, and graft loss. Eighty-six transplants were performed in 84 patients; 34 (40%) underwent diagnostic endoscopy, and 10 (12%) had EoE. Median time to diagnosis of EoE was 3.7 yr (IQR: 2.0-5.2). There were no differences in demographics or use of induction medications between patients with or without EoE. Patients with EoE had fewer episodes of treated rejection (1.0 vs. 2.5; p = 0.04). Four of 10 (40%) EoE patients had PTLD compared with only 2/24 (8%) of those without EoE (p = 0.048; OR 7.33 [95% CI: 1.1-50.2]). There were no differences in CAV or graft loss between groups. EoE should be considered as a cause of GI symptoms in children after cardiac transplantation and may be associated with fewer rejection episodes and increased rates of PTLD, thus representing a marker of over-immunosuppression.

Heart transplantation for the failing Fontan

BACKGROUND

Patients with failing Fontan circulation are at high risk for complications after heart transplantation (HTx) because of multiple prior operations, elevated panel reactive antibody, hepatic dysfunction, coagulopathy, protein-losing enteropathy (PLE), and poor nutrition. The purpose of this review was to evaluate the outcome of HTx for these patients, including those who are status post-Fontan conversion.

METHODS

Of 206 heart transplants at Ann & Robert H. Lurie Children's Hospital of Chicago from 1990 to 2012, 22 patients had a failing Fontan. Median age at HTx was 12.2 years, median interval from initial Fontan to HTx was 7.1 years. Potential preoperative risk factors included PLE (n = 15), mechanical ventilation (n = 8), prior Fontan conversion (n = 7), renal failure (n = 3), and plastic bronchitis (n = 2) Median number of prior operations was 3. Donor branch pulmonary arteries were used in 17 patients.

RESULTS

There were 5 early deaths (23%), due to graft failure (1), pulmonary hypertension (1), and infection (3). There were 3 late deaths (13%) at 1, 5, and 8 years. Two of 3 patients with preoperative renal failure died. Survivors who had preoperative PLE (n = 11) and preoperative plastic bronchitis (n = 2) experienced complete resolution of these pathological conditions after heart transplantation. Median length of stay was 30 days. Five of 7 Fontan conversion patients survived, and 6 of 8 preoperative ventilator-dependent patients survived. One-, 5-, and 10-year survival was 77%, 66%, and 45%, respectively.

CONCLUSIONS

The operative mortality of HTx for patients with a failing Fontan is high. Using the donor branch pulmonary arteries greatly facilitated the transplant. Because infection caused the majority of early deaths, lower intensity initial immunosuppression may be warranted. Transplantation was successful in treating PLE in all survivors. Prior Fontan conversion was not a risk factor. Preoperative mechanical ventilation was not a risk factor. Preoperative renal failure may be a relative contraindication. Earlier referral of failing Fontan patients may improve results.

Pediatric cardiomyopathy: importance of genetic and metabolic evaluation

BACKGROUND

Cardiomyopathy is a heterogeneous disease with a strong genetic component. A research-based pediatric cardiomyopathy registry identified familial, syndromic, or metabolic causes in 30% of children. However, these results predated clinical genetic testing.

METHODS AND RESULTS

We determined the prevalence of familial, syndromic, or metabolic causes in 83 consecutive unrelated patients referred for genetic evaluation of cardiomyopathy from 2006 to 2009. Seventy-six percent of probands (n = 63) were categorized as familial, syndromic, or metabolic. Forty-three percent (n = 18) of hypertrophic cardiomyopathy (HCM) patients had mutations in sarcomeric genes, with MYH7 and MYBPC3 mutations predominating. Syndromic (17%; n = 7) and metabolic (26%; n = 11) causes were frequently identified in HCM patients. The metabolic subgroup was differentiated by decreased endocardial shortening fraction on echocardiography. Dilated cardiomyopathy (DCM) patients had similar rates of syndromic (20%; n = 5) and metabolic (16%; n = 4) causes, but fewer familial cases (24%; n = 6) compared with HCM patients.

CONCLUSIONS

The cause of cardiomyopathy is identifiable in a majority of affected children. An underlying metabolic or syndromic cause is identified in >35% of children with HCM or DCM. Identification of etiology is important for management, family-based risk assessment, and screening.