Survival and risk factors for death after cardiac transplantation in infants. A multi-institutional study. The Pediatric Heart Transplant Study

Uncertain benefit of statins in pediatric heart transplant recipients: A PHTS analysis

BACKGROUND

Cardiac allograft vasculopathy (CAV) is a leading cause of graft failure in pediatric heart transplant recipients (HTRs). Early statin use has been shown to reduce CAV incidence and all-cause mortality in adult HTRs. We sought to evaluate the contemporary prevalence and trends of statin use in pediatric HTRs and the association between statin use with CAV development and graft failure.

METHODS

Patients aged <17 years at the time of primary heart transplant who survived to ≥3 years without CAV were identified from the Pediatric Heart Transplant Society database (2001-2018). Statin use in the first 3 years posttransplant was defined as consecutive, intermediate, or absent. Kaplan-Meier survival, multivariable modeling, and propensity score-matched analyses evaluated associations between statin use and CAV incidence and graft survival, with subanalyses performed on subjects aged ≥10 years at transplant.

RESULTS

Among 3,485 (of which 1,086 aged ≥10 years) HTRs, 584 (17%) received consecutive statin therapy, 647 (19%) received intermediate use, and 2,254 (65%) received no statin therapy. Statin use varied widely between sites, with increasing use in the ≥10-year-old cohort over time. By multivariate analysis, statin use was not associated with graft loss. Consecutive statin use was also not associated with graft survival or freedom from CAV development when compared to absent statin use in unmatched or propensity-matched analyses.

CONCLUSIONS

While statins remain commonly utilized in pediatric HTRs, early consecutive statin therapy did not decrease CAV incidence or graft loss. The differing effects of statins on CAV development and progression in pediatric vs adult HTRs suggest differing risk and mediating factors and require further study.

Early aspirin use and the development of cardiac allograft vasculopathy in pediatric heart transplant recipients: A pediatric heart transplant society analysis

BACKGROUND

Cardiac allograft vasculopathy (CAV) remains a leading cause of graft loss in pediatric heart transplant (HTx) recipients. Adult literature suggests that aspirin (ASA) use in the early post-HTx period may reduce the risk of CAV. This study aimed to determine the impact of early ASA use on the development of CAV in pediatric HTx recipients.

METHODS

All subjects <17 years of age at time of primary HTx who survived ≥3 years without evidence of CAV were identified for inclusion from the Pediatric Heart Transplant Society database (1996-2019). Early ASA use was defined as ASA started within the first 3 years post-HTx and was classified as continuous or intermittent. Frequency of ASA use was described across centers. Kaplan-Meier method assessed freedom from CAV and overall graft survival. Multiphase parametric hazard analyses and propensity score matched analysis were used to identify independent risk factors.

RESULTS

3,011 patients were included with 387 (13%) receiving continuous ASA, 676 (22%) receiving intermittent ASA, and 1,948 (65%) receiving no ASA. ASA use was highly variable across centers (0%-100%). At baseline patients receiving continuous ASA therapy demonstrated inferior graft survival (p < 0.001) and worse freedom from CAV (p = 0.002), but with lower CAV grades (p = 0.05). In multiphase parametric hazard modeling continuous ASA use was not independently associated with CAV, but remained associated with inferior graft survival. Propensity-matched sub-analysis between continuous and no ASA groups demonstrated no difference in freedom from CAV or overall graft loss.

CONCLUSIONS

ASA use varies widely across pediatric HTx centers. Early ASA use did not reduce the risk of CAV or graft loss in pediatric heart transplant recipients.

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.

Risk Factors for Severe Primary Graft Dysfunction in Infants Following Heart Transplant

Background

Previous studies suggest that infant heart transplant (HT) recipients are at higher risk of developing severe primary graft dysfunction (PGD) than older children. We sought to identify risk factors for developing severe PGD in infant HT recipients.

Methods and Results

We identified all HT recipients aged <1 year in the United States during 1996 to 2015 using the Organ Procurement and Transplant Network database. We linked their data to ELSO (Extracorporeal Life Support Organization) registry data to identify those with severe PGD, defined by initiation of extracorporeal membrane oxygenation support for PGD within 2 days following HT. We used multivariable logistic regression to assess risk factors for developing severe PGD. Of 1718 infants analyzed, 600 (35%) were <90 days old and 1079 (63%) had congenital heart disease. Overall, 134 (7.8%) developed severe PGD; 95 (71%) were initiated on extracorporeal membrane oxygenation support on the day of HT, 34 (25%) the next day, and 5 (4%) the following day. In adjusted analysis, recipient congenital heart disease, extracorporeal membrane oxygenation, or biventricular assist device support at transplant, recipient blood type AB, donor‐recipient weight ratio <0.9, and graft ischemic time ≥4 hours were independently associated with developing severe PGD whereas left ventricular assist device support at HT was not. One‐year graft survival was 48% in infants with severe PGD versus 87% without severe PGD.

Conclusions

Infant HT recipients with severe PGD have poor graft survival. Although some recipient‐level risk factors are nonmodifiable, avoiding modifiable risk factors may mitigate further risk in infants at high risk of developing severe PGD.

Extracorporeal Membrane Oxygenation Support After Heart Transplantation in Children-Outcomes of a Single Center Cohort

OBJECTIVES

Extracorporeal membrane oxygenation is used for postcardiotomy low cardiac output but is less established following heart transplantation. We characterized outcomes for children supported with extracorporeal membrane oxygenation after heart transplantation.

DESIGN

Single-center retrospective study.

SETTING

Large pediatric cardiac referral center.

PATIENTS

All patients who received heart transplantation and were cannulated to extracorporeal membrane oxygenation between 1995 and 2016.

INTERVENTIONS

Primary outcome measure was mortality 12 months postextracorporeal membrane oxygenation. Patient characteristics were analyzed for association with outcome according to early graft failure (extracorporeal membrane oxygenation ≤ 7 d after heart transplantation), or late graft failure.

MEASUREMENTS AND MAIN RESULTS

There were 246 heart transplants during the study period and 50 extracorporeal membrane oxygenation runs in 44 patients. Median time from transplant to extracorporeal membrane oxygenation was 1 day (range, 0-11.7 yr), with early graft failure in 28 patients (median 1, range 0-2 d) and 22 extracorporeal membrane oxygenation runs in 20 late graft failure patients (median, 0.8 yr; range, 8 d to 11.7 yr), including four patients with prior extracorporeal membrane oxygenation for early graft failure. Twenty-six patients (59%) survived to hospital discharge, and survival 12 months postextracorporeal membrane oxygenation was 24 patients (55%), lower in those with late graft failure (40% vs 67%; p 0.02). Independent risk factors for 12-month mortality were congenital heart disease, higher pulmonary vascular resistance indexed to body surface area (> 2.2 Woods U/m), and higher creatinine. Higher panel reactive antibody levels were associated with 12-month mortality in the late graft failure group only.

CONCLUSIONS

Extracorporeal membrane oxygenation can be effectively used to rescue patients with graft dysfunction after heart transplantation but is associated with high early mortality. Factors associated with mortality within 12 months include presence of congenital heart disease, renal dysfunction, elevated pulmonary vascular resistance indexed to body surface area and in those supported with extracorporeal membrane oxygenation late after heart transplantation, significant human leukocyte antigen sensitization.

Moderate-severe primary graft dysfunction after pediatric heart transplantation

BACKGROUND

PGD is a complication after heart transplantation (OHT) and a significant cause of mortality, particularly in infant recipients. Lack of standardized definition of PGD in the pediatric population makes the prevalence and magnitude of impact unclear.

METHODS

ISHLT PGD consensus guidelines, which include inotrope scores and need for MCS, were applied retrospectively to 208 pediatric OHT recipients from a single institution from 1/2005-5/2016. PGD was defined as: moderate PGD-inotrope score >10 on postoperative day 1 (24-48 hours), and severe PGD-MCS within 24 hours (in the absence of detectable rejection).

RESULTS

PGD occurred in 34 patients (16.3%); 14 of which had severe PGD (6.7%). Multivariate risk factors for PGD included CPB time (OR 10.3/10 min, 95% 10.05, 10.2, P = 0.03), Fontan palliation (OR 1.9, 95% 1.2, 3.97), and PCM (OR 5.65, 95% 1.52, 22.4); but not age, weight, ischemic time, or donor characteristics. Upon sub-analysis excluding patients with PCM, increased CPB was a significant multivariate risk factor (OR 10.09, 95% 9.89, 10.12, P = 0.003). Patients with PGD had decreased discharge survival compared to those without PGD (85% vs 96%, P < 0.01). Severe PGD was associated with the poorest 1-year survival (57% vs 91% without PGD, P = 0.04).

CONCLUSION

Patients with prolonged CPB are potentially at risk for developing PGD. Neither infant recipients nor donor characteristics were associated with an increased risk of PGD in the current era.

Prelisting predictions of early postoperative survival in infant heart transplantation using classification and regression tree analysis

Infants listed for heart transplantation experience high waitlist and early post-transplant mortality, and thus, optimal allocation of scarce donor organs is required. Unfortunately, the creation and validation of multivariable regression models to identify risk factors and generate individual-level predictions are challenging. We sought to explore the use of data mining methods to generate a prediction model. CART analysis was used to create a model which, at the time of listing, would predict which infants listed for heart transplantation would survive at least 3 months post-transplantation. A total of 48 infants were included; 13 died while waiting, and six died within 3 months of heart transplant. CART analysis identified RRT, blood urea nitrogen, and hematocrit as terminal nodes with alanine transaminase as an intermediate node predicting death. No patients listed on RRT (n = 10) survived and only three of 12 (25%) patients listed on ECLS survived >3 months post-transplant. CART analysis overall accuracy was 83%, with sensitivity of 95% and specificity 76%. This study shows that CART analysis can be used to generate accurate prediction models in small patient populations. Model validation will be necessary before incorporation into decision-making algorithms used to determine transplant candidacy.

Dor procedure for pulmonary atresia with intact ventricular septum in an infant

Pulmonary atresia with intact ventricular septum and right ventricle-dependent coronary circulation confers a high risk for myocardial infarction and complications of ischaemia, including left ventricle aneurysms. We describe an infant with pulmonary atresia with intact ventricular septum and right ventricle-dependent coronary circulation and a left ventricle apical aneurysm who successfully underwent the Dor procedure and a subsequent Fontan operation. Surgery for postinfarction left ventricle aneurysm can be considered in infants.

CARE guidelines for case reports: explanation and elaboration document

BACKGROUND

Well-written and transparent case reports (1) reveal early signals of potential benefits, harms, and information on the use of resources; (2) provide information for clinical research and clinical practice guidelines, and (3) inform medical education. High-quality case reports are more likely when authors follow reporting guidelines. During 2011-2012, a group of clinicians, researchers, and journal editors developed recommendations for the accurate reporting of information in case reports that resulted in the CARE (CAse REport) Statement and Checklist. They were presented at the 2013 International Congress on Peer Review and Biomedical Publication, have been endorsed by multiple medical journals, and translated into nine languages.

OBJECTIVES

This explanation and elaboration document has the objective to increase the use and dissemination of the CARE Checklist in writing and publishing case reports.

ARTICLE DESIGN AND SETTING

Each item from the CARE Checklist is explained and accompanied by published examples. The explanations and examples in this document are designed to support the writing of high-quality case reports by authors and their critical appraisal by editors, peer reviewers, and readers.

RESULTS AND CONCLUSION

This article and the 2013 CARE Statement and Checklist, available from the CARE website [www.care-statement.org] and the EQUATOR Network [www.equator-network.org], are resources for improving the completeness and transparency of case reports.

An infant with out-of-hospital cardiac arrest secondary to enteroviral myocarditis surviving up to cardiac transplantation

We report the case of a 13-day-old infant with enteroviral myocarditis surviving an out-of-hospital cardiac arrest. She underwent orthotopic cardiac transplantation three months later. A year after the transplantation, she is alive and well. Enteroviral infection is common in neonates with high mortality in cases of enteroviral myocarditis. Cardiac transplantation is a treatment option for infants who fail to recover and remain dependent on inotropic support. This is the first report of an infant with out-of-hospital cardiac arrest secondary to enteroviral myocarditis surviving up to cardiac transplantation.

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.

Pediatric heart transplantation

Pediatric heart transplantation (pHTx) represents a small (14%) but very important and particular part in the field of cardiac transplantation. This treatment has lifelong impact on children. To achieve the best short and especially long-term survival with adequate quality of life, which is of crucial importance for this young patient population, one has to realize and understand the differences with adult HTx. Indication for transplantation, waitlist management including ABO incompatible (ABOi) transplantation and immunosuppression differ. Although young transplant recipients are ultimately likely to be considered for re-transplantation. One has to distinguish between myopathy and complex congenital heart disease (CHD). The differences in anatomy and physiology make the surgical procedure much more complex and create unique challenges. These recipients need a well-organized and educated team with pediatric cardiologists and intensivists, including a high skilled surgeon, which is dedicated to pHTx. Therefore, these types of transplants are best concentrated in specialized centers to achieve promising outcome.

Multi-institutional Study of Outcomes After Pediatric Heart Transplantation: Candidate Gene Polymorphism Analysis of ABCC2

OBJECTIVES

Earlier studies have indicated that the pharmacokinetics of mycophenolic acid (MPA) is influenced by polymorphisms of ABCC2, which encodes for the membrane transporter MRP2. The ABCC2 rs717620 A allele has been associated with enterohepatic recirculation of MPA, and our previous work had correlated the discontinuance of MPA with this allele in pediatric heart transplant patients. Therefore, we hypothesized that the ABCC2 rs717620 A allele would be associated with poorer outcomes including rejection with hemodynamic compromise (RHC), graft failure, and death in the pediatric heart transplant (PHTx) population receiving MPA.

METHODS

PHTx recipients from 6 institutions in the Pediatric Heart Transplantation Study (PHTS) from the period of 1993-2009, receiving MPA therapy, were genotyped for ABCC2 rs717620. Genotyping was accomplished by direct sequencing. Demographic and outcome data were limited to the data routinely collected as part of the PHTS and included RHC and mortality.

RESULTS

Two hundred ninety patients were identified who received MPA at some point post transplantation, of which 200 carried the GG genotype, 81 carried the AG genotype, and 9 carried the AA genotype. Follow-up time after transplantation was 6 years. RHC occurred in 76 patients and 18 patients died. In the 281 patients followed up more than 1 year, late RHC (>1 year post transplantation) occurred in 42 patients. While both RHC and late RHC were associated with the ABCC2 rs717620 GG genotype (hazard ratios: 1.80 and 4.57, respectively, p<0.05) in all patients, this association was not significant in PHTx patients receiving only MPA as the antiproliferative agent from the time of transplant (n=142).

CONCLUSIONS

ABCC2 rs717620 polymorphisms varied within racial groups. As a candidate gene assessment, the ABCC2 rs717620 AG and AA genotypes may be associated with improved, rather than poorer, RHC in PHTx patients receiving MPA therapy. ABCC2 rs717620 polymorphisms should be included in any expanded pharmacogenomic analysis of outcomes after pediatric heart transplantation.

Issues in solid-organ transplantation in children: translational research from bench to bedside

In this review, we identify important challenges facing physicians responsible for renal and cardiac transplantation in children based on a review of the contemporary medical literature. Regarding pediatric renal transplantation, we discuss the challenge of antibody-mediated rejection, focusing on both acute and chronic antibody-mediated rejection. We review new diagnostic approaches to antibody-mediated rejection, such as panel-reactive antibodies, donor-specific cross-matching, antibody assays, risk assessment and diagnosis of antibody-mediated rejection, the pathology of antibody-mediated rejection, the issue of ABO incompatibility in renal transplantation, new therapies for antibody-mediated rejection, inhibiting of residual antibodies, the suppression or depletion of B-cells, genetic approaches to treating acute antibody-mediated rejection, and identifying future translational research directions in kidney transplantation in children. Regarding pediatric cardiac transplantation, we discuss the mechanisms of cardiac transplant rejection, including the role of endomyocardial biopsy in detecting graft rejection and the role of biomarkers in detecting cardiac graft rejection, including biomarkers of inflammation, cardiomyocyte injury, or stress. We review cardiac allograft vasculopathy. We also address the role of genetic analyses, including genome-wide association studies, gene expression profiling using entities such as AlloMap®, and adenosine triphosphate release as a measure of immune function using the Cylex® ImmuKnow™ cell function assay. Finally, we identify future translational research directions in heart transplantation in children.

Postoperative care of the transplanted patient

The successful delivery of optimal peri-operative care to pediatric heart transplant recipients is a vital determinant of their overall outcomes. The practitioner caring for these patients must be familiar with and treat multiple simultaneous issues in a patient who may have been critically ill preoperatively. In addition to the complexities involved in treating any child following cardiac surgery, caretakers of newly transplanted patients encounter multiple transplant-specific issues. This chapter details peri-operative management strategies, frequently encountered early morbidities, initiation of immunosuppression including induction, and short-term outcomes.

Graft survival is better without prior surgery in cardiac transplantation for functionally univentricular hearts

BACKGROUND

The effect of surgical history on graft outcomes in patients with functionally univentricular hearts (UH) is not well understood. We compared graft outcomes after heart transplantation in children with a UH between patients who received allografts without prior cardiac surgery (Group A) and patients who underwent transplantation after prior cardiac surgery (Group B).

METHODS

We reviewed all patients who received allografts for UH at our institution from 1990 to 2009. Differences in the probability of acute rejection (AR), incidence of graft vasculopathy (GV), and incidence of death or retransplantation were compared between Group A and Group B. Student's t-test, Mann-Whitney U-test, the log-rank test, logistic regression, and Cox proportional hazards modeling were used as appropriate.

RESULTS

During the study period, 180 patients with a UH received allografts: 105 in Group A and 75 in Group B at a median (interquartile range) age of 84 (47-120) days vs 584 (168-2,956) days, respectively (p < 0.001). The odds of AR were higher in Group B (odds ratio, 2.7, 95% confidence interval, 1.3-5.4). Group A had lower univariable risks of GV (p = 0.034) and graft loss (p = 0.003). Median graft survival was 18 years in Group A vs 8 years in Group B. The risk of graft loss after 5 years post-transplant was higher in Group B patients who were aged ≥ 1 year at time of transplant (p < 0.001).

CONCLUSIONS

Heart transplantation without prior cardiac surgery in patients with a UH was associated with better graft survival and lower probability of AR. The effect of age is complex and time-dependent, with age affecting outcomes after 5 years.

Organizational structure and processes in pediatric heart transplantation: a survey of practices

Despite emerging literature on pediatric heart transplantation, there continues to be variation in current practices. The degree of variability among heart transplant programs has not been previously characterized. The purpose of this study was to evaluate organizational structure and practices of pediatric heart transplant programs. The UNOS database was queried to identify institutions according to volume. Coordinators from 50 institutions were invited to participate with a 70% response rate. Centers were grouped by volume into four categories. Some institutional practices were dominated by clear volume trends. Ninety-five percent of larger centers routinely transplant patients with known antibody sensitization and report a broader range and acuity of recipients. Ninety-four percent report problems with non-adherence. Sixty-nine percent of centers routinely require prospective crossmatches. There was dramatic variation in the use of steroids across all centers. Sixty-five percent of centers transition adolescents to an adult program. Prophylaxis protocols were also highly inconsistent. This survey provided a comprehensive insight into current practices at pediatric heart transplant programs. The results delineated remarkably variable strategies for routine aspects of care. Analysis of divergence along with uniformity across protocols is a valuable exercise and may serve as a stepping-stone toward ongoing cooperation and clarity for evidence-based practice protocols.

Multiple risk factors before pediatric cardiac transplantation are associated with increased graft loss

Identification of heart transplant recipients at highest risk for a poor outcome could lead to improved posttransplantation survival. A chart review of primary heart transplantations from 1993 to 2006 was performed. Analysis was performed to evaluate the risk of graft loss for those with a transplantation age less than 1 year, congenital heart disease (CHD), elevated pulmonary vascular resistance (index > 6), positive panel reactive antibody or crossmatch, liver or renal dysfunction, mechanical ventilation, or mechanical circulatory support (MCS). Primary transplantation was performed for 189 patients. Among these patients, 37% had CHD, 23% had mechanical ventilation, and 6% had renal dysfunction. Overall graft survival was 82% at 1 year and 68% at 5 years. The univariate risk factors for graft loss included mechanical ventilation (hazard ratio [HR], 1.9; 95% confidence interval [CI], 1.15-3.18), CHD (HR, 1.68; 95% CI, 1.04-2.70), and renal dysfunction (HR, 3.05; 95% CI, 1.34-6.70). The multivariate predictors of graft loss were CHD (HR, 1.8; 95% CI, 1.02-2.64), mechanical ventilation (HR, 1.9; 95% CI, 1.13-3.10), and the presence of two or more statistically significant univariate risk factors (SRF) (HR, 3.8; 95% CI, 2.00-7.32). Mechanical ventilation, CHD, and the presence of two or more SRFs identify pediatric patients at higher risk for graft loss and should be considered in the management of children with end-stage heart failure.

Factors associated with in-hospital mortality in infants undergoing heart transplantation in the United States

OBJECTIVE

Infants undergoing heart transplantation have the highest early posttransplant mortality of any age group. We sought to determine the pretransplantation factors associated with in-hospital mortality in transplanted infants in the current era.

METHODS

All infants under 12 months of age who underwent primary heart transplantation during a recent 10-year period (1999-2009) in the United States were identified using the Organ Procurement and Transplant Network database. Multivariable logistic regression was used to identify independent pretransplantation factors associated with in-hospital mortality.

RESULTS

Of 730 infants in the study (median age 3.8 months), 462 (63%) had congenital heart disease, 282 (39%) were supported by a ventilator, 94 (13%) with extracorporeal membrane oxygenation, and 22 (3%) with a ventricular assist device at the time of transplantation. Overall, 82 (11.2%) infants died before their initial hospital discharge. In adjusted analysis, in-hospital mortality was associated with repaired congenital heart disease (odds ratio [OR], 3.6; 95% confidence interval [CI], 1.8, 7.2), unrepaired congenital heart disease not on prostaglandin E (OR, 2.8; CI, 1.3, 6.1), extracorporeal membrane oxygenator support (OR, 6.1; CI, 2.8, 13.4), ventilator support (OR, 4.4; CI, 2.3, 8.3), creatinine clearance less than 40 mL·min(-1)·1.73 m(-2) (OR, 3.1; CI, 1.7, 5.3), and dialysis (OR, 6.2; CI, 2.1, 18.3) at transplantation.

CONCLUSIONS

One in 9 infants undergoing heart transplantation dies before hospital discharge. Pretranplantation factors associated with early mortality include congenital heart disease, extracorporeal membrane oxygenator support, mechanical ventilation, and renal failure. Risk stratification for early posttransplant mortality among infants listed for heart transplantation may improve decision-making for transplant eligibility, organ allocation, and posttransplant interventions to reduce mortality.

Incidence and risk factors for mortality in infants awaiting heart transplantation in the USA

BACKGROUND

Infants awaiting heart transplantation (HT) face the highest wait-list mortality among all children and adults listed for HT in the USA. We sought to determine the risk of death for infants <12 months old while awaiting HT in the current era, and to identify the principle risk factors associated with wait-list mortality.

METHODS

We analyzed outcomes for all infants listed for HT in the USA from January 1999 to July 2006, using data reported to the U.S. Scientific Registry of Transplant Recipients.

RESULTS

Of the 1,133 listed infants, 61% were <3 months of age, 80% were listed as Status 1A, 64% had a congenital heart disease (CHD) and 31% had cardiomyopathy. Of 724 infants with CHD, 25% were on prostaglandin (PG) and 27% had a history of prior surgery. By 6 months after listing, 23% died on the wait-list and 54% were transplanted. Multivariate factors associated with wait-list mortality were weight <3 kg (hazard ratio [HR] 1.4, 95% confidence interval [CI] 1.0 to 1.9), extracorporeal membrane oxygenation (ECMO) support (HR 5.6, CI 4.0 to 7.9), ventilator support (HR 2.1, 95% CI 1.6 to 2.8), CHD with PG support (HR 2.8, 95% CI 1.8 to 4.3), CHD without prior surgery (HR 2.8, 95% CI 1.9 to 3.9) and non-white race/ethnicity (HR 1.8, 95% CI 1.4 to 2.3).

CONCLUSIONS

One in four infants listed for HT in the USA die before a donor heart can be identified. Wait-list mortality is associated with weight <3 kg, level of invasive support and CHD, but not listing status, which captures medical urgency poorly. Measures to expand infant organ donation, especially among neonates, are urgently needed.

Outcome of extracorporeal membrane oxygenation for early primary graft failure after pediatric heart transplantation

OBJECTIVES

We sought to analyze the indications and outcome of extracorporeal membrane oxygenation (ECMO) for early primary graft failure and determine its impact on long-term graft function and rejection risk.

BACKGROUND

Early post-operative graft failure requiring ECMO can complicate heart transplantation.

METHODS

A retrospective review of all children requiring ECMO in the early period after transplantation from 1990 to 2007 was undertaken.

RESULTS

Twenty-eight (9%) of 310 children who underwent transplantation for cardiomyopathy (n = 5) or congenital heart disease (n = 23) required ECMO support. The total ischemic time was significantly longer for ECMO-rescued recipients compared with our overall transplantation population (276 +/- 86 min vs. 242 +/- 70 min, p < 0.01). The indication for transplantation, for ECMO support, and the timing of cannulation had no impact on survival. Hyperacute rejection was uncommon. Fifteen children were successfully weaned off ECMO and discharged alive (54%). Mean duration of ECMO was 2.8 days for survivors (median 3 days) compared with 4.8 days for nonsurvivors (median 5 days). There was 100% 3-year survival in the ECMO survivor group, with 13 patients (46%) currently alive at a mean follow-up of 8.1 +/- 3.8 years. The graft function was preserved (shortening fraction 36 +/- 7%), despite an increased number of early rejection episodes (1.7 +/- 1.6 vs. 0.7 +/- 1.3, overall transplant population, p < 0.05) and hemodynamically comprising rejection episodes (1.3 +/- 1.9 vs. 0.7 +/- 1.3, overall transplant population, p < 0.05).

CONCLUSIONS

Overall survival was 54%, with all patients surviving to at least 3 years after undergoing transplantation. None of the children requiring >4 days of ECMO support survived. Despite an increased number of early and hemodynamically compromising rejections, the long-term graft function is similar to our overall transplantation population.

Genetic polymorphisms impact the risk of acute rejection in pediatric heart transplantation: a multi-institutional study

OBJECTIVE

The objective of this study was to determine the association between the genetic polymorphisms of proinflammatory and regulatory cytokines and long-term rates of repeat and late acute rejection episodes in pediatric heart transplant (PHTx) recipients.

METHODS

Three hundred twenty-three PHTx recipients: 205 White non-Hispanic, 43 Black non-Hispanic, and 75 Hispanic were analyzed for time to first repeat and late acute rejection episodes by race, age at transplantation, and gene polymorphism (interleukin [IL]-6, -174 G/C, IL-10, -1082 G/A, -819 C/T, 592 C/A; vascular endothelial growth factor (VEGF) -2578 C/A, -460 C/T, +405 C/G; tumor necrosis factor alpha (TNF-alpha)-308 G/A).

RESULTS

Recipient black race and older age at transplant were risk factors for both repeat and late rejections, though black race was more significantly related to late rejection (P=0.006). Individually, TNF-alpha high, IL-6 high, VEGF high, and IL-10 low phenotypes did not impact the risk of repeat or late rejection. However, the combination VEGF high/IL-6 high and IL-10 low was associated with increased estimated risk of late rejection (P=0.0004) and only marginally with repeat rejection (P=0.051). In a multivariate analysis, adjusting for age and race, VEGF high/IL-6 high and IL-10 low still remained an independent risk factor for late acute rejection (RR=1.91, P<0.001).

CONCLUSION

This is the largest multicenter study to document the impact of genetic polymorphism combinations on PHTx recipients' outcome. The high proinflammatory (VEGF high/IL-6 high) and lower regulatory (IL-10 low) cytokine gene polymorphism profile exhibited increased risk for late rejection, irrespective of age and race/ethnicity.

Infectious, malignant, and autoimmune complications in pediatric heart transplant recipients

OBJECTIVE

To review clinical courses of pediatric heart transplant survivors after 5 years from transplantation for infections, lymphoproliferative, and autoimmune diseases.

STUDY DESIGN

A total of 71 patients were examined in 2 groups, infant recipients (underwent transplant <1 year of age, n = 38) and older recipients (underwent transplant >1 year, n = 33). All patients received comparable immunosuppression. Calculated occurrence rates were reported as means per 10 years of follow-up with SEs. Differences were examined by using Poisson regression.

RESULTS

Infant recipients had significantly higher (P < .001) occurrence rates of severe (mean, 2.04 +/- 0.5) and chronic infections (mean, 4.58 +/- 0.67) compared with older recipients (means, 0.37 +/- 0.19 and 1.87 +/- 0.70, respectively). Types of infections were similar to those in the general population with extremely rare opportunistic infections; however, they were more severe and resistant to treatment. Autoimmune disorders occurred at a frequency comparable with lymphoproliferative diseases and were observed in 7 of 38 infants (18%). Most common were autoimmune cytopenias.

CONCLUSIONS

Infant heart transplant recipients who survive in the long term have higher occurrence rates of infections compared with older recipients. Autoimmune disorders are a previously unrecognized morbidity in pediatric heart transplantation.

Pediatric cardiac transplantation

Pediatric heart transplantation has undergone major changes over the past two decades, marked by a substantial improvement in survival, reduction in posttransplant complications, and enhancement in quality of life for transplant recipients. Actuarial survival has improved substantially in the last decade. Indications for pediatric heart transplant have changed as surgery for complex congenital heart lesions has evolved. There are now left and right ventricular assist devices that are suitable for use in infants as a bridge to transplantation. New immunosuppressive agents have reduced the risk of rejection while minimizing side effects and strategies to reduce the risk of graft coronary disease are beginning to show promise. Finally, true long-term survival for children after heart transplant has now been demonstrated and quality of life is excellent.

Natural History of Pulmonary Atresia With Intact Ventricular Septum and Right-Ventricle–Dependent Coronary Circulation Managed by the Single-Ventricle Approach

BACKGROUND

Long-term outcome of patients with pulmonary valvar atresia and intact ventricular septum with right-ventricle-dependent coronary circulation (PA/IVS-RVDCC) managed by staged palliation directed toward Fontan circulation is unknown, but should serve as a basis for comparison with management protocols that include initial systemic-to-pulmonary artery shunting followed by listing for cardiac transplantation.

METHODS

Retrospective review of patients admitted to our institution with the diagnosis of PA/IVS-RVDCC from 1989 to 2004. All angiographic imaging studies, operative reports, and follow-up information were reviewed. Right-ventricle-dependent coronary circulation was defined as situations in which ventriculocoronary fistulae with proximal coronary stenosis or atresia were present, putting significant left ventricle myocardium at risk for ischemia with right ventricle decompression.

RESULTS

Thirty-two patients were identified with PA/IVS-RVDCC. All underwent initial palliation with modified Blalock-Taussig shunt (BTS). Median tricuspid valve z-score was -3.62 (-2.42 to -5.15), and all had moderate (n = 13) or severe (n = 19) right ventricular hypoplasia. Median follow-up was 5.1 years (9 months to 14.8 years). Overall mortality was 18.8% (6 of 32), with all deaths occurring within 3 months of BTS. Aortocoronary atresia was associated with 100% mortality (3 of 3). Of the survivors (n = 26), 19 have undergone Fontan operation whereas 7, having undergone bidirectional Glenn shunt, currently await Fontan. Actuarial survival by the Kaplan-Meier method for all patients was 81.3% at 5, 10, and 15 years, whereas mean survival was 12.1 years (95% confidence interval: 10.04 to 14.05). No late mortality occurred among those surviving beyond 3 months of age.

CONCLUSIONS

In patients with PA/IVS-RVDCC, early mortality appears related to coronary ischemia at the time of BTS. Single-ventricle palliation yields excellent long-term survival and should be the preferred management strategy for these patients. Those with aortocoronary atresia have a particularly poor prognosis and should undergo cardiac transplantation.

Management of infants and young children with combined heart and kidney failure

Most infants and children referred for cardiac transplantation have low cardiac output with concurrent renal hypoperfusion leading to renal insufficiency and failure. This article is a review of the literature of and a single center's experience with combined heart and kidney failure in infants and children less than 10 yr of age. While 39 infants less than 10 yr of age were dialyzed pre- or peri-operatively, none required dialysis support at the time of discharge or in 5-10 yr follow-up. Based on our experience we recommend heart transplant alone in infants and young children with primary heart disease even though they have renal dysfunction.

New directions in cardiac transplantation

More than three decades of clinical experience in cardiac transplantation resulted in the spread of the procedure worldwide with a wealth of knowledge and advancements. Developments included liberalization of recipient and donor selection criteria, improved surgical techniques, novel immunosuppressive drugs and protocols, new rejection surveillance techniques, and better understanding of the pathophysiology of cardiac allograft vasculopathy to direct interventions for prevention and treatment.

Altered Ventricular Mechanics in Cardiac Allografts: A Tissue Doppler Study in 30 Children Without Prior Rejection Events

BACKGROUND

Tissue Doppler imaging (TDI), a non-invasive echocardiography technique, permits quantitative analysis of the regional distribution pattern of myocardial velocities. During normal childhood development, regional function changes markedly, including an increasing predominance of longitudinal velocities. This study analyzed the impact of heart transplantation on ventricular mechanics in growing children.

METHODS

TDI was performed in 30 pediatric heart transplant recipients (7.1 +/- 6.2 years) and 32 age-matched healthy children (6.8 +/- 5.4 years). Patients had no rejection history and were 3.1 years (median) post-transplant. Color TDI images from apical and parasternal views were stored as echocardiographic raw data. Off-line analysis was used to measure peak systolic and diastolic myocardial velocities in 6 basal cardiac segments for longitudinal (anterior, inferior, lateral, septal, right ventricle) and radial velocities (posterior). Isovolumic acceleration, a load-insensitive function marker, was determined as slope of the upstroke of the isovolumic contraction wave. Multiple regression modeling was used for statistics.

RESULTS

Systolic myocardial velocities still increased with age after transplantation, but the velocity distribution pattern was changed. In transplanted hearts, left ventricular longitudinal velocities were lower and radial velocities were higher than in the controls, but isovolumic acceleration was similar. In the right ventricle, longitudinal velocities and isovolumic acceleration were significantly decreased after transplantation. Wall motion abnormalities were present in 50% of patients.

CONCLUSIONS

Regional wall motion analysis shows significant alterations of the fundamental biomechanical pump function of the left ventricle after heart transplantation in children, with a shift from longitudinal to radial fibers and depressed right ventricular wall motion. This may have important implications for the long-term graft function required in children.

Successful heart transplantation after 13 hours of donor heart ischemia with the use of HTK solution: a case report

INTRODUCTION

For heart transplantation (HTx), the recommended ischemic time (IT) for donor heart is not to exceed 6 hours. Though Dr Christiaan Barnard used a donor heart with IT of 16 hours, 50 minutes with a portable hypothermic perfusion system in 1981, the recorded IT of donor hearts reported recently is 8 hours, with no adverse effects.

CASE REPORT

The patient, a 14-year-old boy of blood type O, was diagnosed with cardiomyopathy at age 12. In early September 2003, the patient was recommended for HTx. His condition deteriorated 18 days later with low CO, elevated pulmonary vascular resistance, and frequent ventricular tachycardia, further complicated by pneumonia and multiorganism infections, which were contraindications for HTx. On September 22, 2003, a donor heart of blood type O was available 370 km away. Another patient of blood type B with severe heart failure was matched for the HTx. During the intervening time, another donor heart of blood type B became available locally. We matched the type B donor heart to the type B recipient. Since the type O donor heart seemed to be wasted, we performed HTx for the boy. Though preserved for 12 hours in cold cardioplegia, the donor heart was implanted with biatrial anastomosis that took 1 hour. The total IT of this donor heart was 13 hours. The recipient recovered and was discharged 3 months later.

CONCLUSIONS

The IT of 13 hours for this donor heart is believed to be a world record. Our experience demonstrates that preservation time of donor heart may exceed 6 hours.

Heart transplantation in children: clinical outcome during the early postoperative period

As improved understanding of transplant-related death should improve survival, we report a single center's experience with pediatric heart transplantation including potential risk factors and causes of death during the early postoperative period. This prospective longitudinal study involved 51 pediatric patients ranging in age from 12 days to 15.1 yr (median: 3 yr). The following pretransplant risk factors were evaluated: diagnosis, age at transplantation, recipient sex, weight and blood type, blood type match, donor/recipient sex match, weight ratio, ischemic time, recipient's status, requirement for mechanical ventilation or circulatory support, dialysis, or inotropic support at transplantation. We also determined the actuarial survival, clinical outcomes, and causes of death in this population. Survival was 86% during the early postoperative period (</=30 days), 79.3% at 1 yr, and 76.8% at 3 yr. Seven patients died during the early postoperative period (primary graft failure, rejection, and infection). However, there was no difference in the frequency of any of the risk factors analyzed between these patients and those who did not experience early death. There was a correlation between the duration of intubation after transplantation and pretransplant risk factors (diagnosis, recipient status, requirement for dialysis, inotropic and mechanical ventilation support). Our findings indicate that promising short-term results can be obtained with pediatric transplantation. Although we identified no specific risk factors in this study for death, improved rejection surveillance and treatment strategies remain important goals in pediatric heart transplantation. Retransplantation had high mortality during the perioperative period.

Can we reliably predict long-term mortality after exercise testing? An external validation

OBJECTIVE

The aim of the study was to derive and externally validate a mortality prediction rule for patients undergoing exercise testing.

BACKGROUND

The prognostic value of exercise testing is increasingly appreciated. However, global prognosis estimates ideally should account for numerous routinely obtained variables, including demographics, risk factors, resting electrocardiogram, and multiple exercise test measures.

METHODS

A prediction rule was derived by parametric hazards modeling on a derivation set of 46047 Cleveland Clinic patients (age 55 +/- 11 years, 67% male) who had no history of heart failure, valve disease, or atrial fibrillation. Twenty-two variables covering demographics, risk factors, exercise hemodynamics, and electrocardiogram findings at rest and during exercise were considered. The resulting model included 16 variables and was tested on 4981 patients (age 50 +/- 12 years, 55% male) who underwent exercise testing at West Virginia University.

RESULTS

In the derivation cohort there were 3173 deaths during a mean of 7 years of follow-up, whereas in the validation cohort there were 180 deaths during a mean of 5 years of follow-up. Comparisons of predicted and observed death rates showed very good agreement among all patients across all spectrums of risk, as well as among prespecified high-risk subgroups. Model discrimination was also good, with c statistic of c = 0.79 in the derivation group and c = 0.81 in the validation cohort.

CONCLUSIONS

We have externally validated a mortality prediction rule for patients undergoing exercise testing and confirmed its accuracy among a wide spectrum of patients.

The effect of coenzyme Q10 on idiopathic chronic dilated cardiomyopathy in children

The objective of this study was to assess the effect of coenzyme Q10 (CoQ10) as supplementation to conventional antifailure drugs on quality of life and cardiac function in children with chronic heart failure due to dilated cardiomyopathy (DCM). The study was an open-label prospective study performed in two of the largest pediatric centers in Thailand from August 2000 to June 2003. A total of 15 patients with idiopathic chronic DCM were included, with the median age of 4.4 years (range, 0.6-16.3). Presenting symptoms were congestive heart failure in 12 cases (80%), cardiogenic shock in 2 cases (13.3%), and cardiac arrhythmia in 1 case (6.7%). Sixty-one percent of patients were in the New York Heart Association functional class 2 (NYHA 2), 31% in NYHA 3, and 8% in NYHA 4. Cardiothoracic ratio from chest x-ray, left ventricular ejection fraction, and left ventricular end diastolic dimension in echocardiogram were 0.62 (range, 0.55-0.78), 30% (range, 20-40), and 5.2 cm (range, 3.8-6.5), respectively. CoQ10 was given at a dosage of 3.1 ? 0.6 mg/kg/day for 9 months as a supplementation to a fixed amount of conventional antifailure drugs throughout the study. At follow-up periods of 1, 3, 6, and 9 months, NYHA functional class was significantly improved, as was CT ratio and QRS duration at 3 and 9 months follow-up with CoQ10 when compared to the baseline and post-discontinuation of CoQ10 at 9 months (range, 4.8-10.8). However, when multiple comparisons were taken into consideration, there was no statistical significant improvement. In addition to the conventional antifailure drugs, CoQ10 may improve NYHA class and CT ratio and shorten ventricular depolarization in children with chronic idiopathic DCM.