Diagnostic and management roles of FDG PET/CT imaging in post-transplant lympho-proliferation in pediatric heart transplantation.

BACKGROUND: Post-transplant lymphoproliferative disorder (PTLD) is a serious complication of pediatric heart transplant (PHTx). 18F-FDG PET/CT has been used to differentiate early lympho-proliferation from more advanced PTLD. We report our experience with PET/CT in the management of PTLD following PHTx. METHODS: This was a retrospective study of 100 consecutive PHTx recipients at our institution between 2004 and 2018. Patients who underwent PET/CT or conventional CT scans to evaluate for PTLD or high Epstein-Barr viral load were included. RESULTS: Males, eight females. Median age at transplant was 3.5 months (IQR = 1.5-27.5). Median age at PTLD diagnosis was 13.3 years (IQR = 9.2-16.1). Median time between transplant and PTLD diagnosis was 9.5 (IQR = 4.5-15) years. Induction agents were used in 12 patients (50%): Thymoglobulin (N = 9), anti-IL2 (N = 2), and Rituximab (N = 1). Eighteen patients (75%) had PET/CT, of whom 14 had 18FDG-avid PTLD. Six had conventional CT. Nineteen patients (79.2%) had diagnostic biopsy confirmation of PTLD, and 5 (20.8%) had excisional biopsies. Two patients had Hodgkin's lymphoma; nine had monomorphic PTLD; eight had polymorphic PTLD; five were classified as other. Nine patients had monomorphic PTLD, including seven with diffuse large cell lymphoma (DLBC) and one with T cell lymphoma. The majority (16/24) had multi-site involvement at PTLD diagnosis, and PET/CT showed that 31.3% (5/16) had easily accessible subcutaneous nodes. Seventeen patients (overall survival 71%) underwent successful treatment without recurrence of PTLD. Of seven deaths (7/24, 29%), five had DLBC lymphoma, one had polymorphic PTLD and one had T-cell lymphoma. CONCLUSION: PET-CT allowed simultaneous anatomical and functional assessment of PTLD lesions, while guiding biopsy. In patients with multiple lesions, PET/CT revealed the most prominent and active lesions, improving diagnostic accuracy.

Optimal Donor Allograft Function: The Search for the Lowest Acceptable Donor Left Ventricular Ejection Fraction in Pediatric Heart Transplantation.

BACKGROUND: The availability of heart donors is limited by organ shortage. Due to concerns of reduced survival, donors with depressed left ventricular ejection fraction (LVEF <50%) have been cautiously used in pediatric heart transplantation. One strategy to expand the donor pool is to re-evaluate whether lower donor LVEF may be acceptable for transplantation. METHODS: We performed a multicenter retrospective cohort study of patients <18 y receiving heart transplants from April 2007 to September 2021 using the United Network of Organ Sharing dataset. We excluded retransplants and multiorgan transplants. Cut-point analyses of LVEF was performed and Kaplan-Meier method was used to compare 1-y survival for new cut-points and the standard (LVEF >50%). RESULTS: The analytic sample consisted of 5255 patients. Recipients receiving hearts with lower LVEFs were more likely to be on ventilator and extracorporeal membrane oxygenation support. Recipients did not differ in waitlist times or transplant status. Cut-point analysis identified LVEF 45% as a potentially new cutoff. One-year survival of recipients of donors with LVEF ≥45% (92.1%; 95% confidence interval [CI], 91.3%-92.8%) was similar to that of LVEF >50% (92.1%; CI, 91.4%-92.9%). Survival for the LVEF 45%-49% (88.8%; CI, 72.9%-95.7%) cohort was slightly lower than the ≥50% cohort, albeit nonsignificant. CONCLUSIONS: One-year survival among pediatric heart transplants using a donor heart LVEF threshold of 45% or 40% was similar to a threshold of 50%. However, the finding is based on a small number of patients with LVEF <50%, and future larger prospective studies are warranted to confirm the findings of this study before a lower LVEF threshold is considered.

Basiliximab therapy for immune-mediated bowel disease in a pediatric heart transplant patient.

In pediatric patients who undergo heart transplantation, severe immune-mediated bowel disease has been reported. Management is complex, and there are little data discussing the use of basiliximab for immune-mediated bowel disease. This case report discusses a pediatric patient who developed immune-mediated bowel disease following heart transplantation and was successfully managed with basiliximab.

Impact of Coronavirus-2019 On Pediatric and Adult Heart Transplantation Waitlist Activity and Mortality in The United States: A Descriptive Approach.

BACKGROUND: Transplant centers saw a substantial reduction in deceased donor solid organ transplantation since the beginning of the coronavirus 2019 (COVID-19) pandemic in the United States. There is limited data on the impact of COVID-19 on adult and pediatric heart transplant volume and variation in transplant practices. We hypothesized that heart transplant activity decreased during COVID-19 with associated increased waitlist mortality. METHODS: The United Network for Organ Sharing (UNOS) database was used to identify patients at the time of listing for heart transplant from 2017-2020. Patients were categorized as pediatric (<18 years) or adult (≥18 years) and as pre-COVID (2017-2019) or post-COVID (2020). Regional and statewide data were taken from United States Census Bureau. CovidActNow project was used to obtain COVID-19 mortality rates. FINDINGS: Among pediatric patients, average time on the waiting list decreased by 28 days. Even though the average number of pediatric transplants (n=39 per month) did not change significantly during 2020, there was a temporal decline in the first quarter of 2020 followed by a sharp increase. Overall absolute pediatric waitlist mortality decreased from 5•31 to 4•73, however female mortality increased by 2%. Regional differences in pediatric mortality were observed: Northeast, decreased by 7•5%; Midwest, decreased by 9%; West, increased by 3•5%; and South, increased by 13%. North Dakota (0•55), Oklahoma (0•21) and Hawaii (0•33) showed higher mortality than other states per 100,000. In adults, average time on waiting list increased by 40 days and there was an increase in the number of transplants from 242 to 266. Adult waitlist mortality had a larger decrease, 18•44 to 15•70, with an increase in female mortality of 7%. Regional differences in adult mortality were also observed: Northeast, decreased by 3%; Midwest, increased by 5•5%; West, increased by 4•5% and South, decreased by 5%. Iowa (0•37), Wyoming (0•22), Arkansas (0•18) and Vermont (0•19) had the highest mortality per 100,000 compared to the other states. INTERPRETATION: Pediatric heart transplant volume declined in early 2020 followed by a later increase, while adult transplant volume increased all year round. Although, overall pediatric waitlist mortality decreased, female waitlist mortality increased for both adults and pediatrics. Regional differences in waitlist mortality were observed for both pediatrics and adults. Future studies are needed to understand this initial correlation and to determine the impact of COVID-19 on heart transplant recipients. FUNDING: This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Expanded utilization of rituximab in paediatric cardiac transplant patients.

WHAT IS KNOWN AND OBJECTIVE: Epstein-Barr virus (EBV) viraemia and autoimmune cytopenias (AICs) are significant complications that occur following paediatric solid organ transplantation. A variety of treatment methods have been investigated but limited research has focused on the utilization of rituximab in paediatric cardiac transplant recipients for these indications. Rituximab is a monoclonal antibody that binds the CD20 antigen on the surface of B-type lymphocytes resulting in B-cell cytotoxicity. It is considered a second-line therapy for treatment of autoimmune cytopenias and EBV viraemia following adult solid organ transplant (SOT) and haematopoietic stem cell transplant (HSCT). However, data for its use in the paediatric population for treatment of autoimmune cytopenias are lacking. Dosing is based on adult studies, and the frequency and length of therapy associated with resolution of EVB viraemia and AICs in paediatric cardiac transplant recipients is unknown. The objective of this retrospective study was to describe the dosing and length of therapy of expanded off-label use of rituximab for the management of refractory EBV viraemia and AICs, specifically in paediatric cardiac transplant patients. METHODS: A retrospective chart review was conducted evaluating children <18 years of age who underwent cardiac transplantation, were diagnosed with EBV viraemia or autoimmune cytopenia, and subsequently received treatment with rituximab between June 1995 and October 2018. Data were analysed descriptively. RESULTS AND DISCUSSION: Of all (n = 188) paediatric cardiac transplant recipients since 1995, 10 patients met the inclusion/exclusion criteria. Primary diagnoses were EBV viraemia (n = 6), immune haemolytic anaemia (n = 3) and immune thrombocytopenic purpura (n = 1). Complete responses were observed in 83.3% and 100% of patients with EVB viraemia and AICs treated with rituximab, respectively. All patients (n = 10) received rituximab 325 mg/m2 at weekly intervals. The number of total doses associated with complete resolution was 4-6 doses for EBV viraemia and 2-4 doses for AICs. The most common adverse events reported were neutropenia (n = 3), thrombocytopenia (n = 4), infusion reactions (n = 1) and significant anaemia (n = 2). WHAT IS NEW AND CONCLUSION: Although the efficacy of rituximab for treatment of EBV viraemia and autoimmune cytopenia in the paediatric cardiac transplant population remains unclear, our study supported the benefit of rituximab when added to therapy for treatment of EBV viraemia and ACIs.

Heart Transplantation for Pediatric and Congenital Cardiac Disease: A Comparison of Two Eras over 23 Years and 188 Transplants at a Single Institution.

BACKGROUND: To assess changes in patterns of practice and outcomes over time, we reviewed all patients who underwent heart transplantation (HTx) at our institution and compared two consecutive eras with significantly different immunosuppressive protocols (cohort 1 [80 HTx, June 1995-June 2006]; cohort 2 [108 HTx, July 2006-September 2018]). METHODS: Retrospective study of 180 patients undergoing 188 HTx (June 1995-September 2018; 176 first time HTx, 10 second HTx, and 2 third HTx). In 2006, we commenced pre-HTx desensitization for highly sensitized patients and started using tacrolimus as our primary postoperative immunosuppressive agent. The primary outcome was mortality. Survival was modeled by the Kaplan-Meier method. Univariable and multivariable Cox proportional hazard models were created to identify prognostic factors for survival. RESULTS: Our 188 HTx included 18 neonates, 85 infants, 83 children, and 2 adults (>18 years). Median age was 260.0 days (range: 5 days-23.8 years). Median weight was 7.5 kg (range: 2.2-113 kg). Patients in cohort 1 were less likely to have been immunosensitized preoperatively (12.5% vs 28.7%, P = .017). Nevertheless, Kaplan-Meier analysis suggested superior survival in cohort 2 (P = .0045). Patients in cohort 2 were more likely to be alive one year, five years, and ten years after HTx. Multivariable analysis identified the earlier era (hazard ratio [HR] [95% confidence interval] for recent era = 0.32 [0.14-0.73]), transplantation after prior Norwood operation (HR = 4.44 [1.46-13.46]), and number of prior cardiac operations (HR = 1.33 [1.03-1.71]) as risk factors for mortality. CONCLUSIONS: Our analysis of 23 years of pediatric and congenital HTx reveals superior survival in the most recent 12-year era, despite the higher proportion of patients with elevated panel reactive antibody in the most recent era. This improvement was temporally associated with changes in our immunosuppressive strategy.

Resource utilization of cytomegalovirus immune globulin in prevention and treatment of cytomegalovirus infection in pediatric heart transplantation.

BACKGROUND: There is debate whether cytomegalovirus immunoglobulin (CMV-Ig) is also needed for CMV prevention in heart transplant recipients in the era of good anti-viral drugs. METHODS: We conducted a cost-savings quality initiative on CMV-Ig eventually leading to discontinuation of routine use of CMV-Ig for CMV prevention. Subsequently, a retrospective cohort study was conducted, comparing patients in cohort I (CMV-Ig plus anti-viral drugs, 2013-2015) to cohort II (anti-virals alone, 2015-2017). The medication acquisition costs and outcomes of CMV infection were assessed. RESULTS: There were 39 total patients: 22/39(56%) in cohort I, with mean follow-up of 35.14 ± 17.38 months and 17/39(44%) in cohort II, mean follow-up of 19.12 ± 7.08 months. In cohort I, 5/22(22.7%) patients died from causes unrelated to CMV and 0/17 in cohort II died. There were 5/22(22.7%) patients in cohort I, and 2/17(9%) patients in cohort II that developed CMV infection (P = .508). Freedom from rejection was 81.8% (18/22) in cohort I, and 71% (12/17) in cohort II (P = .46), and 100% for allograft vasculopathy. There was significant reduction in medication acquisition cost following the protocol change of $260 839 or $15 343 per patient. CONCLUSION: Our study demonstrated an acquisition cost savings with similar clinical outcomes utilizing anti-viral CMV prophylaxis alone vs anti-viral prophylaxis plus CMV-Ig.

Risk Factors for Survival After Heart Transplantation in Children and Young Adults: A 22-Year Study of 179 Transplants.

BACKGROUND: This article reviews all patients who underwent heart transplantation (HTx) within a single institution (172 patients underwent 179 HTx [167 first-time HTxs, 10 second HTxs, 2 third HTxs]) to describe diagnostic characteristics, management protocols, and risk factors for mortality. METHODS: Descriptive analysis was performed for the entire cohort using mean, standard deviation, median, interquartile range, and overall range, as appropriate. Univariable and multivariable Cox proportional hazards models were performed to identify prognostic factors for outcomes over time. The primary outcome of interest was mortality, which was modeled by Kaplan-Meier analysis. RESULTS: Median age at HTx was 263 days (range, 5 days to 24 years; mean = 4.63 ± 5.95 years; 18 neonates, 79 infants). Median weight at HTx was 7.5 kg (range, 2.2-113 kg; mean = 19.36 ± 23.54). Diagnostic categories were cardiomyopathy (n = 62), primary transplantation for hypoplastic left heart syndrome (HLHS) or HLHS-related malformation (n = 33), transplantation after cardiac surgery for HLHS or HLHS-related malformation (n = 17), non-HLHS congenital heart disease (n = 55), and retransplant (n = 12). Operative mortality was 10.1% (18 patients). Cumulative total follow-up is 1,355 years. Late mortality was 18.4% (33 patients). Overall Kaplan-Meier five-year survival was 76.2%. One hundred twenty-one patients are alive with a mean follow-up of 7.61 ± 6.46 years. No survival differences were seen among the five diagnostic subgroups ( P = .064) or between immunosensitized patients (n = 31) and nonimmunosensitized patients (n = 141; P = .422). CONCLUSIONS: Excellent results are expected for children undergoing HTx with comparable results among diagnostic groups. Pretransplant mechanical circulatory support and posttransplant mechanical circulatory support are risk factors for decreased survival. Survival after transplantation for HLHS or HLHS-related malformation is better with primary HTx in comparison to HTx after prior cardiac surgery.

Case report and review of the literature: the utilisation of a ventricular assist device as bridge to recovery for anthracycline-induced ventricular dysfunction.

Ventricular assist devices are used in children with heart failure as a bridge to myocardial recovery or cardiac transplantation. Anthracyclines cause cardiac toxicity and may result in acute or long-term cardiac failure. We describe the use of a ventricular assist device as a bridge to recovery in a child with severe acute anthracycline-induced cardiomyopathy, and we review the associated literature. A 6-year-old girl was treated for acute myeloblastic leukaemia with daunorubicin and mitoxantrone. After 2 weeks her final dose of chemotherapy, her Left Ventricular Ejection Fraction decreased to 21%. Despite initiation of medical therapy, she had continued deterioration of left ventricular function and developed evidence of poor end-organ perfusion. She was not a candidate for cardiac transplantation, as the post-transplant immune suppression therapy would put her at risk for recurrence of her malignancy. We placed her on a short-term ventricular assist device as a bridge to ultimately placing her on a long-term ventricular assist device versus continuing medical therapy. Her left ventricular ejection fraction improved to 55% 24 days after ventricular assist device insertion. She was separated from the ventricular assist device 26 days after its insertion. She was discharged home 29 days later and is now 28 months after ventricular assist device implantation with stable ventricular function, as documented by a left ventricular ejection fraction of 55%, and normal end organ function. This case is one of the only reports known describing successful use of a short-term ventricular assist device as a bridge to recovery in a child with severe acute anthracycline-induced cardiotoxicity.

Conversion from calcineurin inhibitors to mTOR inhibitors as primary immunosuppressive drugs in pediatric heart transplantation.

There are only a few reports of successful use of mammalian target of rapamycin (mTORI) as primary immunosuppression in pediatric heart transplantation. Compared to calcineurin inhibitors, mTORI have less side effects, especially nephrotoxicity, infections, and malignancies. A retrospective study was conducted at our institution of all 170 heart transplants from 1995 to 2015. Nineteen patients were switched from tacrolimus (n=15) or cyclosporin (n=4) to everolimus (n=4) or sirolimus (n=15) due to nephrotoxicity (n=5), malignancy (n=8), EBV viremia/reactive plasmacytic changes (n=5), and immune hemolytic anemia (n=1). We monitored for rejection, infection, BUN, creatinine, hyperlipidemia, EBV and CMV copies, CBC, cardiac allograft vasculopathy (CAV), and death. Target trough levels of sirolimus and everolimus were 4-10. Four treatment failures included debilitating rash, bone marrow suppression, recurrent rejection, and renal transplantation. There were no deaths. One patient had recurrent rejection episodes, and tacrolimus was reinitiated. One patient with preexisting CAV underwent heart retransplantation. One patient, who was treated for PTLD, transformed to CD30+ Hodgkins disease, and was treated with brentuximab. There were three acute rejection episodes. Median creatinine preswitch was higher 0.82 than postswitch 0.78 (P=.016). Median eGFR was lower preswitch, 75.6, than postswitch, 91.2 (P=.0004). These results indicate that conversion to mTORI as primary immunosuppression may be safely accomplished in some pediatric heart transplant patients.

Outcomes in highly sensitized pediatric heart transplant patients using current management strategies.

BACKGROUND: Previous studies have suggested that children with pre-formed anti-HLA antibodies (PRA) undergoing orthotopic heart transplantation (OHT) have increased risk for rejection, coronary artery vasculopathy (CAV) and death. In 2005, our program started utilizing aggressive desensitization (including plasmapheresis, IVIg, pulse cytoxan and rituximab) with the goal of improving outcomes for these patients. The purpose of this study was to compare outcomes with this new strategy in recipients with pre-OHT high PRA (>10%) vs low PRA ≤10%). METHODS: A retrospective study of 70 consecutive pediatric OHT patients was undertaken between January 2005 and July 2013 to identify patients with pre-OHT PRA >10% (high PRA), or PRA ≤10% (low PRA). Demographic/data information and detailed post-OHT outcomes, including rejection, 30-day and overall mortality, freedom from significant rejection, and CAV, were analyzed. RESULTS: Fourteen (20%) patients had high PRA and 56 (80%) did not. There was a significant decrease in PRA values before and after desensitization. Thirty-day and overall mortality and the proportion of patients with rejections or CAV were lower in the high PRA group, although the difference was not statistically significant. Kaplan-Meier survival analysis revealed no significant difference in survival between the two groups. There was a significant difference in survival in our sensitized patients before 2005 vs after 2005. CONCLUSIONS: We identified no significant differences in outcomes between high or low PRA patients. These preliminary findings may suggest improvement in OHT outcomes for high PRA patients as a result of aggressive desensitization. A larger study is warranted to confirm these findings.

Management of children undergoing cardiac transplantation with high Panel Reactive Antibodies.

Highly sensitised children in need of cardiac transplantation have overall poor outcomes because of increased risk for dysfunction of the cardiac allograft, acute cellular and antibody-mediated rejection, and vasculopathy of the cardiac allograft. Cardiopulmonary bypass and the frequent use of blood products in the operating room and cardiac intensive care unit, as well as the frequent use of homografts, have predisposed potential recipients of transplants to allosensitisation. The expansion in the use of ventricular assist devices and extracorporeal membrane oxygenation has also contributed to increasing rates of allosensitisation in candidates for cardiac transplantation. Antibodies to Human Leukocyte Antigen can be detected before transplantation using several different techniques, the most common being the "complement-dependent lymphocytotoxicity assays". "Solid-phase assays", particularly the "Luminex® single antigen bead method", offer improved specificity and more detailed information regarding specificities of antibodies, leading to improved matching of donors with recipients. Allosensitisation prolongs the time on the waiting list for potential recipients of transplantation and increases the risk of complications and death after transplantation. Aggressive reduction of antibodies to Human Leukocyte Antigen in these high-risk patients is therefore of vital importance for long-term survival of the patient and cardiac allograft. Strategies to decrease Panel Reactive Antibody or percent reactive antibody before transplantation include plasmapheresis, intravenous administration of immunoglobulin, and specific treatment to reduce B-cells, particularly Rituximab. These strategies have resulted in varying degrees of success. Antibody-mediated rejection and cardiac allograft vasculopathy are two of the most important complications of transplantation in patients with high Panel Reactive Antibody. The treatment of antibody-mediated rejection in recipients of cardiac transplants is largely empirical and includes the use of high-dose corticosteroids, plasmapheresis, intravenous administration of immunoglobulins, anti-thymocyte globulin, and Rituximab. Cardiac allograft vasculopathy is believed to be secondary to chronic complement-mediated endothelial injury and chronic vascular rejection. The use of proliferation signal inhibitors, such as sirolimus and everolimus, has been shown to delay the progression of cardiac allograft vasculopathy. In some non-sensitised recipients of cardiac transplants, the de novo formation of antibodies to Human Leukocyte Antigen after transplantation may increase the likelihood of adverse clinical outcomes. The use of serial testing for donor-specific antibodies after cardiac transplantation may be advisable in patients with frequent episodes of rejection and patients with history of sensitisation. Allosensitisation before transplantation can negatively influence outcomes after transplantation. A high incidence of antibody-mediated rejection and graft vasculopathy can result in graft failure and decreased survival. Current strategies to decrease allosensitisation have helped to expand the pool of donors, improve times on the waiting list, and decrease mortality. Centres of transplantation offering desensitisation are currently using plasmapheresis to remove circulating antibodies; intravenous immunoglobulin to inactivate antibodies; cyclophosphamide to suppress B-cell proliferation; and Rituximab to deplete B-lymphocytes. Similar approaches are also used to treat antibody-mediated rejection after transplantation with promising results.

Lessons learned from 119 consecutive cardiac transplants for pediatric and congenital heart disease.

BACKGROUND: This manuscript reviews all patients who underwent orthotopic heart transplantations (OHT) at our program (116 patients underwent 119 OHT) to describe their diagnostic characteristics and to assess risk factors for mortality. METHODS: Median age at OHT was 179 days (mean, 1,446.6 ± 188.9 days [4.0 ± 0.5 years]; range, 5 days to 7,125 days [19.5 years]; 15 neonates, 68 infants). Median weight at OHT was 5.5 kg (mean, 17.2 ± 2.1 kg; range, 2.2 to 113 kg). Diagnoses were cardiomyopathy (n = 37), primary transplantation for hypoplastic left heart syndrome (HLHS) or HLHS-related malformation (n = 29), transplantation after prior cardiac surgery for HLHS or HLHS-related malformation (n = 9), non-HLHS congenital heart disease (n = 39), and retransplant (n = 5). RESULTS: Overall Kaplan-Meier 5-year survival was 72.7%. Operative mortality was 12.6% (15 patients). Late mortality was 13.4% (16 patients). Eighty-five patients survived, with a mean follow-up of 5.76 ± 0.48 years (median, 5.1 years; range, 0.12 to 14.0 years). Total follow-up was 507.0 years. No survival difference was seen among the five diagnostic subgroups (p = 0.20). Univariate association between risk factors and survival was assessed for the following variables: age (p = 0.91), weight (p = 0.86), sex (p = 0.47), race (p = 0.40), insurance classification (p = 0.42), high PRA (p = 0.20), pretransplant mechanical circulatory support (p < 0.001), posttransplant mechanical circulatory support (p < 0.001), redo sternotomy (p = 0.07), heterotaxy (p = 0.02), cardiopulmonary bypass time (p = 0.01), and donor heart cross-clamp time (p = 0.02). CONCLUSIONS: Excellent results are expected for children undergoing OHT regardless of diagnostic classification. Pretransplant mechanical circulatory support, posttransplant mechanical circulatory support, cardiopulmonary bypass time, donor heart cross-clamp time, and heterotaxy are risk factors for decreased survival.