Bruton's tyrosine kinase ablation inhibits B cell responses and antibody production for the prevention of chronic rejection in cardiac transplantation.

Chronic rejection is the primary cause of late allograft failure, however, the current treatments for chronic rejection have not yielded desirable therapeutic effects. B cell activation and donor-specific antibody (DSA) production are the primary factors leading to chronic rejection. Bruton's tyrosine kinase (BTK) plays a key role in the activation and differentiation of B cells and in antibody production. This study investigated the efficacy of blocking BTK signalling in the prevention of chronic rejection. BTK signalling was blocked using the BTK inhibitor ibrutinib and gene knockout. In vitro assays were conducted to examine the consequences and underlying mechanisms of BTK blockade in regards to B cell activation, differentiation, and antibody secretion. Additionally, we established a cardiac transplantation mouse model of chronic rejection to explore the preventive effects and mechanisms of BTK ablation on chronic rejection. Ablating BTK signalling in vitro resulted in the inhibition of B cell activation, differentiation, and antibody production. In vivo experiments provided evidence that ablating BTK signalling alleviated chronic rejection, leading to reduced damage in myocardial tissue, neointimal hyperplasia, interstitial fibrosis, inflammatory cell infiltration, and C4d deposition. Allograft survival was prolonged, and B cell responses and DSA production were inhibited as a result. We confirmed that ablation of BTK signalling inhibited B cell response by blocking downstream PLCγ2 phosphorylation and inhibiting the NF-κB, NFAT, and ERK pathways. Our findings demonstrated that ablation of BTK signalling inhibited B cell activation and differentiation, reduced DSA production, and effectively prevented chronic rejection.

The Association Between Preoperative Pectoralis Muscle Quantity and Outcomes After Cardiac Transplantation.

BACKGROUND: Sarcopenia is underappreciated in advanced heart failure and is not routinely assessed. In patients receiving a left ventricular assist device, preoperative sarcopenia, defined by using computed-tomography (CT)-derived pectoralis muscle-area index (muscle area indexed to body-surface area), is an independent predictor of postoperative mortality. The association between preoperative sarcopenia and outcomes after heart transplant (HT) is unknown. OBJECTIVES: The primary aim of this study was to determine whether preoperative sarcopenia, diagnosed using the pectoralis muscle-area index, is an independent predictor of days alive and out of the hospital (DAOHs) post-transplant. METHODS: Patients who underwent HT between January, 2018, and June, 2022, with available preoperative chest CT scans were included. Sarcopenia was diagnosed as pectoralis muscle-area index in the lowest sex-specific tertile. The primary endpoint was DAOHs at 1 year post-transplant. RESULTS: The study included 169 patients. Patients with sarcopenia (n = 55) had fewer DAOHs compared to those without sarcopenia, with a median difference of 17 days (320 vs 337 days; P = 0.004). Patients with sarcopenia had longer index hospitalizations and were also more likely to be discharged to a facility other than home. In a Poisson regression model, sarcopenia was a significant univariable and the strongest multivariable predictor of DAOHs at 1 year (parameter estimate = -0.17, 95% CI -0.19 to -14; P = < 0.0001). CONCLUSIONS: Preoperative sarcopenia, diagnosed using the pectoralis muscle-area index, is an independent predictor of poor outcomes after HT. This parameter is easily measurable from commonly obtained preoperative CT scans and may be considered in transplant evaluations.

Short communications: Endothelin-1 in cardiac allograft vasculopathy.

INTRODUCTION: Cardiac allograft vasculopathy (CAV) is a leading cause of death following heart transplant. Endothelin-1 (ET-1) is a highly potent vasoconstrictor peptide derived from the vascular endothelium with multiple biological actions known to be relevant for CAV. We assessed the trans-myocardial gradient (TMG: coronary sinus minus coronary artery concentration: negative = extraction, positive = secretion) of ET-1 in heart transplant patients to determine correlations with angiographic, Intravascular Ultrasound (IVUS) and Optical Coherence Tomography (OCT) features of CAV. RESULTS: Vessels with more severe CAV demonstrated significantly higher (more positive) ET-1 TMG (IVUS Stanford Grade IV: -0.05 [-0.21, 0.13] pg/ml versus Stanford Grade I-III: -0.31 [-0.64, -0.11] pg/ml, p = 0.01). ET-1 TMG was positively correlated with mean intimal thickness on both IVUS and OCT (IVUS: Kendall's tau-b = 0.254, p = 0.02 and OCT: Kendall's tau-b = 0.344, p < 0.0001). Patients who died had net ET-1 release compared with surviving patients (died: 0.21 [0.19-0.24] versus surviving: -0.28 [-0.52, -0.17], p = 0.01). CONCLUSION: In heart transplant patients, coronary arteries with more intimal thickening are associated with a higher (more positive) trans-myocardial gradient of ET-1, suggesting that up-regulated ET-1 release in the coronary circulation may be permissive for the development of CAV.

Epstein Barr virus-directed T-cell therapy for refractory EBV-PTLD in a toddler post Orthotopic heart transplantation.

Epstein-Barr Virus (EBV) is a ubiquitous herpes type virus that is associated with post-transplant lymphoproliferative disorder (PTLD). Usual management includes reduction or cessation of immunosuppression and in some cases chemotherapy including rituximab. However, limited therapies are available if PTLD is refractory to rituximab. Several clinical trials have investigated the use of EBV-directed T cells in rituximab-refractory patients; however, data regarding response is scarce and inconclusive. Herein, we describe a patient with EBV-PTLD refractory to rituximab after orthotopic heart transplantation (OHT) requiring EBV-directed T-cell therapy. This article aims to highlight the unique and aggressive clinical presentation and progression of PTLD with utilization of EBV-directed T-cell therapy for management and associated pitfalls.

Prevalence and spectrum of infectious and inflammatory dermatologic conditions occurring in pediatric heart transplant patients on a predominantly mTOR-based immune suppressive regimen: A retrospective chart review.

INTRODUCTION: Pediatric heart transplant patients are routinely followed in dermatology clinics due to elevated risk of cutaneous malignancy. However, transplant patients may experience other, non-cancer-related dermatologic conditions including skin infections, inflammatory diseases, and drug eruptions that can cause significant medical and psychosocial comorbidity. METHODS: A retrospective chart review of all pediatric heart transplant patients at Mayo Clinic Children's Center in Rochester, MN, was performed to determine the prevalence and spectrum of non-cancer dermatologic conditions. Statistical analysis was conducted to look for associations between episodes of rejection and skin condition development. RESULTS: Of the 65 patients who received heart transplants under the age of 18 and were followed at Mayo Clinic, 69% (N = 45) were diagnosed with at least one skin condition between transplant and the time of most recent follow-up. Sixty-two percent (N = 40) of patients were diagnosed with an inflammatory skin condition (most commonly acne and atopic dermatitis), 45% (N = 29) with an infectious skin condition (most commonly warts and dermatophyte infection), and 32% (N = 21) with a drug eruption (most commonly unspecified rash and urticaria). No association was found between presence of skin disease and number of rejection episodes. CONCLUSIONS: Non-cancer dermatologic conditions are prevalent within pediatric heart transplant recipients and may directly impact their medical needs and quality of life. Dermatologist involvement in the care of post-transplant pediatric patients is important, not only for cancer screening but also for diagnosis and treatment of common infectious and inflammatory skin conditions.

The power of "it will be okay".

As caregivers for critically ill children and their families, there are moments when we find ourselves unsure of how best to offer support. The magnitude of the medical experience can cloud our communication with patients and their families. With years of counseling families through some of their most challenging and darkest hours, I aim to emphasize the profound impact of thoughtful and well-informed reassurance; how we can provide hope in hopeless situations.

An Ethics Committee's Evaluation of Normothermic Regional Perfusion (NRP) in 2018-Unsatisfactory Answers Then-and Now.

An adult university hospital ethics committee evaluated a proposed TA-NRP protocol in the fall of 2018. The protocol raised ethical concerns about violation of the Uniform Determination of Death Act and the prohibition known as the Dead Donor Rule, with potential resultant legal consequences. An additional concern was the potential for increased mistrust by the community of organ donation and transplantation. The ethics committee evaluated the responses to these concerns as unable to surmount the ethical and legal boundaries and the ethics committee declined to endorse the procedure. These concerns endure.

Inclusive ABO-Incompatible Listing for Pediatric Heart Transplantation Results in Comparable Post-Transplant Rejection-Free Survival in a Single-Center Series.

ABO-incompatible (ABOi) heart transplantation (HT) has increased organ availability for infants with end-stage heart failure. Despite increasing adoption of ABOi listing for HT, data remain limited regarding pre- and post-HT immunologic profiles to guide listing practices and post-HT follow-up. Thus, the purpose of this study was to evaluate post-HT outcomes at a single center employing inclusive ABOi listing irrespective of pre-HT isohemagglutinin titers. All HT recipients listed at less than 24 months of age at our institution from 2010-2020 were included. Pre- and post-operative variables were compared for ABOi and ABO-compatible (ABOc) recipients. Separate iso-IgG and iso-IgM titers were monitored pre- and post-HT. Primary outcomes were compared between ABOi versus ABOc groups at mid-term follow-up. 51 HTs were performed on 50 patients from 2010-2020 (ABOi, N = 13; ABOc, N = 38). Six ABOi recipients received intra-operative plasma exchange for elevated titers (greater than 1:8 for IgG or IgM or reverse type greater than 2 +). Treated rejection, DSA, CAV, primary graft failure, need for re-HT, and survival were comparable between ABOi and ABOc groups at mid-term follow-up. An inclusive approach to ABOi HT listing for infants less than 24 months of age results in comparable post-transplant rejection-free survival, CAV, and prevalence of DSA at mid-term follow-up. These data define a potential role for specific IgM and IgG testing to promote understanding of risk stratification in pediatric ABOi listing, and support an inclusive strategy irrespective of high pre-HT titers to expand the number of available donor hearts for infants and older children awaiting HT.

Comparison of different porcine models simulating myocardial cold ischemia of pediatric donor hearts.

BACKGROUND: Our team previously identified a stem cell-derived cardioprotective additive that can be added to standard cardioplegia to extend myocardial viability during prolonged myocardial cold ischemic time (CIT) in rodent models. The purpose of this study was to utilize a porcine model to compare in-vivo versus ex-vivo porcine simulation of CIT that accompanies cardiac transplantation in humans, in order to determine an optimal method for translation of our studies to larger animals. METHODS: Eight 39-55 kg Yorkshire X pigs were randomly assigned to either in-vivo or ex-vivo simulation. After administration of general anesthesia and endotracheal intubation, baseline measurement of left ventricular performance was obtained via transesophageal echocardiography (TEE). After midline sternotomy and heparin administration, the aorta was cross-clamped and two liters of HTK-Custodiol were introduced via the aortic root. The in-vivo method utilized cold ischemic heart storage in the chest cavity while supporting the experimental animal with cardiopulmonary bypass (CPB). The ex-vivo method involved standard cardiac procurement, cold ischemic storage outside of the body, and subsequent cardiac reperfusion utilizing cardiac reanimation in a Langendorff heart perfusion mode. After CIT, measurements of post-ischemic left ventricular performance were obtained via echocardiography. Results are presented as: Mean ± Standard Deviation (Median, Minimum-Maximum). RESULTS: Weight (kilograms) was similar in the in-vivo group and the ex-vivo group: 44 ± 1.8 (44, 42-46) versus 44 ± 5.1 (43.5, 39-51), respectively. Cold ischemic time (minutes) was longer in the ex-vivo group: 360 ± 0 (360, 360-360) versus 141 ± 26.7 (149, 102-163). Temperature (degrees Celsius) was colder in the ex-vivo group: 8 ± 0 (8, 8-8) versus 16.5 ± 4.2 (16, 12-16).In the in-vivo group, baseline ejection fraction and ejection fraction after CIT were: 48.25% ± 14.95% (48.5%, 33%-63%) and 41.25% ± 22.32% (41.5%, 20%-62%), respectively. In the ex-vivo group, baseline ejection fraction and ejection fraction after CIT were: 56.4% ± 5.9% (57%, 50%-67%) and 60.4% ± 7.7% (61.5%, 51.9%-67%), respectively. CONCLUSION: The ex-vivo technique is suitable to evaluate cardioplegia additives that may substantially extend myocardial tolerance to cold ischemia.

[Advanced heart failure : what are the prospects for patients ?] / L'insuffisance cardiaque avancée : quelles perspectives pour le patient ?

Heart failure (HF) is a major public health problem in our country and in most developed countries. Despite advances in the diagnosis and management of this condition and numerous therapeutic innovations, many patients with chronic HF progress inexorably to advanced HF, characterized by persistent symptoms despite maximal treatment. The prognosis for this condition is poor. However, mechanical circulatory support and heart transplantation, when considered in suitable candidates, are likely to improve the quality of life and life expectancy of these patients. In this context, timely referral to referral centers for the management of advanced HF is crucial. This article reminds the definition of advanced HF, details its specific management and specifies the criteria and timing for appropriate referral.

L'insuffisance cardiaque (IC) est un problème de santé publique majeur au sein de notre pays et dans la plupart des pays développés. Malgré les progrès réalisés dans le diagnostic et la prise en charge de cette pathologie ainsi que les nombreuses innovations thérapeutiques, beaucoup de patients atteints d'IC progressent inexorablement vers une IC avancée, caractérisée par la persistance de symptômes en dépit d'un traitement maximal. Le pronostic de cette condition est sombre. Cependant, les assistances mécaniques circulatoires et la transplantation cardiaque, lorsqu'elles sont envisagées chez de bons candidats, sont susceptibles d'améliorer la qualité de vie et l'espérance de vie de ces patients. Dans cette optique, le référencement selon un timing adéquat vers des centres de référence de prise en charge de l'IC avancée est crucial. Cet article revient sur la définition de l'IC avancée, détaille sa prise en charge spécifique et précise les critères et le timing pour un référencement adéquat.

Computational Analysis of Routine Biopsies Improves Diagnosis and Prediction of Cardiac Allograft Vasculopathy.

BACKGROUND: Cardiac allograft vasculopathy (CAV) is a leading cause of morbidity and mortality for heart transplant recipients. Although clinical risk factors for CAV have been established, no personalized prognostic test exists to confidently identify patients at high versus low risk of developing aggressive CAV. This investigation aimed to leverage computational methods for analyzing digital pathology images from routine endomyocardial biopsies (EMBs) to develop a precision medicine tool for predicting CAV years before overt clinical presentation. METHODS: Clinical data from 1 year after transplant were collected on 302 transplant recipients from the University of Pennsylvania, including 53 patients with early-onset CAV and 249 no early-onset CAV controls. These data were used to generate a clinical model (Clinical Risk Factor Future Cardiac Allograft Vasculopathy Prediction Model [ClinCAV-Pr]) for predicting future CAV development. From this cohort, 183 archived EMBs were collected for CD31 and modified trichrome staining and then digitally scanned. These included 1-year posttransplant EMBs from 50 patients with early-onset CAV and 82 patients with no early-onset CAV, as well as 51 EMBs from disease control patients obtained at the time of definitive coronary angiography confirming CAV. Using biologically inspired, handcrafted features extracted from digitized EMBs, quantitative histological models for differentiating no early-onset CAV from disease controls (Histological Cardiac Allograft Vasculopathy Diagnostic Model [HistoCAV-Dx]) and for predicting future CAV from 1-year posttransplant EMBs were developed (Histological Future Cardiac Allograft Vasculopathy Prediction Model [HistoCAV-Pr]). The performance of histological and clinical models for predicting future CAV (ie, HistoCAV-Pr and ClinCAV-Pr, respectively) were compared in a held-out validation set before being combined to assess the added predictive value of an integrated predictive model (Integrated Histological/Clinical Risk Factor Future Cardiac Allograft Vasculopathy Prediction Model [iCAV-Pr]). RESULTS: ClinCAV-Pr achieved modest performance on the independent test set, with an area under the receiver operating curve (AUROC) of 0.70. The HistoCAV-Dx model for diagnosing CAV achieved excellent discrimination, with an AUROC of 0.91, whereas the HistoCAV-Pr model for predicting CAV achieved good performance with an AUROC of 0.80. The integrated iCAV-Pr model achieved excellent predictive performance, with an AUROC of 0.93 on the held-out test set. CONCLUSIONS: Prediction of future CAV development is greatly improved by incorporation of computationally extracted histological features. These results suggest morphological details contained within regularly obtained biopsy tissue have the potential to enhance precision and personalization of treatment plans for patients after heart transplant.

Choosing wisely: incorporating appropriate donor-recipient size matching in heart transplantation.

Historically, transplantation of a female donor heart to male recipient has been viewed with caution given evidence of suboptimal outcomes, particularly in special populations such as patients with pulmonary hypertension or those supported by ventricular assist devices. However, the use of predicted heart mass ratio for donor-recipient size matching demonstrated that the size of the organ rather than sex of the donor was most responsible for the outcomes. With the advent of the predicted heart mass ratio, avoiding female donor hearts for male recipients is no longer justified and may result in unnecessary waste of available organs. In this review, we highlight the value of donor-recipient sizing by predicted heart mass ratio and summarize the evidence of different approaches to the donor-to-recipient size and sex matching. We conclude that the utilization of predicted heart mass is currently considered a preferred method of matching heart donors and recipients.

Prognosis of Patients with Hypertrophic Obstructive Cardiomyopathy: A Multicenter Cohort Study with Data-Driven Propensity Score Matching Analysis.

Background: Hypertrophic obstructive cardiomyopathy (HOCM) patients are reported to have a potential risk of sudden cardiac death (SCD); however, HCM with left ventricular outflow tract (LVOT) obstruction, which is regarded as a risk indicator of SCD, is doubtful since the LVOT gradient is dynamic and may be confounded by various environmental factors and routine activities. The purpose of this study was to explore the clinical prognosis of HOCM through a multicenter cohort study with data-driven propensity score matching (PSM) analysis. Methods: The cohort included 2268 patients with HCM from 1996 to 2021 in 13 tertiary hospitals. In the present study, we excluded 458 patients who underwent alcohol septal ablation (ASA) and septal myectomy (SM) surgery so 1810 HCM patients were eventually included. We developed a data-driven propensity score using 24 demographic and clinical variables to create 1:1 propensity-matched cohorts. A Cox proportional hazard regression model was constructed to assess the effect of HOCM on mortality. Results: After logit-matching, there were no significant differences in all-cause mortality (log-rank χ 2 = 1.509, p = 0.22), cardiovascular mortality/cardiac transplantation (log-rank χ 2 = 0.020, p = 0.89) or SCD (log-rank χ 2 = 0.503, p = 0.48) between patients with HOCM and hypertrophic nonobstructive cardiomyopathy (HNCM), and according to the Cox proportional hazard regression model, LVOT obstruction was not a risk predictor in patients with HCM. Conclusions: In both matched and unmatched cohorts, there were no significant differences in clinical prognosis between HOCM and HNCM patients, and LVOT obstruction was not an independent risk predictor of prognosis in patients with HCM. Clinical Trial Registration: ChiCTR1800017330.

Reduction of HLA donor specific antibodies in heart transplant patients treated with proteasome inhibitors for antibody mediated rejection.

In this project, we describe proteasome inhibitor (PI) treatment of antibody-mediated rejection (AMR) in heart transplantation (HTX). From January 2018 to September 2021, 10 patients were treated with PI for AMR: carfilzomib (CFZ) n = 8; bortezomib (BTZ) n = 2. Patients received 1-3 cycles of PI. All patients had ≥1 strong donor-specific antibody (DSA) (mean fluorescence intensity [MFI] > 8000) in undiluted serum. Most DSAs (20/21) had HLA class II specificity. The MFI of strong DSAs had a median reduction of 56% (IQR = 13%-89%) in undiluted serum and 92% (IQR = 53%-95%) at 1:16 dilution. Seventeen DSAs in seven patients were reduced > 50% at 1:16 dilution after treatment. Four DSAs from three patients did not respond. DSA with MFI > 8000 at 1:16 dilution was less responsive to treatment. 60% (6/10) patients presented with graft dysfunction; 4/6 recovered ejection fraction > 40% after treatment. Pathologic AMR was resolved in 5/7 (71.4%) of patients within 1 year after treatment. 9/10 (90%) patients survived to 1 year after AMR diagnosis. Using PI in AMR resulted in significant DSA reduction with some resolution of graft dysfunction. Larger studies are needed to evaluate PI for AMR.

Heart transplantation in neonatal Marfan syndrome: Saving life in a rare and fatal condition.

BACKGROUND: Neonatal Marfan syndrome is a rare disease with mortality in the first year of life reported as high as 95% predominantly due to progressive heart failure from valvar regurgitation and cardiomyopathy. Multisystem involvement and uncertain prognosis have historically precluded transplant candidacy, and current management options are of limited success. CASE REPORT: We present a baby girl with a postnatal diagnosis of neonatal Marfan syndrome who at 1 year of age underwent mitral valve and tricuspid valve repair with postoperative profound left ventricular and moderate right ventricular dysfunction necessitating biventricular assist device (BiVAD) support and subsequent heart transplant. A number of noncardiac issues persisted in our patient; however, she enjoyed a good quality of life for the initial 3 years posttransplant. Unfortunately, she subsequently developed rapidly progressive coronary allograft vasculopathy (CAV) with progressive deterioration in function and cardiac arrest. CONCLUSION: To our best knowledge, this is only the second case of neonatal Marfan syndrome to undergo heart transplant reported in the literature and the first with BiVAD support as a bridge to candidacy. This is also the first case of neonatal Marfan syndrome associated with intragenic duplication. This case though demonstrating that earlier listing, ventricular assist device (VAD) support and even primary transplant as treatment in neonatal Marfan syndrome should all be considered viable options but also portends a cautionary tale given the spectrum of comorbidities in this rare and severe disorder.

Ex situ heart perfusion for optimization of pediatric donor organ utilization: Attitudes and perceptions.

BACKGROUND: Children with heart failure have the highest mortality while awaiting transplantation. Ex situ heart perfusion (ESHP), a method for continuous perfusion of the donor heart, has the potential to improve access to transplant by increasing travel distance between donor and recipient. An adult ESHP device is currently available, but as of yet there is no pediatric device. The aim of this study was to evaluate current knowledge of ESHP among pediatric heart transplant practitioners, define potential barriers, and identify uses of this novel technology. METHODS: An electronic survey was developed to assess perspectives of international pediatric heart transplant stakeholders (n = 68) on ESHP. Select questions were analyzed to evaluate for associations between groups of respondents and patterns of response. RESULTS: Most respondents were familiar but <10% had clinically utilized ESHP. There was optimism that ESHP could decrease waitlist mortality. Respondents were concerned about potential device malfunction and lack of long-term outcomes. There were no differences found in terms of ESHP familiarity among age groups, practitioner center volume, country of work, or discipline. CONCLUSIONS: ESHP has the potential to expand the pediatric heart donor pool and decrease waitlist mortality. More education on outcomes and risks/benefits is needed in order to promote widespread adoption.

Hypertrophic cardiomyopathy in the systemic right ventricle in a patient with congenitally corrected transposition of the great arteries: A case report.

Congenitally corrected transposition of the great arteries is a rare clinical entity, which usually presents during adulthood with associated defects; atrioventricular block, heart failure, systemic valve failure, and arrhythmias usually complicate the clinical course. Even rarer is associated hypertrophic cardiomyopathy, which complicates the disease course and clinical decision-making. Herein, we present a patient with this condition who underwent heart transplantation, with adequate clinical resolution.

Early Postoperative Volume Overload is a Predictor of 1-Year Post-Transplant Mortality in Pediatric Heart Transplant Recipients.

Fluid restriction and diuretic management are mainstays in the postoperative management of cardiac patients, at risk of volume overload and its deleterious effects on primary cardiac function and multi-organ systems. The importance of fluid homeostasis is further emphasized among orthotopic heart transplant recipients (OHT). We sought to investigate the relationship between postoperative volume overload, mortality, and allograft dysfunction among pediatric OHT recipients within 1-year of transplantation. This is a retrospective cohort study from a single pediatric OHT center. Children under 21 years undergoing cardiac transplantation between 2010 and 2018 were included. Cumulative fluid overload (cFO) was assessed as percent fluid accumulation adjusted for preoperative body weight. Greater than 10% cFO defined those with postoperative cFO and a comparison of postoperative cFO vs. no postoperative cFO (< 5%) is reported. 102 pediatric OHT recipients were included. Early cFO at 72 h post-OHT occurred in 14% and overall cFO at 1-week post-OHT occurred in 23% of patients. Risk factors for cFO included younger age, lower weight, and postoperative ECMO. Early cFO was associated with postoperative mortality at 1-year, OR 8.6 (95% CI 1.4, 51.6), p = 0.04, independent of age and weight. There was no significant relationship between cFO and allograft dysfunction, measured by rates of clinical rejection and cardiopulmonary filling pressures within 1-year of transplant. Early postoperative volume overload is prevalent and associated with increased risk of death at 1-year among pediatric OHT recipients. It may be an important postoperative marker of transplant survival, and this relationship warrants further clinical investigation.

Aortic valve replacement using On-X valve in a child postorthotopic heart transplantation.

A 20-month-old girl presented with severe dilated cardiomyopathy and decompensated congestive cardiac failure. Despite escalating inotropic and mechanical ventilation support, she required placement on extracorporeal membrane oxygenation and transfer to the transplant centre in Newcastle, England. She was placed on biventricular assist device and then Berlin Heart but failed to show any recovery of ventricular function. She underwent orthotopic heart transplantation at 2 years of age. She developed bacterial endocarditis with Enterococcus faecalis resulting in severe aortic valve regurgitation requiring aortic valve replacement with a 19 mm On-X valve (Airtivion) 11 days after her transplant. Given the size of the donor heart, it was possible to implant a 19-mm valve in this 12 kg child with minimal risk of patient prosthesis mismatch. She was anticoagulated with warfarin (On-X valve INR 2-3 for first 3 months; INR 1.5-2.0 thereafter). Although she suffered several other post-operative complications, including malabsorption, nasojejunal feeding, liver dysfunction, vertebral fractures, renal impairment and renal calcification, and need for repeat opening of her tracheostomy site following her initial decannulation, her aortic valve function has remained stable.

Cell-Free DNA to Detect Heart Allograft Acute Rejection.

BACKGROUND: After heart transplantation, endomyocardial biopsy (EMBx) is used to monitor for acute rejection (AR). Unfortunately, EMBx is invasive, and its conventional histological interpretation has limitations. This is a validation study to assess the performance of a sensitive blood biomarker-percent donor-derived cell-free DNA (%ddcfDNA)-for detection of AR in cardiac transplant recipients. METHODS: This multicenter, prospective cohort study recruited heart transplant subjects and collected plasma samples contemporaneously with EMBx for %ddcfDNA measurement by shotgun sequencing. Histopathology data were collected to define AR, its 2 phenotypes (acute cellular rejection [ACR] and antibody-mediated rejection [AMR]), and controls without rejection. The primary analysis was to compare %ddcfDNA levels (median and interquartile range [IQR]) for AR, AMR, and ACR with controls and to determine %ddcfDNA test characteristics using receiver-operator characteristics analysis. RESULTS: The study included 171 subjects with median posttransplant follow-up of 17.7 months (IQR, 12.1-23.6), with 1392 EMBx, and 1834 %ddcfDNA measures available for analysis. Median %ddcfDNA levels decayed after surgery to 0.13% (IQR, 0.03%-0.21%) by 28 days. Also, %ddcfDNA increased again with AR compared with control values (0.38% [IQR, 0.31-0.83%], versus 0.03% [IQR, 0.01-0.14%]; P<0.001). The rise was detected 0.5 and 3.2 months before histopathologic diagnosis of ACR and AMR. The area under the receiver operator characteristic curve for AR was 0.92. A 0.25%ddcfDNA threshold had a negative predictive value for AR of 99% and would have safely eliminated 81% of EMBx. In addition, %ddcfDNA showed distinctive characteristics comparing AMR with ACR, including 5-fold higher levels (AMR ≥2, 1.68% [IQR, 0.49-2.79%] versus ACR grade ≥2R, 0.34% [IQR, 0.28-0.72%]), higher area under the receiver operator characteristic curve (0.95 versus 0.85), higher guanosine-cytosine content, and higher percentage of short ddcfDNA fragments. CONCLUSIONS: We found that %ddcfDNA detected AR with a high area under the receiver operator characteristic curve and negative predictive value. Monitoring with ddcfDNA demonstrated excellent performance characteristics for both ACR and AMR and led to earlier detection than the EMBx-based monitoring. This study supports the use of %ddcfDNA to monitor for AR in patients with heart transplant and paves the way for a clinical utility study. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02423070.