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

BACKGROUND: The aims of the study were to assess the performance of a clinically available cell-free DNA (cfDNA) assay in a large cohort of pediatric and adult heart transplant recipients and to evaluate performance at specific cut points in detection of rejection. METHODS: Observational, non-interventional, prospective study enrolled pediatric and adult heart transplant recipients from seven centers. Biopsy-associated plasma samples were used for cfDNA measurements. Pre-determined cut points were tested for analytic performance. RESULTS: A total of 487 samples from 160 subjects were used for the analysis. There were significant differences for df-cfDNA values between rejection [0.21% (IQR 0.12-0.69)] and healthy samples [0.05% (IQR 0.01-0.14), p < .0001]. The pediatric rejection group had a median df-cfDNA value of 0.93% (IQR 0.28-2.84) compared to 0.09% (IQR 0.04-0.23) for healthy samples, p = .005. Overall negative predictive value was 0.94 while it was 0.99 for pediatric patients. Cut points of 0.13% and 0.15% were tested for various types of rejection profiles and were appropriate to rule out rejection. CONCLUSION: The study suggests that pediatric patients with rejection show higher levels of circulating df-cfDNA compared to adults and supports the specific cut points for clinical use in pediatric and adult patients with overall acceptable performance.

Mid-aortic syndrome diagnosed by transesophageal echocardiogram in a patient with dilated cardiomyopathy.

Mid-aortic syndrome is a rare condition characterised by segmental narrowing of the thoracoabdominal aorta. Here, we demonstrate a case of mid-aortic syndrome in a 30-month-old female who was diagnosed via transesophageal echocardiography after presenting with dilated cardiomyopathy and severe heart failure requiring placement of a left ventricular assist device.

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

BACKGROUND: Cell-free DNA is an emerging biomarker. While donor fraction may detect graft events in heart transplant recipients, the prognostic value of total nuclear cell-free DNA (ncfDNA) itself is largely unexplored. OBJECTIVE: Explore the relationship between ncfDNA and clinical events in heart transplant recipients. METHODS: We conducted a multi-center prospective study to investigate the value of cell-free DNA in non-invasive monitoring following heart transplantation. Over 4000 blood samples were collected from 388 heart transplant patients. Total ncfDNA and donor fraction were quantified. Generalized linear models with maximum likelihood estimation for repeated measures with subjects as clusters were used to explore the relationship of ncfDNA and major adverse events. Receiver operating characteristic curves were used to help choose cutpoints. RESULTS: A ncfDNA threshold (50 ng/ml) was identified that was associated with increased risk of major adverse events. NcfDNA was elevated in patients who suffered cardiac arrest, required mechanical circulatory support or died post heart transplantation as well as in patients undergoing treatment for infection. CONCLUSIONS: Elevated ncfDNA correlates with risk for major adverse events in adult and pediatric heart transplant recipients and may indicate a need for enhanced surveillance after transplant.

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

BACKGROUND: Clinical rejection (CR) defined as decision to treat clinically suspected rejection with change in immunotherapy based on clinical presentation with or without diagnostic biopsy findings is an important part of care in heart transplantation. We sought to assess the utility of donor fraction cell-free DNA (DF cfDNA) in CR and the utility of serial DF cfDNA in CR patients in predicting outcomes of clinical interest. METHODS: Patients with heart transplantation were enrolled in two sequential, multi-center, prospective observational studies. Blood samples were collected for surveillance or clinical events. Clinicians were blinded to the results of DF cfDNA. RESULTS: A total of 835 samples from 269 subjects (57% pediatric) were included for this analysis, including 28 samples associated with CR were analyzed. Median DF cfDNA was 0.43 (IQR 0.15, 1.36)% for CR and 0.10 (IQR 0.07, 0.16)% for healthy controls (p < .0001). At cutoff value of 0.13%, the area under curve (AUC) was 0.82, sensitivity of 0.86, specificity of 0.67, and negative predictive value of 0.99. There was serial decline in DF cfDNA post-therapy, however, those with cardiovascular events (cardiac arrest, need for mechanical support or death) showed significantly higher levels of DF cfDNA on Day 0 (2.11 vs 0.31%) and Day 14 (0.51 vs 0.22%) compared to those who did not have such an event (p < .0001). CONCLUSION: DF cfDNA has excellent agreement with clinical rejection and, importantly, serial measurement of DF cfDNA predict clinically significant outcomes post treatment for rejection in these patients.

Risk Factors for Cardiac and Non-cardiac Causes of Death in Males with Duchenne Muscular Dystrophy.

As survival and neuromuscular function in Duchenne muscular dystrophy (DMD) have improved with glucocorticoid (GC) therapy and ventilatory support, cardiac deaths are increasing. Little is known about risk factors for cardiac and non-cardiac causes of death in DMD. A multi-center retrospective cohort study of 408 males with DMD, followed from January 1, 2005 to December 31, 2015, was conducted to identify risk factors for death. Those dying of cardiac causes were compared to those dying of non-cardiac causes and to those alive at study end. There were 29 (7.1%) deaths at a median age of 19.5 (IQR: 16.9-24.6) years; 8 (27.6%) cardiac, and 21 non-cardiac. Those living were younger [14.9 (IQR: 11.0-19.1) years] than those dying of cardiac [18 (IQR 15.5-24) years, p = 0.03] and non-cardiac [19 (IQR: 16.5-23) years, p = 0.002] causes. GC use was lower for those dying of cardiac causes compared to those living [2/8 (25%) vs. 304/378 (80.4%), p = 0.001]. Last ejection fraction prior to death/study end was lower for those dying of cardiac causes compared to those living (37.5% ± 12.8 vs. 54.5% ± 10.8, p = 0.01) but not compared to those dying of non-cardiac causes (37.5% ± 12.8 vs. 41.2% ± 19.3, p = 0.58). In a large DMD cohort, approximately 30% of deaths were cardiac. Lack of GC use was associated with cardiac causes of death, while systolic dysfunction was associated with death from any cause. Further work is needed to ensure guideline adherence and to define optimal management of systolic dysfunction in males with DMD with hopes of extending survival.

Outcomes of Myocarditis in Patients with Normal Left Ventricular Systolic Function on Admission.

The objective of this study was to describe a cohort of patients with clinical myocarditis and normal left ventricular (LV) systolic function on admission. A retrospective chart review at seven tertiary pediatric hospitals identified patients aged < 19 years admitted with an ICD-9 code of myocarditis between 2008 and 2012. Patients were excluded if admission LV systolic ejection fraction was < 50%, fractional shortening (FS) was < 28% or if the admitting or consulting cardiologist did not suspect myocarditis. A total of 75 patients met inclusion criteria. The median age was 15.5 years with an Interquartile Range (IQR) of 13.6-16.6. 33% were female. Patients presented most commonly with chest pain (75%) and dyspnea (24%). On admission, median B-type natriuretic peptide (BNP) was 132 pg/mL (IQR 57-689) and median troponin I (TnI) was 8.4 ng/mL (IQR 2.0-20.3). Electrocardiogram revealed ST elevation in the majority (55%). Magnetic resonance imaging was obtained on 40%, with 63% of those showing evidence of inflammation. Therapies included inotropic support (15%), mechanical ventilation (12%), antiarrhythmic medications (9%), and Extracorporeal Membrane Oxygenation (5%). Those with poor outcomes were noted to have significantly higher BNP, TnI, and creatine kinase levels on presentation. One patient was transplanted and 35% were discharged on heart failure medications. At one year follow-up one patient had died of unspecified causes, 15% required readmission for cardiac reasons, and 21% continued on heart failure medications. The risk associated with clinical myocarditis in the setting of normal ventricular function at presentation may be higher than previously suspected.

Use of advanced heart failure therapies in Duchenne muscular dystrophy.

BACKGROUND: As survival and neuromuscular function in Duchenne Muscular Dystrophy (DMD) improve with glucocorticoid therapy and respiratory advances, the proportion of cardiac deaths is increasing. Little is known about the use and outcomes of advanced heart failure (HF) therapies in this population. METHODS: A retrospective cohort study of 436 males with DMD was performed, from January 1, 2005-January 1, 2018, with the primary outcome being use of advanced HF therapies including: implantable cardioverter defibrillator (ICD), left ventricular assist device (LVAD), and heart transplantation (HTX). RESULTS: Nine subjects had an ICD placed, 2 of whom (22.2%) had appropriate shocks for ventricular tachycardia; 1 and 968 days after implant, and all of whom were alive at last follow-up; median 18 (IQR: 12.5-25.5) months from implant. Four subjects had a LVAD implanted with post-LVAD survival of 75% at 1 year; 2 remaining on support and 1 undergoing HTX. One subject was bridged to HTX with ICD and LVAD and was alive at last follow-up, 53 months after HTX. CONCLUSION: Advanced HF therapies may be used effectively in select subjects with DMD. Further studies are needed to better understand risk stratification for ICD use and optimal candidacy for LVAD implantation and HTX, with hopes of improving cardiac outcomes.

Improved Survival While Waiting and Risk Factors for Death in Pediatric Patients Listed for Cardiac Transplantation.

Our aim is to determine (a) the effect of changes in pre-transplant management and era of listing on survival of children listed for HTx and (b) risk factors for death while waiting. This retrospective study included all children listed between 1/1993 and 12/2009 at our center. Survival was determined using survival analysis and competing outcomes modeling. There were 254 listed patients of whom 144 (57%) had congenital heart disease, 208 (82%) were status 1, 52 used ECMO (20%), and 28 used ventricular assist device support (VAD) (11%) beginning in 2005. Overall mortality while waiting was 17% at 6 months, and 69% underwent transplant. Seven of 95 patients (7%) died waiting after 2004 compared to 36 of 159 (23%) before. ECMO and earlier year of listing were significant risk factors (p < 0.001) for wait-list mortality, whereas mortality was significantly lower (p = 0.002) after availability of VADs. Race, gender, blood type, and congenital diagnosis were not significant risk factors for death. Survival in pediatric patients listed for HTx has improved significantly in the current era at our institution. The availability of pediatric VADs has had a significant impact on survival while waiting in children listed for transplantation.

Characteristics of Clinically Diagnosed Pediatric Myocarditis in a Contemporary Multi-Center Cohort.

The objective of this study was to describe a contemporary cohort of pediatric patients hospitalized for clinically suspected myocarditis. A retrospective chart review was performed at seven tertiary pediatric hospitals. Electronic medical records were searched between 2008 and 2012 for patients ≤18 years admitted with an ICD-9 code consistent with myocarditis. Patients were excluded if the admitting or consulting cardiologist did not suspect myocarditis during the admission or an alternative diagnosis was determined. One hundred seventy-one patients were discharged or died with a primary diagnosis of myocarditis. Median age was 13.1 years (IQR 2.1, 15.9), with a bimodal distribution; 24% <2 years and 46% between 13 and 18 years. Patients with moderate or severe systolic dysfunction were younger, had higher BNPs at admission, but had lower troponin. Mortality, heart transplantation, and readmission did not differ between patients who received only IVIG, only steroids, IVIG and steroids, and no immunotherapy. Ninety-four patients (55%) were discharged on heart failure medications, 16 were transplanted, and seven died. The presence at the time of admission of gastrointestinal (GI) symptoms (p = 0.01) and lower echo shortening fraction (SF) (p < 0.01) was associated with death/transplant. Within one year 16% had a readmission, one underwent heart transplant, and 39% received heart failure therapy. Pediatric myocarditis has a bimodal age distribution. The use of IVIG and steroids is not associated with mortality/heart transplantation. The presence of GI symptoms and lower echo SF may identify patients at risk for death and/or transplantation during the admission.

Longitudinal renal function in pediatric heart transplant recipients: 20-years experience.

This study was initiated to assess the temporal trends of renal function, and define risk factors associated with worsening renal function in pediatric heart transplant recipients in the immediate post-operative period. We performed a single-center retrospective study in children ≤18 yr receiving OHT (1993-2012). The AKIN's validated, three-tiered AKI staging system was used to categorize the degree of WRF. One hundred sixty-four patients qualified for inclusion. Forty-seven patients (28%) were classified as having WRF after OHT. Nineteen patients (11%) required dialysis after heart transplantation. There was a sustained and steady improvement in renal function in children following heart transplantation in all age groups, irrespective of underlying disease process. The significant factors associated with risk of WRF included body surface area (OR: 1.89 for 0.5 unit increase, 95% CI: 1.29-2.76, p = 0.001) and use of ECMO prior to and/or after heart transplantation (OR: 3.50, 95% CI: 1.51-8.13, p = 0.004). Use of VAD prior to heart transplantation was not associated with WRF (OR: 0.50, 95% CI: 0.17-1.51, p = 0.22). On the basis of these data, we demonstrate that worsening renal function improves early after orthotopic heart transplantation.

Heart Transplantation in the Short Term After Chemotherapy.

Anthracycline antibiotics are an effective therapy for a variety of neoplastic diseases. Dilated cardiomyopathy is a known risk of their use. Because of the risk of new or recurrent neoplasm with immunosuppression transplantation is often delayed. Our patient developed early cardiomyopathy with congestive heart failure 3 months after completion of chemotherapy. Given the severity of her cardiac symptoms the decision was made to proceed with heart transplantation in the short term after completion of her chemotherapy. We report the success to 1 year of this decision and discuss the implications of her genetic and oncologic diagnoses in this clinical scenario.

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

OBJECTIVES: Donor-specific cell-free DNA shows promise as a noninvasive marker for allograft rejection, but as yet has not been validated in both adult and pediatric recipients. The study objective was to validate donor fraction cell-free DNA as a noninvasive test to assess for risk of acute cellular rejection and antibody-mediated rejection after heart transplantation in pediatric and adult recipients. METHODS: Pediatric and adult heart transplant recipients were enrolled from 7 participating sites and followed for 12 months or more with plasma samples collected immediately before all endomyocardial biopsies. Donor fraction cell-free DNA was extracted, and quantitative genotyping was performed. Blinded donor fraction cell-free DNA and clinical data were analyzed and compared with a previously determined threshold of 0.14%. Sensitivity, specificity, negative predictive value, positive predictive value, and receiver operating characteristic curves were calculated. RESULTS: A total of 987 samples from 144 subjects were collected. After applying predefined clinical and technical exclusions, 745 samples from 130 subjects produced 54 rejection samples associated with the composite outcome of acute cellular rejection grade 2R or greater and pathologic antibody-mediated rejection 2 or greater and 323 healthy samples. For all participants, donor fraction cell-free DNA at a threshold of 0.14% had a sensitivity of 67%, a specificity of 79%, a positive predictive value of 34%, and a negative predictive value of 94% with an area under the curve of 0.78 for detecting rejection. When analyzed independently, these results held true for both pediatric and adult cohorts at the same threshold of 0.14% (negative predictive value 92% and 95%, respectively). CONCLUSIONS: Donor fraction cell-free DNA at a threshold of 0.14% can be used to assess for risk of rejection after heart transplantation in both pediatric and adult patients with excellent negative predictive value.

NTproBNP as a marker of rejection in pediatric heart transplant recipients.

Acute rejection is a major morbidity in heart transplant recipients; diagnosis is difficult, and rejection must often be treated reactively. Various serum biomarkers have been investigated for non-invasive monitoring of the cardiac allograft. NTproBNP is produced by the ventricular myocardium and may increase with evolving rejection allowing earlier diagnosis. Retrospective review of serum NTproBNP levels in pediatric heart transplant recipients has been carried out to evaluate the association with episodes of acute rejection. Repeated measures logistic regression was used to model associations for variables with first rejection and within an individual for change in NTproBNP and first rejection. Odds ratios for rejection risk given an increase in serum NTproBNP were calculated. Correlation of NTproBNP levels with renal function as estimated by modified Schwartz equation was performed to look for confounding. Higher serum NTproBNP level was associated with increased risk of rejection, but intersubject variability was wide. However, increase in an individual subject's serum level showed increased risk of rejection, greater with greater rise. Serum NTproBNP levels appear not greatly affected by renal function. NTproBNP shows promise in surveillance for pediatric heart transplant recipients. The greatest use appears to be in following trends for an individual instead of using an absolute value.

Relationship of ventricular assist device support duration with pediatric heart transplant outcomes.

BACKGROUND: There is wide variability in the timing of heart transplant (HTx) after pediatric VAD implant. While some centers wait months before listing for HTx, others accept donor heart offers within days of VAD surgery. We sought to determine if HTx within 30 days versus ≥ 30 after VAD impacts post-HTx outcomes. METHODS: Children on VAD pre-HTx were extracted from the Pediatric Heart Transplant Study database. The primary endpoints were post-HTx length of hospital stay (LOS) and one-year survival. Confounding was addressed by propensity score weighting using inverse probability of treatment. Propensity scores were calculated based on age, blood type, primary cardiac diagnosis, decade, VAD type, and allosensitization status. RESULTS: A total of 1064 children underwent VAD prior to HTx between 2000 to 2018. Most underwent HTx ≥ 30 days post-VAD (70%). Infants made up 22% of both groups. Patients ≥ 12 years old were 42% of the < 30 days group and children 1 to 11 years comprised 47% of the ≥ 30 days group (p < 0.001). There was no difference in the prevalence of congenital heart disease vs. cardiomyopathy (p = 0.8) or high allosensitization status (p = 0.9) between groups. Post-HTx LOS was similar between groups (p = 0.11). One-year survival was lower in the < 30 days group (adjusted mortality HR 1.76, 95% CI 1.11-2.78, p = 0.016). CONCLUSIONS: A longer duration of VAD support prior to HTx is associated with a one-year survival benefit in children, although questions of patient complexity, post-VAD complications and the impact on causality remain. Additional studies using linked databases to understand these factors will be needed to fully assess the optimal timing for post-VAD HTx.

Variable Presentation of COVID-19 in Pediatric Patients.

Infection by SARS-CoV-2 has led to disease referred to as coronavirus disease 2019 which, in children has been described as of multisystem inflammatory syndrome in children. Our experience demonstrates 2 distinct presentations of this syndrome which have different clinical courses and may have differing long-term outcomes.

Time-dependent action of carbon monoxide on the newborn cerebrovascular circulation.

Carbon monoxide (CO) causes cerebral arteriolar dilation in newborn pigs by the activation of large-conductance Ca(2+)-activated K(+) channels. In adult rat cerebral and skeletal muscle arterioles, CO has been reported to produce constriction caused by the inhibition of nitric oxide (NO) synthase (NOS). We hypothesized that, in contrast to dilation to acute CO, more prolonged exposure of newborn cerebral arterioles to elevated CO produces constriction by reducing NO. In piglets with closed cranial windows, pial arteriolar responses to isoproterenol (10(-6) M), sodium nitroprusside (SNP; 10(-7) and 3 x 10(-7) M), and L-arginine ethyl ester (L-Arg; 10(-5) and 10(-4) M) were determined before and after 2 h of treatment with CO. CO (10(-7) M) caused transient dilation and had no further effects. CO (2 x 10(-7) and 10(-6) M) initially caused vasodilation, but over the 2-h exposure, pial arterioles constricted and removal of the CO caused dilation. Exposure to elevated CO (2 h) did not alter dilation to SNP or isoproterenol. Conversely, the NOS substrate L-Arg caused dilation before CO that was progressively lost over 90 min of elevated CO. If NO was held constant, CO caused dilation that was sustained for 2 h. We conclude that in neonates, cerebral arteriole responses to CO are biphasic: dilation to acute elevation with subsequent constriction from NOS inhibition after more prolonged exposure. As a result, short episodic production of CO allows function as a dilator gasotransmitter, whereas prolonged elevation can reduce NO to elevate cerebrovascular tone. The interaction between heme oxygenase/CO and NOS/NO could form a negative feedback system in the control of cerebral vascular tone.

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

BACKGROUND: Endomyocardial biopsy (EMB) is the current standard for rejection surveillance in heart transplant recipients. The quantification of donor-specific cell-free DNA (cfDNA) may be an appropriate biomarker for non-invasive rejection surveillance. A multicenter prospective blinded study (DNA-Based Transplant Rejection Test, DTRT) investigated the value of donor fraction (DF), defined as the ratio of cfDNA specific to the transplanted organ to the total amount of cfDNA present in a blood sample. METHODS: A total of 241 heart transplant patients were recruited from 7 centers. Age at transplant ranged from 8 days to 73 years, with 146 subjects <18 years and 95 ≥18 years. All the patients were followed for at least 1 year, with blood samples drawn at routine and for-cause biopsies. A total of 624 biopsy-paired samples were included for analysis through a commercially available cfDNA assay (myTAIHEART, TAI Diagnostics Inc.). A blinded analysis of repeated measures compared the outcomes using receiver operating characteristic (ROC) curves. All primary clinical end-points were monitored at 100%. All analysis and conclusions were reviewed by both an independent external oversight committee and the National Institutes of Health-mandated DTRT steering committee. RESULTS: DF in acute cellular rejection (ACR) 1R/2R (n = 15) was higher than ACR 0R (n = 42) (p = 0.02); DF in antibody-mediated rejection pAMR1 (n = 8) and pAMR2 (n = 12) (p = 0.05) were higher than pAMR0 (n = 466) (p = 0.04 and p = 0.05 respectively). An optimal DF threshold was determined by the use of an ROC analysis, which ruled out the presence of either ACR or antibody-mediated rejection. CONCLUSIONS: The cell-free DNA DF holds promise as a non-invasive diagnostic test to rule out acute rejection in both adult and pediatric heart transplant populations.

Comparison of levalbuterol and racemic albuterol combined with ipratropium bromide in acute pediatric asthma: a randomized controlled trial.

Our study compared levalbuterol (LEV) to the combination of racemic albuterol (RAC) and ipratropium bromide (IB) in 140 patients aged 6-18 years presenting to a tertiary hospital Emergency Department with acute asthma and a peak expired flow rate (PEF)<80% predicted. Patients were randomized to: LEV (

Predictors of myocardial recovery in pediatric tachycardia-induced cardiomyopathy.

BACKGROUND: Tachycardia-induced cardiomyopathy (TIC) carries significant risk of morbidity and mortality, although full recovery is possible. Little is known about the myocardial recovery pattern. OBJECTIVE: The purpose of this study was to determine the time course and predictors of myocardial recovery in pediatric TIC. METHODS: An international multicenter study of pediatric TIC was conducted. Children ≤18 years with incessant tachyarrhythmia, cardiac dysfunction (left ventricular ejection fraction [LVEF] <50%), and left ventricular (LV) dilation (left ventricular end-diastolic dimension [LVEDD] z-score ≥2) were included. Children with congenital heart disease or suspected primary cardiomyopathy were excluded. Primary end-points were time to LV systolic functional recovery (LVEF ≥55%) and normal LV size (LVEDD z-score <2). RESULTS: Eighty-one children from 17 centers met inclusion criteria: median age 4.0 years (range 0.0-17.5 years) and baseline LVEF 28% (interquartile range 19-39). The most common arrhythmias were ectopic atrial tachycardia (59%), permanent junctional reciprocating tachycardia (23%), and ventricular tachycardia (7%). Thirteen required extracorporeal membrane oxygenation (n = 11) or ventricular assist device (n = 2) support. Median time to recovery was 51 days for LVEF and 71 days for LVEDD. Two (4%) underwent heart transplantation, and 1 died (1%). Multivariate predictors of LV systolic functional recovery were age (hazard ratio [HR] 0.61, P = .040), standardized tachycardia rate (HR 1.16, P = .015), mechanical circulatory support (HR 2.61, P = .044), and LVEF (HR 1.33 per 10% increase, p=0.005). For normalization of LV size, only baseline LVEDD (HR 0.86, P = .008) was predictive. CONCLUSION: Pediatric TIC resolves in a predictable fashion. Factors associated with faster recovery include younger age, higher presenting heart rate, use of mechanical circulatory support, and higher LVEF, whereas only smaller baseline LV size predicts reverse remodeling. This knowledge may be useful for clinical evaluation and follow-up of affected children.