BACKGROUND: Rejection remains a primary cause of graft loss after heart transplant (HT). Recognizing the immunomodulation of multi-organ transplant can enhance our understanding of the mechanisms of cardiac rejection.

METHODS: This retrospective cohort study identified patients from the UNOS database with isolated heart (H, N = 37 433), heart-kidney (HKi, N = 1516), heart-liver (HLi, N = 286), and heart-lung (HLu, N = 408) transplants from 2004 to 2019. Propensity score matching reduced baseline differences between groups. Outcomes included risk of rejection prior to transplant hospital discharge and within 1 year, and mortality within 1 year of transplant.

RESULTS: In the propensity score matched data, the relative risk of being treated for rejection prior to transplant hospital discharge was 61% lower for HKi (RR .39, 95% CI .29, .53) and 87% lower for HLi (RR .13, 95% CI .05, .37) compared to H. Similarly, the probability of being treated for rejection in the first year after transplant remained lower in HKi (RR .45, 95% CI .35, .57) and HLi (RR .13, 95% CI .06, .28) compared to H. The 1-year survival analysis revealed an equivalent risk of death in HKi (HR .84, 95% CI .68, 1.03) and HLi (HR 1.41, 95% CI .83, 2.41) compared to H, while HLu had a higher risk of death in the first year after transplant (HR 1.65, 95% CI 1.17, 2.33).

CONCLUSIONS: Recipients of HKi and HLi experience a reduced risk of rejection when compared to H, but an equivalent risk of 1 yr mortality. These findings have important implications for the future of HT medicine.

BACKGROUND: Pediatric heart transplantation (HT) is resource intensive. In adults, there has been an increase in the proportion of HTs funded by public insurance, with post-HT outcomes inferior to those funded by private sources. Trends in the funding of pediatric HT and outcomes in children have not been described.

METHODS: We queried the United Network for Organ Sharing (UNOS) database for children (<18 years) listed for and undergoing HT between 2004 and 2021. We identified the primary payer at listing, HT, 1 year, and 1-5 years following HT. Trends were analyzed using generalized logit models. Multivariable-extended Cox regression models were used to test the relationship between insurance type at the time of transplant and time to death or re-transplant.

RESULTS: There were 6382 pediatric patients who underwent transplants and had either public or private insurance at the time of transplant. The percentage of patients with public insurance at the time of HT increased over time. Public insurance at the time of HT was associated with an increased risk of death or re-transplant beyond 2 months after HT (adjusted HR at 6 months = 1.43, 95% CI: 1.13-1.81, p = .003; adjusted HR at 9 months = 1.67, 95% CI: 1.17-2.37, p = .004).

CONCLUSION: There has been a statistically significant trend toward increasing public insurance for children awaiting, at the time of, and after HT. Black patients and those with public insurance at HT have worse long-term outcomes. This study highlights ongoing disparities in pediatric HT and the need to focus efforts on achieving equitable outcomes.

Importance: The United Network for Organ Sharing (UNOS) evaluates donor risk for acute transmission of HIV, hepatitis B, or hepatitis C based on US Public Health Services (PHS)-specific criteria. However, recent data regarding use and outcomes of those donors with PHS risk criteria among pediatric and adult heart transplant recipients are lacking.

Objective: To compare use and outcomes of graft from donors with PHS risk criteria vs those with a standard-risk donor (SRD) in children vs adults in a contemporary cohort.

Design, Setting, and Participants: This cohort was a nationwide analysis of heart transplants in the US that used data from the UNOS database. Participants were children (<18 years old) and adults (≥18 years old) who received a heart transplant from January 1, 2010, to December 31, 2021.

Exposures: UNOS-defined donor risk status.

Main Outcomes and Measures: Trend analysis compared changes in PHS risk criteria use among children and adults. Patient survival was analyzed using Kaplan-Meier curves with log rank and Cox proportional hazards to compare PHS risk-criteria outcomes vs SRD-criteria outcomes in children and adult heart transplant recipients. Additional analysis was performed among adults who received a PHS-risk criteria graft that was previously declined for pediatric recipients.

Results: Of 5115 pediatric transplant recipients (donor without PHS risk median [IQR] age, 5 [0-13] years and donor with PHS risk median [IQR] age, 8 [0-14] years) and 30 289 adult heart transplant recipients (donor without PHS risk median [IQR] age, 56 [46-63] years and donor with PHS risk median [IQR] age, 57 [47-63] years), PHS risk criteria comprised 8% in children vs 25% in adults. PHS criteria are being increasingly used over the past decade with the proportion of recipients transplanted with PHS risk-criteria donors being approximately 3 times greater among adult recipients than children recipients. Pediatric recipients of a PHS risk-criteria donor had greater pretransplant ventilatory support, whereas adult recipients of a PHS risk-criteria donor had greater pretransplant extracorporeal membrane oxygenation use. Patient survival was similar between pediatric recipients of PHS risk-criteria grafts vs SRD-criteria grafts and slightly higher among adult recipients of PHS risk-criteria grafts vs SRD-criteria grafts. The 1778 adult recipients who received a PHS criteria-risk donor that was previously declined for pediatric recipients had similar patient survival recipients compared with SRD-criteria donors (HR, 0.92; 95% CI, 0.81-1.03; P = .18).

Conclusions and Relevance: In the current era, a 3-fold greater proportion of adult recipients receive a PHS risk-criteria graft compared with children despite similar posttransplant patient survival. The ongoing organ donor shortage underscores the need for consideration of PHS risk criteria where these donors remain underused.

MYH7, encoding the myosin heavy chain sarcomeric β-myosin heavy chain, is a common cause of both hypertrophic and dilated cardiomyopathy. Additionally, families with left ventricular noncompaction cardiomyopathy (LVNC) and congenital heart disease (CHD), typically septal defects or Ebstein anomaly, have been identified to have heterozygous pathogenic variants in MHY7. One previous case of single ventricle CHD with heart failure due to a MYH7 variant has been identified. Herein, we present a single center's experience of complex CHD due to MYH7 variants. Three probands with a history of CHD, LVNC, and/or arrhythmias were identified to have MYH7 variants through multigene panel testing or exome sequencing. These three patients collectively had 12 affected family members, four with a history of Ebstein anomaly and seven with a history of LVNC. These findings suggest a wider phenotypic spectrum in MYH7-related CHD than previously understood. Further investigation into the possible role of MYH7 in CHD and mechanism of disease is necessary to fully delineate the phenotypic spectrum of MYH7-related cardiac disease. MYH7 should be considered for families with multiple individuals with complex CHD in the setting of a family history of LVNC or arrhythmias.

Serum troponin (Tn) is often elevated in viral myocarditis; however, its prognostic significance is unknown. We tested the hypothesis that abnormal serum Tn is associated with mortality in children hospitalized with myocarditis. We retrospectively studied data from six large children's hospitals participating in the Pediatric Health Information System Plus (PHIS+) database. Analysis was performed on patients hospitalized with viral myocarditis between 2007 and 2013, in whom at least one Tn was recorded within 72 h of admission. Abnormal baseline Tn was defined as any value outside the upper limit of normal within the first 72 h. Primary outcome was mortality. Secondary outcomes included mechanical support, defined as use of extracorporeal membrane oxygenation (ECMO) or a ventricular assist device (VAD), cardiac transplantation, intravenous immunoglobulin (IVIg), mechanical ventilation, and inotrope use. A total of 149 patients with myocarditis (61% male, 48% adolescents) across all PHIS+ centers had TnI (n = 113) or TnT (n = 36) recorded. At least one abnormal Tn was present in 81% of cases. Overall mortality was 7.3% and was not associated with abnormal baseline Tn. Abnormal baseline Tn was associated with ECMO (7.1 vs. 25.6%, p = 0.03) and IVIg (46.4 vs. 83.5%, p < 0.001). Abnormal baseline Tn was not associated with transplantation, mechanical ventilation or inotrope use. Abnormal Tn in the first 72 h of hospitalization for myocarditis was associated with the use of ECMO and IVIg, but was not associated with mortality. This finding may help risk stratify this population if it can be prospectively validated.

<p>Children with advanced heart failure may require ventricular assist devices (VAD) while awaiting heart transplantation. Currently, no data exist regarding the safety of exercise rehabilitation (ER) in children on VAD support. The purpose of this study was to determine the safety and feasibility of ER in children on VAD support awaiting heart transplantation. Eligible patients underwent VAD placement between 1998 and 2019; both inpatient and outpatient participants were included. After VAD implantation and when ambulatory, patients were enrolled in ER. Exercise sessions were scheduled three times a week and consisted of aerobic and musculoskeletal conditioning. A total of 29 patients (59% male, mean age 14 ± 3.2&nbsp;years) were included with a median VAD duration of 120 ± 109&nbsp;days. Cardiac diagnoses included cardiomyopathy (81%) and congenital heart disease (19%). VAD type included pulsatile (59%) and continuous-flow devices (41%). Eight hundred and sixty-four (85%) ER sessions were successfully completed and began at a mean of 49&nbsp;days (range 19-108) after VAD implant. No adverse events, including episodes of hypotension, significant complex arrhythmia, or VAD malfunction occurred during exercise testing or ER, and no sessions were discontinued prematurely. Pediatric patients on VAD support can safely participate in ER with relatively high compliance, and sessions can be implemented early after VAD implantation. Given the safety profile, ER in pediatric VAD recipients, which is a modifiable pre-transplant risk factor that may improve functional capacity, warrants further study as a potential modality to improve post-transplant outcomes.</p>

<p><strong>Background</strong> The past decade has seen tremendous growth in patients with ambulatory ventricular assist devices. We sought to identify patients that present to the emergency department (ED) at the highest risk of death. <strong>Methods and Results</strong> This retrospective analysis of ED encounters from the Nationwide Emergency Department Sample includes 2010 to 2017. Using a random sampling of patient encounters, 80% were assigned to development and 20% to validation cohorts. A risk model was derived from independent predictors of mortality. Each patient encounter was assigned to 1 of 3 groups based on risk score. A total of 44&nbsp;042 ED ventricular assist device patient encounters were included. The majority of patients were male (73.6%), &lt;65&nbsp;years old (60.1%), and 29% presented with bleeding, stroke, or device complication. Independent predictors of mortality during the ED visit or subsequent admission included age ≥65&nbsp;years (odds ratio [OR], 1.8; 95% CI, 1.3-4.6), primary diagnoses (stroke [OR, 19.4; 95% CI, 13.1-28.8], device complication [OR, 10.1; 95% CI, 6.5-16.7], cardiac [OR, 4.0; 95% CI, 2.7-6.1], infection [OR, 5.8; 95% CI, 3.5-8.9]), and blood transfusion (OR, 2.6; 95% CI, 1.8-4.0), whereas history of hypertension was protective (OR, 0.69; 95% CI, 0.5-0.9). The risk score predicted mortality areas under the curve of 0.78 and 0.71 for development and validation. Encounters in the highest risk score strata had a 16-fold higher mortality compared with the lowest risk group (15.8% versus 1.0%). <strong>Conclusions</strong> We present a novel risk score and its validation for predicting mortality of patients with ED ventricular assist devices, a high-risk, and growing, population.</p>

<p>The relationship between center-specific variation in indication for pediatric heart transplantation and short-term outcomes after heart transplantation is not well described. We used merged patient- and hospital-level data from the United Network for Organ Sharing and the Pediatric Health Information Systems to analyze outcomes according to transplant indication for a cohort of children (≤ 21&nbsp;years old) who underwent heart transplantation between 2004 and 2015. Outcomes included 30-day mortality, transplant hospital admission mortality, and hospital length of stay, with multivariable adjustment performed according to patient and center characteristics. The merged cohort reflected 2169 heart transplants at 20 U.S. centers. The median number of transplants annually at each center was 11.6, but ranged from 3.5 to 22.6 transplants/year. Congenital heart disease was the indication in the plurality of cases (49.2%), with cardiomyopathy (46%) and myocarditis (4.8%) accounting for the remainder. There was significant center-to-center variability in congenital heart disease as the principal indication, ranging from 15% to 66% (P &lt; 0.0001). After adjustment, neither center volume nor proportion of indications for transplantation were associated with 30-day or transplant hospital admission mortality. In this large, merged pediatric cohort, variation was observed at center level in annual transplant volume and prevalence of indications for heart transplantation. Despite this variability, center volume and proportion of indications represented at a given center did not appear to impact short-term outcomes.</p>

<p>There are minimal data describing outcomes in ambulatory pediatric and young adult ventricular assist device (VAD)-supported patient populations. We performed a retrospective analysis of encounter-level data from 2006 to 2017 Nationwide Emergency Department Sample (NEDS) to compare emergency department (ED) resource utilization and outcomes for pediatric (≤18 years, n = 494) to young adult (19-29 years, n = 2,074) VAD-supported patient encounters. Pediatric encounters were more likely to have a history of congenital heart disease (11.3% vs. 4.8%). However, Pediatric encounters had lower admission/transfer rates (37.8% vs. 57.8%) and median charges ($3,334 (IQR $1,473-$19,818) vs. $13,673 ($3,331-$45,884)) (all p &lt; 0.05). Multivariable logistic regression modeling revealed that age itself was not a predictor of admission, instead high acuity primary diagnoses and medical complexity were: (adjusted odds ratio; 95% confidence intervals): cardiac (3.0; 1.6-5.4), infection (3.4; 1.7-6.5), bleeding (3.9; 1.7-8.8), device complication (7.2; 2.7-18.9), and ≥1 chronic comorbidity (4.1; 2.5-6.7). In this largest study to date describing ED resource use and outcomes for pediatric and young adult VAD-supported patients, we found that, rather than age, high acuity presentations and comorbidities were primary drivers of clinical outcomes. Thus, reducing morbidity in this population should target comorbidities and early recognition of VAD-related complications.</p>