Impact of center volume on outcomes after ventricular assist device implantation in pediatric patients: An analysis of the STS-Pedimacs database.

BACKGROUND: To date, no pediatric studies have highlighted the impact of center's ventricular assist device (VAD) volumes on post implant outcomes. METHODS: Children (age <19) enrolled in Pedimacs undergoing initial left ventricular assist device implantation from 2012 to 2020 were included. Center volume was analyzed as a continuous and categorical variable. For categorical analysis, center volumes were divided as: low volume (1-15 implants), medium volume (15-30 implants), and high volume (>30 implants) during our study period. Patient characteristics and outcomes were compared by center's VAD volumes. RESULTS: Of 44 centers, 16 (36.4%) were low, 11 (25%) were medium, and 17 (38.6%) were high-volume centers. Children at high-volume centers were least likely intubated, sedated, or paralyzed, and most likely ambulating preimplant (p < 0.05 for all). Center's VAD volumes were not a significant risk factor for mortality post implant when treated as a continuous or a categorical variable (p > 0.05). Compared to low volume, children at high-volume centers had fewer early neurological events. Compared to medium volume, those at high-volume centers had fewer late bleeding events (p < 0.05 for all). There were no significant differences in survival after an adverse event by hospital volumes (p > 0.05). CONCLUSIONS: Although hospital volume does not affect post-VAD implant mortality, pediatric centers with higher VAD volumes have fewer patients intubated, sedated, paralyzed pre implant, and have lower adverse events. Failure to rescue was not significantly different between low, medium, and high-volume VAD centers.

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

BACKGROUND: Cardiac allograft vasculopathy (CAV) is a leading cause of graft failure in pediatric heart transplant recipients (HTRs). Early statin use has been shown to reduce CAV incidence and all-cause mortality in adult HTRs. We sought to evaluate the contemporary prevalence and trends of statin use in pediatric HTRs and the association between statin use with CAV development and graft failure. METHODS: Patients aged <17 years at the time of primary heart transplant who survived to ≥3 years without CAV were identified from the Pediatric Heart Transplant Society database (2001-2018). Statin use in the first 3 years posttransplant was defined as consecutive, intermediate, or absent. Kaplan-Meier survival, multivariable modeling, and propensity score-matched analyses evaluated associations between statin use and CAV incidence and graft survival, with subanalyses performed on subjects aged ≥10 years at transplant. RESULTS: Among 3,485 (of which 1,086 aged ≥10 years) HTRs, 584 (17%) received consecutive statin therapy, 647 (19%) received intermediate use, and 2,254 (65%) received no statin therapy. Statin use varied widely between sites, with increasing use in the ≥10-year-old cohort over time. By multivariate analysis, statin use was not associated with graft loss. Consecutive statin use was also not associated with graft survival or freedom from CAV development when compared to absent statin use in unmatched or propensity-matched analyses. CONCLUSIONS: While statins remain commonly utilized in pediatric HTRs, early consecutive statin therapy did not decrease CAV incidence or graft loss. The differing effects of statins on CAV development and progression in pediatric vs adult HTRs suggest differing risk and mediating factors and require further study.

Fetal Left Ventricular Apical Aneurysm Progressing to Dilated Cardiomyopathy Due to Glycogen Storage Disease.

Fetal dilated cardiomyopathy is a rare anomaly characterized by ventricular dilation and dysfunction. Its causes are diverse, and its outcomes are generally dismal. We describe a rare case of prenatally diagnosed left ventricular apical aneurysm that progressed rapidly to dilated cardiomyopathy. At age 2 months, the infant underwent heart transplantation. Pathologic examination of the explanted heart revealed that the cause of the dilated cardiomyopathy was glycogen storage disease. This case highlights the crucial roles of timely diagnosis, frequent close monitoring, and multidisciplinary care in achieving a successful postnatal outcome.

Outcomes of infants with pulmonary atresia with intact ventricular septum listed for heart transplantation: A multi-institutional study.

BACKGROUND: Management of infants with pulmonary atresia/intact ventricular septum (PA/IVS) is variable. Because of higher mortality in more severe forms, heart transplant (HT) is an acceptable approach, but waitlist and post-transplant outcomes are unclear. This study compared outcomes of infants with PA/IVS vs. other single ventricle (SV) anatomies listed for HT. METHODS: Data from the Pediatric Heart Transplant Society (1993-2018) were analyzed for survival and risk factors for mortality. RESULTS: Of 1617 SV infants, 300 had PA/IVS (19%) and 1317 had other SV (81%). Overall, 1-, 5-, and 10-year survival was higher among PA/IVS (74%, 65%, 61%) versus other SV infants (62%, 54%, 50%, p = .004). While waitlist mortality was similar between groups (p = .09), PA/IVS was an independent predictor of improved waitlist survival (HR 0.68, p = .03), and PA/IVS infants had higher incidence of waitlist removal (8% vs. 5.5%, p = .03), most commonly for being "too well." Post-transplant survival was superior among PA/IVS versus other SV infants (1- and 5-year survival 93% and 81% vs. 80% and 71%, p < .0001). Risk factors for PA/IVS waitlist mortality (2008-2018) included extracorporeal membrane oxygenation and mechanical ventilation. Prior aortopulmonary (AP) shunt among PA/IVS infants was associated with improved waitlist survival. CONCLUSIONS: Overall survival among PA/IVS infants listed for HT exceeds that of other SV infants with PA/IVS identified as an independent predictor of improved waitlist and post-transplant survival. Prior AP shunt among listed PA/IVS infants was associated with improved waitlist outcomes, though, which may reflect a listing selection bias.

Waitlist Outcomes for Children With Congenital Heart Disease: Lessons Learned From Over 5000 Heart Transplant Listings in the United States.

BACKGROUND: We evaluated the impact of pediatric heart-allocation policy changes over time and the approval of the Berlin ventricular assist device (VAD) on waitlist (WL) outcomes for children with congenital heart disease (CHD). METHODS: The Scientific Registry of Transplant Recipients database was evaluated to include all children (age < 18) with CHD and cardiomyopathy (CMP) on the WL between 1999 and 2019, divided into 4 eras: Era 1 (1999-2008); Era 2 (2009-2011); Era 3 (2012-2016); and Era 4 (2016-2019). WL characteristics and survival outcomes were evaluated for patients with CHD over time and were compared to those with CMP listed currently (Era 4). RESULTS: We included 5185 children with CHD on the WL during the study period; 1999 (39%) were listed in Era 1; 693 (13%) in Era 2; 1196 (23%) in Era 3; and 1297 (25%) in Era 4. Compared to the CHD WL in eras 1 and 2, those in Era 4 were less likely to be infants (48% vs 49% vs 43%), on mechanical ventilation (30% vs 26% vs 19%), on extracorporeal membrane oxygenation (15% vs 9.7% vs 6.2%), and were more likely to be on a VAD (2.4% vs 2.2% vs 6.0%) (P < .05 for all). WL survival improved in children with CHD from Era 1 to Era 4 (P < .001). However, in Era 4, children with CHD had lower WL survival than those with CMP (P < .001). CONCLUSION: Children with CHD are increasingly being listed with less advanced heart failure, and they have had improved WL survival over time; however, WL outcomes remain inferior to those with CMP. Advances in pediatric medical and VAD therapy may improve future WL outcomes.

Sex disparities in the current era of pediatric heart transplantation in the United States.

BACKGROUND: While sex-related differences in transplant outcomes have been well characterized amongst adults, there are no sex-specific pediatric heart transplant studies over the last decade and none evaluating waitlist outcomes. In a contemporary cohort of children undergoing heart transplantation in the United States, this analysis was performed to determine if there were sex disparities in waitlist and/or post-transplant outcomes. METHODS: Retrospective review of Scientific Registry of Transplant Recipients database from December 16, 2011 to February 28, 2019 to compare male and female children after listing and after transplant. Demographic, clinical characteristics and outcomes were compared unadjusted and after 1:1 propensity matching for selected covariates. RESULTS: Of 4089 patients, 2299 (56%) were males. At listing, males were more likely to be older, have congenital heart disease (58% vs 48%), renal dysfunction (49% vs 44%) and implantable cardioverter defibrillator (9% vs 7%). At transplant, males were more likely to have renal (42 % vs 35%) and liver dysfunction (13% vs 10%), PRA >10% (29% vs 22%) and ischemic time >3.5 hours (p < 0.05 for all). There were no significant sex differences found in unadjusted rates of transplant or mortality. After propensity matching, females had increased waitlist mortality (HR 1.3, 95%CI 1.04-1.5; p =0.019) compared to males. There were no significant differences in post-transplant morbidity or mortality (HR 1.2, 95% CI 0.93-1.5; p = 0.18) between groups. CONCLUSION: In a contemporary pediatric cohort, females have inferior heart transplant waitlist survival compared to propensity-matched males despite lower acuity of illness at listing and similar rates of transplantation. There were no sex-disparities noted in post-transplant outcomes.

Temporary Veno-Venous ECMO for Acute Respiratory Illness in Pediatric Berlin Heart Patient.

We report the unique case of a 2-year-old male with severe heart failure requiring mechanical circulatory support with a left ventricular assist device, who developed adenovirus pneumonitis infection requiring veno-venous extracorporeal membrane oxygenation (ECMO) support. He progressed to acute respiratory failure and refractory hypoxemia despite intubation with maximum respiratory support. The patient was placed on ECMO with improvement in lung function over four days with subsequent successful decannulation. During the ECMO run, anticoagulation required escalation given the increased circuit surface area. Patient has since recovered and undergone heart transplantation.

Significance of pre and post-implant MELD-XI score on survival in children undergoing VAD implantation.

BACKGROUND: Derangements in liver and renal function often accompany end-stage heart failure. We sought to assess the utility of an objective risk assessment tool, the Model for End-stage Liver Disease eXcluding INR (MELD-XI), to identify pediatric patients at increased risk for adverse outcomes post-ventricular assist device (VAD) implantation. METHODS: The Pedimacs database was queried for all pediatric patients who underwent VAD implantation from September 19, 2012 to December 31, 2019. Pre-implant and early (1-week) post-implant MELD-XI scores were used to stratify patients into low, intermediate and high score cohorts. Comparison of pre-implant characteristics and post-implant outcomes were conducted across groups. Multiphase parametric hazard modeling was utilized to identify independent predictors of post-implant mortality. RESULTS: A total of 742 patients had a calculable MELD-XI score pre-implant. When stratified by MELD-XI scores pre-implant, patients in the high MELD-XI score cohort (score >13.6) had inferior survival and increased bleeding, renal dysfunction and respiratory failure post-implant compared to intermediate and low score cohorts. Risk factors for mortality post-VAD implantation were: increasing MELD-XI scores (HR 1.1 per 1 unit rise), Pedimacs profile 1 (HR 1.6), congenital heart disease (HR 2.3) and being on a percutaneous VAD (HR 2.7). Importantly, MELD-XI score was a better predictor of post-VAD implant mortality than bilirubin or creatinine alone, neither of which were significant in the final model. Patients with increasing or continued high MELD-XI scores early post-implant had the worst survival. CONCLUSION: The MELD-XI is an easily calculated score that serves as a promising risk assessment tool in identifying children at risk for poor outcomes post VAD implantation.

Racial and Ethnic Disparities Persist in the Current Era of Pediatric Heart Transplantation.

BACKGROUND: Previous studies have demonstrated that children in the United States who were of racial and ethnic minorities have inferior waitlist and post-heart transplant (HT) outcomes. Whether these disparities still exist in the contemporary era of increased ventricular assist device use remains unknown. METHODS: All children (age <18 years) in the Scientific Registry of Transplant Recipients database listed for HT from December 2011 to February 2019 were included and were separated into 5 races/ethnicities: Caucasian, African American, Hispanic, Asian, and Other. Differences in clinical characteristics and survival among children of different racial/ethnic groups were compared at listing and at HT. RESULTS: The waitlist cohort consisted of 2134 (52.2%) Caucasian, 840 (20.5%) African American, 808 (19.8%) Hispanic, 161 (3.9%) Asian, and 146 children of Other races (3.6%). At listing, Asian children mostly had cardiomyopathy (70.8%), whereas Caucasian children had congenital heart disease (58.7%). African American children were most likely to be listed as Status 1A and to have renal dysfunction and hypoalbuminemia at listing. African American and Hispanic children were most likely to be on Medicaid. After multivariable analysis, it was found that only African American children were at increased risk for waitlist mortality as compared to Caucasian children (adjusted hazard ratio = 1.25; P = 0.029). Post-HT, there were no disparities in early and midterm graft survival among groups, but African American children had increased numbers of rejection episodes compared to Caucasian and Hispanic children. CONCLUSION: African American children continue to experience increased waitlist mortality and have increased rejection episodes post-HT. Studies exploring barriers to health care access and implicit bias as reasons for these disparities need to be conducted.

Association of low center performance evaluations and pediatric heart transplant center behavior in the United States.

BACKGROUND: To date, no study has evaluated the effects of low center performance evaluations (CPE) on pediatric heart transplant center behavior. We sought to assess the impact of low CPE flags on pediatric heart transplant center listing and transplant volumes and center recipient and donor characteristics. METHODS: We included centers performing at least 10 pediatric (age <18 years) transplants during the Scientific Registry of Transplant Recipients reporting period January 2009-June 2011 and evaluated consecutive biannual program specific reports until the last reporting period January 2016-June 2018. We evaluated changes in center behavior at following time points: a year before flagging, a year and two years after the flag; and at last reporting period. RESULTS: During our study period, 24 pediatric centers were non-flagged and 6 were flagged. Compared to non-flagged centers, there was a decline in candidate listings in flagged centers at the last reporting period (mean increase of 5.5 ± 12.4 listings vs"?> mean decrease of 14.0 ± 14.9 listings; p = .003). Similarly, the number of transplants declined in flagged centers (mean increase of 2.6 ± 9.6 transplants vs"?> mean decrease of 10.0 ± 12.8 transplants; p = .012). Flagged centers had declines in listings for patients with restrictive cardiomyopathy, re-transplant, renal dysfunction, those on mechanical ventilation and extracorporeal membrane oxygenation. There was no significant change in donor characteristics between flagged and non-flagged centers. CONCLUSIONS: Low CPE may have unintended negative consequences on center behavior leading to declines in listing and transplant volumes and potentially leading to decreased listing for higher risk recipients.

Waitlist and Post-Heart Transplant Outcomes for Children with Kawasaki Disease in the United States.

We evaluated waitlist and post-heart transplant outcomes for children with Kawasaki disease and found that over 3 decades the number of patients requiring heart transplantation in the US is low. Also, patients with Kawasaki disease have similar waitlist and post-transplant outcomes compared with patients with dilated cardiomyopathy.

Waitlist and Post-Heart Transplant Outcomes for Children With Nondilated Cardiomyopathy.

BACKGROUND: Although outcomes for pediatric cardiomyopathy (CMP) patients have improved, an understanding of outcomes by CMP phenotype is essential. This study assessed changes in waitlist and post-transplant survival in nondilated cardiomyopathy (DCM) patients over 2 decades, explored ventricular assist device (VAD) utilization in this cohort, and identified risk factors for waitlist and posttransplant mortality in the current era. METHODS: Pediatric patients with a diagnosis of CMP listed for heart transplantation during three eras: Era 1: March 5, 1999 to December 31, 2004; Era 2: January 1, 2005 to December 15, 2011; and Era 3 (current era): December 16, 2011 to February 28, 2018 were included. Multivariable Cox proportional hazards regression was performed to assess waitlist and posttransplant survival. RESULTS: Compared with patients with DCM, those with hypertrophic and restrictive cardiomyopathy in the current era are less likely to be on VAD (23.4% vs 2.7% vs 4.5%); listed United Network for Organ Sharing Status 1A (75.6% vs 39.8% vs 34.8%), and more likely to have longer waitlist times (P < .01 for all). Only 3.3% hypertrophic and 2.4% restrictive cardiomyopathy patients had VAD implantation, although VAD use did not adversely impact waitlist survival in weighted non-DCM patients. Significant improvements have occurred in waitlist survival of hypertrophic and posttransplant survival of both types of non-DCM patients. CONCLUSIONS: Currently, waitlist and posttransplant survival is similar for all CMP phenotypes. VAD use is low in patients with non-DCM, although this did not increase waitlist mortality in adjusted analysis. Further studies in patients with non-DCM are needed to determine optimal timing and anatomic characteristics most likely to benefit from VAD implantation during the waitlist period.

Arrhythmias and fasciculoventricular pathways in patients with Danon disease: A single center experience.

BACKGROUND: Danon disease is a rare X-linked storage disorder characterized by hypertrophic cardiomyopathy leading to arrhythmias and heart failure. A preexcitation pattern on electrocardiogram (ECG) has been described in these patients, however, invasive studies to distinguish between Wolff-Parkinson-White syndrome syndrome and fasciculoventricular pathways (FVP) are limited. OBJECTIVES: The purpose of this study was to delineate the electrophysiological cardiac abnormalities in patients with Danon disease and to describe the presence of FVP in this population. METHODS: We performed a retrospective study of all patients with a confirmed diagnosis of Danon disease presenting to a single center from May 2005 to May 2018. Baseline demographics, clinical characteristics, ECG findings, and electrophysiology study (EPS) results were collected. RESULTS: Ten patients with Danon disease (30% male, average age 17.4 years) were identified. Seven patients (70%) had tachyarrhythmias including five with atrial arrhythmias and six with nonsustained ventricular tachycardia. Preexcitation pattern on ECG was found in four (40%) patients. Of these, two underwent an EPS which confirmed the presence of an FVP. One patient underwent an adenosine challenge which supported a FVP. Implantable cardioverter defibrillator was placed in five patients for primary prevention with no patients receiving an appropriate discharge. Over a follow-up of 5.3 years, five underwent heart transplantation. CONCLUSIONS: This study reports a high incidence of FVP in patients with Danon disease and preexcitation. It underscores an alternate etiology of preexcitation in this population which can potentially be diagnosed without invasive EPS testing. Future multicenter studies are needed to expand this experience.

When a Child Needs a Transplant but Lacks Familial Social Support.

We present the case of a 19-month-old boy with complex congenital heart disease. His single father is skeptical of traditional medicine and does not offer the social support needed to make heart transplantation successful for his son. After the father demonstrates commitment to transplant success and provides enhanced social support, doctors place the child on a Berlin Heart (a biventricular assist device) as a bridge to transplantation and list him for transplant. When the child is matched to a donor heart, the father refuses transplantation, despite that it is the child's only chance for survival. His doctors report the case to child protective services, but they decline to take protective custody. The father then changes his mind and asks that the child be put back on the waiting list for transplant. By this time, the social supports the father implemented are no longer in place. This case raises a number of issues. First, should courts order heart transplantation when doctors believe that it is in the child's best interest and parents do not consent? Second, once parents refuse a transplant, can they change their minds? Third, if there are uncertainties regarding whether the child has the social support to make transplantation successful, should the child be relisted? Finally, should a child who is not currently a transplant candidate but who may become one in the future be supported with ventricular assist devices?

Radiation Reduction in the Pediatric Catheterization Laboratory Using a Novel Imaging System.

OBJECTIVES: Radiation dose was compared between two modern imaging systems with different x-ray tube technology (Megalix vs Gigalix) and detector type (amorphous vs crystalline silicon) at the same institution. BACKGROUND: Further reduction in radiation dose than currently reported may be achievable with advances in x-ray tube and detector technology. METHODS: Radiation dose (air kerma, dose-area product [DAP]) was retrospectively compared for post-transplant pediatric patients undergoing right heart catheterization/biopsy (fluoroscopy only) or "annual" catheterization with coronary angiography in one of two imaging systems between January 2014 and December 2016. Comparisons were also made with published radiation doses. RESULTS: A total of 122 right heart catheterizations with biopsy were performed in the Megalix/amorphous silicon (Si) lab and 168 in the Gigalix/crystalline Si lab. Age and weight were not statistically different for the two groups. There was a 50% decrease in median air kerma (2.2 mGy vs 1.1 mGy; P<.001) and 66% decrease in median DAP (52.2 µGy•m² vs 18.0 µGy•m²; P<.001) for the Gigalix/crystalline Si lab. A total of 24 "annual" catheterizations were performed in the Megalix/amorphous Si lab and 22 were performed in the Gigalix/crystalline Si lab. There was a 57% reduction in median air kerma (458.6 mGy vs 198.6 mGy; P<.001) and a 46% reduction in median DAP (2548.0 µGy•m² vs 1367.1 µGy•m²; P<.01) for the Gigalix/crystalline Si lab. Similar reductions were found on comparison with published doses. CONCLUSION: The Gigalix tube and crystalline Si detector decrease radiation dose by 50%-60% for fluoroscopy and cine acquisition in pediatric patients.

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.

Cancer recurrence and mortality after pediatric heart transplantation for anthracycline cardiomyopathy: A report from the Pediatric Heart Transplant Study (PHTS) group.

We aimed to determine whether malignancy after pediatric HTx for ACM affects overall post-HTx survival. Patients <18y listed for HTx for ACM in the PHTS database between 1993 and 2014 were compared to those with DCM. A 2:1 matched DCM cohort was also compared. Wait-list and post-HTx survival, along with freedom from common HTx complications, were compared. Eighty subjects were listed due to ACM, whereas 1985 were listed for DCM. Although wait-list survival was higher in the ACM group, post-HTx survival was lower for the ACM cohort. Neither difference persisted in the matched cohort analysis. Primary cause of death in the ACM group was infection, which was higher than the DCM group. Malignancy rates were not different. All ACM malignancies were due to PTLD without primary cancer recurrence or SMN. Long-term graft survival after pediatric HTx for ACM is no different than for matched DCM peers, nor is there an increased risk of any malignancy. However, risk of infection and death from infection after HTx are higher in the ACM group. Further studies are needed to assess the effects of prior chemotherapy on susceptibility to infection in this group.

Protein Losing Enteropathy After Cardiac Transplantation Successfully Treated by Stent Implantation.

Protein losing enteropathy (PLE) is a severe consequence of Fontan physiology that sometimes requires heart transplantation for definitive treatment. We describe transplant refractory PLE in a patient with heterotaxia and complex systemic and hepatic venous connections, successfully treated by transcatheter relief of multiple venous obstructions.

Use of sirolimus in pediatric heart transplant patients: A multi-institutional study from the Pediatric Heart Transplant Study Group.

BACKGROUND: Proliferation signal inhibitors, such as sirolimus, are increasingly used in solid-organ transplantation. However, limited data exist on sirolimus-treated pediatric patients. We aimed to describe sirolimus use in pediatric heart transplant patients and test the hypothesis that sirolimus use is associated with improved outcomes. METHODS: A retrospective review and propensity-matched analysis of the Pediatric Heart Transplant Study database was performed on patients undergoing primary heart transplantation from 2004 to 2013 with at least 1 year of follow-up comparing patients treated vs not treated with sirolimus at 1 year after transplant. The primary outcome of interest was patient survival, with secondary outcomes including cardiac allograft vasculopathy, rejection, malignancy, and renal insufficiency. RESULTS: Between 2004 and 2013, 2,531 patients underwent transplantation. At least 1 year of follow-up was available for 2,080 patients, of whom 144 (7%) were on sirolimus at 1 year post-transplant. Sirolimus-treated and non-treated patients had similar survival in the overall cohorts and in the propensity-matched analysis. The secondary outcomes measures were also similar, including a composite end point of all outcome measures. There was a trend toward increased time to cardiac allograft vasculopathy (p = 0.09) and decreased time to infection (p = 0.05) among sirolimus-treated patients in the overall cohort (p = 0.19) but not in the propensity-matched cohort (p = 0.17). CONCLUSIONS: Sirolimus was used in less than 10% of patients at 1 year post-transplant. Overall outcomes of sirolimus treated and non-treated patients were similar with respect to survival and major transplant adverse events. Further study of sirolimus in pediatric heart transplant patients is needed.