Practice variation in the diagnosis of acute rejection among pediatric heart transplant centers: An analysis of the pediatric heart transplant society (PHTS) registry.

BACKGROUND: Freedom from rejection in pediatric heart transplant recipients is highly variable across centers. This study aimed to assess the center variation in methods used to diagnose rejection in the first-year post-transplant and determine the impact of this variation on patient outcomes. METHODS: The PHTS registry was queried for all rejection episodes in the first-year post-transplant (2010-2019). The primary method for rejection diagnosis was determined for each event as surveillance biopsy, echo diagnosis, or clinical. The percentage of first-year rejection events diagnosed by surveillance biopsy was used to approximate the surveillance strategy across centers. Methods of rejection diagnosis were described and patient outcomes were assessed based on surveillance biopsy utilization among centers. RESULTS: A total of 3985 patients from 56 centers were included. Of this group, 873 (22%) developed rejection within the first-year post-transplant. Surveillance biopsy was the most common method of rejection diagnosis (71.7%), but practices were highly variable across centers. The majority (73.6%) of first rejection events occurred within 3-months of transplantation. Diagnosis modality in the first-year was not independently associated with freedom from rejection, freedom from rejection with hemodynamic compromise, or overall graft survival. CONCLUSIONS: Rejection in the first-year after pediatric heart transplant occurs in 22% of patients and most commonly in the first 3 months post-transplant. Significant variation exists across centers in the methods used to diagnose rejection in pediatric heart transplant recipients, however, these variable strategies are not independently associated with freedom from rejection, rejection with hemodynamic compromise, or overall graft survival.

Biallelic variants in PPP1R13L cause paediatric dilated cardiomyopathy.

Childhood dilated cardiomyopathy (DCM) is a leading cause of heart failure requiring cardiac transplantation and approximately 5% of cases result in sudden death. Knowledge of the underlying genetic cause can aid prognostication and clinical management and enables accurate recurrence risk counselling for the family. Here we used genomic sequencing to identify the causative genetic variant(s) in families with children affected by severe DCM. In an international collaborative effort facilitated by GeneMatcher, biallelic variants in PPP1R13L were identified in seven children with severe DCM from five unrelated families following exome or genome sequencing and inheritance-based variant filtering. PPP1R13L encodes inhibitor of apoptosis-stimulating protein of p53 protein (iASPP). In addition to roles in apoptosis, iASPP acts as a regulator of desmosomes and has been implicated in inflammatory pathways. DCM presented early (mean: 2 years 10 months; range: 3 months-9 years) and was progressive, resulting in death (n = 3) or transplant (n = 3), with one child currently awaiting transplant. Genomic sequencing technologies are valuable for the identification of novel and emerging candidate genes. Biallelic variants in PPP1R13L were previously reported in a single consanguineous family with paediatric DCM. The identification here of a further five families now provides sufficient evidence to support a robust gene-disease association between PPP1R13L and severe paediatric DCM. The PPP1R13L gene should be included in panel-based genetic testing for paediatric DCM.

Cardiomyopathy and hypotonia in a 5-month-old infant with malonyl-coa decarboxylase deficiency: potential for preclinical diagnosis with expanded newborn screening.

Malonyl-CoA decarboxylase deficiency is an inborn error of metabolism that may cause hypotonia and a fatal cardiomyopathy in infancy. Newborn metabolic screening programs do not include this disorder, although there is a possibility that presymptomatic treatment may attenuate the development of cardiomyopathy. We report a case of malonyl-CoA decarboxylase deficiency in a 5-month-old boy who presented with cardiomyopathy and hypotonia. Retrospective analysis of the newborn screening test showed an elevation in the concentration of malonylcarnitine at age 3 days. Unfortunately, this perturbation was missed because the screening test did not routinely measure malonylcarnitine in the newborn blood. Our experience confirms the possibility of screening for malonyl-CoA decarboxylase deficiency with tandem mass spectrometry. This finding should enable studies to determine if presymptomatic treatment could change the outcome in this often fatal disorder.

Fate of infants with hypoplastic left heart syndrome listed for cardiac transplantation: a multicenter study.

BACKGROUND: Infants with hypoplastic left heart syndrome (HLHS) commonly undergo cardiac transplantation as primary management. METHODS: We examined outcomes of primary transplantation for unpalliated HLHS. We analyzed data from the 20 institutions of the Pediatric Heart Transplant Study Group, from January 1, 1993, through December 31, 1998, using actuarial and parametric survival analysis and competing outcomes analysis. RESULTS: During the 6 years studied, 1,234 patients were listed for cardiac transplantation; 262 patients (21.2%) had unpalliated HLHS. The number (and percentage) of patients with HLHS decreased from 58 (27% of patients listed) in 1993 to 30 (14%) in 1998. Overall, 25% of infants with HLHS died while waiting; primary cause of death was cardiac failure (50%). Of the remaining patients awaiting transplantation, 23 (9%) underwent Norwood/Fontan-type surgeries as interim palliation: 52% died. Ultimately, 175 patients underwent cardiac transplantation (67%); 50% received organs by 2 months after listing. Post-transplant actuarial survival was 72% at 5 years, with 76% of deaths (35/46) occurring within 3 months; early mortality was caused primarily by graft failure within the first 30 days after transplantation (in 54%). Among 1-month survivors, survival at 1 and at 5 years was 92% and 85%, respectively. Of the 262 patients listed with unpalliated HLHS, overall survival, taking into account mortality after listing and after transplantation, was 68% at 3 months and 54% at 5 years. CONCLUSIONS: Cardiac transplantation offers good intermediate survival for infants with unpalliated HLHS.

Carvedilol as therapy in pediatric heart failure: an initial multicenter experience.

OBJECTIVE: The objective was to determine the dosing, efficacy, and side effects of the nonselective beta-blocker carvedilol for the management of heart failure in children. STUDY DESIGN: Carvedilol use in addition to standard medical therapy for pediatric heart failure was reviewed at 6 centers. RESULTS: Children with dilated cardiomyopathy (80%) and congenital heart disease (20%), age 3 months to 19 years (n = 46), were treated with carvedilol. The average initial dose was 0.08 mg/kg, uptitrated over a mean of 11.3 weeks to an average maintenance dose of 0.46 mg/kg. After 3 months on carvedilol, there were improvements in modified New York Heart Association class in 67% of patients (P =.0005, chi2 analysis) and improvement in mean shortening fraction from 16.2% to 19.0% (P =.005, paired t test). Side effects, mainly dizziness, hypotension, and headache, occurred in 54% of patients but were well tolerated. Adverse outcomes (death, cardiac transplantation, and ventricular-assist device placement) occurred in 30% of patients. CONCLUSIONS: Carvedilol as an adjunct to standard therapy for pediatric heart failure improves symptoms and left ventricular function. Side effects are common but well tolerated. Further prospective study is required to determine the effect of carvedilol on survival and to clearly define its role in pediatric heart failure therapy.