Arrhythmogenic cardiomyopathy is under-recognized in end-stage pediatric heart failure: A 36-year single-center experience.

BACKGROUND: Although ventricular failure is a late finding in adults with AC, we hypothesize that this is a presenting symptom in pediatric heart failure patients who undergo HT and that their ventricular arrhythmia burden could differentiate AC from other cardiomyopathies. METHODS: We performed a single-center retrospective cohort study reviewing 457 consecutive pediatric (≤18 years) HT recipients at our institution. Explanted hearts were examined to establish the primary diagnosis, based on pathologic findings. Demographic and clinical variables were compared between AC versus non-HCM cardiomyopathy cases. RESULTS: Forty-five percent (n = 205/457) had non-HCM cardiomyopathies as the underlying primary diagnosis. Ten cases (10/205 = 4.9%) were diagnosed with AC. All 10 had biventricular disease. In 8/10 patients (80%), AC diagnosis was unrecognized pre-HT. Compared with non-AC cardiomyopathies, the AC group was older at diagnosis (9.3 years vs. 4.3 years, p = .012) and transplant (11.1 years vs. 6.5 years, p = .010), had more ventricular arrhythmias (80.0% vs 32.8%, p = .003), and required more anti-arrhythmic use (80.0% vs 32.3%, p = .001). Genetic testing yielded causative pathogenic variants in all tested individuals (n = 5/5, 100%). CONCLUSION: AC is often an unrecognized cardiomyopathy pretransplant in children who undergo HT. Pediatric non-HCM phenotypes with heart failure who have a significant ventricular arrhythmia burden should be investigated for AC.

LMOD2-related dilated cardiomyopathy presenting in late infancy.

Leiomodin-2 (LMOD2) is an important regulator of the thin filament length, known to promote elongation of actin through polymerization at pointed ends. Mice with Lmod2 deficiency die around 3 weeks of age due to severe dilated cardiomyopathy (DCM), resulting from decreased heart contractility due to shorter thin filaments. To date, there have been three infants from two families reported with biallelic variants in LMOD2, presenting with perinatal onset DCM. Here, we describe a third family with a child harboring a previously described homozygous frameshift variant, c.1243_1244delCT (p.L415Vfs*108) with DCM, presenting later in infancy at 9 months of age. Family history was relevant for a sibling who died suddenly at 1 year of age after being diagnosed with cardiomegaly. LMOD2-related cardiomyopathy is a rare form of inherited cardiomyopathy resulting from thin filament length dysregulation and should be considered in genetic evaluation of newborns and infants with suspected autosomal recessive inheritance or sporadic early onset cardiomyopathy.

Simultaneous pediatric heart-kidney transplant outcomes in the US: A-25 year National Cohort Study.

BACKGROUND: Pediatric sHKTx remains uncommon in the US. We examined outcomes of pediatric sHKTx compared to PHTx alone. Our objective was to identify a threshold eGFR that justified pediatric sHKTx. METHODS: Data from the SRTR heart and kidney databases were used to identify 9245 PHTx, and 63 pediatric sHKTx performed between 1992 and 2017 (age ≤21 years). RESULTS: The median age for sHKTx was 16 years, and included 31 males (31/63 = 49%). Over half of sHKTx (36/63 = 57%) were performed in cases where pretransplant dialysis was initiated. Among patients who required pretransplant dialysis, the risk of death in sHKTx recipients was significantly lower than PHTx alone (sHKTx vs. PHTx: HR 0.4, 95% CI [0.2, 0.9], p = .01). In those without pretransplant dialysis, there was no improvement in survival between sHKTx and PHTx (p = .2). When stratified by eGFR, PHTx alone recipients had worse survival than sHKTx in the group with eGFR ≤35 ml/min/1.73 m2 (p = .04). The 1- and 5-year actuarial survival rates in pediatric sHKTx recipients were 87% and 81.5% respectively and was similar to isolated PHTx (p = .5). One-year rates of treated heart (11%) and kidney (7.9%) rejection were similar in sHKTx compared to PHTx alone (p = .7) and pediatric kidney transplant alone (p = .5) respectively. CONCLUSION: Pediatric sHKTx should be considered in HTx candidates with kidney failure requiring dialysis or eGFR ≤35 ml/min/1.73 m2 . The utility of sHKTx in cases of kidney failure not requiring dialysis warrants further study.

Outcomes following use of pediatric and young adult donor hearts with bicuspid aortic valves: A single-center case series.

BACKGROUND: Valvular disease in pediatric and young adult donor hearts may be a relative contraindication to graft use. Outcomes following the use of donor hearts with bicuspid aortic valve (BAV) have not been previously reported in children. We describe 4 cases of pediatric heart transplantation (HTx) utilizing a donor heart with a BAV. CASE SERIES: Of the 469 HTx included in this study, 4 utilized a donor heart with a BAV. All recipients were female; median age was 11 years (range 0.3 to 19 years). In all cases, the BAV was not discovered until after HTx. All donors were less than 30 years old. The patients were followed for a median of 6 years (range 2 to 9 years) with all patients alive at last follow-up. Two patients have transitioned to adult care, and 2 patients continue to follow in our clinic. In follow-up, no patient has required an aortic valve intervention or had infective endocarditis. At last review, no patient had greater than mild aortic insufficiency or more than mild aortic stenosis. Three patients developed mild-to-moderate left ventricular hypertrophy in the first year post-transplant that improved over time. One patient experienced a peri-operative embolic stroke at time of transplant unrelated to the BAV. CONCLUSION: On short- and intermediate-term follow-up, pediatric and young adult donor hearts with BAV demonstrated acceptable graft longevity and valvular function. A functionally normal BAV in a pediatric heart transplant donor should not be a contraindication to organ acceptance.

Ventricular assist device support for children with chemotherapy-induced cardiomyopathy and advanced heart failure: Perspectives gained from a single-center experience.

BACKGROUND: Guidance and data on ventricular assist device (VAD) support for children with chemotherapy-induced cardiomyopathy, particularly within the first 2 years after chemotherapy, are limited. METHODS: We performed a single-center retrospective case series, reviewing medical records of children <18 years of age with chemotherapy-induced cardiomyopathy and advanced heart failure (HF) who received durable VAD support. RESULTS: Six patients met inclusion criteria-5 HeartWare™ HVAD, 1 Berlin Heart EXCOR® . Median age at cancer diagnosis was 6 years (IQR 4.5-10 years). Median dose of anthracycline received was 540 mg/m2 (IQR 450-630 mg/m2 ). All patients developed HF within 1 year after initiation of cancer treatment (median 8 months, IQR 6-11.5 months) and were initiated on durable VAD support at a median of 8 months after completion of cancer treatment (IQR 3.3-43.5 months). Four patients had significant right ventricular dysfunction needing oral pulmonary vasodilator therapy, one patient had a major bleeding complication, and two patients had thromboembolic strokes while on VAD support. Median duration of VAD support was 7.5 months (IQR 3-11.3 months). Two patients underwent VAD explant due to recovery of LV function, one died due to cancer progression, and three underwent heart transplantation. CONCLUSIONS: Durable VAD support should be considered as a therapeutic option for children who have advanced HF due to chemotherapy-induced cardiomyopathy, even within 2 years of completing cancer treatment. A multi-disciplinary approach is essential for appropriate patient selection prior to implant and to ensure comprehensive care throughout the duration of VAD support.

Bivalirudin or Unfractionated Heparin for Anticoagulation in Pediatric Patients on Continuous Flow Ventricular Assist Device Support: Single-Center Retrospective Cohort Study.

OBJECTIVES: Bivalirudin is a direct thrombin inhibitor that is being increasingly used for anticoagulation in children after ventricular assist device (VAD) implantation. While the data on bivalirudin use in pulsatile flow VADs are growing, reports on its use in patients on continuous flow (CF) VAD as well as comparisons of associated outcomes with unfractionated heparin (UFH) remain limited. DESIGN: Retrospective cohort study. SETTING: Single tertiary-quaternary referral center. PATIENTS: All patients less than 21 years old on CF-VAD support who received bivalirudin or UFH for anticoagulation between the years 2016 and 2020. INTERVENTIONS: Not applicable. MEASUREMENTS AND MAIN RESULTS: Clinical characteristics compared between the cohorts included time to target range of anticoagulation, markers of hemolysis, and prevalence of hemocompatibility-related adverse events such as major hemorrhagic complications, ischemic stroke, and pump thrombosis. In 42 unique patients (41 HeartWare HVAD [Medtronic, Minneapolis, MN], one HeartMate 3 LVAD [Abbott Laboratories, Abbott Park, IL]) during the study period, a total of 67 encounters of IV anticoagulation infusions (29 UFH and 38 bivalirudin) were retrospectively reviewed. In comparison with use of UFH, bivalirudin was associated with lesser odds of major bleeding complications (odds ratio [OR], 0.29; 95% CI, 0.09-0.97; p = 0.038). We failed to identify any difference in odds of major thrombotic complications (OR, 2.53; 95% CI, 0.47-13.59; p = 0.450). Eight of the patients (28%) on UFH were switched to bivalirudin due to hemorrhagic or thrombotic complications or inability to achieve therapeutic anticoagulation, while two of the patients (5%) on bivalirudin were switched to UFH due to hemorrhagic complications. Bivalirudin was used for a "washout" in eight cases with concern for pump thrombosis-six had resolution of the pump thrombosis, while two needed pump exchange. CONCLUSIONS: Use of bivalirudin for anticoagulation in patients on CF-VAD support was associated with lesser odds of hemorrhagic complications compared with use of UFH. Bivalirudin "washout" was successful in medical management of six of eight cases of possible pump thrombosis.

Poor efficacy of oral iron replacement therapy in pediatric patients with heart failure.

INTRODUCTION: Iron deficiency is associated with worse outcomes in children and adults with systolic heart failure. While oral iron replacement has been shown to be ineffective in adults with heart failure, its efficacy in children with heart failure is unknown. We hypothesised that oral iron would be ineffective in replenishing iron stores in ≥50% of children with heart failure. METHODS: We performed a single-centre retrospective cohort study of patients aged ≤21 years with systolic heart failure and iron deficiency who received oral iron between 01/2013 and 04/2019. Iron deficiency was defined as ≥2 of the following: serum iron <50 mcg/dL, serum ferritin <20 ng/mL, transferrin >300 ng/mL, transferrin saturation <15%. Iron studies and haematologic indices pre- and post-iron therapy were compared using paired-samples Wilcoxon test. RESULTS: Fifty-one children with systolic heart failure and iron deficiency (median age 11 years, 49% female) met inclusion criteria. Heart failure aetiologies included cardiomyopathy (51%), congenital heart disease (37%), and history of heart transplantation with graft dysfunction (12%). Median dose of oral iron therapy was 2.9 mg/kg/day of elemental iron, prescribed for a median duration of 96 days. Follow-up iron testing was available for 20 patients, of whom 55% (11/20) remained iron deficient despite oral iron therapy. CONCLUSIONS: This is the first report on the efficacy of oral iron therapy in children with heart failure. Over half of the children with heart failure did not respond to oral iron and remained iron deficient.

Immunosuppressant Drugs and Their Effects on Children Undergoing Solid Organ Transplant.

More than 112,000 men, women, and children are awaiting solid organ transplant (SOT) as of March 2020, and more than 39,000 transplants were performed in the United States in 2019. Approximately 2,000 children undergo SOT every year in the United States, and the number of children awaiting SOT continues to increase. Immunosuppression is the mainstay of prevention and treatment of solid organ rejection, a significant source of morbidity and mortality after SOT. There are several different classes of immunosuppressive drugs, and the phases of immunosuppression after SOT can be divided into early, maintenance, and rescue therapies. The specific class and dose of drug will be determined by the type of organ transplant, time since transplant, phase of therapy, and other patient-specific considerations. The goal of the transplant team is to find the optimal balance between too little immunosuppression and too much immunosuppression. Too little immunosuppression can result in organ rejection, but too much immunosuppression can result in increased infections, increased malignancy, and adverse drug events such as nephrotoxicity. Although the specific drug choice and dosage will be managed by specialized transplant physicians, these immunosuppressive drugs have many drug interactions with commonly prescribed medications and require dose titration. To provide the best care to children who have received a SOT, pediatricians should be aware of these interactions and be able to distinguish routine pediatric concerns from transplant immunosuppression-related infections or complications. Current vaccine recommendations for children receiving immunosuppression after SOT are also discussed.

Pediatric heart-liver transplant outcomes in the United States: A 25-year National Cohort Study.

BACKGROUND: Pediatric HLT remains uncommon in the United States and criteria for HLT are unclear. The objectives of this study were to review the indications, and outcomes of pediatric HLT. METHODS: Data from the Scientific Registry of Transplant Recipients heart and liver databases were used to identify 9245 pediatric isolated heart transplants (PHT), 14 134 pediatric isolated liver transplant (PLT), and 20 pediatric HLT (16 patients underwent sHLT [same organ donor] and four patients with a history of PHT followed by PLT [different organ donors]; age ≤21 years) between 1992 and 2017. Outcomes included patient survival, and 1-year rates of acute heart and liver rejection. RESULTS: The median age for pediatric HLT was 15.6 (IQR: 10.5, 17.9) years, and included 12 males (12/20 = 60%). In the HLT group, the most common indication for HT was CHD (12/20 = 60%), and the most common indication for liver transplant was cirrhosis (9/20 = 45%). The 1, 3, and 5 year actuarial survival rates in pediatric simultaneous HLT recipients (n = 16) were 93%, 93%, and 93%, respectively, and was similar to isolated PHT alone (88%, 81%, and 75.5%, respectively and isolated PLT alone (84%, 82%, and 80%), respectively. There was no heart or liver rejection reported in the HLT group versus 9.9% in heart and 10.6% in liver transplant-only groups, respectively. CONCLUSION: Pediatric HLT is an uncommon but acceptable option for recipients with combined end-organ failure, with intermediate survival outcomes comparable to those of single-organ recipients.

Hospital outcomes for pediatric heart transplant recipients undergoing tracheostomy: A multi-institutional analysis.

Tracheostomy is associated with increased mortality and resource utilization in children with CHD. However, the prevalence and hospital outcomes of tracheostomy in children with HTx are not known. We describe the prevalence and compare the post-HTx hospital outcomes of pediatric patients with Pre-TT and Post-TT to those without tracheostomy. A multi-institutional retrospective cohort study was performed using the Pediatric Health Information System database. Hospital mortality, mediastinitis, LOS, and costs were compared among patients with Pre-TT, Post-TT, and no tracheostomy. Pre-TT was identified in 29 (1.1%) and Post-TT was identified in 41 (1.6%) of 2603 index HTx hospitalizations. Patients with Pre-TT were younger and more likely to have CHD, a non-cardiac birth defect, or an airway anomaly compared to those without Pre-TT. Pre-TT was not independently associated with increased post-HTx in-hospital mortality. Age at HTx < 1 year, CHD, and Post-TT were associated with increased in-hospital mortality. Pre-TT that occurred during the HTx hospitalization and Post-TT were associated with increased resource utilization. Tracheostomy was not associated with mediastinitis.

Epidemiology of Pediatric Heart Failure in the USA-a 15-Year Multi-Institutional Study.

The epidemiology of pediatric heart failure (HF) has been characterized for congenital heart disease (CHD) and cardiomyopathies (CM), but the impact of CM associated with CHD has not been studied. This study aims to describe the characteristics and outcomes of inpatient pediatric HF patients with CHD, CM, and CHD with CM (CHD + CM) across the USA. We included all HF patients with CM diagnoses with and without CHD using ICD 9/10 codes ≤ 19 years old from January 2004 to September 2019 using the Pediatric Health Information System database. We identified 67,349 unique patients ≤ 19 years old with HF, of which 87% had CHD, 7% had CHD + CM, and 6% had CM. Pediatric HF admissions increased significantly from 2004 to 2018 with an associated increase in extracorporeal circulatory support (ECLS) use. Heart transplantation (HTX) increased only in the CHD and CHD + CM groups. CHD patients required less ECLS with and without HTX; however, they had significantly higher inpatient mortality after those procedures than the other groups (p < 0.001). CM patients were older (median 115 months) and had the lowest inpatient mortality after HTX with and without ECLS (p < 0.05). CHD + CM showed the highest overall inpatient mortality (15%), and cumulative hospital billed charges (median US$ 541,374), all p < 0.001. Pediatric HF admissions have increased from 2004 to 2018. ECLS use and HTX have expanded in this population, with an associated decrease in inpatient mortality in the CHD and CM groups. CHD + CM patients are a growing population with the highest inpatient mortality.

Iron Deficiency Is Associated with Adverse Outcomes in Pediatric Heart Failure.

OBJECTIVE: To evaluate the prevalence of iron deficiency and its association with outcomes in children with heart failure. STUDY DESIGN: A single-center retrospective cohort study of patients with heart failure aged 1-21 years from July 2012 to June 2017 with available serum iron studies was performed. Subjects were analyzed in 2 groups: biventricular systolic heart failure (BiV) and single-ventricle congenital heart disease with systolic heart failure (SV). Iron deficiency was defined as ≥2 of the following: serum iron <50 µg/dL, serum ferritin <20 ng/mL, transferrin >300 ng/mL, or transferrin saturation <15%. The primary outcome was a composite adverse event (CAE) of ventricular assist device implantation, heart transplantation, or death, at 3 and 6 months from time of iron studies. RESULTS: Of the 107 subjects (77 BiV, 30 SV) included in the study, 56% were iron deficient. Demographics, etiology of heart failure, and chronicity of heart failure symptoms were not associated with iron deficiency. On multivariable analysis, in group BiV, iron deficiency was associated with CAE at 3 months (79% iron deficiency in CAE group vs 37% iron deficiency in non-CAE, P = .001, OR 7, 95% CI 2-21) and 6 months (76% iron deficiency in CAE vs 35% iron deficiency in non-CAE, P = .002, OR 7, 95% CI 2-24). In group SV, iron deficiency was associated with CAE at 6 months (79% iron deficiency in CAE vs 29% iron deficiency in non-CAE, P = .014, OR 8, 95% CI 2-32). CONCLUSIONS: Iron deficiency was present in 56% of the pediatric patients with heart failure who were evaluated with iron studies. Iron deficiency was associated with greater risk of ventricular assist device implantation, heart transplantation, or death.

Percutaneous Impella RP use for refractory right heart failure in adolescents and young adults-A multicenter U.S. experience.

OBJECTIVE: To assess the outcomes of the use of the percutaneous Impella RP device (Abiomed, Danvers, MA) in adolescents and young adults. BACKGROUND: Results of the Impella RP device have been reported in adults, but a multicenter experience in adolescents and young adults has yet to be reported. METHODS: Patients ≤21 years of age who underwent implantation of an Impella RP device for refractory right heart failure from June, 2016 to April, 2018 at nine U.S. Centers were included. RESULTS: A total of 12 adolescents, median age of 18 (14-21) years and median weight 74.4 (49-112.4) kg underwent Impella RP implantation (INTERMACS Profile 1 in nine and Profile 2 in three patients. The central venous pressure decreased from 20 (16-35) to 12 (7-17) mmHg, (p = .001). One patient was concomitantly supported with an intra-aortic balloon pump (IABP) and the rest with a percutaneous/surgically placed left ventricular assist device. There was one adverse event related to the Impella RP device (thrombosis requiring explant). The support duration was 6.5 days (4.8 hr-18.4 days) and survival to hospital discharge was 83%. At a median follow-up of 11 months (5 days-2.5 years), 8 of 12 (67%) patients are alive. CONCLUSIONS: In this multicenter experience, the Impella RP device was found to be efficacious and safe when used in adolescents and young adults. Further studies are warranted to identify suitable young/pediatric candidates for Impella RP therapy for right heart failure.

Pediatric cardiac waitlist mortality-Still too high.

Cardiac transplantation for children with end-stage cardiac disease with no other medical or surgical options is now standard. The number of children in need of cardiac transplant continues to exceed the number of donors considered "acceptable." Therefore, there is an urgent need to understand which recipients are in greatest need of transplant before becoming "too ill" and which "marginal" donors are acceptable in order to reduce waitlist mortality. This article reviewed primarily pediatric studies reported over the last 15 years on waitlist mortality around the world for the various subgroups of children awaiting heart transplant and discusses strategies to try to reduce the cardiac waitlist mortality.

Fecal microbiota transplantation in a toddler after heart transplant was a safe and effective treatment for recurrent Clostridiodes difficile infection: A case report.

Pediatric recipients of SOT have a significantly increased risk of Clostridiodes (formerly Clostridium) difficile infection (CDI), which is associated with adverse outcomes after SOT. Alterations to the intestinal microbiota community structure increase the risk of CDI. FMT is a safe and effective treatment for recurrent CDI in immunocompetent children and adults. While there are increasing data that FMT in immunosuppressed patients is safe and effective without increased risk of infection, data regarding safety and efficacy of FMT in children after SOT are limited. To our knowledge, we report the youngest immunocompromised patient to undergo FMT and the third overall case of FMT in a child after HTx. Our patient presented with five episodes of rCDI in 6 months, and 16S rRNA genetic analysis revealed significant loss of overall microbiota community structure and diversity prior to FMT compared with a donor and a healthy, age-matched control. After FMT, marked and prolonged (at least 16 months) shifts in the recipient microbiota community structure and diversity were evident, approaching that of donor and healthy, age-matched control. FMT was well tolerated, restored microbial diversity without any graft or transplant complications, and prevented further rCDI episodes after more than 4 years of follow-up.

Missed Diagnosis of New-Onset Systolic Heart Failure at First Presentation in Children with No Known Heart Disease.

OBJECTIVE: To determine frequency of missed heart failure diagnosis at first presentation among children with no known heart disease admitted with new-onset heart failure. STUDY DESIGN: Using a retrospective design, we reviewed electronic medical records of all patients aged <21 years with no known heart disease, hospitalized with new-onset heart failure during 2003-2015 at a tertiary-quaternary care institution. We assessed records for missed diagnosis of heart failure (primary outcome), associated process breakdowns, and clinical outcomes using a structured data collection instrument. RESULTS: Of 191 patients meeting inclusion criteria, 49% (94/191) were missed on first presentation. Most common incorrect diagnostic labels given to "missed" patients were bacterial infection (29%; 27/94), followed by viral illness (22%; 21/94) and gastroenteritis/hepatitis (21%; 20/94). On multivariable analysis, presentation to primary care provider (PCP), longer duration of symptoms (median 7 days), more than 2 symptoms of heart failure, and nausea/emesis were associated with missed diagnosis. On examining process breakdowns, 49% had errors in history-taking and 50% had no documentation of differential diagnoses. There was no difference in hospital mortality, length of stay, or mechanical circulatory support in missed vs not-missed cohorts. Unnecessary noninvasive and invasive tests were performed in 18% and 4% of patients, respectively. CONCLUSIONS: Nearly one-half of children with no known heart disease hospitalized with systolic heart failure were missed at first presentation and underwent significant nonrelevant treatment and testing. Initial presentation to the PCP, longer duration of symptoms before presentation, and nausea/emesis were associated with missed diagnosis.

Diuretic Responsiveness and Its Prognostic Significance in Children With Heart Failure.

BACKGROUND: Loop diuretics are considered first-line therapy for congestion in children with heart failure, although some patients remain volume overloaded during treatment. We sought to characterize loop diuretic responsiveness (DR) in children hospitalized with acute decompensated failure and to determine whether a decreased response was associated with worse outcomes. METHODS AND RESULTS: DR was calculated for 108 consecutive children ˂21 years of age who were hospitalized with acute decompensated heart failure. DR was defined as net fluid (mL) output per 1 mg of furosemide equivalents during the first 72 hours of treatment with a loop diuretic. The primary outcome was the composite end point of inpatient death or use of mechanical circulatory support. The median DR was 6.0 mL/mg (interquartile range -2.4 to 15.7 mL/mg). Thirty-two percent of patients remained in a positive fluid balance after 72 hours of treatment with a loop diuretic. Death or use of mechanical circulatory support occurred in 29 patients (27%). Low DR was associated with the composite end point, even after adjusting for net urine output and loop diuretic dose indexed to weight (odds ratio 5.3; P = .003). Patients with low DR also experienced longer length of hospital stay than patients with greater DR (median 33 days vs 11 days; P = .002). CONCLUSION: In children hospitalized with acute decompensated heart failure, early diminished loop DR during decongestion therapy is common and portends a poor prognosis.

Association of Wolff-Parkinson-White With Left Ventricular Noncompaction Cardiomyopathy in Children.

BACKGROUND: Wolff-Parkinson-White (WPW) has been associated with left ventricular noncompaction (LVNC) in children. Little is known about the prevalence of this association, clinical outcomes, and treatment options. METHODS: Retrospective review of subjects with LVNC. LVNC was defined by established criteria; those with congenital heart disease were excluded. Electrocardiograms (ECGs) were reviewed for presence of pre-excitation. Outcomes were compared between those with isolated LVNC and those with WPW and LVNC. RESULTS: A total of 348 patients with LVNC were identified. Thirty-eight (11%) were found to have WPW pattern on ECG, and 84% of those with WPW and LVNC had cardiac dysfunction. In Kaplan-Meier analysis, there was significantly lower freedom from significant dysfunction (ejection fraction ≤ 40%) among those with WPW and LVNC (P < .001). Further analysis showed a higher risk of developing significant dysfunction in patients with WPW and LVNC versus LVNC alone (hazard ratio 4.64 [2.79, 9.90]). Twelve patients underwent an ablation procedure with an acute success rate of 83%. Four patients with cardiac dysfunction were successfully ablated, 3 having improvement in function. CONCLUSION: WPW is common among children with LVNC and is associated with cardiac dysfunction. Ablation therapy can be safely and effectively performed and may result in improvement in function.

Cardiac transplantation in children with Noonan syndrome.

NS and related RAS/MAPK pathway (RASopathy) disorders are the leading genetic cause of HCM presenting in infancy. HCM is a major cause of morbidity and mortality in children with Noonan spectrum disorders, especially in the first year of life. Previously, there have been only isolated reports of heart transplantation as a treatment for heart failure in NS. We report on 18 patients with NS disorders who underwent heart transplantation at seven US pediatric heart transplant centers. All patients carried a NS diagnosis: 15 were diagnosed with NS and three with NSML. Sixteen of eighteen patients had comprehensive molecular genetic testing for RAS pathway mutations, with 15 having confirmed pathogenic mutations in PTPN11, RAF1, and RIT1 genes. Medical aspects of transplantation are reported as well as NS-specific medical issues. Twelve of eighteen patients described in this series were surviving at the time of data collection. Three patients died following transplantation prior to discharge from the hospital, and another three died post-discharge. Heart transplantation in NS may be a more frequent occurrence than is evident from the literature or registry data. A mortality rate of 33% is consistent with previous reports of patients with HCM transplanted in infancy and early childhood. Specific considerations may be important in evaluation of this population for heart transplant, including a potentially increased risk for malignancies as well as lymphatic, bleeding, and coagulopathy complications.

A genome-wide association study of congenital cardiovascular left-sided lesions shows association with a locus on chromosome 20.

Congenital heart defects involving left-sided lesions (LSLs) are relatively common birth defects with substantial morbidity and mortality. Previous studies have suggested a high heritability with a complex genetic architecture, such that only a few LSL loci have been identified. We performed a genome-wide case-control association study to address the role of common variants using a discovery cohort of 778 cases and 2756 controls. We identified a genome-wide significant association mapping to a 200 kb region on chromosome 20q11 [P= 1.72 × 10-8 for rs3746446; imputed Single Nucleotide Polymorphism (SNP) rs6088703 P= 3.01 × 10-9, odds ratio (OR)= 1.6 for both]. This result was supported by transmission disequilibrium analyses using a subset of 541 case families (lowest P in region= 4.51 × 10-5, OR= 1.5). Replication in a cohort of 367 LSL cases and 5159 controls showed nominal association (P= 0.03 for rs3746446) resulting in P= 9.49 × 10-9 for rs3746446 upon meta-analysis of the combined cohorts. In addition, a group of seven SNPs on chromosome 1q21.3 met threshold for suggestive association (lowest P= 9.35 × 10-7 for rs12045807). Both regions include genes involved in cardiac development-MYH7B/miR499A on chromosome 20 and CTSK, CTSS and ARNT on chromosome 1. Genome-wide heritability analysis using case-control genotyped SNPs suggested that the mean heritability of LSLs attributable to common variants is moderately high ([Formula: see text] range= 0.26-0.34) and consistent with previous assertions. These results provide evidence for the role of common variation in LSLs, proffer new genes as potential biological candidates, and give further insight to the complex genetic architecture of congenital heart disease.