Atypical infiltrates on endomyocardial biopsy are associated with adverse outcomes in pediatric heart transplantation

BACKGROUND

The significance of atypical infiltrates (eosinophils or plasma cells) on endomyocardial biopsy (EMB) after pediatric heart transplant (HTx) is not known. We hypothesized that atypical infiltrates are associated with worse post-HTx outcomes.

METHODS

We performed a retrospective cohort study of consecutive patients <21 years old who underwent primary HTx between 2013 and 2017. Multiorgan transplants were excluded. The presence of atypical infiltrates and burden of atypical infiltrates (rare vs predominant) on EMB were recorded. Primary outcome was a composite of cardiac allograft vasculopathy, graft failure (relisting or retransplant), or death. Presence of atypical infiltrates was evaluated: (1) overall using Cox regression with time-dependent covariates and (2) if present by 1 year post-HTx using Kaplan-Meier analysis.

RESULTS

Atypical infiltrates were present in 24 out of 95 patients (25%) and were associated with a higher likelihood of reaching the composite outcome (hazard ratio (HR) 6.22, 95% confidence interval (CI) 2.60-14.89, p < 0.0001). This persisted when controlling for rejection in multivariable analysis. There was also a greater risk of the composite outcome if ≥2 nonconsecutive EMBs had atypical infiltrates (HR 11.80, 95%CI 3.17-43.84, p = 0.0002) or if atypical infiltrates were the predominant feature on EMB (HR 30.58, 95%CI 9.34-100.06, p < 0.0001). Patients with atypical infiltrates by 1-year post-HTx had a 5-year freedom from the composite outcome of 48%, compared to 90% if no atypical infiltrates had been present by this timepoint (log rank p = 0.002).

CONCLUSIONS

The presence of atypical infiltrates on EMB is associated with significantly worse outcomes in children following HTx. These patients require closer follow-up to assess for developing graft dysfunction.

Nonsense Variant PRDM16-Q187X Causes Impaired Myocardial Development and TGF-β Signaling Resulting in Noncompaction Cardiomyopathy in Humans and Mice

BACKGROUND

PRDM16 plays a role in myocardial development through TGF-β (transforming growth factor-beta) signaling. Recent evidence suggests that loss of PRDM16 expression is associated with cardiomyopathy development in mice, although its role in human cardiomyopathy development is unclear. This study aims to determine the impact of PRDM16 loss-of-function variants on cardiomyopathy in humans.

METHODS

Individuals with PRDM16 variants were identified and consented. Induced pluripotent stem cell-derived cardiomyocytes were generated from a proband hosting a Q187X nonsense variant as an in vitro model and underwent proliferative and transcriptional analyses. CRISPR (clustered regularly interspaced short palindromic repeats)-mediated knock-in mouse model hosting the Prdm16Q187X allele was generated and subjected to ECG, histological, and transcriptional analysis.

RESULTS

We report 2 probands with loss-of-function PRDM16 variants and pediatric left ventricular noncompaction cardiomyopathy. One proband hosts a PRDM16-Q187X variant with left ventricular noncompaction cardiomyopathy and demonstrated infant-onset heart failure, which was selected for further study. Induced pluripotent stem cell-derived cardiomyocytes prepared from the PRDM16-Q187X proband demonstrated a statistically significant impairment in myocyte proliferation and increased apoptosis associated with transcriptional dysregulation of genes implicated in cardiac maturation, including TGF-β-associated transcripts. Homozygous Prdm16Q187X/Q187X mice demonstrated an underdeveloped compact myocardium and were embryonically lethal. Heterozygous Prdm16Q187X/WT mice demonstrated significantly smaller ventricular dimensions, heightened fibrosis, and age-dependent loss of TGF-β expression. Mechanistic studies were undertaken in H9c2 cardiomyoblasts to show that PRDM16 binds TGFB3 promoter and represses its transcription.

CONCLUSIONS

Novel loss-of-function PRDM16 variant impairs myocardial development resulting in noncompaction cardiomyopathy in humans and mice associated with altered TGF-β signaling.

The Many Faces of Arrhythmogenic Cardiomyopathy: An Overview

Arrhythmogenic cardiomyopathy (AC) is a disease that involves electromechanical uncoupling of cardiomyocytes. This leads to characteristic histologic changes that ultimately lead to the arrhythmogenic clinical features of the disease. Initially thought to affect the right ventricle predominantly, more recent data show that it can affect both the ventricles or the left ventricle alone. Throughout the recent era, diagnostic modalities and criteria for AC have continued to evolve and our understanding of its clinical features in different age groups as well as the genotype to the phenotype correlations have improved. In this review, we set out to detail the epidemiology, etiologies, presentations, evaluation, and management of AC across the age continuum.

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.

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.

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.

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.

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.

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.

Management of Advanced Heart Failure in Children with Cancer Therapy-Related Cardiac Dysfunction

The evolution of cancer therapies has led to marked improvement in survival of those affected by childhood malignancies, while also increasing the recognition of early and late toxicities associated with cancer therapies. Cardiotoxicity can include cardiomyopathy/heart failure, coronary artery disease, stroke, pericardial disease, arrhythmias, and valvular and vascular dysfunction as a result of exposure to chemotherapy and/or radiation. Anthracyclines remain the most common cause of chemotherapy-induced cardiomyopathy (CCM) with varying clinical presentations including: acute, early onset, and late-onset. Many individuals develop cardiac dysfunction over the long-term, ranging from subclinical cardiac dysfunction to end-stage symptomatic heart failure. The focus of this review is on characterization of symptomatic heart failure in children with cancer therapy-related cardiac dysfunction (CTRCD) primarily due to CCM and utilization of advanced heart failure therapies, including ventricular assist device (VAD) support and heart transplantation, with consideration of unique patient-related factors.

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.

Amino Acid-Level Signal-to-Noise Analysis Aids in Pathogenicity Prediction of Incidentally Identified TTN-Encoded Titin Truncating Variants

BACKGROUND

TTN, the largest gene in the human body, encodes TTN (titin), a protein that plays key structural, developmental, and regulatory roles in skeletal and cardiac muscle. Variants in TTN, particularly truncating variants (TTNtvs), have been implicated in the pathogenicity of cardiomyopathy. Despite this link, there is also a high burden of TTNtvs in the ostensibly healthy general population. This complicates the diagnostic interpretation of incidentally identified TTNtvs, which are of increasing abundance given expanding clinical exome sequencing.

METHODS

Incidentally identified TTNtvs were obtained from a large referral database of clinical exome sequencing (Baylor Genetics) and compared with rare population variants from genome aggregation database and cardiomyopathy-associated variants from cohort studies in the literature. A subset of TTNtv-positive children evaluated for cardiomyopathy at Texas Children's Hospital was retrospectively reviewed for clinical features of cardiomyopathy. Amino acid-level signal-to-noise analysis was performed.

RESULTS

Pathological hotspots were identified within the A-band and N-terminal I-band that closely correlated with regions of high percent-spliced in of exons. Incidental TTNtvs and population TTNtvs did not localize to these regions. Variants were reclassified based on current American College of Medical Genetics and Genomics criteria with incorporation of signal-to-noise analysis among Texas Children's Hospital cases. Those reclassified as likely pathogenic or pathogenic were more likely to have evidence of cardiomyopathy on echocardiography than those reclassified as variants of unknown significance.

CONCLUSIONS

Incidentally found TTNtvs are common among clinical exome sequencing referrals. Pathological hotspots within the A-band of TTN may be informative in determining variant pathogenicity when incorporated into current American College of Medical Genetics and Genomics guidelines.

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.

Left Atrial Strain Correlates with Elevated Filling Pressures in Pediatric Heart Transplantation Recipients

BACKGROUND

Noninvasive assessment of diastolic function in pediatric heart transplantation (PHTx) patients is important for monitoring of rejection, cardiac allograft vasculopathy, and nonspecific graft failure. We hypothesized that left atrial strain (LAS) would correlate with pulmonary capillary wedge pressure (PCWP) and that cutoff values to identify elevated left ventricular (LV) filling pressure could be derived for clinical practice and future testing.

METHODS

This was a secondary analysis of a prospectively collected cohort of PHTx patients undergoing same-day cardiac catheterization with biopsy and transthoracic echo. There were 70 patients with 85 clinical encounters. Traditional mitral inflow Doppler, LAS, LV diastolic strain and strain rate, and ratios for mitral E to LV diastolic strain and strain rate were assessed. Correlation with PCWP was performed, and receiver operator characteristic curves were generated for an elevated mean PCWP, acute rejection, and cardiac allograft vasculopathy.

RESULTS

Decreased LAS during the atrial reservoir phase (Ɛres) correlated with higher invasively measured PCWP (r = -0.40, P < .001). An Ɛres cutoff of 14.5% had good discriminatory ability for an elevated PCWP (sensitivity 75%, specificity 82%), and Ɛres > 22.0% had 100% negative predictive value; Ɛres was superior to other measures of diastolic function. Subanalyses for recent acute rejection (n = 9) showed good discriminatory ability for Ɛres of 14.5% (sensitivity 89%, specificity 74%).

CONCLUSIONS

LAS correlates with invasively measured PCWP and can identify elevated pressures better than traditional and other advanced diastolic function parameters. Use of LAS in PHTx patients may aid in noninvasive monitoring for rejection and nonspecific graft dysfunction.

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.

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.

A 14-year-old in heart failure with multiple cardiomyopathy variants illustrates a role for signal-to-noise analysis in gene test re-interpretation

Variants of unknown significance in cardiomyopathic disease should be analyzed systematically based on the prevalence of the variant in the population compared to prevalence of disease, evidence that other variants in the gene are pathologic, consistency of prediction software on pathogenicity, and the current clinical consensus.

Fatal cardiac arrest in pediatric heart transplant recipients: Query of the UNOS database

The incidence of death by CA after PHTx is unknown. We aimed to determine the incidence and factors for fatal CA after PHTx, and whether a PM affects survival. Retrospective cohort study utilizing the United Network of Organ Sharing registry of patients transplanted ≤18 years. Multivariable analyses in hazard-function domain and Kaplan-Meier analyses were performed for an outcome of death due to CA. There were 7719 PHTx patients queried. CA was the reported cause of death in 11%. Age ≥13 years at time of transplant, presence of a PM, and depressed EF were identified as significant factors for fatal CA. Death due to CA beyond 10 years post-transplant was associated with depressed EF, CAV, and presence of a PM. Kaplan-Meier analysis demonstrated higher likelihood of fatal CA in patients with CAV and in those with a PM vs those without. In total, 15% of patients with a PM died from CA. CA is a relatively common cause of death after PHTx. The benefit of a PM remains unclear, but its presence does not confer complete protection. Patients with associated factors warrant vigilant surveillance and consideration for retransplantation.

Titanium Plug Closure after HeartWare Ventricular Assist Device Explantation in a 15-Year-Old Girl: First U.S. Experience

We describe the case of a teenage girl with anthracycline-induced cardiomyopathy who received a HeartWare ventricular assist device and underwent successful device explantation after cardiac recovery. During device support, the patient's cardiac function returned to normal. Twelve months after implantation, we explanted the device via repeat median sternotomy. To close the hole in the left ventricular apex and preserve the sewing ring in case future device support is needed, we used a German-manufactured titanium plug, developed specifically for this purpose. To our knowledge, this is the first use of this plug in the United States. The patient recovered uneventfully and was discharged from the hospital on postoperative day 11. Left ventricular biopsy specimens at explantation revealed the resolution of previous degenerative sarcomeric changes. Our patient did well clinically; however, recurrent late anthracycline cardiotoxicity might subsequently cause her cardiac function to deteriorate. In this event, our use of the titanium plug to preserve the left ventricular sewing ring would enable easier device replacement than would other explantation options.

Incidence, Severity, and Association With Adverse Outcome of Hyponatremia in Children Hospitalized With Heart Failure

Hyponatremia is a common finding in adults hospitalized with heart failure (HF) and is associated with longer hospital stays and increased mortality. The significance of hyponatremia in children with HF is not known. We sought to determine the incidence of hyponatremia and association with clinical outcome in children hospitalized with HF. Admission and inpatient serum sodium concentrations were analyzed in 141 consecutive children hospitalized with acute decompensated HF. Inclusion criteria include patients (age, birth to 21 years) with biventricular hearts who were hospitalized for HF from January 2007 to December 2012. The primary composite end point was death, cardiac transplantation, or the use of mechanical circulatory support (MCS) during hospitalization. Data for 141 patients were included in the analysis. The cohort included 48 patients (34%) with preexisting HF. Mean serum sodium at admission was 136 ± 4 mmol/L (range 124 to 150 mmol/L). Hyponatremia (serum sodium <135 mmol/L) was present in 45 patients (32%) at admission. Seventy-one patients (75%) with normal serum sodium concentrations at admission subsequently developed acquired hyponatremia during their hospitalization. Hyponatremia persisted at discharge in 17 of 66 patients (26%). Fifty-eight patients (41%) reached the composite end point during hospitalization (death, n = 15; cardiac transplantation, n = 27; MCS, n = 46). Hyponatremia at admission was independently associated with death, cardiac transplantation, or the use of MCS during hospitalization (odds ratio 3.1, p = 0.02). In conclusion, hyponatremia occurs commonly in children hospitalized with acute decompensated HF and is associated with increased risk of in-hospital mortality, cardiac transplantation, and need for MCS.

Echocardiographic Parameters and Outcomes in Primary Fetal Cardiomyopathy

OBJECTIVES

Primary fetal cardiomyopathy is a rare entity, with a poor prognosis. We sought to describe its echocardiographic characteristics and outcomes.

METHODS

We performed a 12-year retrospective review of fetuses with primary cardiomyopathy.

RESULTS

Of more than 6000 fetuses evaluated, 25 met criteria for primary cardiomyopathy, and 18 had sufficient echocardiographic and pregnancy outcome data for inclusion. At echocardiography, the median gestational age was 29.6 weeks (range, 21.0-36.4 weeks); median cardiovascular profile score was 6 (range, 1-9); median right ventricular Tei index was 0.52 (range, 0.32-0.94); and median left ventricular Tei index was 0.40 (range, 0.15-0.88). Two had fetal demise, and 16 survived to delivery. The median cardiovascular profile score in those with fetal demise was 3.0 and in those who survived to delivery was 6.5 (range, 3-9; P = .14). The median right ventricular Tei index in those with fetal demise was 0.39 and in those surviving to delivery was 0.53 (range, 0.38-0.94; P = .49). The median left ventricular Tei index in those with fetal demise was 0.29 and in those surviving to delivery was 0.42 (range, 0.15-0.88; P = .50). Sixty-day survival was available in 11 of 16 fetuses. In addition to the 2 with fetal demise, 4 had postnatal demise, and 5 were alive at a median follow-up of 39 months. Hydrops (P = .01), skin edema (P = .01), and mild or greater mitral regurgitation (P = .02) were associated with fetal or postnatal demise, with a trend toward an association between moderate or greater tricuspid regurgitation (P = .07) and fetal or postnatal demise.

CONCLUSIONS

Hydrops and atrioventricular valvar regurgitation are ominous signs in primary fetal cardiomyopathy. Although other commonly used methods for assessing cardiovascular performance may help in diagnosing primary cardiomyopathy, these data suggest limited predictive value.

Hospital Charges for Pediatric Heart Failure-Related Hospitalizations from 2000 to 2009

Scarce data exist regarding costs of pediatric heart failure-related hospitalizations (HFRH) or how costs have changed over time. Pediatric HFRH costs, due to advances in management, will have increased significantly over time. A retrospective analysis of Healthcare Cost and Utilization Project Kids' Inpatient Database was performed on all pediatric HFRH. Inflation-adjusted charges are used as a proxy for cost. There were a total of 33,189 HFRH captured from 2000 to 2009. Median charges per HFRH rose from $35,079 in 2000 to $72,087 in 2009 (p < 0.0001). The greatest median charges were incurred in patients on extracorporeal membrane oxygenation ($442,134 vs $53,998) or ventricular assist devices ($462,647 vs $55,151). Comorbidities, including sepsis ($207,511 vs $48,995), renal failure ($180,624 vs $52,812), stroke ($198,260 vs $54,974) and respiratory failure ($146,200 vs $48,797), were associated with greater charges (p < 0.0001). Comorbidities and use of mechanical support increased over time. After adjusting for these factors, later year remained associated with greater median charges per HFRH (p < 0.0001). From 2000 to 2009, there has been an almost twofold increase in pediatric HFRH charges, after adjustment for inflation. Although comorbidities and use of mechanical support account for some of this increase, later year remained independently associated with greater charges. Further study is needed to understand potential factors driving these higher costs over time and to identify more cost-effective therapies in this population.

Assessing ST Segment Changes and Ischemia During Exercise Stress Testing in Patients with Hypoplastic Left Heart Syndrome and Fontan Palliation

While exercise stress testing (EST) is an important tool, little is known about its use for determining ischemia in patients with hypoplastic left heart syndrome (HLHS) and Fontan palliation. We sought to determine the frequency of ST segment changes during EST in HLHS patients after Fontan and examine results of further testing performed in response to ST changes. A single-center chart review of HLHS patients post-Fontan from January 1995 to December 2012 was performed. Data collected included demographics, indications for EST, resting electrocardiogram findings, EST and echocardiogram results and outcomes. ESTs were evaluated for ST segment changes concerning for ischemia. Results of additional testing performed based on concerning EST findings were collected. Twenty-seven patients underwent 64 ESTs (mean 2.4 ESTs/patient). Median age at first EST was 9.6 years (range 6.2-16.4). EST was concerning for ischemia in 13 patients (48 %) on 25 (39 %) ESTs. Based on EST results, two patients had stress sestamibi testing, two underwent coronary angiography, and one had both. No reversible perfusion defects or coronary artery obstructions were demonstrated. No patient who underwent EST has died. ST segment depression was not associated with ventricular dysfunction prior to EST or at the end of follow-up (p > 0.05). In patients with HLHS post-Fontan palliation, ST segment depression on EST is common. In patients who underwent further testing, no evidence of ischemia or coronary abnormalities was found. Additional testing may not be necessary in all patients.

Clinical Characteristics and Treatment of Cardiomyopathies in Children

Cardiomyopathies are diseases of the heart muscle, a term introduced in 1957 to identify a group of myocardial diseases not attributable to coronary artery disease. The definition has since been modified to refer to structural and or functional abnormalities of the myocardium where other known causes of myocardial dysfunction, such as systemic hypertension, valvular disease and ischemic heart disease, have been excluded. In this review, we discuss the pathophysiology, clinical assessment and therapeutic strategies for hypertrophic, dilated and hypertrophic cardiomyopathies, with a particular focus on aspects unique to children.

Novel Use of Tolvaptan in a Pediatric Patient With Congestive Heart Failure Due to Duchenne Muscular Dystrophy and Congenital Adrenal Hyperplasia

Successful management of hyponatremia in heart failure patients requires a multifaceted approach in order to preserve end-organ function. We describe the novel use of a selective vasopressin receptor antagonist, tolvaptan, for management of hyponatremia in a 17-year-old Caucasian male with severe Duchenne muscular dystrophy, congestive heart failure (CHF), and congenital adrenal hyperplasia. The medical history was significant for recurrent admissions for hyponatremia secondary to adrenal crises, which was also exacerbated by his CHF. After initiation of tolvaptan and its extended administration, he had no further hyponatremia-related admissions and no adverse reactions. The complexity of this combination of conditions is presented, and the efficacy of the drug and the rationale behind the treatment approach is discussed.

Characteristics and outcomes of heart failure-related intensive care unit admissions in children with cardiomyopathy

OBJECTIVE

The purpose of this study was to describe patient characteristics and outcomes of heart failure (HF)-related intensive care unit (ICU) hospitalizations in children with cardiomyopathy (CM).

METHODS AND RESULTS

A query of the Pediatric Health Information System database, a large administrative and billing database of 43 tertiary children's hospitals, was performed. A total of 17,309 HF-related ICU hospitalizations from 2005 to 2010 of 14,985 children ≤18 years old were analyzed. Of those, 2,058 (12%) hospitalizations for CM-HF in 1,599 (11%) children were identified. Classification into CM subtypes was not possible owing to database limitations. The number of yearly CM-HF hospitalizations significantly increased during the study period (P = .036). Overall mortality was 11%, and cardiac transplantation occurred in 20% of hospitalizations. Mechanical circulatory support (MCS) was used in 261 (13%) of hospitalizations. Renal failure, MCS, respiratory failure, sepsis, and vasoactive medications were associated with mortality on multivariable analysis. Significant comorbidities associated with these hospitalizations included arrhythmias in 42%, renal failure in 13%, cerebrovascular disease in 6%, and hepatic impairment in 5%.

CONCLUSIONS

HF-related ICU hospitalizations in children with cardiomyopathy are increasing. These children are at high risk for poor outcomes with an in-hospital mortality of 11%.

Postoperative complications associated with perioperative sirolimus prior to pediatric cardiac retransplantation

OBJECTIVES

Sirolimus has been used in pediatric cardiac transplantation for the past decade for chronic renal dysfunction, recurrent rejection, and/or coronary allograft vasculopathy. There has been concern regarding the effect of sirolimus on wound healing and other postoperative complications. To date, the pediatric literature on its use is limited and has not specifically addressed its use in the perioperative period following repeat cardiac transplantation.

METHODS

We compared the patients in our institution who received sirolimus before repeat cardiac transplantation to those in the same era who did not receive sirolimus.

RESULTS

Of the 5 patients in the study group, 5 (100%) developed pleural effusions vs 1 (17%) in the control group (p=0.013). There was no increase in mortality in the sirolimus group, and there were no significant differences in renal dysfunction, serious bacterial infection, rejection, or postoperative length of stay.

CONCLUSIONS

In this small data set, there was a statistically significant increase in pleural effusions in patients on sirolimus. Further study is needed to develop an appropriate strategy to avoid postoperative complications in this patient population.

Mortality and sudden death in pediatric left ventricular noncompaction in a tertiary referral center

BACKGROUND

Left ventricular noncompaction is a cardiomyopathy characterized by excessive trabeculation of the left ventricle, progressive myocardial dysfunction, and early mortality. Left ventricular noncompaction has a heterogeneous clinical presentation that includes arrhythmia and sudden cardiac death.

METHODS AND RESULTS

We retrospectively reviewed all children diagnosed with left ventricular noncompaction at Texas Children's Hospital from January 1990 to January 2009. Patients with congenital cardiac lesions were excluded. Two hundred forty-two children were diagnosed with isolated left ventricular noncompaction over the study period. Thirty-one (12.8%) died, and 13 (5.4%) were received a transplant. One hundred fifty (62%) presented with or developed cardiac dysfunction. The presence of cardiac dysfunction was strongly associated with mortality (hazard ratio, 11; P<0.001). ECG abnormalities were present in 87%, with ventricular hypertrophy and repolarization abnormalities occurring most commonly. Repolarization abnormalities were associated with increased mortality (hazard ratio, 2.1; P=0.02). Eighty children (33.1%) had an arrhythmia, and those with arrhythmias had increased mortality (hazard ratio, 2.8; P=0.002). Forty-two (17.4%) had ventricular tachycardia, with 5 presenting with resuscitated sudden cardiac death. In total, there were 15 cases of sudden cardiac death in the cohort (6.2%). Nearly all patients with sudden death (14 of 15) had abnormal cardiac dimensions or cardiac dysfunction. No patient with normal cardiac dimensions and function without preceding arrhythmias died.

CONCLUSIONS

Left ventricular noncompaction has a high mortality rate and is strongly associated with arrhythmias in children. Preceding cardiac dysfunction or ventricular arrhythmias are associated with increased mortality. Children with normal cardiac dimensions and normal function are at low risk for sudden death.

Parvovirus B19 myocarditis causes significant morbidity and mortality in children

Although parvovirus B19 (PVB19) currently is the most common cause of viral myocarditis, limited pediatric data exist. Whereas other viruses infect cardiomyocytes, PVB19 targets coronary endothelium, leading to myocardial ischemia and dysfunction. A retrospective review investigated patients with polymerase chain reaction (PCR)-verified PVB19 myocarditis at Texas Children's Hospital and Arkansas Children's Hospital (January 2005 to August 2008). The primary end points of the study were transplant-free survival and circulatory collapse (death, mechanical support, or transplantation). For the 19 patients identified (age, 6 months to 15 years), the most common presenting symptoms were respiratory and gastrointestinal. At admission, all the patients demonstrated ventricular dysfunction requiring inotropic support (median ejection fraction, 24 %; median left ventricle end-diastolic diameter [LVEDD] z-score, 4.6). Whereas T-wave abnormalities were common, ST elevation was evident in five patients (two died and three required transplantation). Serum B-type natrietic peptide was elevated in all 12 patients tested (range, 348-8,058 pg/ml), and troponin I was high in 7 of 9 patients (range, 0.04-14.5 ng/ml). Of the 15 patients with circulatory collapse, nine received mechanical support, eight underwent successful transplantation, and five died. Only six patients (32 %) experienced transplant-free survival, and five patients had full recovery of function at discharge. In the transplant-free survival group, ST changes on presenting electrocardiography were less likely (p = 0.03), and the admission LVEDD z-score tended to be lower (3.3 vs 5.6; p = 0.08). In children, PVB19 myocarditis causes significant mortality and morbidity. Although mechanical intervention can support patients in the initial stage of decompensated heart failure, patients with PVB19 myocarditis often demonstrate persistent dysfunction requiring medical therapy and transplantation.

Prevalence, morbidity, and mortality of heart failure-related hospitalizations in children in the United States: a population-based study

BACKGROUND

Few data exist on prevalence, morbidity, and mortality of pediatric heart failure hospitalizations. We tested the hypotheses that pediatric heart failure-related hospitalizations increased over time but that mortality decreased. Factors associated with mortality and length of stay were also assessed.

METHODS AND RESULTS

A retrospective analysis of the Healthcare Cost and Utilization Project Kids' Inpatient Database was performed for pediatric (age ≤18 years) heart failure-related hospitalizations for the years 1997, 2000, 2003, and 2006. Hospitalizations did not significantly increase over time, ranging from 11,153 (95% confidence interval [CI] 8,898-13,409) in 2003 to 13,892 (95% CI 11,528-16,256) in 2006. Hospital length of stay increased from 1997 (mean 13.8 days, 95% CI 12.5-15.2) to 2006 (mean 19.4 days, 95% CI 18.2 to 20.6). Hospital mortality was 7.3% (95% CI 6.9-8.0) and did not vary significantly between years; however, risk-adjusted mortality was less in 2006 (odds ratio 0.70, 95% CI 0.61 to 0.80). The greatest risk of mortality occurred with extracorporeal membrane oxygenation, acute renal failure, and sepsis.

CONCLUSIONS

Heart failure-related hospitalizations occur in 11,000-14,000 children annually in the United States, with an overall mortality of 7%. Many comorbid conditions influenced hospital mortality.

Restrictive cardiomyopathy in childhood

Depending on the part of the world one lives in, restrictive cardiomyopathy is either one of the rarest forms of cardiomyopathy in childhood, with no cause usually identified, or it is secondary to a poorly understood disease, endomyocardial fibrosis, that is endemic in some populations. Regardless of the underlying cause, the outcome is poor once symptoms develop. This article reviews the definitions, epidemiology, etiologies, genetics, "overlap" phenotypes, clinical presentation, diagnostic evaluation, outcome, and management of pediatric patients with restrictive cardiomyopathy.