Symptomatic presentation influences outcomes in pediatric restrictive cardiomyopathy.

Introduction: Children with restrictive cardiomyopathy (RCM) traditionally have a poor prognosis, with most patients either dying or requiring heart transplantation within 2 years of diagnosis. The development of symptoms in RCM suggests advanced disease. However, as screening practices evolve and lead to diagnosis of early disease, identifying appropriate timing of transplant listing becomes increasingly important. In this context we compared outcomes of children with RCM presenting with clinical symptoms to those asymptomatic at initial presentation. Methods: This retrospective cohort study included 25 patients with RCM presenting to a quaternary care center between 2001 and 2018. Times to transplantation, death, and a composite outcome of adverse cardiac events (CPR, cardioversion, inotropic support, mechanical ventilation, mechanical support, or heart transplant) were compared between those symptomatic and asymptomatic at presentation. Results: At 2 years following diagnosis, patients asymptomatic at presentation had a significantly better transplant-free survival at 57% compared to 17% for symptomatic patients (p = 0.03). Those asymptomatic at diagnosis also had significantly improved cardiac event-free survival at 71% compared to symptomatic patients at 25% (p = 0.01). In multivariable analysis, cardiac symptoms at presentation remained an independent risk factor for heart-transplant or death [hazard ratio 5.17 (1.28-20.85), p = 0.02]. Conclusion: Patients with RCM who are symptomatic at time of diagnosis have significantly worse transplant-free survival and cardiac event-free survival. Given current practice variability in timing of transplant listing, the presence of any cardiac symptoms is an important negative prognostic marker and should prompt urgent transplant listing.

Pitfalls and Possibilities of Ventricular Assist Device Support in Congenitally Corrected Transposition of the Great Arteries in Children.

Congenitally corrected transposition of the great arteries (ccTGAs) represents a complex form of congenital heart disease that is associated with several cardiac complications. Herein is a case series of three children with ccTGA and ventricular assist device (VAD) inserted for systemic right ventricle failure at a single institution. All patients remained hemodynamically stable postimplant and were successfully discharged from the intensive care unit to undergo postoperative rehabilitation. All three patients received an orthotopic heart transplant with uneventful posttransplant courses. This case series provides insight into the medical management and technical feasibility of VAD support in children with ccTGA with end-stage heart failure.

Quantification of lymphatic burden in patients with Fontan circulation by T2 MR lymphangiography and associations with adverse Fontan status.

AIMS: To quantify thoracic lymphatic burden in paediatric Fontan patients using MRI and correlate with clinical status. METHODS AND RESULTS: Paediatric Fontan patients (<18-years-old) with clinical cardiac MRI that had routine lymphatic 3D T2 fast spin echo (FSE) imaging performed from May 2017 to October 2019 were included. 'Lymphatic burden' was quantified by thresholding-based segmentation of the 3D T2 FSE maximum intensity projection image and indexed to body surface area, performed by two independent readers blinded to patient status. There were 48 patients (27 males) with median age at MRI of 12.9 (9.4-14.7) years, time from Fontan surgery to MRI of 9.1 (5.9-10.4) years, and follow-up time post-Fontan surgery of 9.4 (6.6-11.0) years. Intraclass correlation coefficient between two observers for lymphatic burden was 0.96 (0.94-0.98). Greater lymphatic burden correlated with post-Fontan operation hospital length of stay and duration of chest tube drainage (rs = 0.416, P = 0.004 and rs = 0.439, P = 0.002). Median lymphatic burden was greater in patients with chylous effusions immediately post-Fontan (178 (118-393) vs. 113 (46-190) mL/m2, P = 0.028), and in patients with composite adverse Fontan status (n = 13) defined by heart failure (n = 3), transplant assessment (n = 2), recurrent effusions (n = 6), Fontan thrombus (n = 2), and/or PLE (n = 6) post-Fontan (435 (137-822) vs. 114 (51-178) mL/m2, P = 0.003). Lymphatic burden > 600 mL/m2 was associated with late adverse Fontan status with sensitivity of 57% and specificity of 95%. CONCLUSION: Quantification of MR lymphatic burden is a reliable tool to assess the lymphatics post-Fontan and is associated with clinical status.

HERVs characterize normal and leukemia stem cells and represent a source of shared epitopes for cancer immunotherapy.

Human endogenous retroviruses (HERVs) represent 8% of the human genome. The expression of HERVs and their immune impact have not been extensively studied in Acute Myeloid Leukemia (AML). In this study, we used a reference of 14 968 HERV functional units to provide a thorough analysis of HERV expression in normal and AML bone marrow cells. We show that the HERV retrotranscriptome accurately characterizes normal and leukemic cell subpopulations, including leukemia stem cells, in line with different epigenetic profiles. We then show that HERV expression delineates AML subtypes with different prognoses. We finally propose a method to select and prioritize CD8+ T cell epitopes derived from AML-specific HERVs and we show that lymphocytes infiltrating patient bone marrow at diagnosis contain naturally occurring CD8+ T cells against these HERV epitopes. We also provide in vitro data supporting the functionality of HERV-specific CD8+ T-cells against AML cells. These results show that HERVs represent an important source of genetic information that can help enhancing disease stratification or biomarker identification and an important reservoir of alternative tumor-specific T cell epitopes relevant for cancer immunotherapy.

MRI Phase-Contrast Blood Flow in Fasting Pediatric Patients with Fontan Circulation Correlates with Exercise Capacity.

Purpose: To assess regional blood flow in fasting pediatric patients with Fontan circulation by using MRI and to explore associations with clinical parameters. Materials and Methods: In this retrospective study, pediatric patients who had undergone the Fontan procedure (<18 years of age) and had undergone clinical cardiac MRI, performed after at least 4 hours of fasting, between 2018 and 2021 were included. Regional blood flow was compared with published healthy volunteer data (n = 19) and assessed in relation to hemodynamic parameters and clinical status. Data are presented as medians, with first to third quartiles in parentheses. Mann-Whitney U, Kruskal-Wallis, χ2, and Spearman rank correlation tests were used. Results: Fifty-five patients (38 boys) with median age at MRI of 14 years (IQR, 11-16 years) and median time from Fontan procedure to MRI of 10 years (IQR, 8-12 years) were included. Patients after Fontan procedure had lower ascending aortic, inferior vena cava, and total systemic blood flow compared with healthy volunteers (3.00 L/min/m2 [IQR, 2.75-3.30 L/min/m2] vs 3.61 L/min/m2 [IQR, 3.29-4.07 L/min/m2]; 1.73 L/min/m2 [IQR, 1.40-1.94 L/min/m2] vs 2.24 L/min/m2 [IQR, 2.06-2.75 L/min/m2]; 2.78 L/min/m2 [IQR, 2.45-3.10 L/min/m2] vs 3.95 L/min/m2 [IQR, 3.20-4.30 L/min/m2], respectively; P < .001). Portal vein flow was greater than hepatic vein flow in 25% of patients. Fontan blood flow was inversely correlated with pre-Fontan mean pulmonary artery pressure (Spearman rank correlation coefficient [rs ]= -0.42, P = .005) and ventricular end diastolic pressure (rs = -0.33, P = .04) and positively correlated with post-Fontan percent predicted oxygen consumption at peak workload (rs = 0.34, P = .02). Conclusion: Reference ranges are provided for regional systemic blood flow derived by using MRI in fasting pediatric patients with Fontan circulation, who had lower systemic blood flow compared with healthy volunteers. Lower fasting Fontan blood flow correlated with lower exercise capacity.Keywords: Pediatrics, Heart, Congenital, MR Imaging, Hemodynamics/Flow Dynamics, Cardiac Supplemental material is available for this article. © RSNA, 2022.

"Acquired" Brugada syndrome in a cardiac allograft.

INTRODUCTION: Brugada syndrome is an inherited channelopathy characterized by arrhythmia and an increased risk of sudden cardiac death (SCD). Implantation of a defibrillator for primary or secondary prevention is the only effective strategy to decrease the risk of SCD in Brugada syndrome. We present a case in which a cardiac donor had a pathogenic variant for Brugada syndrome, discovered on genetic testing after transplantation. CASE REPORT: A young child with dilated cardiomyopathy underwent orthotopic heart transplantation from a donor with in-hospital cardiac arrest in the context of fever and a normal ECG. Approximately 1 month after transplant, the donor's post mortem genetic testing revealed a pathogenic loss-of-function SCN5A variant associated with Brugada syndrome, which was confirmed on genetic testing on a post-transplant endomyocardial biopsy from the recipient. The recipient's post-transplant electrocardiographic monitoring revealed persistent right bundle branch block and progressive, asymptomatic sinus node dysfunction. The recipient was managed with precautionary measures including aggressive fever management, avoidance of drugs that increase arrhythmia risk in Brugada syndrome, and increased frequency of arrhythmia surveillance. The recipient remains asymptomatic at over 3 years post-transplant with preserved graft function and no documented ventricular arrhythmias. CONCLUSION: We describe the clinical course of "acquired" Brugada syndrome in a cardiac allograft recipient, which has not been previously reported. The time-sensitive nature of donor organ selection, especially in critically ill recipients, combined with the growing use of molecular autopsies in patients with unexplained etiologies for death may increasingly result in important donor genetic information being made available after transplantation.

Left Ventricular Noncompaction Cardiomyopathy: Left Ventricular Dilation and Dysfunction at Baseline Portend the Risk of Death or Heart Transplantation.

BACKGROUND: Left ventricular noncompaction (LVNC) is associated with genetic and phenotypic variability that influences outcomes. We aimed to identify risk factors for death or heart transplantation (HTx) in a paediatric LVNC cohort. METHODS: We reviewed patients < 18 years of age (2001-2018) with LVNC, either isolated (I-LVNC) or with dilated phenotype (D-LVNC), and at least mildly reduced left ventricular ejection fraction (EF). Patients with dilated cardiomyopathy (DCM) were included as control subjects. Descriptive statistics, multivariate analysis, and time-to-event analysis were used. RESULTS: We included 188 patients, 34 (18%) with I-LVNC, 37 (20%) with D-LVNC, and 117 (62%) with DCM. Overall median age at diagnosis was 1.08 years (interquartile range [IQR] 0.22-10.65) and median follow-up was 1.4 years (IQR 0.2-5.2) years. I-LVNC patients' median baseline LVEF was 47%, compared with 33% for D-LVNC, and 21% for DCM (P < 0.0001); 62% of I-LVNC patients developed moderate to severe LV dysfunction during follow-up. The incidence of death or transplantation was 43.6% in the overall cohort. Freedom from death or HTx at 10 years after diagnosis was 88.6% (95% CI 76%-100%) for I-LVNC, 47% (95% CI 29%-65%) for D-LVNC, and 42.3% (95% CI 33%-52%) for DCM. On multivariable analysis, baseline LVEF and LV end-diastolic diameter (LVEDD) z-score were associated with death or transplantation. Patients with a baseline LVEDD z-score > 4 and moderate to severe LV dysfunction had a transplantation-free survival of 38%. CONCLUSIONS: Baseline LV dilation and systolic dysfunction were independently associated with progression to death or HTx in LVNC patients.

Identification of shared tumor epitopes from endogenous retroviruses inducing high-avidity cytotoxic T cells for cancer immunotherapy.

Human endogenous retroviruses (HERVs) represent 8% of the human genome. HERV products may represent tumor antigens relevant for cancer immunotherapy. We developed a bioinformatic approach to identify shared CD8+ T cell epitopes derived from cancer-associated HERVs in solid tumors. Six candidates among the most commonly shared HLA-A2 epitopes with evidence of translation were selected for immunological evaluation. In vitro priming assays confirmed the immunogenicity of these epitopes, which induced high-avidity CD8+ T cell clones. These T cells specifically recognize and kill HLA-A2+ tumor cells presenting HERV epitopes on HLA molecules, as demonstrated by mass spectrometry. Furthermore, epitope-specific CD8+ T cells were identified by dextramer staining among tumor-infiltrating lymphocytes from HLA-A2+ patients with breast cancer. Last, we showed that HERV-specific T cells lyse patient-derived organoids. These shared virus-like epitopes are of major interest for the development of cancer vaccines or T cell-based immunotherapies, especially in tumors with low/intermediate mutational burden.

The Canadian Pediatric Cardiology Research Network: A Model National Data-Sharing Organization to Facilitate the Study of Pediatric Heart Diseases.

BACKGROUND: Common hurdles to pediatric cardiology research include the heterogeneity and relative rarity of specific cardiac malformations, the potential for effect of residual lesions occurring decades after repair, and the scarcity of objective and easily measurable outcomes such as death and transplantation. METHODS: To help meet these challenges, the Canadian Pediatric Cardiology Research Network (CPCRN) was founded by the Canadian Pediatric Cardiology Association to link Canadian academic institutions to promote and facilitate multicollaborations for the benefit of pediatric and congenital cardiology research. The overarching goal of the CPCRN is to build a national framework that harnesses the strong desire for collaboration within the pediatric cardiology community and to identify solutions to barriers that impede multicentre partnerships. RESULTS: In this report, the authors describe the approach and the components of the CPCRN. Specifically, we detail the rolling out of a pan-Canadian master agreement that covers current and future studies, the systematic banking of all project data, and the mechanisms developed to facilitate secondary use of data. CONCLUSIONS: This experience could help guide the formation of other national research groups, particularly those focused on congenital or rare diseases.

CONTEXTE: Les obstacles courants dans le domaine de la recherche en cardiologie pédiatrique comprennent l'hétérogénéité et la rareté des malformations cardiaques, le fait que des lésions résiduelles aient des répercussions qui se manifesteront des décennies après une intervention, et la rareté des issues cliniques objectives et facilement mesurables comme les décès et les transplantations. MÉTHODOLOGIE: Pour remédier à ces obstacles, le Réseau canadien de recherche en cardiologie pédiatrique (CPCRN) a été fondé par la l'Association canadienne de cardiologie pédiatrique afin de mettre en relation les établissements universitaires canadiens et de promouvoir ainsi des collaborations multiples qui bénéficieront à la recherche en cardiologie pédiatrique et congénitale. L'objectif principal du CPCRN est de mettre sur pied une structure nationale qui tire profit de l'important désir de collaboration dans le domaine de la cardiologie pédiatrique et de trouver des solutions aux obstacles qui nuisent aux partenariats entre les différents établissements. RÉSULTATS: Dans cet article, les auteurs décrivent l'approche et les composantes du CPCRN. Ils passent en revue les détails du déploiement d'une entente-cadre pancanadienne concernant les études en cours et à venir, la mise en banque systématique de toutes les données de recherche et les mécanismes mis au point pour permettre l'utilisation secondaire de ces données. CONCLUSIONS: Cette expérience pourrait permettre de guider la formation d'autres groupes de recherche nationaux, plus particulièrement dans les domaines des maladies rares ou congénitales.

A Validated Model for Sudden Cardiac Death Risk Prediction in Pediatric Hypertrophic Cardiomyopathy.

BACKGROUND: Hypertrophic cardiomyopathy is the leading cause of sudden cardiac death (SCD) in children and young adults. Our objective was to develop and validate a SCD risk prediction model in pediatric hypertrophic cardiomyopathy to guide SCD prevention strategies. METHODS: In an international multicenter observational cohort study, phenotype-positive patients with isolated hypertrophic cardiomyopathy <18 years of age at diagnosis were eligible. The primary outcome variable was the time from diagnosis to a composite of SCD events at 5-year follow-up: SCD, resuscitated sudden cardiac arrest, and aborted SCD, that is, appropriate shock following primary prevention implantable cardioverter defibrillators. Competing risk models with cause-specific hazard regression were used to identify and quantify clinical and genetic factors associated with SCD. The cause-specific regression model was implemented using boosting, and tuned with 10 repeated 4-fold cross-validations. The final model was fitted using all data with the tuned hyperparameter value that maximizes the c-statistic, and its performance was characterized by using the c-statistic for competing risk models. The final model was validated in an independent external cohort (SHaRe [Sarcomeric Human Cardiomyopathy Registry], n=285). RESULTS: Overall, 572 patients met eligibility criteria with 2855 patient-years of follow-up. The 5-year cumulative proportion of SCD events was 9.1% (14 SCD, 25 resuscitated sudden cardiac arrests, and 14 aborted SCD). Risk predictors included age at diagnosis, documented nonsustained ventricular tachycardia, unexplained syncope, septal diameter z-score, left ventricular posterior wall diameter z score, left atrial diameter z score, peak left ventricular outflow tract gradient, and presence of a pathogenic variant. Unlike in adults, left ventricular outflow tract gradient had an inverse association, and family history of SCD had no association with SCD. Clinical and clinical/genetic models were developed to predict 5-year freedom from SCD. Both models adequately discriminated between patients with and without SCD events with a c-statistic of 0.75 and 0.76, respectively, and demonstrated good agreement between predicted and observed events in the primary and validation cohorts (validation c-statistic 0.71 and 0.72, respectively). CONCLUSION: Our study provides a validated SCD risk prediction model with >70% prediction accuracy and incorporates risk factors that are unique to pediatric hypertrophic cardiomyopathy. An individualized risk prediction model has the potential to improve the application of clinical practice guidelines and shared decision making for implantable cardioverter defibrillator insertion. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT0403679.

Survival to Stage II with Ventricular Dysfunction: Secondary Analysis of the Single Ventricle Reconstruction Trial.

Ventricular dysfunction affects survival in patients with single right ventricle (RV), and remains one of the primary indications for heart transplantation. Since it is challenging to predict the capacity of patients with ventricular dysfunction to proceed to the stage II procedure, we sought to identify factors that would be associated with death or heart transplantation without achieving stage II for single RV patients with ventricular dysfunction after Norwood procedure. The Single Ventricle Reconstruction (SVR) trial public-use database was used. Patients with a RV ejection fraction less than 44% or a RV fractional area of change less than 35% on the post-Norwood echocardiogram were included. Parametric risk hazard analysis was used to identify risk factors for death or transplantation without achieving stage II. Of 365 patients with ventricular function measurements on the post-Norwood echocardiogram, 123 (34%) patients had RV dysfunction. The transplantation-free survival was significantly lower for those with ventricular dysfunction compared to those with normal function (log rank Chi-square = 4.23, p = 0.04). Furthermore, having a Blalock-Taussig (BT) shunt, a large RV, a post-Norwood infectious complication, and a surgeon who performs five or less Norwood per year were independent risk factors for death or transplantation without achieving stage II. The predicted 6-month transplantation-free survival for patients with all four identified risk factors was 1% (70% CI 0-13%). Early heart transplantation referral might be considered for post-Norwood patients with BT shunt and RV dysfunction, especially if other high-risk features are present.

Short-term remote ischemic preconditioning is not associated with improved blood pressure and exercise capacity in young adults.

We sought to determine whether a 9-day remote ischemic preconditioning (IPC) causes improvements in exercise performance, energetics, and blood pressure. Ten participants (mean age 24 ± 4 years) had no changes in aerobic capacity (preintervention: 38 ± 10 mL/(kg·min)(-1) vs. postintervention: 38 ± 10 mL/(kg·min)(-1)), blood pressure (preintervention: 112 ± 7/66 ± 6 mm Hg vs. postintervention: 112 ± 10/62 ± 5 mm Hg), cardiac phosphocreatinine-to-adenosine-triphosphate ratio (preintervention: 2.1 ± 0.5 vs. postintervention: 2.3 ± 0.4), and postexercise skeletal muscle phosphocreatine recovery (preintervention: 34 ± 11 s vs. postintervention: 31 ± 11 s). Short-term remote IPC may be ineffective in improving these outcomes.

Outcomes in Patients with Persistent Ventricular Dysfunction After Stage I Palliation for Hypoplastic Left Heart Syndrome.

We sought to describe the clinical course for patients with hypoplastic left heart syndrome and persistent ventricular dysfunction and identify risk factors for death or transplantation before stage II palliation. 138 children undergoing stage I palliation from 2004 to 2011 were reviewed. Twenty-two (16 %) patients (seven Hybrid, 15 Norwood) with two consecutive echocardiograms reporting at least moderate dysfunction were included and compared to case-matched controls. Eleven of the 22 patients with dysfunction (50 %) underwent stage II, seven (32 %) were transplanted, and four (18 %) died prior to stage II. Of the patients who survived to hospital discharge (n = 17) following stage 1, 14 (82 %) required readmission for heart failure (HF) compared to only two (10 %) for controls (p < 0.001). Among patients with ventricular dysfunction, there was an increased use of ACE inhibitors or beta-blockers (82 vs. 25 %; p = 0.001), inotropes (71 vs. 15 %; p = 0.001), ventilation (58 vs. 10 %; p = 0.001), and ECMO (29 vs. 0 %; p = 0.014) for HF management post-discharge when compared to controls. There was a lower heart transplant-free survival at 7 months in patients with dysfunction compared to controls (50.6 vs. 90.9 %; p = 0.040). ECMO support (p = 0.001) and duration of inotropic support (p = 0.04) were significantly associated with death or transplantation before stage II palliation. Patients with ventricular dysfunction received more HF management and related admissions. Longer inotropic support should prompt discussion regarding alternative treatment strategies given its association with death or transplant.

Characterizing blood oxygen level-dependent (BOLD) response following in-magnet quadriceps exercise.

OBJECT: There have been no studies to investigate the effects of cycling exercise protocols, as well as repeated bouts of exercise, on the blood oxygen level-dependent (BOLD) response in the quadriceps muscles. This study characterized BOLD signal recovery following non-ischemic bouts of exercise in the quadriceps muscles of healthy adults in order to provide a basis for application of a protocol for clinical populations. MATERIALS AND METHODS: Healthy male subjects (23.7 ± 2.0 years of age, n = 10) completed three cycles of one-minute exercise (65 % of maximum workload), with two minutes of rest between each bout, on an MRI-compatible ergometer. The BOLD responses during recovery were fitted to a sigmoid model, and response kinetics (post-exercise intensity [S0]), response time (α), change in baseline BOLD signal (κ), and inflection point (ß)] were measured. RESULTS: The sigmoid function fit well to the post-exercise BOLD data (r (2) = 0.95 ± 0.04). The mean response time was 10.5 ± 3.8 seconds, change in baseline BOLD intensity was 0.15 ± 0.068, and time to half-peak was 20.2 ± 8.6 seconds. CONCLUSION: The proposed sigmoid model is a robust method for quantifying quadriceps BOLD response post-exercise without induced ischemia. Extension of this model to evaluate microvascular responses in patients with chronic disease could improve our understanding of exercise intolerance.