Complications of endomyocardial biopsy in children

Donor-derived cell-free dna as a diagnostic biomarker for acute rejection in heart transplantation: A systematic review and meta-analysis

BACKGROUND

Endomyocardial biopsy is widely acknowledged as the gold standard for detecting rejection following heart transplantation. However, the operation itself carries a risk of myocardial tissue damage and associated complications during and after surgery. Given the limitations of existing diagnostic approaches, non-invasive biomarkers are crucial.

OBJECTIVE

This study assessed the diagnostic utility of donor-derived cell-free DNA (dd-cfDNA) in detecting AR in heart transplant recipients.

METHODS

A systematic literature search was conducted across PubMed, Embase, Cochrane Library, and Web of Science from inception to August 1, 2024, to identify studies evaluating the diagnostic performance of dd-cfDNA for AR in heart transplant recipients. Retrieved studies were screened using EndNote X9. Meta-analysis was performed using Meta-Disc software version 1.4 and STATA/SE 14.0.

RESULTS

Ten studies were included in the meta-analysis. The pooled sensitivity, specificity, and area under the receiver operating characteristic curve with 95 % confidence intervals (CIs) were 65 % (95 % CI, 61-68 %), 79 % (95 % CI, 78-80 %), and 0.83, respectively.

CONCLUSIONS

This meta-analysis indicates that plasma dd-cfDNA may serve as a promising non-invasive biomarker for the diagnosis of acute rejection in heart transplant recipients. However, further research is warranted to investigate factors influencing diagnostic performance and optimize clinical utility.

How to behave with paediatric myocarditis: imaging methods and clinical considerations

Paediatric myocarditis is a challenging and heterogeneous condition, with varied clinical presentations ranging from mild symptoms to life-threatening complications such as heart failure, arrhythmias, and sudden cardiac death. Effective management hinges on early diagnosis, appropriate treatment, and ongoing monitoring, which can be significantly enhanced through multimodal imaging techniques. This review emphasizes the crucial role of advanced imaging in the diagnosis, prognostication, and management of paediatric myocarditis. While traditional echocardiography remains the first-line imaging tool, it is often insufficient in detecting subtle myocardial changes and it does not allow the identification of myocardial inflammation and fibrosis, particularly in cases with preserved left ventricular function. Recent advancements, including speckle-tracking echocardiography, provide enhanced sensitivity for detecting early signs of myocardial dysfunction, even in the absence of overt abnormalities. Cardiovascular magnetic resonance (CMR) has emerged as a cornerstone in the non-invasive evaluation of myocarditis, offering unparalleled tissue characterization. Indeed, CMR provides critical insights into myocardial oedema, necrosis, and fibrosis, which are essential for confirming the diagnosis, stratifying prognosis, and guiding therapy. Parametric mapping techniques allow for highly accurate detection of myocardial fibrosis (native T1 mapping) and inflammation (T2 mapping), even in the absence of gadolinium contrast, making it particularly valuable in paediatric patients. In conclusion, multimodality imaging, integrating echocardiography and CMR, allows for a comprehensive understanding of disease severity, guiding treatment decisions and optimizing long-term outcomes. This review underscores the importance of a tailored, imaging-driven approach to managing paediatric myocarditis, ensuring the best possible care for this special population.

Decreasing Endomyocardial Biopsy Frequency in Pediatric Heart Transplantation Using A Rejection Risk Prediction Score-A Single Center Study

BACKGROUND

Rejection remains an important cause of morbidity and mortality after pediatric heart transplantation (HT). Endomyocardial biopsy (EMB) is the gold standard for rejection diagnosis, but it comes with procedural risk. The frequency of EMB varies significantly across centers. Since April 2018, our center's surveillance EMB schedule is based on a rejection risk prediction score employing age, pre-HT diagnosis, and panel reactive antibodies (PRA). We aimed to evaluate outcomes in the 1st year post-HT before and after risk score implementation.

METHODS

Patients who underwent HT at our center at ≤ 18 years of age from January 2015 to December 2020 were reviewed. The primary endpoint was rejection-free survival at 1 year-post- HT. Clinical characteristics were compared for patients transplanted in Era 1 (January 2015-April 2018) and Era 2 (April 2018-December 2020). Cumulative 1-year survival free from rejection and from rejection with hemodynamic compromise (RHC) was compared between eras using Kaplan-Meier survival analysis.

RESULTS

115 patients underwent HT during our study period (52 in Era 1 and 63 in Era 2). There was an increase in VAD utilization between eras (19% in Era 1 vs. 40% in Era 2, p = 0.025), but otherwise no significant difference in demographic or clinical variables between the two eras. No statistically significant difference in freedom from rejection or freedom from RHC was identified between the two eras. There was a 60% reduction in the median number of EMB per patient in the first year post-HT after employing the score (5 in Era 1 vs. 2 in Era 2, p < 0.001).

CONCLUSIONS

After employing a rejection risk prediction score, our center decreased the frequency of EMB without worsening early post-HT outcomes, thus establishing the clinical applicability of this tool.

Practice patterns of cardiovascular magnetic resonance use in the diagnosis of pediatric myocarditis: A survey-based study

BACKGROUND

Cardiovascular magnetic resonance (CMR) is used to diagnose myocarditis in adults and children based on the original Lake Louise criteria (LLC) and more recently the revised LLC. The major change included in the revised LLC was the incorporation of parametric mapping, which significantly increases the sensitivity and specificity of diagnosis. Subsequently, scientific statements have recommended the use of parametric mapping in the diagnosis of myocarditis in children. However, there are some challenges to parametric mapping that are unique to the pediatric population. Our goal is to characterize clinical CMR and parametric mapping practice patterns for the diagnosis of myocarditis in pediatric centers.

METHODS

The Cardiovascular Magnetic Resonance Evaluation in Return to Athletes for Myocarditis in Coronavirus Disease 2019 and Immunization Consortium (CERAMICi) created a Research Electronic Data Capture (REDCap) survey to evaluate clinical practice patterns for diagnosis of myocarditis in pediatrics. This survey was distributed to the Society for Cardiovascular Magnetic Resonance community.

RESULTS

Fifty-nine responses from 51 centers were received, with only one response from each center being utilized. Only 35% (18/51) of centers (37% (14/38) North America, 31% (4/13) international) reported using CMR routinely in all patients with a suspicion of myocarditis. Diagnostic uncertainty was noted as the most important reason for CMR, while cost was noted as the least important consideration. The majority of centers reported using the revised LLC (37/51, 72%) compared to original LLC (7/51, 14%) or a hybrid criteria (6/51, 12%). When looking at the use of parametric mapping, only 5/47 (11%) for T1 mapping and 11/49 (22%) for T2 mapping reported having scanner-specific pediatric normative data.

CONCLUSION

Routine CMR imaging for diagnosis of myocarditis in pediatrics is infrequently performed at surveyed centers despite the focus on a group of non-invasive cardiac imagers. While the majority reported using parametric mapping, few centers reported having pediatric scanner-specific normative data. This highlights an important gap in the utilization of CMR that may aid in the diagnosis of myocardial disease.

A Review of Pediatric Cardiomyopathy

Though pediatric cardiomyopathy is rare in children, there is significant associated morbidity and mortality. Etiology varies from inborn errors of metabolism to familial genetic mutations and myocyte injury. Major classes include dilated, hypertrophic, restrictive, and non-compaction. Diagnosis generally involves a combination of clinical history and echocardiography. The use of cross-sectional imaging is gaining popularity. Management varies between subtype and may involve a combination of medical and surgical interventions depending on clinical status.

Cardiac magnetic resonance assessment of acute rejection and cardiac allograft vasculopathy in pediatric heart transplant

BACKGROUND

In pediatric heart transplant (PHT), cardiac catheterization with endomyocardial biopsy (EMB) is standard for diagnosing acute rejection (AR) and cardiac allograft vasculopathy (CAV) but is costly and invasive.

OBJECTIVES

To evaluate the ability of cardiac magnetic resonance (CMR) to noninvasively identify differences in PHT patients with AR and CAV.

METHODS

Patients were enrolled at three children's hospitals. Data were collected from surveillance EMB or EMB for-cause AR. Patients were excluded if they had concurrent diagnoses of AR and CAV, CMR obtained >7days from AR diagnosis, they had EMB negative AR, or could not undergo contrasted, unsedated CMR. Kruskal-Wallis test was used to compare groups: (1) No AR or CAV (Healthy), (2) AR, (3) CAV. Wilcoxon rank-sum test was used for pairwise comparisons.

RESULTS

Fifty-nine patients met inclusion criteria (median age 17years [IQR 15-19]) 10 (17%) with AR, and 11 (19%) with CAV. AR subjects had worse left ventricular ejection fraction compared to Healthy patients (p = 0.001). Global circumferential strain (GCS) was worse in AR (p = 0.054) and CAV (p = 0.019), compared to Healthy patients. ECV, native T1, and T2 z-scores were elevated in patients with AR.

CONCLUSIONS

CMR was able to identify differences between CAV and AR. CAV subjects had normal global function but abnormal GCS which may suggest subclinical dysfunction. AR patients have abnormal function and tissue characteristics consistent with edema (elevated ECV, native T1 and T2 z-scores). Characterization of CMR patterns is critical for the development of noninvasive biomarkers for PHT and may decrease dependence on EMB.

Focus on Paediatric Restrictive Cardiomyopathy: Frequently Asked Questions

Restrictive cardiomyopathy (RCM) is characterized by restrictive ventricular pathophysiology determined by increased myocardial stiffness. While suspicion of RCM is initially raised by clinical evaluation and supported by electrocardiographic and echocardiographic findings, invasive hemodynamic evaluation is often required for diagnosis and management of patients during follow-up. RCM is commonly associated with a poor prognosis and a high incidence of heart failure, and PH is reported in paediatric patients with RCM. Currently, only a few therapies are available for specific RCM aetiologies. Early referral to centres for advanced heart failure treatment is often necessary. The aim of this review is to address questions frequently asked when facing paediatric patients with RCM, including issues related to aetiologies, clinical presentation, diagnostic process and prognosis.

Selection and Interpretation of Molecular Diagnostics in Heart Transplantation

The number of heart transplants performed annually in the United States and worldwide continues to increase, but there has been little change in graft longevity and patient survival over the past 2 decades. The reference standard for diagnosis of acute cellular and antibody-mediated rejection includes histologic and immunofluorescence evaluation of endomyocardial biopsy samples, despite invasiveness and high interrater variability for grading histologic rejection. Circulating biomarkers and molecular diagnostics have shown substantial predictive value in rejection monitoring, and emerging data support their use in diagnosing other posttransplant complications. The use of genomic (cell-free DNA), transcriptomic (mRNA and microRNA profiling), and proteomic (protein expression quantitation) methodologies in diagnosis of these posttransplant outcomes has been evaluated with varying levels of evidence. In parallel, growing knowledge about the genetically mediated immune response leading to rejection (immunogenetics) has enhanced understanding of antibody-mediated rejection, associated graft dysfunction, and death. Antibodies to donor human leukocyte antigens and the technology available to evaluate these antibodies continues to evolve. This review aims to provide an overview of biomarker and immunologic tests used to diagnose posttransplant complications. This includes a discussion of pediatric heart transplantation and the disparate rates of rejection and death experienced by Black patients receiving a heart transplant. This review describes diagnostic modalities that are available and used after transplant and the landscape of future investigations needed to enhance patient outcomes after heart transplantation.

Leitlinie Myokarditis der Deutschen Gesellschaft für Pädiatrische Kardiologie

This consensus statement presents updated recommendations on diagnosis and treatment of myocarditis in childhood.

Pediatric Myocarditis

Myocarditis is a condition caused by acute or chronic inflammation of the cardiac myocytes, resulting in associated myocardial edema and myocardial injury or necrosis. The exact incidence is unknown, but is likely underestimated, with more mild cases going unreported. Diagnosis and appropriate management are paramount in pediatric myocarditis, as it remains a recognized cause of sudden cardiac death in children and athletes. Myocarditis in children is most often caused by a viral or infectious etiology. In addition, there are now two highly recognized etiologies related to Coronavirus disease of 2019 (COVID-19) infection and the COVID-19 mRNA vaccine. The clinic presentation of children with myocarditis can range from asymptomatic to critically ill. Related to severe acute respiratory syndrome-Coronavirus 2 (SARs-CoV-2), children are at greater risk of developing myocarditis secondary to COVID-19 compared to the mRNA COVID-19 vaccine. Diagnosis of myocarditis typically includes laboratory testing, electrocardiography (ECG), chest X-ray, and additional non-invasive imaging studies with echocardiogram typically being the first-line imaging modality. While the reference standard for diagnosing myocarditis was previously endomyocardial biopsy, with the new revised Lake Louise Criteria, cardiac magnetic resonance (CMR) has emerged as an integral non-invasive imaging tool to assist in the diagnosis. CMR remains critical, as it allows for assessment of ventricular function and tissue characterization, with newer techniques, such as myocardial strain, to help guide management both acutely and long term.

Elective and non-elective endomyocardial biopsy in heart transplant patients and procedural outcomes: An IMPACT registry analysis

BACKGROUND

Endomyocardial biopsies are standard of care for transplant surveillance, however the procedural risks are not well established, especially in children. The purpose of the study was therefore to assess procedural risks and outcomes associated with elective (surveillance) biopsies and non-elective (clinically indicated) biopsies.

METHODS

We used the NCDR IMPACT registry database for this retrospective analysis. Patients undergoing an endomyocardial biopsy were identified using the procedural code, with a diagnosis of heart transplantation required. Data regarding indication, hemodynamics, adverse events and outcomes was gathered and analyzed.

RESULTS

A total of 32 547 endomyocardial biopsies were performed between 2012-2020; 31 298 (96.5%) elective and 1133 (3.5%) were non-elective biopsies. Non-elective biopsy was more commonly performed in infants and in those above 18 years of age, in female and in Black race patients and in those with non-private insurance (all p < .05) and showed hemodynamic derangements. Overall rate of complications was low. Combined major adverse events were more common in non-elective patients, with sicker patient profile, use of general anesthesia and femoral access with overall decline in these events over time.

CONCLUSIONS

This large-scale analysis shows safety of surveillance biopsies and that non-elective biopsies carry a small but significant risk of major adverse event. Patient profile impacts the safety of the procedure. These data may serve as important comparison point for newer non-invasive tests and for bench marking, especially in children.

Treating Pediatric Myocarditis with High Dose Steroids and Immunoglobulin

There is considerable variability in practice among pediatric centers for treatment of myocarditis. We report outcomes using high dose steroids in conjunction with IVIG. This is a single center retrospective study of children < 21 years of age diagnosed with myocarditis and treated with high dose steroids and IVIG from January 2004-April 2021. Diagnostic criteria for myocarditis included positive endomyocardial biopsy, cardiac magnetic resonance (CMR) imaging meeting Lake Louise criteria, or strictly defined clinical diagnosis. Forty patients met inclusion criteria. Median age at diagnosis was 11.6 years (0.7-14.6). Diagnosis was made clinically in 70% of cases (N = 28), by CMR in 12.5% (N = 5) and by biopsy in 17.5% (N = 7). Median ejection fraction (EF) at diagnosis was 35% (IQR 24-48). Median duration of IV steroids was 7 days (IQR 4-12) followed by an oral taper. Median cumulative dose of IV immunoglobulin (IVIG) was 2 g/kg. There were no serious secondary bacterial infections after steroid initiation. Ten patients (25%) required mechanical circulatory support. Overall transplant free survival was 92.5% with median follow-up of 1 year (IQR 0-6 years). Six patients required re-admission for cardiovascular reasons. By 3 months from diagnosis, 70% of patients regained normal left ventricular function. High dose steroids in conjunction with IVIG to treat acute myocarditis can be safe without significant infections or long-term side effects. Our cohort had excellent recovery of ventricular function and survival without transplant. Prospective comparison of a combination of high dose steroids with IVIG versus other therapies is needed.

Cardiac magnetic resonance diastolic indices correlate with ventricular filling pressures in pediatric heart transplant recipients

BACKGROUND

Atrial and ventricular filling pressures are routinely used in pediatric heart transplant (PHTx) recipients to assess graft function. We hypothesized that cardiac magnetic resonance (CMR) diastolic indices correlate with filling pressures, providing a noninvasive method of hemodynamic assessment.

METHODS

Pediatric heart transplant recipients were prospectively enrolled at the time of cardiac catheterization. Pulmonary capillary wedge pressure (PCWP) and right atrial pressure (RAP) were measured. CMR included standard volumetric analysis. Filling curves were calculated by contouring every phase in the short-axis stack. Global longitudinal and circumferential strain (GLS, GCS) were calculated using feature tracking. Atrial volumes and ejection fraction were calculated from 4-chamber and 2-chamber cine images. Correlations were analyzed using Spearman's Rho; modeling was performed with multivariable logistic regression.

RESULTS

A total of 35 patients with a mean age of 15.5 years were included, 12 with acute rejection. The median time post-transplant was 6.2 years. Peak filling rate (PFR) and peak LV ejection rate/end-diastolic volume (PER/EDV) correlated with PCWP (rho = 0.48 p = .005, and rho = -0.35 p = .046, respectively) as did GLS and GCS (rho = 0.52 p = .002, and 0.40 p = .01). Indexed maximum and minimum left atrial (LA) volume correlated with PCWP (rho = 0.41, p = .01, rho = 0.41 p = .01), and LA ejection fraction inversely correlated with PCWP (rho = -0.40, p = .02). GLS and GCS correlated with RAP (rho = 0.55, p = .001 and rho = 0.43, p = .01). A model including LV GLS and PFR estimated PCWP ≥12 mmHg with an area under the curve of 0.84.

CONCLUSIONS

Cardiac magnetic resonance can be a useful noninvasive modality to assess for signs of diastolic dysfunction after PHTx.

Findings and Outcome of Transcatheter Right Ventricular Endomyocardial Biopsy and Hemodynamic Assessment in Children with Suspected Myocarditis or Cardiomyopathy

OBJECTIVE

The study objective is assessing findings and outcome in children with suspected cardiomyopathy (CMP) or myocarditis undergoing cardiac catheterization with transcatheter right ventricular endomyocardial biopsy (RV-EMB).

METHODS

All consecutive children undergoing cardiac catheterization with RV-EMB for suspected CMP/myocarditis between 2002-2021 were analysed regarding clinical presentation, cardiac biomarkers, periprocedural management, hemodynamic, histological/immunohistological findings, and outcome.

RESULTS

Eighty-five RV-EMBs were performed in 81 patients at a median age of 6.8 (IQR 9.9) years and a bodyweight of 20 (32.2) kg. Histological/immunohistological findings of RV-EMB revealed dilated CMP in 10 (12%), chronic myocarditis in 28 (33%), healing myocarditis in 5 (6%), acute myocarditis in 9 (11%), other heart muscle diseases in 23 (27%) (7 restrictive CMP, 5 hypertrophic CMP, 4 toxic/anthracycline-induced CMP, 4 endocardfibroelastosis, 1 arrhythmogenic right ventricular CMP, 1 laminin CMP, 1 haemangioma), no conclusive histology in 7 (8%), and normal histology in 3 (4%) patients. Median LVEDP was 17 mmHg (IQR 9), LAP 15 mmHg (10), and PVR 1.83 (1.87) Wood Units/m². There were 3 major complications (3%), all patients recovered without any sequelae. At follow-up (median 1153, IQR 1799 days) 47 (59%) patients were alive, 11 (13%) dead, 15 (18%) underwent cardiac transplantation, and 8 (9%) were lost to follow-up. Death/cardiac transplantation occurred within 3 years from RV-EMB. All patients with an acute myocarditis survived. NT-pro-BNP, echo parameters, and invasive hemodynamics correlate independently with death/cardiac transplant.

CONCLUSION

Hemodynamic invasive data and morphological findings in RV-EMB complete clinical diagnosis in children with suspected CMP/myocarditis and provide important information for further clinical management.

Multimodality Imaging to Detect Rejection, and Cardiac Allograft Vasculopathy in Pediatric Heart Transplant Recipients—An Illustrative Review

The three most common modalities of graft surveillance in pediatric heart transplant (HT) recipients include echocardiography, coronary angiography, and endomyocardial biopsy (EMB). The survival outcomes after HT in children have improved considerably in recent years. However, allograft rejection and cardiac allograft vasculopathy remain the leading cause of death or re-transplantation. The routine surveillance by EMB and coronary angiography are invasive and risky. Newer noninvasive echocardiographic techniques, including tissue Doppler imaging (TDI), 2-D speckle tracking echocardiography, CT coronary angiography (CTCA), cardiovascular magnetic resonance (CMR), single-photon emission computed tomography (SPECT), and positron emission tomography (PET) and invasive techniques such as intravascular ultrasound (IVUS), functional flow reserve (CFR) of coronary arteries, optical coherence tomography (OCT), have emerged as powerful tools which may help early recognition of sub-clinical rejection, response to treatment, early detection, and progression of CAV. The multimodality imaging approach, including noninvasive and invasive tests, is the future for the transplanted heart to detect dysfunction, rejections, and early CAV. This review illustrates noninvasive and invasive imaging techniques currently used or could be considered for clinical use in detecting heart transplant rejection, dysfunction, and CAV in children.

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the use of cardiovascular magnetic resonance in pediatric congenital and acquired heart disease : Endorsed by The American Heart Association

Cardiovascular magnetic resonance (CMR) has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of CMR in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of CMR in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the Use of Cardiac Magnetic Resonance in Pediatric Congenital and Acquired Heart Disease: Endorsed by The American Heart Association

Cardiovascular magnetic resonance has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of cardiovascular magnetic resonance in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of cardiovascular magnetic resonance in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Are clinical features and cardiac biomarkers at admission related to severity in pediatric acute myocarditis?: Clinical features and cardiac biomarkers in pediatric acute myocarditis

OBJECTIVES

To evaluate the factors associated with intensive care requirement and mortality in pediatric myocarditis.

METHODS

Children aged 28 days to 18 years who were diagnosed with acute myocarditis in a pediatric emergency department between January 2010 and September 2020 were enrolled in the study retrospectively. Demographic and clinical features, cardiac biomarkers, and imaging findings were evaluated. Length of hospital stay, need for hospitalization in the pediatric intensive care unit (PICU), treatments, and survival outcomes were recorded. To define the severity of disease, three groups were created and the data were compared in terms of clinical, laboratory, and imaging findings. The patients treated in the pediatric ward were compared with those hospitalized in the PICU. Ventricular dysfunction was defined in patients with a left ventricular ejection fraction (LVEF) of <50% and these patients were compared with those who had an LVEF of >50%. Also, survivor and non-survivor patients were compared.

RESULTS

A total number of 62 patients with a median age of 8 years were included. Chest pain and tachycardia were the most common findings on physical examination. The mean LVEF was 59.3 ± 13.0% at admission. Of the patients, 17 were hospitalized in the PICU (27.4%). Chest pain was more common in patients hospitalized in the pediatric ward (p<0.001), and hypotension, vomiting, arrhythmia, were more common and LVEF was lower in patients in the PICU (p = 0.017, p = 0.008, p = 0.006, and p = 0.025, respectively). The children treated in the PICU were younger than those in the pediatric ward (p = 0.009). Troponin I levels were significantly higher in the pediatric ward (p = 0.035), and brain natriuretic peptide (BNP) levels were higher in patients in the PICU (p = 0.012). Death occurred in four patients. Hypotension and vomiting were significantly more common in non-survivors (p = 0.020 and 0.004, respectively). Inotropes and intravenous immunoglobulin (IVIG) were more commonly used in non-survivors (p = 0.001 and p = 0.015, respectively). BNP levels were higher in non-survivors (p = 0.008), and troponin I levels were not different between survivors and non-survivors (p = 0.260).

CONCLUSION

In pediatric acute myocarditis, lower LVEF, increased BNP, as well as the presence of hypotension and arrhythmia were found to be related to intensive care requirement. Hypotension and vomiting were found to be more common in non-survivors. Due to the possibility of rapidly worsening disease, physicians should be alert to the presence of these findings.

Pediatric Myocarditis: What Have We Learnt So Far?

Myocarditis is an inflammatory disease of the myocardium that is troublesome to diagnose and manage, especially in children. Since the introduction of endomyocardial biopsy (EMB), new diagnostic tools have provided useful data. Especially when enhanced with immunohistochemistry and polymerase chain reaction (PCR) studies, EMB remains the gold standard for the diagnosis. Notably, cardiac magnetic resonance (MRI) is a non-invasive tool that can confirm the diagnosis and has a particular usefulness during the follow-up. The causes of myocarditis are heterogeneous (mostly viral in children). The course and outcome of the illness in the pediatric population represent a complex interaction between etiologic agents and the immune system, which is still not fully understood. The clinical presentation and course of myocarditis vary widely from paucisymptomatic illness to acute heart failure refractory to therapy, arrhythmias, angina-like presentation and sudden cardiac death. In this setting, cardiac biomarkers (i.e., troponins and BNP), although unspecific, can be used to support the diagnosis. Finally, the efficacy of therapeutic strategies is controversial and not confirmed by clinical trials. In this review, we summarized the milestones in diagnosis and provided an overview of the therapeutic options for myocarditis in children.

Rejection surveillance in pediatric heart transplant recipients: Critical reflection on the role of frequent and long-term routine surveillance endomyocardial biopsies and comprehensive review of non-invasive rejection screening tools

BACKGROUND

Despite significant medical advances in the field of pediatric heart transplantation (HT), acute rejection remains an important cause of morbidity and mortality. Endomyocardial biopsy (EMB) remains the gold-standard method for diagnosing rejection but is an invasive, expensive, and stressful process. Given the potential adverse consequences of rejection, routine post-transplant rejection surveillance protocols incorporating EMB are widely employed to detect asymptomatic rejection. Each center employs their own specific routine rejection surveillance protocol, with no consensus on the optimal approach and with high inter-center variability. The utility of high-frequency and long-term routine surveillance biopsies (RSB) in pediatric HT has been called into question.

METHODS

Sources for this comprehensive review were primarily identified through searches in biomedical databases including MEDLINE and Embase.

RESULTS

The available literature suggests that the diagnostic yield of RSB is low beyond the first year post-HT and that a reduction in RSB intensity from high-frequency to low-frequency can be done safely with no impact on early and mid-term survival. Though there are emerging non-invasive methods of detecting asymptomatic rejection, the evidence is not yet strong enough for any test to replace EMB.

CONCLUSION

Overall, pediatric HT centers in North America should likely be doing fewer RSB than are currently performed. Risk factors for rejection should be considered when designing the optimal rejection surveillance strategy. Noninvasive testing including emerging biomarkers may have a complementary role to aid in safely reducing the need for RSB.

Changes in circumferential strain can differentiate pediatric heart transplant recipients with and without graft rejection

BACKGROUND

Routine surveillance protocols rely heavily on endomyocardial biopsy (EMB) for detection of rejection in pediatric heart transplant recipients. More sensitive echocardiographic tools to assess rejection may help limit the number of EMBs. This study compared changes in left ventricular (LV) strain in patients who had rejection versus those who did not.

METHODS

A single center retrospective review was conducted between 2013 and 2020. Patients were categorized based on rejection history. Echocardiograms were evaluated at the time of 2 consecutive EMBs; in the rejection group, the second echocardiogram was collected at the time of a rejection episode. Conventional measures of LV function and speckle-tracking echocardiography-derived longitudinal (LS) and circumferential strain (CS) were measured.

RESULTS

17 patients were in the non-rejection group and 17 were in the rejection group (30 total rejection episodes). The rejection group was older at the time of transplant (12.5 vs. 1.3 years, p = .01). A decline in CS was seen in the rejection group at the second echocardiogram [-18.5 (IQR -21.5, -14.6) to -15.7 (IQR -19.8, -13.2)] while CS improved in the non-rejection group [-20.8 (IQR -23.9, -17.8) to -23.9 (IQR -24.9, -20.1)]. This difference in change reached significance (p = .02). A similar pattern was seen in LS that neared significance (p = .06). There was no significant difference in ejection fraction change (p = .24).

CONCLUSIONS

Patients in the non-rejection group displayed improvement in CS between echocardiograms while patients in the rejection group showed subsequent decline. Worsening of LV CS may help identify acute rejection in the early post-transplant period.

Early findings after integration of donor-derived cell-free DNA into clinical care following pediatric heart transplantation

BACKGROUND

Endomyocardial biopsy (EMB) is costly and discomforting yet remains a key component of surveillance after pediatric heart transplantation (HT). Donor-derived cell-free DNA (dd-cfDNA) has been histologically validated with high negative predictive value, offering an alternative to surveillance EMB (sEMB).

METHODS

We implemented an alternative surveillance protocol using commercially available dd-cfDNA assays in place of sEMB after pediatric HT. Recipients ≧7 months post-HT with reassuring clinical assessment were referred for dd-cfDNA. When not elevated above the manufacturers' threshold, sEMB was deferred. Subsequent clinical status and results of follow-up EMB were analyzed.

RESULTS

Over 17 months, 58 recipients [34% female, median age at HT 3.1 years (IQR 0.6-10.6)] had dd-cfDNA assessed per protocol. Median age was 14.8 years (8.4-18.3) and time from HT 6.0 years (2.2-11.2). Forty-seven (81%) had non-elevated dd-cfDNA and 11 (19%) were elevated. During a median of 8.7 months (4.2-15), all are alive without allograft loss/new dysfunction. Among those with non-elevated dd-cfDNA, 24 (51%) had subsequent sEMB at 12.1 months (6.9-12.9) with 23 showing no acute rejection (AR): grade 0R/pAMR0 (n = 16); 1R(1A)/pAMR0 (n = 7). One had AR (grade 2R(3A)/pAMR0) on follow-up sEMB after decreased immunosuppression following a diagnosis of PTLD. All 11 with elevated dd-cfDNA had reflex EMB at 19 days (12-32) with AR in 4: grade 1R(1B-2)/pAMR0 (n = 3); 1R(1B)/pAMR2 (n = 1).

CONCLUSIONS

dd-cfDNA assessment in place of selected, per-protocol EMB decreased surveillance EMB by 81% in our pediatric HT recipient cohort with no short-term adverse outcomes. Individual center approach to surveillance EMB will influence the utility of these findings.

Pediatric Myopericarditis Presenting to the Emergency Department as Chest Pain: A Comparative Study With Myocarditis

METHODS

A database query was performed and identified patients over a 9-year period, and clinical data, laboratory data, and cardiac studies were extracted and analyzed from the electronic health record.

RESULTS

A total of 36 patients were identified with the discharge diagnosis of myopericarditis and 22 with myocarditis. The median age for myopericarditis patients was 16.2 years, and 97% were male. The median initial troponin was 7.1 ng/mL, the peak was at 16.6 ng/mL, and 58% had ST changes on electrocardiogram. The median length of stay for myopericarditis patients was 1.7 days, and 50% were discharged home on nonsteroidal anti-inflammatory medication. Compared with myocarditis, myopericarditis patients were older, had a higher incidence of chest pain, and were less likely to have fever, vomiting, abdominal pain, upper respiratory infection symptoms, chest radiograph abnormalities, or T-wave inversion (P < 0.05). Myopericarditis patients also had lower Pediatric Risk of Mortality version 3 scores, B-type natriuretic peptide levels, and higher left ventricular ejection fractions on admission (67% vs 41%; P < 0.05). A classification model incorporating initial left ventricular ejection fraction, B-type natriuretic peptide, electrocardiogram, and chest radiograph findings distinguished myopericarditis from myocarditis with correct classification in 95% of patients.

CONCLUSIONS

Myopericarditis is a relatively common cause of chest pain for patients admitted to the pediatric intensive care unit, presents differently than true myocarditis, and carries a good prognosis.

Myocarditis and pericarditis: Case definition and guidelines for data collection, analysis, and presentation of immunization safety data

Myocarditis and/or pericarditis (also known as myopericarditis) are inflammatory diseases involving the myocardium (with non-ischemic myocyte necrosis) and/or the pericardial sac. Myocarditis/pericarditis (MPC) may present with variable clinical signs, symptoms, etiologies and outcomes, including acute heart failure, sudden death, and chronic dilated cardiomyopathy. Possible undiagnosed and/or subclinical acute myocarditis, with undefined potential for delayed manifestations, presents further challenges for diagnosing an acute disease and may go undetected in the setting of infection as well as adverse drug/vaccine reactions. The most common causes of MPC are viral, with non-infectious, drug/vaccine associated hypersensitivity and/or autoimmune causes being less well defined and with potentially different inflammatory mechanisms and treatment responses. Potential cardiac adverse events following immunization (AEFIs) encompass a larger scope of diagnoses such as triggering or exacerbating ischemic cardiac events, cardiomyopathy with potential heart failure, arrhythmias and sudden death. The current published experience does not support a potential causal association with vaccines based on epidemiologic evidence of relative risk increases compared with background unvaccinated incidence. The only evidence supporting a possible causal association of MPC with a vaccine comes from case reports. Hypersensitivity MPC as a drug/vaccine induced cardiac adverse event has long been a concern for post-licensure safety surveillance, as well as safety data submission for licensure. Other cardiac adverse events, such as dilated cardiomyopathy, were also defined in the CDC definitions for adverse events after smallpox vaccination in 2006. In addition, several groups have attempted to develop and improve the definition and adjudication of post-vaccination cardiovascular events. We developed the current case definitions for myocarditis and pericarditis as an AEFI building on experience and lessons learnt, as well as a comprehensive literature review. Considerations of other etiologies and causal relationships are outside the scope of this document.

Endomyocardial Biopsy in Pediatric Myocarditis and Dilated Cardiomyopathy: A Tool in Search for a Role

Endomyocardial biopsy (EMB) is a well-known diagnostic tool for the investigation and treatment of myocardial diseases and remains the gold standard for the diagnosis of myocarditis. Due to its invasiveness, with a complication rate ranging from 1 to 15%, its role in the diagnostic work-up of pediatric heart failure is not well established. The aim of this review is to define the role of EMB as diagnostic technique in the work up of children presenting with severe left ventricular dysfunction with the support of our center experience.

Sex Differences in Incidence, Clinical Characteristics and Outcomes in Children and Young Adults Hospitalized for Clinically Suspected Myocarditis in the Last Ten Years-Data from the MYO-PL Nationwide Database

There is a widespread lack of systematic knowledge about myocarditis in children and young adults in European populations. The MYO-PL nationwide study aimed to evaluate sex differences in the incidence, clinical characteristics, management and outcomes of all young patients with a clinical diagnosis of myocarditis, hospitalized in the last ten years. The study involved data (from the only public healthcare insurer in Poland) of all (n = 3659) patients aged 0–20 years hospitalized for myocarditis in the years 2011–2019. We assessed clinical characteristics, management and five-year outcomes. Males comprised 75.4% of the study population. The standardized incidence rate of myocarditis increased over the last ten years and was, on average, 7.8 and 2.5 (in males and females, respectively). It was the highest (19.5) in males aged 16–20 years. The highest rates of hospital admissions occurred from late autumn to early spring. Most myocarditis-directed diagnostic procedures, including laboratory tests, echocardiography, coronary angiography, cardiac magnetic resonance and endomyocardial biopsy, were performed in a low number of patients, particularly in females. Most patients required rehospitalization for cardiovascular reasons. The results of this large epidemiological study showed an increasing incidence of myocarditis hospitalizations in young patients over last ten years and that it was sex-, age- and season-dependent. Survival in young patients with myocarditis was age- and sex-related and usually it was worse than in the national population. The general management of myocarditis requires significant improvement.

Multiple Coronary Fistulas After Several Penetrating Chest Wounds: A Rare Case of Refractory Heart Failure

Coronary artery fistulas are rare coronary abnormalities. Most of these fistulas have a congenital origin, and only a few are acquired. We report the case of a patient with late-acquired multiple coronary fistulas secondary to a stab wound, diagnosed in the setting of ischemic heart failure secondary to coronary steal syndrome. (Level of Difficulty: Intermediate.)

Multiparametric cardiac magnetic resonance imaging in pediatric and adolescent patients with acute myocarditis

BACKGROUND

The diagnostic value of cardiac magnetic resonance imaging (MRI) employing the 2018 Lake Louise criteria in pediatric and adolescent patients with acute myocarditis is undefined.

OBJECTIVE

To evaluate the diagnostic value of the Lake Louise criteria in pediatric and adolescent patients with suspected acute myocarditis and to show the utility of cardiac MRI for follow-up in this patient cohort.

MATERIALS AND METHODS

Forty-three patients (age range: 8-21 years) with suspected acute myocarditis and 13 control patients who underwent cardiac MRI were retrospectively analyzed. T2-weighted and late gadolinium enhancement imaging were performed in all patients. T1 and T2 mapping were available in 26/43 patients (60%). The Lake Louise criteria were assessed. In 27/43 patients (63%), cardiac MRI follow-up was available. Receiver operating characteristic analysis, Pearson's correlation coefficient and paired Student's t-test were used for statistical analysis.

RESULTS

In the total cohort, the Lake Louise criteria achieved a sensitivity of 86% (95% confidence interval [CI]: 72-95%) and a specificity of 100% (95% CI: 79-100%) for the diagnosis of acute myocarditis. In the subgroup of patients with available mapping parameters, the diagnostic performance of the Lake Louise criteria was higher when mapping parameters were implemented into the score (area under the receiver operating characteristic curve: 0.944 vs. 0.870; P=0.033). T2 relaxation times were higher in patients with admission to the intermediate care unit and were associated with the length of intermediate care unit stay (r=0.879, P=0.049). Cardiac MRI markers of active inflammation decreased on follow-up examinations (e.g., T1 relaxation times: 1,032±39 ms vs. 975±33 ms, P<0.001; T2 relaxation times: 58±5 ms vs. 54±5 ms, P=0.003).

CONCLUSION

The Lake Louise criteria have a high diagnostic performance for the diagnosis of acute myocarditis and are a valuable tool for follow-up in pediatric and adolescent patients. The mapping techniques enhance the diagnostic performance of the 2018 Lake Louise criteria.

Lone Atrial Flutter in Children and Adolescents: Is It Really "Lone"?

Atrial flutter (AFL) in children and adolescents beyond the neonatal period in the absence of any underlying myocardial disease ("lone AFL") is rare and data is limited. Our study aims to present clinical and electrophysiological data of presumed "lone AFL" in pediatric patients and discuss the role of endomyocardial biopsy (EMB) and further follow-up. Since July 2005, eight consecutive patients at a median age of 12.7 (range 10.4-16.7) years presenting with presumed "lone AFL" after negative non-invasive diagnostic work-up had electrophysiological study (EPS) and induction of cavotricuspid isthmus (CTI) conduction block by radiofrequency (RF) current application. In 6/8 patients EMB could be taken. Induction of CTI conduction block was achieved in all patients. Histopathological examination of EMB from the right ventricular septum exhibited myocarditis or cardiomyopathy in 4/6 patients, respectively. During follow-up, 4/8 patients had recurrent arrhythmia (AFL n = 2, wide QRS complex tachycardia n = 1, monomorphic premature ventricular contractions n = 1) after the ablation procedure. 3/4 patients with recurrent arrhythmia had pathological EMB results. The remaining patient with recurrent arrhythmia had a negative EMB but was diagnosed with Brugada syndrome during further follow-up. Taking together results of EMB and further clinical course, only 3/8 patients finally turned out to have true "lone AFL". Our study demonstrates that true "lone AFL" in children and adolescents is rare. EMB and clinical course revealed an underlying cardiac pathology in the majority of the individuals studied. EMB was very helpful in order to timely establish the diagnosis of myocarditis or cardiomyopathy.

Diagnosis, Evaluation, and Treatment of Myocarditis in Children

Myocarditis in the pediatric population can be a challenging diagnosis to make and often requires utilization of multiple diagnostic modalities. The cause is often due to a viral infection with activation of the innate and acquired immune response with either recovery or disease progression. Laboratory testing often includes inflammatory markers, cardiac troponin levels, and natriuretic peptides. Noninvasive testing should include electrocardiogram, echocardiogram, and possibly an MRI. Treatment of myocarditis remains controversial with most providers using immune modulators with intravenous immunoglobulin and corticosteroids.

Factors Associated With In-hospital Mortality of Children With Acute Fulminant Myocarditis on Extracorporeal Membrane Oxygenation

Aim: To analyze the factors associated with in-hospital mortality of children with acute fulminant myocarditis on venoarterial extracorporeal membrane oxygenation (VA-ECMO). Methods: This was a retrospective cohort study using chart reviews of patients diagnosed with acute fulminant myocarditis at the pediatric intensive care unit of two tertiary medical centers between January 1, 2005 and December 31, 2017. The inclusion criteria for this study were: (1) age from 1 month to 18 years; (2) diagnosed with acute myocarditis; (3) cardiogenic shock and need vasoactive-inotropic score ≥20 within 48 h after the use of vasoactive-inotropic agents; and (4) the need for ECMO placement. Results: Thirty-three children with acute fulminant myocarditis who needed ECMO were included. Clinical parameters were retrospectively reviewed. The overall survival rate was 69.6%. Higher levels of pre-ECMO troponin-I and pre-ECMO lactate, and lower post-ECMO left ventricular ejection fraction (LVEF) were significantly associated with in-hospital mortality in univariate analysis. Only higher pre-ECMO lactate and lower post-ECMO LVEF remained as predictors for in-hospital mortality in multivariate analysis. The areas under the curve of pre-ECMO lactate and post-ECMO LVEF in predicting survival were 0.848 (95% CI, 0.697-0.999, p = 0.002) and 0.824 (95% CI, 0.704-0.996, p = 0.01), respectively. A pre-ECMO lactate level of 79.8 mg/dL and post-ECMO LVEF of 39% were appropriate cutoff points to predict mortality. Conclusion: Pre-ECMO lactate level was associated with mortality in children with acute fulminant myocarditis, with an optimal cutoff value of 79.8 mg/dL. After VA-ECMO implantation, post-ECMO LVEF was associated with mortality, with an optimal cutoff value of 39%. The use of LVADs or urgent heart transplantation should be considered if the post-ECMO LVEF does not improve.

Correlation of gene expression profiling score, cardiac hemodynamics and echocardiographic parameters in asymptomatic, rejection-free pediatric heart transplant recipients

OBJECTIVES

To correlate gene expression profiling scores obtained by AlloMap® with cardiac hemodynamics, cardiac allograft vasculopathy (CAV), and echocardiographic parameters in asymptomatic, rejection-free pediatric heart transplant (HT) recipients.

METHODS

Single-institution retrospective study of 210 AlloMap scores obtained concomitantly with cardiac catheterization and echocardiogram from 55 children during follow-up after cardiac transplantation.

RESULTS

The median age at HT was 5.1 years (range, 0.9-14.1), with 29 males and 26 females. AlloMap scores were high in <2 years vs ≥2 years of age at the time of HT (P = .001), and trending higher with time after HT (R2  = .04, P = .004). There was no significant difference in scores between ACR grades 0 and 1R or CAV. There was mild to modest correlation of AlloMap scores with the mean right atrial pressure (P = .002), and pulmonary capillary wedge pressure (P = .02), but no correlation was found with LV SF% (P = .3), LV EF% (P = .5), or RV FAC % (P = .8).

CONCLUSIONS

Our study provides preliminary data that the AlloMap score must be studied carefully before it can be used in children, particularly in those under 2 years of age. Monitoring of serial scores for each patient could potentially reflect changes in allograft performance that may determine indications for catheterization and biopsy which needs to be validated in future studies.

Free-breathing T2* mapping for MR myocardial iron assessment at 3 T

BACKGROUND

Timely diagnosis of cardiac iron overload is important for children with transfusion-dependent anaemias and requires modern measure methods. Nowadays, myocardial iron quantification is performed by magnetic resonance (MR) breath-hold techniques, sensitive to respiratory motion and unfeasible in patients who are unable to hold their breath. Free-breathing T2* mapping sequences would allow to scan children who cannot hold their breath for a specified duration. Our aim was to test a free-breathing T2* mapping sequence, based on motion correction by multiple signal accumulation technique.

METHODS

We used an electrocardiographically gated T2* mapping sequence based on multiple gradient echo at 3-T in 37 paediatric patients with haematologic disorders aged from 2 to 16. We compared T2* values of myocardium and signal-to-noise ratio of this new sequence with standard breath-holding T2* mapping sequence. T2* values were measured in the interventricular septum for both methods in studies with adequate image quality.

RESULTS

All children were scanned without complications. Five patients were excluded from analysis because of the presence of respiratory artefacts on the T2* images with breath-holding technique due to patient's inability to hold their breath. Breath-holding T2* was 19.5 ± 7.7 ms (mean ± standard deviation), free-breathing T2* was 19.4 ± 7.6 ms, with positive correlation (r = 0.99, R2 = 0.98; p < 0.001). The free-breathing sequence had a higher signal-to-noise ratio (median 212.8, interquartile range 148.5-566.5) than the breath-holding sequence (112.6, 71.1-334.1) (p = 0.03).

CONCLUSION

A free-breathing sequence provided accurate measurement of myocardial T2* values in children.

Cardiovascular magnetic resonance-derived myocardial strain in asymptomatic heart transplanted patients and its correlation with late gadolinium enhancement

OBJECTIVES

To investigate whether cardiovascular magnetic resonance (CMR)-derived myocardial strains were abnormal in asymptomatic heart transplant (HT) patients with normal left ventricular ejection fraction (LVEF) and to detect the relationship between CMR-derived myocardial strain parameters and late gadolinium enhancement (LGE) in asymptomatic HT patients.

METHODS

A total of 72 HT patients and 35 healthy volunteers underwent 1.5-T MR scanning. The examination protocol included basic cine imaging and LGE. The deformation registration algorithm (DRA) and feature tracking (FT) software were used for the strain analyses. Myocardial strain measurements included left ventricular global longitudinal strain (LVGLS), LV global circumferential strain (LVGCS), LV global radial strain (LVGRS) and right ventricular longitudinal strain (RVLS).

RESULTS

Compared with healthy volunteers, HT patients had significantly decreased DRA- and FT- derived myocardial strain measurements (all p < 0.05). There was a significant correlation and high reproducibility between the DRA- and FT-derived strain parameters. Both CMR-derived LVGLS and LVGRS were significantly related to the presence of LGE, and multivariate logistic regression analyses showed that the LVGLS measurement obtained from both techniques was independently associated with the presence of LGE. The odds ratios (ORs) for DRA- and FT-LVGLS were 1.340 and 1.342, respectively.

CONCLUSIONS

Asymptomatic HT patients with preserved LVEF exhibited reduced myocardial strain parameters. The CMR-derived LVGLS was independently related to the presence of LGE in HT patients.

KEY POINTS

• Reduced myocardial strain parameters were found in asymptomatic heart transplanted (HT) patients with normal left ventricular ejection fraction (LVEF). • The deformation registration algorithm (DRA) and feature tracking (FT)-derived strains in asymptomatic HT patients had high reproducibility. • DRA- and FT-derived LVGLS had an independent relationship with late gadolinium enhancement (LGE) in asymptomatic HT patients.

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.

Predictors for In-hospital Mortality in Pediatric Patients with Acute Myocarditis – a Retrospective Study

Background: Acute myocarditis, a primary inflammatory cardiac disease commonly caused by viral infection, is an important cause of morbidity and mortality in children. Data obtained from forensic studies found an incidence of 15–33% for acute myocarditis in sudden deaths in the pediatric age group. Currently, there is a lack of data regarding the incidence and factors associated with short-term outcomes in pediatric patients admitted for acute myocarditis.

The aim of the study was to identify predictors for in-hospital mortality in a pediatric population admitted with acute myocarditis.

Material and methods: We conducted a retrospective observational cohort study that included 21 patients admitted for acute myocarditis. Clinical, laboratory, ECG, and imaging data acquired via 2D transthoracic echocardiography and cardiac magnetic resonance imaging were collected from the medical charts of each included patient. The primary end-point of the study was all-cause mortality occurring during hospitalization (period ranging from 10 to 14 days). The study population was divided into 2 groups according to the occurrence of the primary end-point.

Results: The mean age of the study population was 99.62 ± 77.25 months, and 61.90% (n = 13) of the patients were males. The in-hospital mortality rate was 23.9% (n = 5). Patients in the deceased group were significantly younger than the survivors (55.60 ± 56.18 months vs. 113.4 ± 78.50 months, p = 0.039). Patients that had deceased presented a significantly higher level of LDH (365 ± 21.38 U/L vs. 234.4 ± 63.30 U/L, p = 0.0002) and a significantly higher rate of ventricular extrasystolic dysrhythmias (60% vs. 6.25%, p = 0.02, OR: 22.5, 95% CI: 1.5–335) compared to survivors. The 2D echocardiography showed that patients that had deceased presented more frequently an impaired left ventricular ejection fraction (<30%) (p = 0.001) and a significantly higher rate of severe mitral regurgitation (p = 0.001) compared to survivors.

Conclusions: The most powerful predictors for in-hospital mortality in pediatric patients admitted for acute myocarditis were the presence of ventricular extrasystolic dysrhythmias on the 24h Holter ECG monitoring, impaired left ventricular systolic function (LVEF <30%), the presence of severe mitral regurgitation, and confirmed infection with Mycoplasma pneumoniae.

Cell-free DNA donor fraction analysis in pediatric and adult heart transplant patients by multiplexed allele-specific quantitative PCR: Validation of a rapid and highly sensitive clinical test for stratification of rejection probability

Lifelong noninvasive rejection monitoring in heart transplant patients is a critical clinical need historically poorly met in adults and unavailable for children and infants. Cell-free DNA (cfDNA) donor-specific fraction (DF), a direct marker of selective donor organ injury, is a promising analytical target. Methodological differences in sample processing and DF determination profoundly affect quality and sensitivity of cfDNA analyses, requiring specialized optimization for low cfDNA levels typical of transplant patients. Using next-generation sequencing, we previously correlated elevated DF with acute cellular and antibody-mediated rejection (ACR and AMR) in pediatric and adult heart transplant patients. However, next-generation sequencing is limited by cost, TAT, and sensitivity, leading us to clinically validate a rapid, highly sensitive, quantitative genotyping test, myTAI_HEART^®, addressing these limitations. To assure pre-analytical quality and consider interrelated cfDNA measures, plasma preparation was optimized and total cfDNA (TCF) concentration, DNA fragmentation, and DF quantification were validated in parallel for integration into myTAI_HEART reporting. Analytical validations employed individual and reconstructed mixtures of human blood-derived genomic DNA (gDNA), cfDNA, and gDNA sheared to apoptotic length. Precision, linearity, and limits of blank/detection/quantification were established for TCF concentration, DNA fragmentation ratio, and DF determinations. For DF, multiplexed high-fidelity amplification followed by quantitative genotyping of 94 SNP targets was applied to 1168 samples to evaluate donor options in staged simulations, demonstrating DF call equivalency with/without donor genotype. Clinical validation studies using 158 matched endomyocardial biopsy-plasma pairs from 76 pediatric and adult heart transplant recipients selected a DF cutoff (0.32%) producing 100% NPV for ≥2R ACR. This supports the assay’s conservative intended use of stratifying low versus increased probability of ≥2R ACR. myTAI_HEART is clinically validated for heart transplant recipients ≥2 months old and ≥8 days post-transplant, expanding opportunity for noninvasive transplant rejection assessment to infants and children and to all recipients >1 week post-transplant.

Outcomes of low-intensity biopsy surveillance for rejection in paediatric cardiac transplantation

BACKGROUND

Significant inter-centre variability in the intensity of endomyocardial biopsy surveillance for rejection following paediatric cardiac transplantation has been reported. Our aim was to determine if low-intensity biopsy surveillance with two scheduled biopsies in the first year would produce outcomes similar to published registry outcomes.

METHODS

A retrospective study of paediatric recipients transplanted between 2008 and 2014 using a low-intensity biopsy protocol consisting of two surveillance biopsies at 3 and 12-13 months in the first post-transplant year, then annually thereafter. Additional biopsies were performed based on echocardiographic and clinical surveillance. Excluded were recipients that were re-transplanted or multi-organ transplanted or were followed at another institution.

RESULTS

A total of 81 recipients in the first 13 months after transplant underwent an average of 2 (SD ± 1.3) biopsies, 24 ± 6.8 echocardiograms, and 17 ± 4.4 clinic visits per recipient. During the 13-month period, 19 recipients had 24 treated rejection episodes, with the first at an average of 2.8 months post-transplant. The 3-, 12-, 36-, and 60-month conditional on discharge graft survival were 100%, 98.8%, 98.8%, and 90.4%, respectively, comparable to reported figures in major paediatric registries. At a mean follow-up of 4.7 ± 2.1 years, four patients (4.9%) developed cardiac allograft vasculopathy, three (3.7%) developed a malignancy, and seven (8.6%) suffered graft loss.

CONCLUSION

Rejection surveillance with a low-intensity biopsy protocol demonstrated similar intermediate-term outcomes and safety measures as international registries up to 5 years post-transplant.

In-hospital and post-discharge outcomes of pediatric acute myocarditis underwent after high-dose steroid or intravenous immunoglobulin therapy

Background

High-dose steroids and intravenous immunoglobulin (IVIG) are controversial treatments for pediatric patients with acute myocarditis. This study aimed to investigate their efficacies in the Taiwanese pediatric population.

Methods

This study evaluated 5563 acute myocarditis patients from the Taiwan’s National Health Insurance Research Database and identified 1542 pediatric patients hospitalized for acute myocarditis between January 1, 2001 and December 31, 2011. The exclusion criteria were age of > 11 years, associated cardiovascular comorbidities, autoimmune disease, malignancy before the index hospitalization, extracorporeal membrane oxygenation, intra-aortic balloon pumping, and dual therapy using IVIG and high-dose steroids.

Results

After 2:1 propensity score matching, we identified 208 subjects without steroid therapy and 104 subjects who received high-dose steroids. The mean age in that cohort was 2.6 ± 2.9 years, and high-dose steroid therapy had no significant effects on major in-hospital complications and post-discharge outcomes. After 2:1 propensity score matching, we identified 178 subjects without IVIG therapy and 89 subjects who received IVIG. The mean age in that cohort was 2.0 ± 2.1 years, and IVIG had no significant effects on the major outcomes.

Conclusions

The present study revealed that high-dose steroid or IVIG therapy had no significant effects on major in-hospital complications, late heart failure hospitalization, and long-term mortality.

Utility of screening echocardiogram after endomyocardial biopsy for identification of cardiac perforation or tricuspid valve injury

Per protocol, our institution obtains echocardiograms immediately after each EMB to rule out procedural complication. We sought to determine the incidence of echocardiogram-detected cardiac perforation and TV injury and to evaluate the utility of routine screening echocardiogram after each EMB in the current era. At a single center, 99% (1917/1942) EMB performed in 162 patients were immediately followed by an echocardiogram per protocol. There were five newly diagnosed pericardial effusions, and only one required pericardiocentesis. In the three echocardiograms demonstrating new flail TV, only one patient underwent surgical repair 2 months later. This study demonstrates the very low incidence of significant hemopericardium and TV injury after EMB in pediatric heart transplant recipients and argues against the utility of post-EMB echocardiograms to screen solely for procedural complications.

Identifying Non-invasive Tools to Distinguish Acute Myocarditis from Dilated Cardiomyopathy in Children

There is often a diagnostic dilemma in pediatric patients presenting with depressed ventricular function, as myocarditis and dilated cardiomyopathy (DCM) of other etiologies can appear very similar. Accurate identification is critical to guide treatment and to provide families with the most accurate expectation of long-term outcomes. The objective of this study was to identify patterns of clinical presentation and to assess non-invasive measures to differentiate patients with acute myocarditis from other forms of DCM. We identified all children (< 18 years) from our institution with a diagnosis of idiopathic DCM or myocarditis based on endomyocardial biopsy or explant pathology (1996-2015). Characteristics at the time of presentation were compared between patients with a definite diagnosis of myocarditis and those with idiopathic DCM. Data collected included clinical and laboratory data, radiography, echocardiography, and cardiac catheterization data. A total of 58 patients were included in the study; 46 (79%) with idiopathic DCM and 12 (21%) with acute myocarditis. Findings favoring a diagnosis of myocarditis included a history of fever (58 vs. 15%, p = 0.002), arrhythmia (17 vs. 0%, p = 0.003), higher degree of cardiac enzyme elevation, absence of left ventricular dilation (42 vs. 7%, p = 0.002), segmental wall motion abnormalities (58 vs. 13%, p = 0.001), lower left ventricular dimension z-score (3.7 vs. 5.2, p = 0.031), and less severe depression of left ventricular systolic function. There are notable differences between patients with myocarditis and other forms of DCM that can be detected non-invasively at the time of presentation without the need for endomyocardial biopsy. These data suggest that it may be possible to develop a predictive model to differentiate myocarditis from other forms of DCM using non-invasive measures.

National Trends and Outcomes of Endomyocardial Biopsy for Patients With Myocarditis: From the National Inpatient Sample Database

BACKGROUND

The utility of endomyocardial biopsy (EMB) in the management of myocarditis in the era of advanced cardiac imaging has been challenged.

METHODS AND RESULTS

The Nationwide Inpatient Sample Database (years 1998-2013) was queried to identify hospitalization records with a primary diagnosis of myocarditis, and underwent EMB procedure. We identified 22,299 hospitalization records with a diagnosis of myocarditis during the study period. Of those, 798 (3.6%) underwent EMB procedures. There was an average decrease in the incidence of EMB for myocarditis by 0.15% (P < .01) over the study period. Younger patients, women, and those with chronic kidney disease were more likely to undergo EMB. On multivariate analysis, patients with myocarditis who underwent EMB had higher in-hospital mortality (hazard ratio [HR] 1.97, 95% confidence interval [CI] 1.41-2.74) and longer median hospital stay (9 days vs 3 days; P < .001). EMB was associated with a higher incidence of cardiac tamponade (odds ratio [OR] 5.21, 95% CI 2.76-9.82), cardiogenic shock (OR 4.66, 95% CI 3.75-5.78), need for intra-aortic balloon pump (OR 3.52, 95% CI 2.49-4.97), and need for extracorporeal membrane oxygenation (OR 4.26, 95% CI 2.78-6.53).

CONCLUSIONS

The use of EMB in hospitalizations with myocarditis has decreased over time. The use of EMB was associated with a higher likelihood of in-hospital mortality and morbidity. Whether these findings represent a causative association from the procedure or a consequence of more severe disease in this group could not be confirmed in this study.

Identification of targeting peptides for the diagnosis of myocarditis

Aim: Current diagnostic tests for myocarditis are invasive and have low diagnostic value. Our aim was to identify potential targeting peptides to detect early myocarditis following intravenous delivery. Materials & methods: We used an animal model of experimental autoimmune myocarditis and a phage display library to identify potential targeting peptides. After several steps, we selected two peptides, MyH-PhD-05 and MyH-PhD-120, for in vivo screening using fluorescent imaging. Immunofluorescence and proteonomic analysis was used to identify potential cellular and molecular targets of MyH-PhD-05. Echocardiography was used to assess functional changes. Results: Peptide MyH-PhD-05 was able to detect animals with severe myocarditis even in the absence of functional changes. Immunofluorescence demonstrated that MyH-PhD-05 colocalizes with CD4+ T cells and monocytes (CD11b+) in cardiac infiltrates. Conclusion: We identified potential targeting peptides for the diagnosis of myocarditis. Future studies will focus on better identification of potential targets and translating this technology to clinically relevant imaging modalities.

Intravenous immunoglobulins in children with new onset dilated cardiomyopathy

BACKGROUND

Dilated cardiomyopathy is a rare but serious disorder in children. No effective diagnostic or treatment tools are readily available. This study aimed to evaluate the efficacy of intravenous immunoglobulins in children with new onset dilated cardiomyopathy. Methods and results In this retrospective cohort study, 94 children with new onset dilated cardiomyopathy were followed during a median period of 33 months. All patients with secondary dilated cardiomyopathy - for example, genetic, auto-immune or structural defects - had been excluded. Viral tests were performed in all patients and 18 (19%) children met the criteria for the diagnosis "probable or definite viral myocarditis". Intravenous immunoglobulins were administered to 21 (22%) patients. Overall transplant-free survival was 75% in 5 years and did not differ between treatment groups. The treatment was associated with a higher recovery rate within 5 years, compared with non-treated children (70 versus 43%, log rank=0.045). After correction for possible confounders the hazard ratio for recovery with intravenous immunoglobulins was not significant (hazard ratio: 2.1; 95% CI: 1.0-4.6; p=0.056). Administration of intravenous immunoglobulins resulted in a greater improvement in the shortening fraction of the left ventricle.

CONCLUSION

In our population of children with new onset dilated cardiomyopathy, of either viral or idiopathic origin, intravenous immunoglobulins were administered to a minority of the patients and did not influence transplant-free survival, but were associated with better improvement of systolic left ventricular function and with better recovery. Our results support the concept that children with new onset dilated cardiomyopathy might benefit from intravenous immunoglobulins.

Identifying low-grade cellular rejection after heart transplantation in children by using gene expression profiling

Endomyocardial biopsy (EMB) remains the gold standard for detecting rejection after heart transplantation but is costly and invasive. This study aims to distinguish no rejection (0R) from low-grade rejection (1R/2R) after heart transplantation in children by using global gene expression profiling in blood. A total of 106 blood samples with corresponding EMB from 18 children who underwent heart transplantation from 2011 to 2014 were analyzed (18 baseline/pretransplantation samples, 88 EMB samples). Corresponding rejection grades for each blood sample were 0R in 39% (34/88), 1R in 51% (45/88), and 2R in 10% (9/88). mRNA from each sample was sequenced. Differential expression analysis was performed at the gene level. A k-nearest neighbor (kNN) analysis was applied to the most differentially expressed (DE) genes to identify rejection after transplantation. Mean age at transplantation was 10.0 ± 5.4 yr. Expression of B cell and T cell receptor sequences was used to measure the effect of posttransplantation immunosuppression. Follow-up samples had lower levels of immunoglobulin gene families compared with pretransplantation ( P < 3E-5) (lower numbers of activated B cells). T cell receptor alpha and beta gene families had decreased expression in 0R samples compared with pretransplantation ( P < 4E-5) but recovered to near baseline levels in 1R/2R samples. kNN using the most DE gene (MKS1) and k = 9 nearest neighbors correctly identified 83% (73/88) of 1R/2R compared with 0R by leave-one-out cross validation. Using a genomic approach we can distinguish low-grade cellular allograft rejection (1R/2R) from no rejection (0R) after heart transplantation in children despite a wide age range.

Survival Without Cardiac Transplantation Among Children With Dilated Cardiomyopathy

BACKGROUND

Studies of children with dilated cardiomyopathy (DCM) have suggested that improved survival has been primarily due to utilization of heart transplantation.

OBJECTIVES

This study sought to determine transplant-free survival for these children over 20 years and identify the clinical characteristics at diagnosis that predicted death.

METHODS

Children <18 years of age with some type of DCM enrolled in the Pediatric Cardiomyopathy Registry were divided by year of diagnosis into an early cohort (1990 to 1999) and a late cohort (2000 to 2009). Competing risks and multivariable modeling were used to estimate the cumulative incidence of death, transplant, and echocardiographic normalization by cohort and to identify the factors associated with death.

RESULTS

Of 1,953 children, 1,199 were in the early cohort and 754 were in the late cohort. Most children in both cohorts had idiopathic DCM (64% vs. 63%, respectively). Median age (1.6 vs. 1.7 years), left ventricular end-diastolic z-scores (+4.2 vs. +4.2), and left ventricular fractional shortening (16% vs. 17%) at diagnosis were similar between cohorts. Although the rates of echocardiographic normalization (30% and 27%) and heart transplantation (24% and 24%) were similar, the death rate was higher in the early cohort than in the late cohort (18% vs. 9%; p = 0.04). Being in the early cohort (hazard ratio: 1.4; 95% confidence interval: 1.04 to 1.9; p = 0.03) independently predicted death.

CONCLUSIONS

Children with DCM have improved survival in the more recent era. This appears to be associated with factors other than heart transplantation, which was equally prevalent in both eras. (Pediatric Cardiomyopathy Registry [PCMR]; NCT00005391).