The Prevalence and Association of Exercise Test Abnormalities With Sudden Cardiac Death and Transplant-Free Survival in Childhood Hypertrophic Cardiomyopathy.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) can be associated with an abnormal exercise response. In adults with HCM, abnormal results on exercise stress testing are predictive of heart failure outcomes. Our goal was to determine whether an abnormal exercise response is associated with adverse outcomes in pediatric patients with HCM. METHODS: In an international cohort study including 20 centers, phenotype-positive patients with primary HCM who were <18 years of age at diagnosis were included. Abnormal exercise response was defined as a blunted blood pressure response and new or worsened ST- or T-wave segment changes or complex ventricular ectopy. Sudden cardiac death (SCD) events were defined as a composite of SCD and aborted sudden cardiac arrest. Using Kaplan-Meier survival, competing outcomes, and Cox regression analyses, we analyzed the association of abnormal exercise test results with transplant and SCD event-free survival. RESULTS: Of 724 eligible patients, 630 underwent at least 1 exercise test. There were no major differences in clinical characteristics between those with or without an exercise test. The median age at exercise testing was 13.8 years (interquartile range, 4.7 years); 78% were male and 39% were receiving beta-blockers. A total of 175 (28%) had abnormal test results. Patients with abnormal test results had more severe septal hypertrophy, higher left atrial diameter z scores, higher resting left ventricular outflow tract gradient, and higher frequency of myectomy compared with participants with normal test results (P<0.05). Compared with normal test results, abnormal test results were independently associated with lower 5-year transplant-free survival (97% versus 88%, respectively; P=0.005). Patients with exercise-induced ischemia were most likely to experience all-cause death or transplant (hazard ratio, 4.86 [95% CI, 1.69-13.99]), followed by those with an abnormal blood pressure response (hazard ratio, 3.19 [95% CI, 1.32-7.71]). Exercise-induced ischemia was also independently associated with lower SCD event-free survival (hazard ratio, 3.32 [95% CI, 1.27-8.70]). Exercise-induced ectopy was not associated with survival. CONCLUSIONS: Exercise abnormalities are common in childhood HCM. An abnormal exercise test result was independently associated with lower transplant-free survival, especially in those with an ischemic or abnormal blood pressure response with exercise. Exercise-induced ischemia was also independently associated with SCD events. These findings argue for routine exercise testing in childhood HCM as part of ongoing risk assessment.

"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.

Use of Photovoice to Explore Pediatric Patients with Hypertrophic Cardiomyopathy and their Parents' Perceptions of a Heart-Healthy Lifestyle.

Background Heart-healthy lifestyles promote lifelong cardiovascular health. However, patients with hypertrophic cardiomyopathy are often advised to avoid strenuous exercise because of the risk of sudden cardiac death. Given these restrictions, this study explored youth and parent perceptions of a heart-healthy lifestyle and the barriers and facilitators to this lifestyle. Methods and Results Youth and parents were purposefully recruited at 2 Canadian hospitals for this photovoice project. Participants were given cameras and took pictures of everyday heart-healthy or heart-unhealthy choices. Photos were discussed during one-on-one qualitative interviews with youth and parents separately to understand the photos' meaning and significance. Inductive descriptive thematic analysis was employed. A total of 16 youth (median age, 14.4 years [range, 10.5-17.7 years]; 63% boys) and 16 parents (100% women) participated. A total of 15 youth were activity restricted. Data analysis revealed 7 categories organized into perceptions of healthy living (health is holistic and individualized) and factors influencing engagement in healthy living (self-awareness, ownership and autonomy, feeling restricted and peer pressure, support from parents, and support from the cardiologist). Participants had a complex understanding of health and discussed the importance of physical, mental, and social well-being. Youth used self-awareness and taking responsibility as facilitators of healthy living. Healthy living was shaped by peers, parent role-modeling, and cardiologist recommendations. Conclusions This study depicts the realities for youth with hypertrophic cardiomyopathy and can be used to inform the development of responsive interventions. Holistic, patient-specific interventions may be more successful, and strategies such as shared decision making may be important to promote self-awareness and autonomy.

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.

Adverse Events Associated with Cardiac Catheterization in Children Supported with Ventricular Assist Devices.

Children on ventricular assist device (VAD) support can present several unique challenges, including small patient size, univentricular or biventricular congenital heart disease (1V- or 2V-CHD) and need for biventricular VAD (BiVAD) support. While cardiac catheterization can provide valuable information, it is an invasive procedure with inherent risks. We sought to evaluate the safety of catheterization in pediatric patients on VAD support. We performed a retrospective review of patients on VAD support who underwent catheterization at Lucile Packard Children's Hospital between January 1, 2014 and September 1, 2019. Using definitions adapted from Pedimacs, adverse events (AEs) after catheterization were identified, including arrhythmia; major bleeding or acute kidney injury within 24 hours; respiratory failure persisting at 24 hours; and stroke, pericardial effusion, device malfunction, bacteremia or death within 7 days. AEs were categorized as related or unrelated to catheterization. Sixty procedures were performed on 39 patients. Underlying diagnoses were dilated cardiomyopathy (48%), 1V-CHD (35%), 2V-CHD (8%), and other (8%). Devices were implantable continuous flow (72%), paracorporeal pulsatile (18%) and paracorporeal continuous flow (10%). Catheterizations were performed on patients in the ICU (60%), on inotropic support (42%), with deteriorating clinical status (37%) and on BiVAD support (12%). There were 9 AEs possibly related to catheterization including 6 episodes of respiratory failure, 2 major bleeding events, and 1 procedural arrhythmia. AE occurrence was associated with ICU status ( P = 0.01), BiVAD support ( P = 0.04) and procedural indication to evaluate worsening clinical status ( P = 0.04). Despite high medical acuity, catheterization can be performed with an acceptable AE profile in children on VAD support.

Fetal Diagnosis is Associated with Improved Perioperative Condition of Neonates Requiring Surgical Intervention for Coarctation.

To define the relative importance of fetal diagnosis and comorbidities in severity of preoperative compromise, outcomes and hospitalization in neonatal coarctation of the aorta (CoA). Retrospective comparison of preoperative condition and postoperative course of neonates prenatally (PreDx n = 48) or postnatally diagnosed (PostDx n = 67) with CoA. Congenital and non-congenital comorbidities were adjusted for. Postnatal diagnosis was associated with preoperative mortality (n = 2), and severe acidosis (lactate > 5 mM or pH < 7.20) on multivariate analysis (OR 4.2 (1.3-14.4, p = 0.02), with extracardiac congenital anomalies also a risk factor (OR 3.2 (1.03-10, p = 0.044). Median age at operation was delayed in the PostDx group (PreDx 6.5 days (IQR 4-9) vs PostDx 10 days (IQR 6-17)). Only comorbid left heart disease and extracardiac congenital anomalies were associated with prolonged total length of hospital stay. Prenatal diagnosis is the major adjustable risk factor affecting preoperative condition in critical CoA but does not reduce length of stay.

Kawasaki Disease Shock Syndrome Versus Septic Shock: Early Differentiating Features Despite Overlapping Clinical Profiles.

OBJECTIVES: To compare the clinical features and resuscitative measures of children with Kawasaki disease shock syndrome vs septic shock. STUDY DESIGN: In this retrospective case-control study, children with Kawasaki disease shock syndrome admitted to the intensive care unit from 2007 to 2017 were identified and compared with age-matched controls with septic shock. We studied 9 children with Kawasaki disease shock syndrome and 18 children with septic shock. Clinical characteristics were abstracted and between-group differences were compared. RESULTS: Compared with septic shock controls, children with Kawasaki disease shock syndrome were less likely to have an underlying comorbid illness (1/9 [11%] vs 11/18 [61%]; P = .02) and were more likely to have at least 1 of the 5 classic diagnostic signs of Kawasaki disease at presentation (9/9 [100%] vs 0/18 [0%]; P < .001), a longer duration of illness before admission (9 days [IQR, 7-14 days] vs 3 days [IQR, 1-5 days]; P = .004), and a lower platelet count at presentation (140 [IQR 73, 167]) vs 258 [IQR, 137-334]; P = .02). Among patients who underwent echocardiography, abnormalities such as ventricular dysfunction, valvulitis, and coronary artery dilation were more common in the Kawasaki disease shock syndrome cohort (5/9 [56%] vs 0/7 [0%]; P = .03). There were no differences in volume of fluid resuscitation, vasoactive-inotropic scores, duration of inotropic therapy, or biochemical markers of illness severity (other than platelet count) between the matched groups. CONCLUSIONS: A longer duration of illness before admission, lack of any significant underlying medical comorbidities, a lower platelet count, echocardiographic abnormalities, and the presence of classic diagnostic signs of Kawasaki disease at presentation may be useful early features to differentiate Kawasaki disease shock syndrome from septic shock.

Growth stunting in single ventricle patients after heart transplantation.

BACKGROUND: Malnutrition is common among children with single ventricle (SV) congenital heart disease (CHD). The impact of heart transplantation (HT) on nutritional status in SV patients is understudied. Our aim was to evaluate anthropometric changes in SV patients after HT, compared with those transplanted for cardiomyopathy (CM). METHODS: We performed a single-center retrospective chart review of SV and CM patients < 18 years who underwent HT from January 01, 2010 to December 05, 2017. Wasting and stunting were defined as z-scores for weight-for-age or height-for-age ≤-2, respectively. Changes in these indices between HT and 3 years post-HT were analyzed. RESULTS: Of 86 eligible patients, 28 (33%) had SV CHD and 58 (67%) had CM. Data were available at 3 years post-HT for 57 patients. At transplant, wasting was equally present in SV versus CM patients (7/28, 25% vs. 9/58, 16%, P = .22), which remained true at 3 years post-HT (2/16, 13% vs. 3/41, 7%, P = .61). At transplant, stunting was more common in SV than CM patients (17/28, 61% vs. 8/58, 14%, P < .001). At 3 years post-HT, 6 of 16 (38%) SV patients and 3 of 41 (7%) CM patients remained stunted (P = .01). Among all patients, wasting decreased from transplant to end-point (19% vs. 9%, P = .05), but stunting did not (29% vs. 16%, P = .2), such that wasting and stunting were associated at transplant (P < .001) but not at end-point (P = .17). CONCLUSIONS: Longitudinal growth remains impaired for several years after HT in SV patients, even when weight gain is achieved, suggesting that some factors contributing to growth impairment persist despite resolution of SV physiology.

Current Cardiac Imaging Approaches in Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD) is an X-linked neuromuscular condition caused by mutations in the dystrophin gene leading to skeletal muscle weakness and dilated cardiomyopathy. The prevalence of DMD-related cardiomyopathy increases with age and is almost universal by the third decade of life. Myocardial fibrosis and progressive left ventricular dysfunction lead to the development of heart failure and premature death. With modern advances in medical and surgical management for patients with DMD increasing their life expectancy, cardiac dysfunction represents an increasing cause of morbidity and mortality in these patients. Early diagnosis of dilated cardiomyopathy before symptom development enables the initiation of potentially disease-modifying therapies, but requires regular dedicated imaging surveillance with sufficient sensitivity to detect subclinical changes in cardiac structure and function. Currently, transthoracic echocardiography (TTE) and cardiac magnetic resonance imaging (CMR) are commonly used and have complementary roles. TTE is rapid and readily available, whereas CMR is the gold standard for the quantification of ventricular structure and function and can detect the presence and extent of myocardial fibrosis, an increasingly appreciated marker for early disease. This review describes the clinical applications, advantages, and disadvantages of cardiac imaging screening and surveillance for the myocardial manifestations of DMD, with a particular focus on TTE and CMR.

Fetal Right Ventricular Prominence: Associated Postnatal Abnormalities and Coarctation Clinical Prediction Tool.

Fetal right ventricular (RV) prominence is a known indicator of possible left-sided structural heart disease with a low positive predictive value for aortic coarctation. There is a paucity of data on identifying which fetuses with RV prominence will have postnatal arch obstruction. Our study objectives were to create a clinical prediction tool for coarctation and to describe the diagnostic outcomes of our cohort with fetal RV prominence. We performed a retrospective review of patients referred with fetal RV prominence from January 2009 to October 2015. Recorded fetal echocardiographic variables included gestational age, semilunar and atrioventricular valve dimensions, left and right ventricular mid-cavitary dimensions, foramen ovale and aortic arch flow direction, and isthmal diameter. Postnatal cardiac and non-cardiac diagnoses were documented. We performed descriptive analysis for postnatal outcomes and classification tree analysis to create a clinical prediction tool. Eighty-eight patients were reviewed; 58 (66%) had abnormal postnatal echocardiograms, 45 (51%) had left-sided lesions, including 26 (30%) with coarctation, and 6 (7%) had pulmonary hypertension. Our clinical prediction tool employs gestational age, RV mid-cavitary dimension z-score, and isthmal diameter z-score to predict coarctation with 85% accuracy, 95% confidence interval [75.3, 92.4%]. Our model correctly classified 45/54 non-coarctation and 19/21 coarctation cases, with 90% sensitivity and 83% specificity. Developing an accurate prediction tool for coarctation in cases of fetal RV prominence is an important first step in improving our management of these challenging cases.

Echocardiographic Image Quality Deteriorates with Age in Children and Young Adults with Duchenne Muscular Dystrophy.

BACKGROUND: Advances in medical care for patients with Duchenne muscular dystrophy (DMD) have resulted in improved survival and an increased prevalence of cardiomyopathy. Serial echocardiographic surveillance is recommended to detect early cardiac dysfunction and initiate medical therapy. Clinical anecdote suggests that echocardiographic quality diminishes over time, impeding accurate assessment of left ventricular systolic function. Furthermore, evidence-based guidelines for the use of cardiac imaging in DMD, including cardiac magnetic resonance imaging (CMR), are limited. The objective of our single-center, retrospective study was to quantify the deterioration in echocardiographic image quality with increasing patient age and identify an age at which CMR should be considered. METHODS: We retrospectively reviewed and graded the image quality of serial echocardiograms obtained in young patients with DMD. The quality of 16 left ventricular segments in two echocardiographic views was visually graded using a binary scoring system. An endocardial border delineation percentage (EBDP) score was calculated by dividing the number of segments with adequate endocardial delineation in each imaging window by the total number of segments present in that window and multiplying by 100. Linear regression analysis was performed to model the relationship between the EBDP scores and patient age. RESULTS: Fifty-five echocardiograms from 13 patients (mean age 11.6 years, range 3.6-19.9) were systematically reviewed. By 13 years of age, 50% of the echocardiograms were classified as suboptimal with ≥30% of segments inadequately visualized, and by 15 years of age, 78% of studies were suboptimal. Linear regression analysis revealed a negative correlation between patient age and EBDP score (r = -2.49, 95% confidence intervals -4.73, -0.25; p = 0.032), with the score decreasing by 2.5% for each 1 year increase in age. CONCLUSION: Echocardiographic image quality declines with increasing age in DMD. Alternate imaging modalities may play a role in cases of poor echocardiographic image quality.

Justify Your Answer: The Role of Written Think Aloud in Script Concordance Testing.

Construct: Clinical reasoning assessment is a growing area of interest in the medical education literature. Script concordance testing (SCT) evaluates clinical reasoning in conditions of uncertainty and has emerged as an innovative tool in the domain of clinical reasoning assessment. SCT quantifies the degree of concordance between a learner and an experienced clinician and attempts to capture the breadth of responses of expert clinicians, acknowledging the significant yet acceptable variation in practice under situations of uncertainty. BACKGROUND: SCT has been shown to be a valid and reliable clinical reasoning assessment tool. However, as SCT provides only quantitative information, it may not provide a complete assessment of clinical reasoning. APPROACH: Think aloud (TA) is a qualitative research tool used in clinical reasoning assessment in which learners verbalize their thought process around an assigned task. This study explores the use of TA, in the form of written reflection, in SCT to assess resident clinical reasoning, hypothesizing that the information obtained from the written TA would enrich the quantitative data obtained through SCT. Ninety-one pediatric postgraduate trainees and 21 pediatricians from 4 Canadian training centers completed an online test consisting of 24 SCT cases immediately followed by retrospective written TA. Six of 24 cases were selected to gather TA data. These cases were chosen to allow all phases of clinical decision making (diagnosis, investigation, and treatment) to be represented in the TA data. Inductive thematic analysis was employed when systematically reviewing TA responses. RESULTS: Three main benefits of adding written TA to SCT were identified: (a) uncovering instances of incorrect clinical reasoning despite a correct SCT response, (b) revealing sound clinical reasoning in the context of a suboptimal SCT response, and (c) detecting question misinterpretation. CONCLUSIONS: Written TA can optimize SCT by demonstrating when correct examinee responses are based on guessing or uncertainty rather than robust clinical rationale. TA can also enhance SCT by allowing examinees to provide justification for responses that otherwise would have been considered incorrect and by identifying questions that are frequently misinterpreted to avoid including them in future examinations. TA also has significant value in differentiating between acceptable variations in expert clinician responses and deviance associated with faulty rationale or question misinterpretation; this could improve SCT reliability. A written TA protocol appears to be a valuable tool to assess trainees' clinical reasoning and can strengthen the quantitative assessment provided by SCT.

The Impact of Infective Endocarditis Prophylaxis Recommendations on the Practices of Pediatric and Adult Congenital Cardiologists.

BACKGROUND: Compliance with the April 2007 American Heart Association (AHA) infective endocarditis (IE) guidelines is not well described. We sought to evaluate the impact of these guidelines on the clinical practices of pediatric and adult congenital cardiologists. METHODS: We conducted a 2-centre retrospective cohort study, including patients who had at least 1 outpatient cardiology visit after April 1, 2008 and had 1 of 11 prespecified high- or low-risk congenital cardiac lesions. High-risk lesions required prophylaxis per the AHA guidelines; low-risk patients no longer required prophylaxis. Cardiology clinic letters were reviewed to determine if antibiotic prophylaxis and oral hygiene were addressed and whether prophylaxis was recommended. Comparisons were made before April 2007 vs at least 1 year after guideline publication. RESULTS: We included 238 high-risk and 201 low-risk patients. IE prophylaxis was recommended for all study patients before April 2007. After April 2008, IE prophylaxis recommendations were reduced by 44.9% for low-risk patients (P < 0.0001) and 9.3% for high-risk patients (P = 0.0156). IE prophylaxis recommendations were documented in the medical record of 92% of patients (95% confidence interval, 88%-95%) before April 2007 vs 81% (77%-84%) after April 2008. Oral hygiene was emphasized for only 44% and 28% of patients before and after guideline revision (P = 0.0005). CONCLUSIONS: The 2007 AHA guidelines resulted in significantly fewer recommendations for IE prophylaxis in low-risk patients. However, cardiologists continue to recommend prophylaxis for some low-risk patients and advise some high-risk patients against prophylaxis. These findings suggest disagreement or uncertainty within the cardiology community regarding current IE guidelines.