Functional status predicts pediatric heart transplant outcomes: A united network for organ sharing (UNOS) database study

BACKGROUND

Functional status predicts waitlist survival in adult heart transplantation and is an independent predictor of outcomes in pediatric liver transplantation. This has not been studied in pediatric heart transplantation. Study aims were to determine the association of: (1) functional status at listing with waitlist and post-transplant outcomes, and (2) functional status at transplant with post-transplant outcomes in pediatric heart transplantation.

METHODS

Retrospective United Network of Organ Sharing database study of pediatric patients listed for heart transplant between 2005 and 2019 with Lansky Play Performance Scale (LPPS) scores at listing. Standard statistical methods were used to assess relationships between LPPS and outcomes (waitlist and post-transplant). Negative waitlist outcome was defined as death or removal from waitlist due to clinical deterioration.

RESULTS

There were 4,169 patients identified, including 1,080 with LPPS 80-100 (normal activity), 1,603 with LPPS 50-70 (mild limitations), and 1,486 with LPPS 10-40 (severe limitations). LPPS 10-40 correlated with negative waitlist outcomes (HR 1.69, CI 1.59-1.80, p < 0.0001). While LLPS at listing had no association with post-transplant survival, those with LPPS 10-40 at transplant had inferior 1-year post-transplant survival compared to those with LPPS ≥50 (92% vs 95%-96%, p = 0.0011). Functional status was an independent predictor of post-transplant outcomes in patients with cardiomyopathy. A functional improvement of ≥20 points between listing and transplant (N = 770, 24%) was associated with higher 1-year post-transplant survival (HR 1.63, 95% CI: 1.10-2.41, p = 0.018).

CONCLUSIONS

Functional status is associated with waitlist and post-transplant outcomes. Interventions targeting functional impairment may improve pediatric heart transplantation outcomes.

Facility-Based and Virtual Cardiac Rehabilitation in Young Patients with Heart Disease During the COVID-19 Era

Cardiac rehabilitation (CR) is an important tool for improving fitness and quality of life in those with heart disease (HD). Few pediatric centers use CR to care for these patients, and virtual CR is rarely used. In addition, it is unclear how the COVID-19 era has changed CR outcomes. This study assessed fitness improvements in young HD patients participating in both facility-based and virtual CR during the COVID-19 pandemic. This retrospective single-center cohort study included new patients who completed CR from March 2020 through July 2022. CR outcomes included physical, performance, and psychosocial measures. Comparison between serial testing was performed with a paired t test with P < 0.05 was considered significant. Data are reported as mean ± standard deviation. There were 47 patients (19 ± 7.3 years old; 49% male) who completed CR. Improvements were seen in peak oxygen consumption (VO₂, 62.3 ± 16.1 v 71 ± 18.2% of predicted, p = 0.0007), 6-min walk (6 MW) distance (401 ± 163.8 v 480.7 ± 119.2 m, p =  < 0.0001), sit to stand (16.2 ± 4.9 v 22.1 ± 6.6 repetitions; p =  < 0.0001), Patient Health Questionnaire-9 (PHQ-9) (5.9 ± 4.3 v 4.4 ± 4.2; p = 0.002), and Physical Component Score (39.9 ± 10.1 v 44.9 ± 8.8; p = 0.002). Facility-based CR enrollees were less likely to complete CR than virtual patients (60%, 33/55 v 80%, 12/15; p = 0.005). Increases in peak VO₂ (60 ± 15.3 v 70.2 ± 17.8% of predicted; p = 0.002) were seen among those that completed facility-based CR; this was not observed in the virtual group. Both groups demonstrated improvement in 6 MW distance, sit-to-stand repetitions, and sit-and-reach distance. Completion of a CR program resulted in fitness improvements during the COVID-19 era regardless of location, although peak VO₂ improved more for the in-person group.

Heart transplant offers are less likely to be accepted on weekends, holidays, and conferences

BACKGROUND

The existence of a "weekend effect" in heart transplantation (HTx) is understudied. The present study sought to determine whether the odds of (HTx) offer acceptance differed for adult and pediatric candidates depending upon the day on which the offer occurred.

METHODS

United Network for Organ Sharing data were used to identify all HTx offers to adult (listing age ≥18) and pediatric candidates from 2000-2019. Odds of offer acceptance were studied, comparing weekends, holidays, and conferences (Society of Thoracic Surgeons [STS], American Association for Thoracic Surgery [AATS], International Society for Heart and Lung Transplantation [ISHLT]) to "baseline" (all other days). Multivariable binary logistic regression analyses were performed to determine independent predictors of offer nonacceptance, controlling for the impacts of program transplant volume, region, and candidate characteristics.

RESULTS

A total of 323,953 offers occurred - 298,405 to adults and 25,548 to pediatric candidates. Clinically significant differences did not exist in donor or candidate characteristics between baseline or other events. The number of offers per day was stable throughout the year for both adults (p = 0.191) and pediatrics (p = 0.976). In adults, independently lower odds of acceptance existed on weekends (OR 0.88 [95% CI 0.84-0.92]), conferences in aggregate (0.86 [0.77-0.95]), and holidays in aggregate (0.81 [0.72-0.91]). In children, independently lower odds of acceptance were seen on weekends (0.88 [0.79-0.98]), during STS (0.46 [0.25-0.83], and during Christmas (0.32 [0.14-0.76]).

CONCLUSIONS

The day on which a HTx offer occurs significantly impacts its likelihood of acceptance. Further work can determine the impacts of human behavior or resource distribution, but knowledge of this phenomenon can inform efforts to ensure ideal organ allocation throughout the year.

Pediatric Cardiology Fellowship Standards for Training in Exercise Medicine and Curriculum Outline

Over the past 2 decades, fundamentals of exercise medicine, including clinical exercise testing, assessment and promotion of physical activity, exercise prescription, and supervised exercise training/rehabilitation programming have demonstrated considerable clinical value in the management of children and adolescents with congenital and acquired heart disease. Although the principles of exercise medicine have become an integral component in pediatric cardiology, there are no standardized training recommendations for exercise physiology during pediatric cardiology fellowship at this time. Thus, the Pediatric Cardiology Exercise Medicine Curriculum Committee (PCEMCC) was formed to establish core and advanced exercise physiology training recommendations for pediatric cardiology trainees. The PCEMCC includes a diverse group of pediatric cardiologists, exercise physiologists, and fellowship program directors. The expert consensus training recommendations are by no means a mandate and are summarized herein, including suggestions for achieving the minimum knowledge and training needed for general pediatric cardiology practice.

Stable fitness during COVID-19: Results of serial testing in a cohort of youth with heart disease

Background

Little is known about how sport and school restrictions early during the novel coronavirus 2019 (COVID-19) pandemic impacted exercise performance and body composition in youth with heart disease (HD).

Methods

A retrospective chart review was performed on all patients with HD who had serial exercise testing and body composition via bioimpedance analysis performed within 12 months before and during the COVID-19 pandemic. Formal activity restriction was noted as present or absent. Analysis was performed with a paired t-test.

Results

There were 33 patients (mean age 15.3 ± 3.4 years; 46% male) with serial testing completed (18 electrophysiologic diagnosis, 15 congenital HD). There was an increase in skeletal muscle mass (SMM) (24.1 ± 9.2-25.9 ± 9.1 kg, p < 0.0001), weight (58.7 ± 21.5-63.9 ± 22 kg, p < 0.0001), and body fat percentage (22.7 ± 9.4-24.7 ± 10.4%, p = 0.04). The results were similar when stratified by age <18 years old (n = 27) or by sex (male 16, female 17), consistent with typical pubertal changes in this predominantly adolescent population. Absolute peak VO₂ increased, but this was due to somatic growth and aging as evidenced by no change in % of predicted peak VO₂. There remained no difference in predicted peak VO₂ when excluding patients with pre-existing activity restrictions (n = 12). Review of similar serial testing in 65 patients in the 3 years before the pandemic demonstrated equivalent findings.

Conclusions

The COVID-19 pandemic and related lifestyle changes do not appear to have had substantial negative impacts on aerobic fitness or body composition in children and young adults with HD.

Peak Work Rate Increases With Lower Extremity-Focused Exercise Training in Adolescents With Fontan Circulation

Background Skeletal muscle deficits are associated with worse exercise performance in the Fontan circulation and may be improved by exercise training. We aimed to assess the change in leg lean mass (a marker of skeletal muscle), exercise performance, and functional health status after a lower extremity-focused exercise intervention in adolescents with Fontan circulation. Methods and Results Densitometry for measurement of leg lean mass, cardiopulmonary exercise test, exercise cardiac magnetic resonance, peripheral vascular testing, physical activity questionnaire, and quality of life assessment were performed at baseline and after a 24-week, hybrid center- and home-based training program. Leg lean mass Z-scores were generated, and exercise parameters were expressed as percentage expected based on reference data. The effect of training was assessed by paired t-tests and simple linear regression. Twenty participants (15.6±1.7 years, 50% male) demonstrated low baseline leg lean mass Z-scores with no significant improvement with training (-1.38±1.02 pre versus -1.31±1.06 post, P=0.33). Maximum and percent predicted work increased from 121.9±29.8 (0.66±0.12) to 131.3±35.1 (0.70±0.15) watts (P=0.02). Peak respiratory exchange ratio increased (1.19±0.02 versus 1.25±0.01, P=0.02) but percent predicted oxygen consumption was unchanged, suggesting higher anaerobic activity after training. Physical activity questionnaire score positively associated with peak work at baseline (ß=18.13 [95% CI, 0.83-35.44], R²=0.21; P=0.04) but physical activity questionnaire, quality of life scores, exercise cardiac magnetic resonance performance, and peripheral vascular function were unchanged with training. Conclusions Peak work rate and anaerobic activity increased with lower extremity-focused training in adolescents with Fontan circulation. Larger studies should test the impact of these changes on functional status and quality of life.

Arrhythmia Burden and Heart Rate Response During Exercise in Anderson-Fabry Disease

Patients with Anderson-Fabry disease (AFD) have an elevated incidence of resting arrhythmias and ischemic heart disease, but their exercise arrhythmia burden and ischemic changes are not well understood. In addition, little research has been done on heart rate recovery in these patients. We retrospectively reviewed charts of patients with AFD who underwent maximal effort cardiopulmonary exercise testing (CPET) (n=44; 38.2 ± 13.8 yr; 23 men) from 2012 through 2018. Electrocardiographic, Holter monitoring, echocardiographic, cardiac magnetic resonance imaging, and patient demographic data were collected. No patient had adverse events that necessitated CPET termination, whereas 25 (57%) had ectopy during CPET, including 3 (7%) with frequent premature atrial contractions and 5 (11%) with frequent premature ventricular contractions. The ectopic burden was higher during resting electrocardiographic monitoring before exercise. In addition, 7 patients (16%) had pathologic ST-segment or T-wave changes on CPET, defined as ST-segment changes ≥2 mm. Among the patients who had concurrent cardiac magnetic resonance findings with their CPET (n=27), ST-segment or T-wave changes were associated with left ventricular myocardial mass (r=0.43, P=0.02). Chronotropic incompetence was seen during CPET in 28 patients (64%); however, only 2 patients (4%) had abnormal heart rate recovery at 1 minute. This study shows that patients with AFD can safely undergo exercise testing but have a high incidence of exercise-induced arrhythmias and ischemic changes. Ischemic electrocardiographic changes during exercise testing are associated with myocardial mass. Despite the chronotropic incompetence associated with AFD, heart rate recovery appears to be generally preserved in these patients.

External validation of the HCM Risk-Kids model for predicting sudden cardiac death in childhood hypertrophic cardiomyopathy

AIMS

Sudden cardiac death (SCD) is the most common mode of death in childhood hypertrophic cardiomyopathy (HCM). The newly developed HCM Risk-Kids model provides clinicians with individualized estimates of risk. The aim of this study was to externally validate the model in a large independent, multi-centre patient cohort.

METHODS AND RESULTS

A retrospective, longitudinal cohort of 421 patients diagnosed with HCM aged 1-16 years independent of the HCM Risk-Kids development and internal validation cohort was studied. Data on HCM Risk-Kids predictor variables (unexplained syncope, non-sustained ventricular tachycardia, maximal left ventricular wall thickness, left atrial diameter, and left ventricular outflow tract gradient) were collected from the time of baseline clinical evaluation. The performance of the HCM Risk-Kids model in predicting risk at 5 years was assessed. Twenty-three patients (5.4%) met the SCD end-point within 5 years, with an overall incidence rate of 2.03 per 100 patient-years [95% confidence interval (CI) 1.48-2.78]. Model validation showed a Harrell's C-index of 0.745 (95% CI 0.52-0.97) and Uno's C-index 0.714 (95% 0.58-0.85) with a calibration slope of 1.15 (95% 0.51-1.80). A 5-year predicted risk threshold of ≥6% identified 17 (73.9%) SCD events with a corresponding C-statistic of 0.702 (95% CI 0.60-0.81).

CONCLUSIONS

This study reports the first external validation of the HCM Risk-Kids model in a large and geographically diverse patient population. A 5-year predicted risk of ≥6% identified over 70% of events, confirming that HCM Risk-Kids provides a method for individualized risk predictions and shared decision-making in children with HCM.

Emergency Planning as Part of Healthcare Transition Preparation for Patients with Duchenne Muscular Dystrophy

BACKGROUND

Emergency care planning is an important component of healthcare transition, particularly for patients with medical complexity. Duchenne muscular dystrophy (DMD) is a complex, progressive pediatric-onset disease affecting multiple organ systems including impairment of cardiac and pulmonary function, high risk for fractures, fat embolism, adrenal crisis and malignant hyperthermia. Appropriate interdisciplinary emergency management is critical for survival for these patients. The purpose of this quality improvement project was to develop a process to reliably share an individualized emergency care plan (ECP) with patients and their families as part of a larger plan to develop an integrated transition program.

METHODS

An interdisciplinary team of nurses and clinicians used the principles of quality improvement to develop a reliable process to assure patients with DMD received an individualized, multidisciplinary ECP at routine interdisciplinary clinic visits. Additionally, the project used surveys to assess patient and family satisfaction with the letter and whether it improved their knowledge of emergency care.

RESULTS

Sixty-two patients were seen during the study timeframe. All received an ECP. Sixty-two surveys were sent and twenty-three surveys were returned. Of those that responded, the majority stated the ECP increased their knowledge of emergency care.

CONCLUSION

ECPs can be developed and disseminated to patients with DMD and their caregivers. This tool can potentially promote timely and appropriate emergency care for these patients with unique and complex medical needs.

Worldwide differences in primary prevention implantable cardioverter defibrillator utilization and outcomes in hypertrophic cardiomyopathy

AIMS

Risk stratification algorithms for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) and regional differences in clinical practice have evolved over time. We sought to compare primary prevention implantable cardioverter defibrillator (ICD) implantation rates and associated clinical outcomes in US vs. non-US tertiary HCM centres within the international Sarcomeric Human Cardiomyopathy Registry.

METHODS AND RESULTS

We included patients with HCM enrolled from eight US sites (n = 2650) and five non-US (n = 2660) sites and used multivariable Cox-proportional hazards models to compare outcomes between sites. Primary prevention ICD implantation rates in US sites were two-fold higher than non-US sites (hazard ratio (HR) 2.27 [1.89-2.74]), including in individuals deemed at high 5-year SCD risk (≥6%) based on the HCM risk-SCD score (HR 3.27 [1.76-6.05]). US ICD recipients also had fewer traditional SCD risk factors. Among ICD recipients, rates of appropriate ICD therapy were significantly lower in US vs. non-US sites (HR 0.52 [0.28-0.97]). No significant difference was identified in the incidence of SCD/resuscitated cardiac arrest among non-recipients of ICDs in US vs. non-US sites (HR 1.21 [0.74-1.97]).

CONCLUSION

Primary prevention ICDs are implanted more frequently in patients with HCM in US vs. non-US sites across the spectrum of SCD risk. There was a lower rate of appropriate ICD therapy in US sites, consistent with a lower-risk population, and no significant difference in SCD in US vs. non-US patients who did not receive an ICD. Further studies are needed to understand what drives malignant arrhythmias, optimize ICD allocation, and examine the impact of different ICD utilization strategies on long-term outcomes in HCM.

Antithymocyte globulin induction therapy and myocardial complement deposition in pediatric heart transplantation

BACKGROUND

Antithymocyte globulin (ATG) consists of polyclonal antibodies directed primarily against human T lymphocytes but may contain antibodies with affinity for other tissues in the transplanted organ, resulting in complement (C4d) deposition. This phenomenon has been demonstrated in endomyocardial biopsies (EMBs) of adult cardiac transplants. We examined the relationship of induction immunosuppression with ATG and C4d deposition in EMB of pediatric cardiac transplants.

METHODS

Results of C4d immunohistochemistry were available from all EMB of patients transplanted at our center between June 2012 and April 2018 (n = 48) who received induction immunosuppression with either ATG (n = 20) or basiliximab (n = 28) as the standard of care.

RESULTS

C4d deposition in the first year post-heart transplant was more commonly seen among patients who received ATG induction (20% of EMBs in ATG group vs 1% of EMBs in basiliximab group; p < .0001). C4d deposition related to ATG was observed early post-transplant (50% ATG vs 0% basiliximab on first EMB; p < .0001 and 35% ATG vs 0% basiliximab on the second EMB; p = .0012). While this difference waned by the third EMB (5% ATG vs 0% basiliximab; p = .41), positive C4d staining persisted to the sixth EMB in the ATG group only (6%).

CONCLUSION

C4d deposition is common on EMB up to 1 year post-pediatric cardiac transplant following ATG induction. This high rate of positive C4d staining in the absence of histologic AMR after ATG induction therapy must be accounted for in making clinical decisions regarding cardiac allograft rejection diagnosis and treatment.

Pediatric Cardiology Fellowship Training in Exercise Medicine: A General Needs Assessment

The aim of this study was to improve understanding of exercise medicine training needs for pediatric cardiology fellows. A survey was sent via email to all (N = 63) pediatric cardiology training program directors in the United States to evaluate the perceived exercise training needs of pediatric cardiology fellows. The survey consisted of multiple-choice responses as well as a few open-ended responses. A 60% response rate was achieved. 74% of programs did not have a pre-existing exercise core program. This type of training was felt to be important or very important in 84%. A wide variability of time allotted for exercise training exists amongst programs from < 1 week to > 4 weeks, with 2 weeks being most common. There was no consensus on a target number of total exercise tests nor types of tests in which fellows should participate. Preferred methods in training consisted of lectures and online media. Less preferred methods of teaching methods included dedicated reading of a handbook, a dedicated rotation, or live webinars. There was general support to develop exercise training competencies as well as the associated online learning materials with a focus on competency rather than target numbers. There is a need for educational recommendations for exercise training in pediatric cardiology fellowships as well as a unified method of achieving competencies.

Clinical characteristics and outcomes in childhood-onset hypertrophic cardiomyopathy

AIMS

Childhood-onset hypertrophic cardiomyopathy (HCM) is far less common than adult-onset disease, thus natural history is not well characterized. We aim to describe the characteristics and outcomes of childhood-onset HCM.

METHODS AND RESULTS

We performed an observational cohort study of 7677 HCM patients from the Sarcomeric Human Cardiomyopathy Registry (SHaRe). Hypertrophic cardiomyopathy patients were stratified by age at diagnosis [<1 year (infancy), 1-18 years (childhood), >18 years (adulthood)] and assessed for composite endpoints reflecting heart failure (HF), life-threatening ventricular arrhythmias, atrial fibrillation (AF), and an overall composite that also included stroke and death. Stratifying by age of diagnosis, 184 (2.4%) patients were diagnosed in infancy; 1128 (14.7%) in childhood; and 6365 (82.9%) in adulthood. Childhood-onset HCM patients had an ∼2%/year event rate for the overall composite endpoint, with ventricular arrhythmias representing the most common event in the 1st decade following baseline visit, but HF and AF becoming more common by the end of the 2nd decade. Sarcomeric variants were more common in childhood-onset HCM (63%) and carried a worse prognosis than non-sarcomeric disease, including a greater than two-fold increased risk of HF [HRadj 2.39 (1.36-4.20), P = 0.003] and 67% increased risk of the overall composite outcome [HRadj 1.67 (1.16-2.41), P = 0.006]. When compared with adult-onset HCM, childhood-onset was 36% more likely to develop life-threatening ventricular arrhythmias [HRadj 1.36 (1.03-1.80)] and twice as likely to require transplant or ventricular assist device [HRadj 1.99 (1.23-3.23)].

CONCLUSION

Patients with childhood-onset HCM are more likely to have sarcomeric disease, carry a higher risk of life-threatening ventricular arrythmias, and have greater need for advanced HF therapies. These findings provide insight into the natural history of disease and can help inform clinical risk stratification.

Cardiac medication management in Duchenne muscular dystrophy

There have been significant improvements in the skeletal muscle and respiratory care for patients with Duchenne muscular dystrophy (DMD) over the last two decades. This has resulted in longer expected survival as many patients will live into their 20s and 30s. This timeline has resulted in a greater proportion of patients experiencing heart failure and cardiac-related mortality. Herein, we describe the current indications for medical therapy for patients with DMD.

Landscape of Mentorship and its Effects on Success in Cardiology

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Mentees are more satisfied with their mentorship experience when they have had more than 3 mentors or a mentor from outside of their practice/institution.

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Satisfaction with the mentoring relationship is significantly associated with perceived satisfaction in achieving professional goals.

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Sex and race/ethnicity concordance in mentoring relationships is associated with positive outcomes.

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Characteristics that mentees desire in a mentor tend to change with time/career stage.

The effects of mentorship on measurable outcomes of success and the aspects of mentorship that are most valuable in promoting the careers of cardiologists are unclear. To address this, we conducted a large-scale survey of cardiologists in a real-world setting. We identified factors that enhance the mentorship experience, and found that mentee needs change with career stage. Importantly, satisfaction with the mentoring relationship is significantly associated with perceived satisfaction in achieving professional goals. Furthermore, we found that gender and race concordance in mentoring relationships is an important variable with the potential to increase diversity in the field of cardiology.

Body Composition and Exercise Performance in Youth With a Fontan Circulation: A Bio-Impedance Based Study

Background Adults with a Fontan circulation tend to have myopenia and elevated adiposity when measured by dual energy x-ray absorptiometry. Bioelectrical impedance analysis is an alternative validated approach to assess body composition. We used bioelectrical impedance analysis to compare body composition between pediatric patients with a Fontan circulation and control individuals without heart disease. Methods and Results A retrospective chart review identified all patients aged <22 years with a Fontan circulation who presented for cardiopulmonary exercise testing and bioelectrical impedance analysis from April 2019 to January 2020. Data were compared with control subjects tested during the same period. We studied 47 patients with a Fontan circulation (53% boys; 15±3.1 years) and 165 controls (48% boys; 14.4±2.5 years). Fontan status was associated with shorter height, but similar age, sex, and overall body mass. Patients with Fontan had lower lean body mass (-12.0±22%, Z-score -0.5±1, P=0.005), skeletal muscle mass (-13.6±1.4%; Z-score, -0.5±1; P=0.004), skeletal muscle indexed to height (-10.3±13.3%; Z-score, -0.5±1; P=0.005), and higher percent body fat (+13.8±18.6%; Z-score, 0.4±1.2; P=0.03). Greater skeletal muscle mass was associated with higher peak oxygen consumption (r2=0.52, P<0.0001) and oxygen pulse (r2=0.68, P<0.0001). Patients who had suffered a late complication (ie, heart transplant referral or evidence of extracardiac organ dysfunction) of the Fontan operation (13 of 47, 27.7%) had lower skeletal muscle mass (P=0.048) and higher body fat percentage (P=0.003). Conclusions The Fontan circulation is associated with marked myopenia and increased adiposity. Higher muscle mass was associated with better exercise capacity. Fontan complications are associated with lower muscle mass and increased adiposity.

Implementation of a Pediatric Chest Pain Local Consensus Guideline Decreases the Total Tests Performed Without Negatively Affecting the Yield of Abnormal Cardiac Results

Pediatric chest pain is common and though usually benign often leads to unnecessary diagnostic testing. There is limited evidence as to whether a local consensus guideline can decrease testing frequency without negatively affecting the overall yield. In addition, it is unknown whether the addition of pulmonary function testing to a cardiopulmonary exercise test increases the diagnostic yield in pediatric patients with chest pain. A retrospective chart review was performed on all new pediatric patients who presented with chest pain at our academic center's pediatric cardiology clinic 18 months before and after the implementation of a standard management guideline. Data from the encounter-associated echocardiogram, cardiopulmonary exercise test, and pulmonary function test, when available, were analyzed. There were no significant differences in patient volume or demographic characteristics in the 18 months before (n = 768) and after (n = 778) guideline implementation. There were significant reductions in the number of ordered echocardiograms (n = 131; 17% vs. n = 75; 9.6%, p < 0.001) and cardiopulmonary exercise tests (n = 46; 6% vs. n = 29; 4%, p = 0.04) with no concerning pathology discovered in either group. Associated pulmonary function testing performed prior to with exercise testing discovered abnormalities in 19% of the total patients tested. The implementation of a local consensus guideline for pediatric chest pain results in fewer unnecessary tests ordered. There was no concerning pathology before or after guideline implementation, therefore conclusions regarding the diagnostic yield of these guidelines are unfeasible. The addition of pulmonary function testing to cardiopulmonary exercise tests increases the potential diagnostic yield in these patients.

Left Ventricular Magnetic Resonance Imaging Strain Predicts the Onset of Duchenne Muscular Dystrophy-Associated Cardiomyopathy

BACKGROUND

Early detection of left ventricular (LV) dysfunction before the onset of overt Duchenne muscular dystrophy-associated cardiomyopathy (DMDAC) may direct clinical management to slow onset of dysfunction. We aimed to assess whether LV strain will predict those who develop DMDAC.

METHODS

We performed a single center retrospective case control study of patients with Duchenne muscular dystrophy who underwent serial cardiac magnetic resonance between 2006 and 2019. Patients with Duchenne muscular dystrophy with an LV ejection fraction ≥55% on ≥1 cardiac magnetic resonance were identified and grouped into age-matched +DMDAC and -DMDAC. Within 3 years, +DMDAC had a subsequent cardiac magnetic resonance with a decline in LV ejection fraction ≥10% and absolute LV ejection fraction ≤50%. -DMDAC maintained an LV ejection fraction ≥55% on serial cardiac magnetic resonances. Two-dimensional and 3-dimensional global radial strain, global circumferential strain (GCS), and global longitudinal strain were measured using tissue tracking software and their ability to predict DMDAC onset was assessed. Multivariable analysis adjusted for late gadolinium enhancement.

RESULTS

Thirty +DMDAC and 30 age-matched -DMDAC patients were included with a total of 164 studies analyzed. Before DMDAC onset, 2-dimensional global radial strain and GCS were significantly worse in +DMDAC compared with -DMDAC (25.1±6.0 versus 29.0±6.3, P=0.011; -15.4%±2.4 versus -17.3%±2.6, P=0.003). Three-dimensional GCS and global radial strain had similar findings. Among strain measures, 3-dimensional GCS had the highest area under the curve to predict DMDAC in our cohort. These findings persisted after adjusting for the presence of late gadolinium enhancement.

CONCLUSIONS

Reduced global radial strain and GCS may predict those at risk for developing DMDAC before onset of LV dysfunction and its clinical utility warrants further exploration.

Exercise testing and cardiac rehabilitation in patients treated for cancer

Cardiovascular disease (CVD) is a major competing cause of morbidity and mortality in patients with cancer. Cancer treatment can have detrimental short- and long-term cardiovascular effects. Moreover, cancer patients may have a significant loss in cardiorespiratory fitness, a key CVD risk factor, during and after cancer treatment. Exercise training has emerged as a potential intervention to improve fitness and reduce the risk of CVD in cancer. In this review, we discuss the role of cardiorespiratory fitness to predict cancer and CVD outcomes, as well as explore the impact of exercise training to improve fitness and other key outcomes in patients with cancer. The role of cardio-oncology rehabilitation will also be highlighted.

Spatial and Functional Distribution of MYBPC3 Pathogenic Variants and Clinical Outcomes in Patients With Hypertrophic Cardiomyopathy

Supplemental Digital Content is available in the text.

Pathogenic variants in MYBPC3, encoding cardiac MyBP-C (myosin binding protein C), are the most common cause of familial hypertrophic cardiomyopathy. A large number of unique MYBPC3 variants and relatively small genotyped hypertrophic cardiomyopathy cohorts have precluded detailed genotype-phenotype correlations.

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

BACKGROUND

Hypertrophic cardiomyopathy is the leading cause of sudden cardiac death (SCD) in children and young adults. Our objective was to develop and validate a SCD risk prediction model in pediatric hypertrophic cardiomyopathy to guide SCD prevention strategies.

METHODS

In an international multicenter observational cohort study, phenotype-positive patients with isolated hypertrophic cardiomyopathy <18 years of age at diagnosis were eligible. The primary outcome variable was the time from diagnosis to a composite of SCD events at 5-year follow-up: SCD, resuscitated sudden cardiac arrest, and aborted SCD, that is, appropriate shock following primary prevention implantable cardioverter defibrillators. Competing risk models with cause-specific hazard regression were used to identify and quantify clinical and genetic factors associated with SCD. The cause-specific regression model was implemented using boosting, and tuned with 10 repeated 4-fold cross-validations. The final model was fitted using all data with the tuned hyperparameter value that maximizes the c-statistic, and its performance was characterized by using the c-statistic for competing risk models. The final model was validated in an independent external cohort (SHaRe [Sarcomeric Human Cardiomyopathy Registry], n=285).

RESULTS

Overall, 572 patients met eligibility criteria with 2855 patient-years of follow-up. The 5-year cumulative proportion of SCD events was 9.1% (14 SCD, 25 resuscitated sudden cardiac arrests, and 14 aborted SCD). Risk predictors included age at diagnosis, documented nonsustained ventricular tachycardia, unexplained syncope, septal diameter z-score, left ventricular posterior wall diameter z score, left atrial diameter z score, peak left ventricular outflow tract gradient, and presence of a pathogenic variant. Unlike in adults, left ventricular outflow tract gradient had an inverse association, and family history of SCD had no association with SCD. Clinical and clinical/genetic models were developed to predict 5-year freedom from SCD. Both models adequately discriminated between patients with and without SCD events with a c-statistic of 0.75 and 0.76, respectively, and demonstrated good agreement between predicted and observed events in the primary and validation cohorts (validation c-statistic 0.71 and 0.72, respectively).

CONCLUSION

Our study provides a validated SCD risk prediction model with >70% prediction accuracy and incorporates risk factors that are unique to pediatric hypertrophic cardiomyopathy. An individualized risk prediction model has the potential to improve the application of clinical practice guidelines and shared decision making for implantable cardioverter defibrillator insertion. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT0403679.

Hypertrophic Cardiomyopathy With Left Ventricular Systolic Dysfunction: Insights From the SHaRe Registry

Supplemental Digital Content is available in the text.

The term “end stage” has been used to describe hypertrophic cardiomyopathy (HCM) with left ventricular systolic dysfunction (LVSD), defined as occurring when left ventricular ejection fraction is <50%. The prognosis of HCM-LVSD has reportedly been poor, but because of its relative rarity, the natural history remains incompletely characterized.

Cost-utility of continuous-flow ventricular assist devices as bridge to transplant in pediatrics

OBJECTIVE

The initial costs of a CF-VAD exceed those of a PF-VAD. However, the safety profile of CF-VAD is superior and the possibility of outpatient device support may justify the additional initial costs. This study analyzed the cost-utility of CF-VAD use in the pediatric population.

METHODS

A Markov-state transition model was constructed for the clinical course of the two VAD subtypes from implantation until death with variables extracted from internal financial records and the published literature. The modeled population consisted of pediatric heart failure patients who met indications for VAD implant (INTERMACS profile 1 or 2) and were size-eligible for either a PF-VAD or CF-VAD.

RESULTS

The cost-utility analysis illustrated that CF-VAD is both more effective and less costly compared to PF-VAD at base-case conditions. Sensitivity analyses demonstrated that only in extreme conditions did a CF-VAD strategy not meet criteria for cost-effectiveness (if readmission rate >20% weekly, neurologic event rate >8% weekly, or CF-VAD discharge rates <18% in a month) or VAD support duration shortens to ≤12 weeks.

CONCLUSION

While the implantation costs of a CF-VAD exceed those of a PF-VAD, after 12 weeks of device support CF-VAD becomes the more cost-effective strategy if the anticipated outpatient device care is sufficiently long. The cost efficacy of the CF-VAD will be further heightened as initiatives that result in earlier and safer discharges, as well as reductions in readmission rates continue to be successful.

Contemporary Outcomes of Pediatric Restrictive Cardiomyopathy: A Single-Center Experience

BACKGROUND

Pediatric restrictive cardiomyopathy (RCM) has high mortality in historical cohorts, and traditional management often involves early referral for heart transplantation (HTx). This study sought to determine outcomes of pediatric RCM at a center that has favored medical management over early listing for HTx.

METHODS

All patients (N = 43) with pure RCM phenotype (RCM, N = 26) and hypertrophic cardiomyopathy with restrictive physiology (RCM/HCM, N = 17) managed at our center over a 15-year period were investigated. Outcomes of those listed for HTx (N = 18) were compared to a benchmark of contemporaneous pediatric RCM patients in the UNOS database (N = 377). Proportional hazards models were used to determine predictors of adverse outcomes.

RESULTS

The mean age was 11 ± 9 years and 49% were male. 14 of 18 patients listed received HTx. Overall mortality (12%) was identical between the phenotypes; however, RCM patients were more likely to be listed (P = 0.001) and receive HTx (P = 0.02) compared to RCM/HCM. Prior to HTx, 60% had documented arrhythmia, 16% had cardiac arrest, and 7% required mechanical circulatory support. 4 of 17 patients with an ICD/PM received device therapies (four of five shocks appropriate for VT/VF, and two effective anti-tachycardia pacing interventions). Outcomes of those listed for HTx at our center were similar to the UNOS benchmark. In multivariate analysis, markers of congestive heart failure were associated with adverse outcomes.

CONCLUSION

Heart failure and arrhythmia treatments can delay or possibly prevent the need for HTx in some cases of pediatric RCM. Survival post-HTx is not compromised using this approach.

Cardiac Rehabilitation Improves Cardiometabolic Health in Young Patients with Nonischemic Dilated Cardiomyopathy

Nonischemic dilated cardiomyopathy is deadly and costly, and treatment options are limited. Cardiac rehabilitation has proved safe and beneficial for adults with various types of heart failure. Therefore, we retrospectively evaluated the hypothesis that rehabilitation is safe and improves cardiometabolic health in young patients with nonischemic dilated cardiomypathy. From 2011 through 2015, 8 patients (4 males) (mean age, 20.6 ± 6.6 yr; range, 10-31 yr) underwent rehabilitation at our institution. They were in American Heart Association class C or D heart failure and were on maximal medical therapy. Their mean left ventricular ejection fraction at baseline was 0.26 ± 0.15. Two patients had a left ventricular assist device, and 2 were inpatients. To evaluate safety, we documented adverse events during rehabilitation sessions. Clinical endpoints were measured at baseline, immediately after completing rehabilitation, and after one year. Patients attended 120 of 141 possible sessions (85%), with no adverse events. There were no marked changes in mean left ventricular ejection fraction or body mass index. The patients' mean waist circumference decreased by 1.37 ± 0.6 in (n=5; 95% CI, -2.1 to -0.63). Their 6-minute walk distance increased by a mean of 111 ± 75 m (n=5; 95% CI, 18-205). In our small sample of young patients with nonischemic dilated cardiomyopathy, cardiac rehabilitation was feasible and was associated with minimal risk. Our findings suggest that prospective studies in this population are warranted.

Regional variation in quality of life in patients with a Fontan circulation: A multinational perspective

BACKGROUND

Impaired quality of life (QOL) is associated with congenital heart disease (CHD) and country of residence; however, few studies have compared QOL in patients with differing complexities of CHD across regional populations. The current study examined regional variation in QOL outcomes in a large multinational sample of patients with a Fontan relative to patients with atrial septal defects (ASDs) and ventricular septal defects (VSDs).

METHODS

From the Assessment of Patterns of Patient-Reported Outcomes in Adults with Congenital Heart disease-International Study (APPROACH-IS), 405 patients (163 Fontan and 242 ASD/VSD) across Asia, Europe, and North America provided consent for access to their medical records and completed a survey evaluating QOL (0 to 100 linear analog scale). Primary CHD diagnosis, disease complexity, surgical history, and documented history of mood and anxiety disorders were recorded. Differences in QOL, medical complications, and mood and anxiety disorders between Fontan and ASD/VSD patients, and across geographic regions, were examined using analysis of covariance. Hierarchical regression analyses were conducted to identify variables associated with the QOL ratings.

RESULTS

Patients with a Fontan reported significantly lower QOL, and greater medical complications and mood and anxiety disorders relative to patients with ASD/VSD. Inpatient cardiac admissions, mood disorders, and anxiety disorders were associated with lower QOL among patients with a Fontan, and mood disorders were associated with lower QOL among patients with ASD/VSD. Regional differences for QOL were not observed in patients with a Fontan; however, significant differences were identified in patients with ASD/VSD.

CONCLUSIONS

Regional variation of QOL is commonplace in adults with CHD; however, it appears affected by greater disease burden. Among patients with a Fontan, regional variation of QOL is lost. Specific attempts to screen for QOL and mood and anxiety disorders among CHD patients may improve the care of patients with the greatest disease burden.

Neonatal Enterovirus Myocarditis With Severe Dystrophic Calcification: Novel Treatment With Pocapavir

Dystrophic myocardial calcification occurs in the setting of myocardial injury and normal serum calcium. We present a case of a neonate with prominent dystrophic calcification and severe left ventricular systolic dysfunction in the setting of enterovirus myocarditis. These findings are superbly illustrated by multiple imaging modalities. The patient was treated with the novel antiviral, pocapavir, in addition to a standard heart failure regimen. The dystrophic calcification persisted but the left ventricle remodeled significantly. To our knowledge, this is the first reported use of pocapavir for this indication. The literature regarding enterovirus myocarditis and pocapavir is briefly reviewed.

Two pediatric cases of variant neurogenic stress cardiomyopathy after intracranial hemorrhage

Takotsubo cardiomyopathy, also known as stress-induced cardiomyopathy, is an acquired form of left ventricular systolic dysfunction seen in the setting of physiologic stress and the absence of coronary artery disease. It is thought to be caused by excessive sympathetic stimulation. It is well described in the adult literature associated with subarachnoid hemorrhage where it is known as neurogenic stress cardiomyopathy (NSC), but few such pediatric cases have been reported. We describe our experience with 2 children (13- and 10-year-old girls) who presented with spontaneous intracranial hemorrhage followed by pulmonary edema and shock. Echocardiography revealed similar patterns of left ventricular wall motion abnormalities consistent with NSC, inverted Takotsubo variant. One child progressed to death, whereas the other made a remarkable recovery, including significant improvement in cardiac function over the course of 1 week. We argue that at least 1 of these cases represents true stress-induced cardiomyopathy. This report will alert pediatricians to this transient cardiomyopathy that is likely underdiagnosed in pediatric intensive care. We also highlight the challenges of managing both shock and elevated intracranial pressure in the setting of NSC.

Pacemaker-associated cyanosis in an adolescent: The answer hiding behind shadows

Lead thrombosis is a recognized complication of permanent transvenous pacemaker (PM) implantation. We present the interesting case of an adolescent with a dual-chamber PM presenting with fatigue and hypoxemia. Due to limitations of various imaging modalities, the diagnosis was difficult. She was eventually diagnosed with intracardiac PM lead thrombi obstructing tricuspid valve inflow. The pediatric literature on PM lead thrombosis is also briefly reviewed.

Ictal asystole: an indication for pacemaker implantation and emerging cause of sudden death

Ictal asystole is being recognized as a potential mechanism of sudden unexplained death in epilepsy (SUDEP). We report a case of a patient without known cardiac disease presenting with ictal asystole resulting in syncope, trauma, and need for pacemaker implantation. The management of ictal asystole is also briefly reviewed. This case is notable for the asystolic episode wholly captured on video-electroencephalogram/electrocardiogram, the serious risk of trauma and death posed to the patient, and its implications for the mechanism of ictal asystole. This report will alert physicians to the possibility of ictal arrhythmias as a cause of syncope and SUDEP in vulnerable patients.

STAM and Hrs down-regulate ciliary TRP receptors

Cilia are endowed with membrane receptors, channels, and signaling components whose localization and function must be tightly controlled. In primary cilia of mammalian kidney epithelia and sensory cilia of Caenorhabditis elegans neurons, polycystin-1 (PC1) and transient receptor polycystin-2 channel (TRPP2 or PC2), function together as a mechanosensory receptor-channel complex. Despite the importance of the polycystins in sensory transduction, the mechanisms that regulate polycystin activity and localization, or ciliary membrane receptors in general, remain poorly understood. We demonstrate that signal transduction adaptor molecule STAM-1A interacts with C. elegans LOV-1 (PC1), and that STAM functions with hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) on early endosomes to direct the LOV-1-PKD-2 complex for lysosomal degradation. In a stam-1 mutant, both LOV-1 and PKD-2 improperly accumulate at the ciliary base. Conversely, overexpression of STAM or Hrs promotes the removal of PKD-2 from cilia, culminating in sensory behavioral defects. These data reveal that the STAM-Hrs complex, which down-regulates ligand-activated growth factor receptors from the cell surface of yeast and mammalian cells, also regulates the localization and signaling of a ciliary PC1 receptor-TRPP2 complex.