OBJECTIVE:In 2021, the American Academy of Pediatrics (AAP) recommended universal, history-based sudden cardiac death risk screening, representing an expansion from history- and exam-based screening for sports preparticipation. We studied the implementation of universal cardiac risk screening within a large pediatric primary care network to better understand optimal workflow design, screening positivity rate, and potential system-based effects that may arise from expanded screening. METHODS:We adapted the AAP guidelines to a 3-question screener implemented into the electronic health record as a patient portal questionnaire with a back-up paper-based workflow. A noninterruptive alert provided clinical decision support. Screening positivity rates and rates of follow-up actions were measured. Screening rates were compared across patient demographics using a multivariable model. RESULTS:Between March 1, 2024, and February 28, 2025, of 72,037 eligible patients, 41,433 (58%) were screened. Of these, 3463 (8.4%) had a clinically actionable positive screen. Follow-up evaluation was ordered in 31% of cases. A multivariable model demonstrated that inactive patient portal status, teenage patient age, patient race of "Unknown," and public insurance were associated with lower screening rates. CONCLUSIONS:Implementing universal history-based sudden cardiac death risk screening in a pediatric primary care network exhibited an 8.4% positivity rate after clinician review, representing a large potential burden of cardiology referrals. Over half of eligible patients were screened, and follow-up evaluation was ordered in a minority of positive cases, signaling a gap in adoption/adherence. This implementation was associated with lower screening rates in certain disadvantaged populations.

Introduction: Patients with coarctation of the aorta (CoA) have decreased exercise capacity despite successful repair with no anatomic obstruction. Altered aortic arch shape after surgical repair may increase resistance to flow and affect flow distribution. This study correlates parameters of aorta size and flow with exercise capacity after successful CoA repair. Methods: We retrospectively reviewed patients with repaired CoA at 4 centers who had cardiac magnetic resonance imaging (CMR) and an exercise stress test with respiratory exchange ratio ≥ 1.09 within 1 year. Patients with significant valve disease, outflow tract obstruction, or need for cardiac bypass outside of their arch repair were excluded. Aorta size mismatch (D AAo /D DAo ), defined by the ratio of ascending (AAo) to proximal descending aorta (DAo) diameter, and DAo flow as a percentage of AAo flow, were measured from CMR. Each parameter was correlated with percent predicted peak oxygen consumption (VO2 max). Results: Forty-six patients (age 26 ± 8.4 years) with left ventricular ejection fraction (LVEF) > 52%, met inclusion criteria. Larger D AAo /D DAo and lower %DAo flow correlated significantly with lower VO2 max (Fig). Compared to those with normal VO2 max (n=25), patients with VO2 max <90% predicted (n=21) had a primary repair at an older age (p=0.03) and smaller DAo diameter/m 2 (p=0.04). There were no significant differences in prevalence of arch obstruction by echocardiogram, LVEF, hypertension, blood pressure gradient at rest or exercise, or AAo diameter/m 2 between groups. Conclusions: Aorta size mismatch, due to AAo dilation or small DAo, and associated decreased %DAo flow, correlate significantly with decreased exercise capacity after CoA repair in patients with normal left ventricular systolic function. CMR measurements of aorta geometry and flow can inform the definition of a successful repair and suggest that indications for re-intervention may not be limited to discrete re-coarctation.

Background Change in the oxygen consumption (VO2) at the ventilatory anaerobic threshold (VAT) is an important outcome in research studies of children with congenital heart disease (CHD). The range of values reported by different raters for any given VAT is needed to contextualize a change in VAT in intervention studies. Methods Sixty maximal cardiopulmonary exercise tests (CPET) for CHD patients 8-21 years old were independently reviewed by six exercise physiologists and four pediatric cardiologists. For each of the unique rater pairs for the 60 CPETs, the absolute difference in VAT was calculated and displayed on a histogram to demonstrate the distribution of inter-rater variability. This method was repeated for subgroups of test modality (cycle/treadmill), patient factors (diagnoses, exercise capacity), and rater factors (cardiologist/physiologist, years of experience). Results Rater agreement was good with an intraclass correlation coefficient of 0.79-0.91 but the distribution of differences was broad. The median difference was 2.7% predicted peak VO2 (60mL/min, 1.0mL/kg/min), the 75th percentile was 6.4% (140mL/min, 2.5mL/kg/min), and the 95th percentile was 16.3% (421mL/min, 6.5mL/kg/min). Distributions were similar for CPET modality and years of rater experience, but differed for other factors. Conclusions The baseline distribution of reported VAT is relatively broad, varied by units, and was not explained by differences in rater experience or test modality, but varies by patient factors. When evaluating clinical relevance, a change in the VO2 at VAT in response to an intervention of <6.5% predicted falls within the majority (75th percentile) of expected variability and should be interpreted with caution.

BACKGROUND: Artificial intelligence–enhanced ECG analysis shows promise to detect ventricular dysfunction and remodeling in adult populations. However, its application to pediatric populations remains underexplored. METHODS: A convolutional neural network was trained on paired ECG–echocardiograms (≤2 days apart) from patients ≤18 years of age without major congenital heart disease to detect human expert–classified greater than mild left ventricular (LV) dysfunction, hypertrophy, and dilation (individually and as a composite outcome). Model performance was evaluated on single ECG–echocardiogram pairs per patient at Boston Children’s Hospital and externally at Mount Sinai Hospital using area under the receiver operating characteristic curve (AUROC) and area under the precision-recall curve (AUPRC). RESULTS: The training cohort comprised 92 377 ECG–echocardiogram pairs (46 261 patients; median age, 8.2 years). Test groups included internal testing (12 631 patients; median age, 8.8 years; 4.6% composite outcomes), emergency department (2830 patients; median age, 7.7 years; 10.0% composite outcomes), and external validation (5088 patients; median age, 4.3 years; 6.1% composite outcomes) cohorts. Model performance was similar on internal test and emergency department cohorts, with model predictions of LV hypertrophy outperforming the pediatric cardiologist expert benchmark. Adding age and sex to the model added no benefit to model performance. When using quantitative outcome cutoffs, model performance was similar between internal testing (composite outcome: AUROC, 0.88, AUPRC, 0.43; LV dysfunction: AUROC, 0.92, AUPRC, 0.23; LV hypertrophy: AUROC, 0.88, AUPRC, 0.28; LV dilation: AUROC, 0.91, AUPRC, 0.47) and external validation (composite outcome: AUROC, 0.86, AUPRC, 0.39; LV dysfunction: AUROC, 0.94, AUPRC, 0.32; LV hypertrophy: AUROC, 0.84, AUPRC, 0.25; LV dilation: AUROC, 0.87, AUPRC, 0.33), with composite outcome negative predictive values of 99.0% and 99.2%, respectively. Saliency mapping highlighted ECG components that influenced model predictions (precordial QRS complexes for all outcomes; T waves for LV dysfunction). High-risk ECG features include lateral T-wave inversion (LV dysfunction), deep S waves in V1 and V2 and tall R waves in V6 (LV hypertrophy), and tall R waves in V4 through V6 (LV dilation). CONCLUSIONS: This externally validated algorithm shows promise to inexpensively screen for LV dysfunction and remodeling in children, which may facilitate improved access to care by democratizing the expertise of pediatric cardiologists.

BACKGROUND:Postoperative arrhythmias are most often transient and medically treated, but some patients may require electrophysiology study (EPS) and ablation. OBJECTIVE:The purpose of this study was to describe the efficacy and safety of early postoperative ablation. METHODS:This study presents a retrospective series of patients who underwent EPS within 12 months of surgery for congenital heart disease between 2000 and 2021. The procedural outcome included complete or partial success, empirical ablation or failure, and complications. The long-term outcome included arrhythmia recurrence and burden according to a 12-point clinical arrhythmia severity score (documented arrhythmia, arrhythmia severity, cardioversion, and antiarrhythmic medication). RESULTS:Among 28,902 operations during the study period, 24 patients (0.1%) underwent EPS within 3 months of surgery and 26 (0.1%) 3-12 months after surgery. Most patients had great (n = 27 [50%]) or moderate (n = 21 [42%]) congenital heart disease complexity. Mechanisms of arrhythmias included intra-atrial reentrant tachycardia (n = 23 [46%]), ectopic atrial tachycardia (n = 13 [26%]), accessory pathway (n = 6 [12%]), atrioventricular nodal reentrant tachycardia (n = 7 [14%]), twin atrioventricular node (n = 1 [2%]), atrial fibrillation (n = 1 [2%]), junctional ectopic tachycardia (n = 1 [2%]), and ventricular tachycardia (n = 2 [4%]). The procedure was acutely successful in 41 patients (82%), empirical in 5 (10%), and unsuccessful in 4 (8%). Complications occurred in 4 (8%) patients (major in 1, moderate in 1, and minor in 2). The recurrence of arrhythmia was documented in 27 patients (54%), although the burden of arrhythmia was significantly reduced. CONCLUSION:A minority of patients require early postoperative EPS and ablation. For those, the procedure can be performed with reasonable acute success and manageable morbidity even in critically ill patients with complex surgical anatomy.

Catheter-based slow pathway modification (SPM) for atrioventricular nodal reentrant tachycardia (AVNRT) is traditionally performed at empiric sites using anatomical landmarks and test ablation feedback within the triangle of Koch (TK). While studies have described more tailored techniques such as bipolar low voltage bridge (LVB) and wavefront collision identification, few have systematically compared the diagnostic yields of each and none have investigated whether omnipolar mapping technology provides incremental benefit. The objective of this study was to compare the utility of omnipolar and bipolar-derived qualitative and quantitative measurements in identifying and localizing dual AVN substrate in patients with versus without AVNRT. A retrospective case-control study of consecutive patients with paroxysmal supraventricular tachycardia undergoing electrophysiology study with both omnipolar and bipolar mapping from 2022-2023. Thirteen AVNRT cases (median age 16.1 years, 512 TK points) were compared to nine non-AVNRT controls (median age 15.7 years, 332 TK points). Among qualitative variables, an omnipolar activation vector pivot, defined as a ≥45 degree change in activation direction within the TK, had the highest positive (81

Objective To determine if socioeconomic status (SES) has a greater effect than standard demographic values on predicted peak oxygen consumption (pVO(2)). Study design We conducted a single-institution, retrospective analysis of maximal cardiopulmonary exercise test (CPET) data from 2010 to 2020 for healthy patients age <19 years with body mass index (BMI) percentile (BMI%) between 5-95. Data were sorted by self-identified race, BMI%, and adjusted gross income (AGI); AGI served as a surrogate for SES. Mean percent predicted pVO(2) (pppVO(2)) was compared between groups. Linear regression was used to adjust for differences. Results A total of 541 CPETs met inclusion criteria. Mean pppVO(2) was 97% +/- 22.6 predicted (P < .01) with 30% below criterion standard for normal (85% predicted). After excluding unknown AGI and race, 418 CPETs remained. Mean pppVO(2) was lower for Blacks (n = 36) and Latinx (n = 26) compared with Whites (n = 333, P < .01). Mean pppVO(2) declined as AGI decreased (P < .01). The differences in pppVO(2) between racial categories remained significant when adjusted for BMI% (Black r = -7.3, P = .035; Latinx r = -15.4, P < .01). These differences both decreased in magnitude and were no longer significant when adjusted for AGI (Black r = -6.0, P = .150; Latinx r = -9.3, P = .06). Conclusions Lower SES correlates with lower measured cardiovascular fitness and may confound data interpretation. When using normative reference ranges in clinical decision making, providers should recognize that social determinants of health may influence predicted fitness. Social inequities should be considered when assessing pediatric cardiovascular fitness.

Background: Prior ECG standards in children have largely been defined without echo confirmation of normal anatomy. The Pediatric Heart Network Normal Echocardiogram Z-score Project provides a racially diverse age/sex classified group of healthy children with normal echos that included 2170 matched contemporaneous digitally acquired ECGs. We hypothesized that ECG measures and z-scores of left ventricular (LV) dimensions are correlated in healthy children. Methods: This was a secondary analysis of the previously described cohort. Six ECG measures historically associated with LV size (R V5, R V6, S V1, Q III, axis, R V6+S V1), and 13 paired echo measures were identified a-priori with LV Mass (LVMass-z) and left ventricular end diastolic volume (LVEDV-z) z-scores serving as primary echo measurement predictors. Pearson or Spearman correlations were calculated for each of the 78 ECG- echo pairs. Regression analyses were performed to assess how much variance in ECG measures was explained by variation in LV dimensions and by demographic variables (age, sex, race). Results: ECG and echo measurement correlations were significant and concordant in 41/78 (53%), though many were significant and discordant in 13, (17%) or not correlated in 24 (31%). Of the 6 ECG measures of LV size, 5 correlated in the clinically predicted direction for LV Mass-z and LVEDV-z. While many of the correlations were statistically significant, the correlations were weak (0.05-0.25). R 2 was higher for demographic variables than for echo measures in all pairs, but even with demographic variables included, the overall R 2 was < 0.17. Conclusions: In a large, diverse cohort of healthy children, there was a positive association between echo measures of LV dimension and mass and the most commonly used ECG measures of LVH. However, these correlations were weak and most of the variability in ECG measures was explained by factors other than echo derived mass or volume or measured patient demographic variables. These data question the utility of traditional ECG measurements of LV size as standalone indications for further cardiac evaluation in healthy children.

Implantable-cardioverter defibrillators (ICDs) can deliver shocks under inappropriate clinical circumstances [including supraventricular tachycardia (SVT)]. Delayed detection programming has been studied in adults to reduce inappropriate shocks, but the data is limited in the pediatric population.

INTRODUCTION:The use of flecainide and propafenone for medical cardioversion of atrial fibrillation (AF) and atrial flutter/intra-atrial reentrant tachycardia (IART) is well-described in adults without congenital heart disease (CHD). Data are sparse regarding their use for the same purpose in adults with CHD and in adolescent patients with anatomically normal hearts and we sought to describe the use of class IC drugs in this population and identify factors associated with decreased likelihood of success. METHODS:Single center retrospective cohort study of patients who received oral flecainide or propafenone for medical cardioversion of AF or IART from 2000 to 2022. The unit of analysis was each episode of AF/IART. We performed a time-to-sinus rhythm analysis using a Cox proportional hazards model clustering on the patient to identify factors associated with increased likelihood of success. RESULTS:We identified 45 episodes involving 41 patients. As only episodes of AF were successfully cardioverted with medical therapy, episodes of IART were excluded from our analyses. Use of flecainide was the only factor associated with increased likelihood of success. There was a statistically insignificant trend toward decreased likelihood of success in patients with CHD. CONCLUSIONS:Flecainide was more effective than propafenone. We did not detect a difference in rate of conversion to sinus rhythm between patients with and without CHD and were likely underpowered to do so, however, there was a trend toward decreased likelihood of success in patients with CHD. That said, medical therapy was effective in >50% of patients with CHD with AF.

While operational efficiency has been evaluated in adult interventional and surgical specialties, limited data exist regarding the prediction of case complexity in the pediatric and congenital electrophysiology (EP) laboratory.

Accessory atrioventricular pathways (APs) may mediate atrioventricular reciprocating tachycardia and, in some cases, have the potential to conduct atrial tachycardia rapidly, which can be life threatening. While catheter ablation can be curative, ablation of right free wall APs is associated with a high rate of recurrence, likely secondary to reduced catheter stability along the right free wall atrioventricular groove. We sought to identify characteristics associated with a lower rate of recurrence and hypothesized ablation lesions placed on the ventricular side of the atrioventricular groove using a retroflexed catheter approach would decrease rates of recurrence.

Catheter ablation in children has evolved to become a highly effective and safe therapy. Each iterative improvement in ablation technology provides another opportunity to investigate how much incremental benefit can be made without sacrificing safety. Contact force sensing catheters represent an example of such technology that has become commonplace in adult ablation. Its capability in predicting lesion size and collateral damage to critical structures has not been meticulously explored. Backhoff and colleagues describe an animal ablation model where they quantitate lesion characteristics at the atrium, atrioventricular groove, and ventricle using low and high contact force targets, with a specific focus on assessing for coronary arterial injury. In this controlled experiment, chronic lesion characteristics were widely variable (~0-8 mm diameter) yet there was a statistically significant (albeit small) increase in lesion diameter for high (vs low) contact force lesions delivered to the atrioventricular groove. The risk of chronic sub-clinical coronary artery injury was 1-2%.

Introduction: SARS CoV2 has been associated with acute and subacute myocarditis. Screening after COVID-19 has been recommended prior to returning to physical activity. The yield of such investigations, particularly in youth, remains unknown. Methods: Retrospective chart review was performed of patients evaluated in a cardiology clinic for return to play (RTP) after COVID-19 between 01/20 - 06/21. Iteratively updated guidance for testing was provided to ambulatory providers. Patients with MIS-C were excluded. We reviewed demographics, clinical evaluation, and cardiac imaging. Results: Of 429 patients (age 16.3 ± 2.7 [range 8-21] yrs, 44% male) evaluated including 9 with pre-existing heart disease, 318 underwent echocardiograms and 23 also had cardiac MRI. Cardiac MRI was performed for abnormal screening ECG or echocardiogram or cardiovascular symptoms. New echocardiographic abnormalities were detected in 69 patients: 4 were possibly related to COVID-19 infection, 3 were new structural heart disease (2 anomalous coronary, 1 bicuspid aortic valve), and 62 were normal variants or trivial findings. New ventricular dysfunction (right or left, qualitative dysfunction or LV ejection fraction [EF] <55%) was noted in 11 patients (LV EF mean 52.7 ± 2.6%, minimum 46%). Eight underwent cardiac MRI confirming trivial to no ventricular dysfunction and none of the 23 MRIs demonstrated late gadolinium enhancement or met Lake Louise criteria for myocarditis. All patients without new diagnoses of structural heart disease were ultimately deemed safe to return to previous levels of physical activity. Conclusions: Cardiovascular evaluation for RTP of youth after COVID-19 demonstrated mild transient abnormalities and incidental findings, but no diagnoses of myocarditis. These data suggest early concerns about subclinical myocarditis may have been overestimated. Future studies should consider the costs and benefits of current society algorithms for such evaluations.