Comparative utility of omnipolar and bipolar electroanatomic mapping methods to detect and localize dual nodal substrate in patients with atrioventricular nodal reentrant tachycardia.

BACKGROUND: 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. METHODS: A retrospective case-control study of consecutive patients with paroxysmal supraventricular tachycardia undergoing electrophysiology study with both omnipolar and bipolar mapping from 2022-2023. RESULTS: 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%) and negative predictive values (100%) for identifying AVNRT cases and had a median distance of 1 mm from SPM sites. Among quantitative variables, the optimal discriminatory performance for successful SPM sites was observed using bipolar voltage restricted to a peak frequency >340 Hz (c statistic 0.75). CONCLUSIONS: Omnipolar vector pivot analysis represents an automated, annotation-independent qualitative technique that is sensitive and specific for AVNRT substrate and co-localizes with successful SPM sites. Bipolar voltage quantitatively describes SP anisotropy better than omnipolar voltage, and the addition of peak frequency signal analysis further optimizes the selection of SPM sites.

Limited Relationship Between Echocardiographic Measures and Electrocardiographic Markers of Left Ventricular Size in Healthy Children.

Pediatric ECG standards have been defined without echocardiographic confirmation of normal anatomy. The Pediatric Heart Network Normal Echocardiogram Z-score Project provides a racially diverse group of healthy children with normal echocardiograms. We hypothesized that ECG and echocardiographic measures of left ventricular (LV) dimensions are sufficiently correlated in healthy children to imply a clinically meaningful relationship. This was a secondary analysis of a previously described cohort including 2170 digital ECGs. The relationship between 6 ECG measures associated with LV size were analyzed with LV Mass (LVMass-z) and left ventricular end-diastolic volume (LVEDV-z) along with 11 additional parameters. Pearson or Spearman correlations were calculated for the 78 ECG-echocardiographic pairs with regression analyses assessing the variance in ECG measures explained by variation in LV dimensions and demographic variables. ECG/echocardiographic measurement correlations were significant and concordant in 41/78 (53%), though many were significant and discordant (13/78). Of the 6 ECG parameters, 5 correlated in the clinically predicted direction for LV Mass-z and LVEDV-z. Even when statistically significant, correlations were weak (0.05-0.24). R2 was higher for demographic variables than for echocardiographic measures or body surface area in all pairs, but remained weak (R2 ≤ 0.17). In a large cohort of healthy children, there was a positive association between echocardiographic measures of LV size and ECG measures of LVH. These correlations were weak and dependent on factors other than echocardiographic or patient derived variables. Thus, our data support deemphasizing the use of solitary, traditional measurement-based ECG markers traditionally thought to be characteristic of LVH as standalone indications for further cardiac evaluation of LVH in children and adolescents.

Pediatric ECG-Based Deep Learning to Predict Left Ventricular Dysfunction and Remodeling.

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.

Medical cardioversion of atrial fibrillation and flutter with class IC antiarrhythmic drugs in young patients with and without congenital heart disease.

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.

Clinical risk prediction score for postoperative accelerated junctional rhythm and junctional ectopic tachycardia in children with congenital heart disease.

BACKGROUND: Accelerated junctional rhythm (AJR) and junctional ectopic tachycardia (JET) are common postoperative arrhythmias associated with morbidity/mortality. Studies suggest that pre- or intraoperative treatment may improve outcomes, but patient selection remains a challenge. OBJECTIVES: The purpose of this study was to describe contemporary outcomes of postoperative AJR/JET and develop a risk prediction score to identify patients at highest risk. METHODS: This was a retrospective cohort study of children aged 0-18 years undergoing cardiac surgery (2011-2018). AJR was defined as usual complex tachycardia with ≥1:1 ventricular-atrial association and junctional rate >25th percentile of sinus rate for age but <170 bpm, whereas JET was defined as a rate >170 bpm. A risk prediction score was developed using random forest analysis and logistic regression. RESULTS: Among 6364 surgeries, AJR occurred in 215 (3.4%) and JET in 59 (0.9%). Age, heterotaxy syndrome, aortic cross-clamp time, ventricular septal defect closure, and atrioventricular canal repair were independent predictors of AJR/JET on multivariate analysis and included in the risk prediction score. The model accurately predicted the risk of AJR/JET with a C-index of 0.72 (95% confidence interval 0.70-0.75). Postoperative AJR and JET were associated with prolonged intensive care unit and hospital length of stay, but not with early mortality. CONCLUSION: We describe a novel risk prediction score to estimate the risk of postoperative AJR/JET permitting early identification of at-risk patients who may benefit from prophylactic treatment.

Conduction mapping during complex congenital heart surgery: Creating a predictive model of conduction anatomy.

OBJECTIVES: The study objectives were to report on a growing experience of conduction system mapping during complex congenital heart surgery and create a predictive model of conduction anatomy. METHODS: Patients undergoing complex cardiac repair with conduction mapping were studied. Intraoperative mapping used a multielectrode catheter to collect His bundle electrograms in the open, decompressed, beating heart. Patient anatomy, operative details, His bundle location, and postoperative conduction status were analyzed. By using classification and regression tree analysis, a predictive model of conduction location was created. RESULTS: A total of 109 patients underwent mapping. Median age and weight were 1.8 years (range, 0.2-14.9) and 10.8 kg (range, 3.5-50.4), respectively. Conduction was identified in 96% (105/109). Median mapping time was 6 minutes (range, 2-33). Anatomy included atrioventricular canal defect, double outlet right ventricle, complex transposition of the great arteries, and multiple ventricular septal defects. By classification and regression tree analysis, ventricular looping and visceroatrial situs were the greatest discriminators of conduction location. A total of 94 of 105 patients (89.5%) were free of complete heart block. Only 1 patient (2.9%) with heterotaxy syndrome developed complete heart block. CONCLUSIONS: The precise anatomic location of the conduction system in patients with complex congenital heart defects can be difficult for the surgeon to accurately predict. Intraoperative conduction mapping enables localization of the His bundle and adds to our understanding of the anatomic factors associated with conduction location. Predictive modeling of conduction anatomy may build on what is already known about the conduction system and help surgeons to better anticipate conduction location preoperatively and intraoperatively.

Pediatric Electrophysiology Device Needs: A Survey from the Pediatric and Congenital Electrophysiology Society Taskforce on Pediatric-Specific Devices.

Background There are few US Food and Drug Administration (FDA)-approved devices specifically aimed at the pediatric patient with arrhythmia. This has led to a high off-label utilization of devices in this vulnerable population. The Pediatric and Congenital Electrophysiology Society (PACES), the international organization representing pediatric and congenital heart disease arrhythmia specialists, developed a task force to comprehensively address device development issues relevant to pediatric patients with congenital arrhythmia. Methods and Results As a first step, the taskforce developed a 26-question survey for the pediatric arrhythmia community to assess providers' understanding of the FDA approval process, specifically in regard to pediatric labeling. There were 92/211 respondents (44%) with a >90% completion rate. The vast majority of respondents believed there was a paucity of devices available for children (96%). More than 60% of respondents stated that they did not understand the FDA regulatory process and were not aware of whether the devices they used were labeled for pediatric use. Conclusions Pediatric electrophysiologists are keenly aware of the deficit of available pediatric devices for their patients. The majority do not understand the FDA approval process and could benefit from additional educational resources regarding this. A collaborative forum including PACES, FDA, patients and their families, and Industry would be an important next step in clarifying opportunities and priorities to serve this vulnerable population.

Radiofrequency Catheter Ablation for Pediatric Atrioventricular Nodal Reentrant Tachycardia: Impact of Age on Procedural Methods and Durable Success.

Background Catheter-based slow-pathway modification (SPM) is the treatment of choice for symptomatic atrioventricular nodal reentrant tachycardia (AVNRT). We sought to investigate the interactions between patient age and procedural outcomes in pediatric patients undergoing catheter-based SPM for AVNRT. Methods and Results A retrospective cohort study was performed, including consecutive patients undergoing acutely successful SPM for AVNRT from 2008 to 2017. Those with congenital heart disease, cardiomyopathy, and accessory pathways were excluded. Patients were stratified by age quartile at time of SPM. The primary outcome was AVNRT recurrence. A total of 512 patients underwent successful SPM for AVNRT. Age quartile 1 had 129 patients with a median age and weight of 8.9 years and 30.6 kg, respectively. Radiofrequency energy was used in 98% of cases. Follow-up was available in 447 (87%) patients with a median duration of 0.8 years (interquartile range, 0.2-2.5 years). AVNRT recurred in 22 patients. Multivariable Cox proportional hazard modeling identified atypical AVNRT (hazard ratio [HR], 5.83; 95% CI, 2.01-16.96; P=0.001), dual atrioventricular nodal only (HR, 4.09; 95% CI, 1.39-12.02; P=0.011), total radiofrequency lesions (HR, 1.06 per lesion; 95% CI, 1.01-1.12; P=0.032), and the use of a long sheath (HR, 3.52; 95% CI, 1.23-10.03; P=0.010) as predictors of AVNRT recurrence; quartile 1 patients were not at higher risk of recurrence (HR, 0.45; 95% CI, 0.10-1.97; P=0.29). Complete heart block requiring permanent pacing occurred in one quartile 2 patient at 14.9 years of age. Conclusions Pediatric AVNRT can be treated with radiofrequency-SPM with high procedural efficacy and minimal risk of complications, including heart block. Atypical AVNRT and dual atrioventricular nodal physiology without inducible tachycardia remain challenging substrates.

Intraoperative conduction mapping in complex congenital heart surgery.

Objective: Postoperative heart block is a significant problem in congenital heart surgery because of the unpredictability and variability of conduction tissue location in complex congenital heart defects. A novel technique for intraoperative conduction system mapping during complex congenital heart surgery is described. Methods: Intraoperative conduction system mapping was performed utilizing a high-density multielectrode grid catheter to collect intracardiac electrograms on open, beating hearts during repair of complex congenital heart defects. Electrograms were interpreted by electrophysiologists, and conduction tissue location was communicated in real time to the surgeon. After localizing conduction tissue, the heart was arrested and the repair was completed taking care to avoid injury to the mapped conduction system. Results: Two patients with complex heterotaxy syndrome underwent intraoperative conduction mapping during biventricular repair. Mapping accurately identified the location of conduction tissue thereby enabling avoidance of conduction system injury during surgery. Notably, conduction was unexpectedly found to be located inferiorly in a patient with L-looped ventricles. Successful biventricular repair was accomplished in both patients without injury to the conduction system. Conclusions: Intraoperative conduction mapping can effectively localize the conduction system during surgery and enable the surgeon to avoid its injury. This can lower the risk of heart block requiring pacemaker in children undergoing complex congenital heart surgery.

Lead Extraction at a Pediatric/Congenital Heart Disease Center: The Importance of Patient Age at Implant.

OBJECTIVES: This study sought to evaluate the safety and efficacy of transvenous lead extraction (TLE) at a single pediatric/congenital heart disease (CHD) center. BACKGROUND: Data on TLE in pediatric and CHD patients are limited. METHODS: Retrospective cohort study evaluating TLE from 2008 to 2019. RESULTS: A total of 113 patients underwent TLE with 162 leads removed (including 38 high-voltage leads). Median age at lead implantation was 13 years (range 0.6-61.8 years), with a median age at extraction of 21.6 years (6.4-64.3 years). Median lead age was 7.2 years (1.0-35.3 years). Successful extraction occurred in 110 (97%) patients, 159 (98%) leads. Complex extraction was needed for 120 leads; 52 (44%) using laser alone, 27 (23%) mechanical sheath alone, and 21 (18%) using both. Femoral extraction was used for 19 (16%) leads. Risk factors for complex extraction were ≥2 leads extracted (odds ratio: 3.36; 95% confidence interval [CI]: 1.2-9.36; P = 0.021), lead within the right ventricle (odds ratio: 2.8; 95% CI: 1.2-6.5; P = 0.017), and a combination of younger patient age at implant and older lead age at extraction, with patients ≤12 years of age at implant and leads ≥7 years of age having an odds ratio: of 10.1 (95% CI: 2.21-45.9; P = 0.003). Major complications occurred in 5 (4.4%) of patients, with no mortality, but a high incidence of tricuspid valve injury. CONCLUSIONS: TLE can be performed successfully and safely in a pediatric and CHD center. Patient age at lead implantation, not age at extraction, is an important predictor of needing a complex extraction, with younger patients at implant and older leads at extraction having the highest risk.

Activity During the COVID-19 Pandemic in Children with Cardiac Rhythm Management Devices.

Decreased physical activity is associated with cardiovascular, metabolic and mental health disease. While decreases in physical activity during the COVID-19 pandemic have been described in the general population, there is a paucity of data regarding children with underlying cardiovascular disease. We hypothesized there would be a decrease in physical activity at the onset of the COVID-19 pandemic. Performed a single-center, retrospective cohort study of children aged < 19 years with cardiac rhythm management devices. Patients were included if they had device-measured physical activity data from > 80% of dates from February 3, 2020 through June 30, 2020. Patients with significant neurologic/neuromuscular disease were excluded. We identified 144 patients with a median age of 15.4 years. 47% were female. 34% had congenital heart disease, 20% had cardiomyopathy, 19% had an inherited arrhythmia syndrome and 5% had atrioventricular block without congenital heart disease. 47% of patients had an implantable loop recorder, 29% had a permanent pacemaker and 24% had an implantable cardioverter-defibrillator. We observed a significant decrease in device-measured physical activity from baseline (February 3-March 9), with up to a 21% decrease in physical activity during mid-March through early May. Activity levels returned to pre-pandemic levels in June. Physical activity sharply declined in children with cardiac rhythm management devices at the onset of the COVID-19 pandemic. These data highlight the importance of finding strategies to maintain physical activity during the current pandemic and future public health crises.

Pediatric T-wave memory after accessory pathway ablation in Wolff-Parkinson-White syndrome.

BACKGROUND: Altered ventricular depolarization due to manifest accessory pathway conduction (ie, Wolff-Parkinson-White syndrome) leads to repolarization abnormalities that persist after pathway ablation. The term T-wave memory (TWM) has been applied to these changes, as the postablation T-wave vector "remembers" the pre-excited QRS vector. In adults, these abnormalities can be misinterpreted as ischemia leading to unnecessary interventions. To date, no comprehensive studies have evaluated this phenomenon in the pediatric population. OBJECTIVE: The purpose of this study was to define TWM in the pediatric population, identify preablation risk factors, and delineate the timeline of recovery. METHODS: Pre- and postablation electrocardiograms (ECGs) in patients ≤25 years were analyzed over a 5-year period. Frontal plane QTc interval, T-wave axis, QRST angle, and T-wave inversions were used to identify patients with TWM. Univariate analysis was performed to determine the association of preablation ECG features with the outcome of TWM. RESULTS: TWM was present in 42% of pediatric patients, with resolution occurring within 3 months of ablation. Preablation QRS axis <0° was a strong predictor of TWM (odds ratio [OR] 15.2; 95% confidence interval [CI] 5.7-40), followed by posteroseptal pathway location (right posteroseptal-OR 8.9; 95% CI 4.2-18.8; left posteroseptal-OR 6.1; 95% CI 1.7-22.3). The degree of pre-excitation had a modest association with the development of TWM. No adverse events were observed. CONCLUSION: TWM is less common in children compared to adults, and normalization occurred within 3 months postablation. The most predictive features for the development of TWM include a leftward pre-excited QRS axis and posteroseptal pathway location.

Accessory pathway ablation in Ebstein anomaly: A challenging substrate.

BACKGROUND: Catheter ablation of accessory pathways (APs) in Ebstein anomaly (EA) has been associated with a high recurrence risk. OBJECTIVE: The purpose of this study was to compare outcomes of AP ablation in EA in an early (1990-2004) vs a recent (2005-2019) era and identify variables associated with recurrence. METHODS: A retrospective review of all catheter ablations for supraventricular tachycardia in EA at our institution was performed. RESULTS: We identified 76 patients with median (25th-75th quartiles) age 9 (2.6-13.3) years. Of these patients, 52 had AP alone, 12 had atrial flutter, 3 had atrioventricular nodal reentrant tachycardia, and 9 had AP plus at least 1 additional arrhythmia. Of the 61 patients with APs, a total of 78 separate APs were identified: 40 right-sided, 37 septal, and 1 left-sided. Acute success for AP first procedure was 89% and did not differ between early and recent eras (89% vs 88%; P = .48). However, 19 patients (31%) required repeat procedures (average 1.4 per patient) due to AP recurrence or ablation failure at first attempt. In comparison to early era, recent era ablations had significantly lower recurrence rates at 1 year (62% vs 19%; P = .005). At median follow-up of 2.5 (0.2-7) years, ultimate AP elimination after all procedures was 93%. Younger age at time of electrophysiological study (<2 vs 12-47 years: hazard ratio [HR] 7.3; P = .003) and ablation era (early era vs recent era: HR 3.65; P = .009) predicted recurrence. CONCLUSION: Outcomes for AP ablation in patients with EA have improved, but there is still a relatedly high recurrence risk requiring repeat procedures.

Preventing Arrhythmic Death in Patients With Tetralogy of Fallot: JACC Review Topic of the Week.

Patients with tetralogy of Fallot are at risk for ventricular arrhythmias and sudden cardiac death. These abnormalities are associated with pulmonary regurgitation, right ventricular enlargement, and a substrate of discrete, slowly-conducting isthmuses. Although these arrhythmic events are rare, their prediction is challenging. This review will address contemporary risk assessment and prevention strategies. Numerous variables have been proposed to predict who would benefit from an implantable cardioverter-defibrillator. Current risk stratification models combine independently associated factors into risk scores. Cardiac magnetic resonance imaging, QRS fragmentation assessment, and electrophysiology testing in selected patients may refine some of these models. Interaction between right and left ventricular function is emerging as a critical factor in our understanding of disease progression and risk assessment. Multicenter studies evaluating risk factors and risk mitigating strategies such as pulmonary valve replacement, ablative strategies, and use of implantable cardiac-defibrillators are needed moving forward.

Risk Factors for Early Recurrence Following Ablation for Accessory Pathways: The Role of Consolidation Lesions.

BACKGROUND: Atrioventricular reentrant tachycardia is common in children. Catheter ablation is increasingly used as a first-line therapy with a high acute success rate, but recurrence during follow-up remains a concern. The aim of this study was to identify risk factors for recurrence after accessory pathway (AP) ablation. METHODS: Retrospective cohort study including patients who underwent AP ablation between 2013 and 2018. Cox proportional hazards model was used to examine the association between patient and procedural characteristics and recurrence during follow-up. RESULTS: From 558 AP ablation procedure, 542 (97%) were acutely successful. During a median follow-up of 0.4 (interquartile range, 0.1-1.4) years, there were 42 (8%) patients with documented recurrence. On univariate analysis, early recurrence was associated with younger age, congenital heart disease, multiple AP, AP location (right sided and posteroseptal versus left sided), cryoablation (versus radiofrequency), empirical ablation, the lack of full power radiofrequency lesions (<50 W), radiofrequency consolidation time <90 seconds and the use of fluoroscopy without a 3-dimensional electroanatomic mapping system. On multivariable analysis, only multiple AP (hazard ratio, 2.78 [95% CI, 1.063-4.74]) and radiofrequency consolidation time < 90 seconds (hazard ratio, 4.38 [95% CI, 1.92-9.51]) remained significantly associated with early recurrence; this association remained true when analyzed in subgroups by pathway location for right and left free wall AP. CONCLUSIONS: In our institutional experience, radiofrequency consolidation time <90 seconds after ablation of AP was associated with an increased risk of early recurrence.

Difference in the prevalence of intracardiac thrombus on the first presentation of atrial fibrillation versus flutter in the pediatric and congenital heart disease population.

INTRODUCTION: Guidelines recommend trans-esophageal echocardiography (TEE) for patients with atrial fibrillation (AF) or atrial flutter (AFL) for >48 h, due to risk of intracardiac thrombus formation. With growing evidence that AFL in adults with structurally normal hearts has less thrombogenic potential compared to AF, and the need for TEE questioned, we compared prevalence of intracardiac thrombus detected by TEE in pediatric and congenital heart disease (CHD) patients presenting in AF and AFL. METHODS/RESULTS: Single-center, cross-sectional analysis for unique first-time presentations of patients for either AF, AFL, or intra-atrial reentrant tachycardia (IART) between 2000 and 2019. Patients were categorized by presenting arrhythmia (AF vs. AFL/IART), with the exclusion of other forms of atrial tachycardia, hemodynamic instability, chronic anti-coagulation before TEE, and presentation for a reason other than TEE examination for thrombus. A total of 201 patients had TEE with co-diagnosis of AF or AFL. Of these, 105 patients (29 AF, 76 AFL) met inclusion criteria, with no difference in age between AF (median 24.9 years; IQR 18.6-38.3 years) and AFL/IART (23.3 years; 15.4-38.4 years). The prevalence of thrombus in the entire cohort was 9.5%, with no difference between AF (13.8%) and AFL groups (7.9%), p = .46. Patients with thrombus demonstrated no difference in age, systemic ventricular function, cardiac complexity, or CHADS2/CHA2DS2VASc score at presentation. CONCLUSIONS: The risk for intracardiac thrombus is high in the pediatric and CHD population, with no apparent distinguishing factors to warrant a change in the recommendations for TEE, with all levels of cardiac complexity being at risk for clot.

Value of provocative electrophysiology testing in the management of pediatric patients after congenital heart surgery.

OBJECTIVE: To determine the impact of provocative electrophysiology testing in postoperative congenital heart disease (CHD) patients on the management of supraventricular tachycardia (SVT) and clinical outcomes. METHODS: This is a retrospective study including patients <18 years of age with surgery for CHD who had postoperative SVT between 2006 and 2017. Postoperative outcomes were compared between patients with and without postoperative electrophysiology testing using the Wilcoxon rank sum test, Fisher's exact test, Kaplan-Meier method with the log-rank test, and Cox proportional hazard model. RESULTS: From 341 patients who had SVT after surgery for CHD, 65 (19%) had postoperative electrophysiology testing. There was no significant difference in baseline patient characteristics or surgical complexity between patients with and without electrophysiology testing. Patients with inducible SVT on electrophysiology testing were more likely to have recurrence of SVT prior to hospital discharge with an odds ratio 4.0 (95% confidence interval 1.3, 12.0). Patients who underwent postoperative electrophysiology testing had shorter intensive care unit (12 [6, 20] vs 16 [9, 32] days, HR 2.1 [95% CI 1.6, 2.8], P < .001) and hospital (25 [13, 38] vs 31 [18, 54] days, HR 1.8 [95% CI 1.4, 2.4], P < .001) length of stay. CONCLUSION: Postoperative electrophysiology testing was associated with improved postoperative outcomes, likely related to the ability to predict recurrence of arrhythmia and tailored antiarrhythmic management.

Adverse event rate during inpatient sotalol initiation for the management of supraventricular and ventricular tachycardia in the pediatric and young adult population.

BACKGROUND: Sotalol is an important antiarrhythmic drug in the pediatric population. Given the risk of proarrhythmia, sotalol is initiated in inpatient settings, with adult studies as recent as 2015 supporting this practice. OBJECTIVE: The purpose of this study was to determine the frequency of adverse events (AEs) during sotalol initiation for the management of atrial, supraventricular, or ventricular arrhythmias in pediatric patients. METHODS: A retrospective cohort analysis of pediatric patients 21 years or younger initiated on oral sotalol for supraventricular tachycardia or ventricular tachycardia (VT) at Boston Children's Hospital from January 1, 2007, through July 1, 2016, was performed. The primary end point was an AE defined as significant bradycardia, new or increased ventricular arrhythmias, conduction block, or corrected QT interval (QTc) prolongation, resulting in dose reduction or cessation. RESULTS: There were 190 patients who met inclusion criteria, with 110 patients (58%) 6 months or younger. A total of 115 patients (60%) had congenital heart disease. Arrhythmias for which sotalol was initiated included atrioventricular reciprocating tachycardia/atrioventricular nodal reciprocating tachycardia (n = 105 [55%]), atrial flutter (n = 31 [16%]), ectopic atrial tachycardia (n = 26 [14%]), VT (n = 21 [11%]), and atrial fibrillation (n = 7 [4%]). The median pre-sotalol QTc was 438 ms (interquartile range 348-530 ms). Five patients (3%) (aged 0.1-18 years) had AEs including bradycardia <40 beats/min (n = 2) and <100 beats/min (n = 1) and QTc prolongation (n = 2). All 5 patients with AEs had repaired congenital heart disease. CONCLUSION: The incidence of AEs in pediatric patients initiating sotalol for atrial tachycardia, supraventricular tachycardia, or VT is low (3%), with no deaths or malignant rhythms reported in this series.