Surgical Debulking of Large Ventricular Fibromas in Children.

OBJECTIVE: This study aims to provide an update on the clinical presentation, diagnostic work-up, operative strategies, and mid-term outcomes in children undergoing ventricular fibroma resection. METHODS: Single-center, retrospective cohort study of patients undergoing ventricular fibroma resection between 2000 and 2023. RESULTS: Among 52 patients, median age at surgery was 2.0 years (IQR 0.8-4.6) and median tumor volume index was 69 milliliters/m2 (IQR 49-169). Tumor distorted the atrioventricular (AV) valve/subvalvar apparatus in 30 (58%) patients and abutted major epicardial coronary arteries in 41 (79%) patients. Surgery was indicated for arrythmia (n=45, 86%), symptoms (n=14, 27%), and/or hemodynamic compromise (n=11, 21%). Tumor was debulked in 34 (65%) patients, including the last 21 patients. Concomitant AV valvuloplasty was performed in 18 patients and ventricular cavity closure in 15 (29%) patients. During a median follow-up of 2.4 years (IQR 0.8-6.2), there was no mortality, cardiac arrests, heart transplants, or single ventricle palliation. The 15-year risk of reoperation and clinical ventricular tachycardia/fibrillation was 6.7% (95% CI 0-14.3%) and 2.4% (95% CI 0-7.2%), respectively. On latest imaging, pre- and post-debulking LV ejection fraction did not significantly differ (P=.069), while no patients had signs of outflow tract obstruction, inflow tract obstruction, or > moderate AV valve regurgitation. CONCLUSIONS: Large ventricular fibromas can be resected safely with appropriate surgical planning and an emphasis on debulking. Most children maintain left ventricular function and remain free of recurrent ventricular arrhythmias at follow-up. Extended follow-up is warranted to understand whether patients remain at risk for scar-based ventricular arrhythmias in the future.

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.

Long-Term Outcomes of Cardiac Resynchronization Therapy in Patients With Repaired Tetralogy of Fallot: A Multicenter Study.

BACKGROUND: A growing number of patients with tetralogy of Fallot develop left ventricular systolic dysfunction and heart failure, in addition to right ventricular dysfunction. Although cardiac resynchronization therapy (CRT) is an established treatment option, the effect of CRT in this population is still not well defined. This study aimed to investigate the early and late efficacy, survival, and safety of CRT in patients with tetralogy of Fallot. METHODS: Data were analyzed from an observational, retrospective, multicenter cohort, initiated jointly by the Pediatric and Congenital Electrophysiology Society and the International Society of Adult Congenital Heart Disease. Twelve centers contributed baseline and longitudinal data, including vital status, left ventricular ejection fraction (LVEF), QRS duration, and NYHA functional class. Outcomes were analyzed at early (3 months), intermediate (1 year), and late follow-up (≥2 years) after CRT implantation. RESULTS: A total of 44 patients (40.3±19.2 years) with tetralogy of Fallot and CRT were enrolled. Twenty-nine (65.9%) patients had right ventricular pacing before CRT upgrade. The left ventricular ejection fraction improved from 32% [24%-44%] at baseline to 42% [32%-50%] at early follow-up (P<0.001) and remained improved from baseline thereafter (P≤0.002). The QRS duration decreased from 180 [160-205] ms at baseline to 152 [133-182] ms at early follow-up (P<0.001) and remained decreased at intermediate and late follow-up (P≤0.001). Patients with upgraded CRT had consistent improvement in left ventricular ejection fraction and QRS duration at each time point (P≤0.004). Patients had a significantly improved New York Heart Association functional class after CRT implantation at each time point compared with baseline (P≤0.002). The transplant-free survival rates at 3, 5, and 8 years after CRT implantation were 85%, 79%, and 73%. CONCLUSIONS: In patients with tetralogy of Fallot treated with CRT consistent improvement in QRS duration, left ventricular ejection fraction, New York Heart Association functional class, and reasonable long-term survival were observed. The findings from this multicenter study support the consideration of CRT in this unique population.

Safety and efficacy of combined dilation/stenting of venous abnormalities, including complete obstructions, during lead extractions in patients with congenital heart disease.

INTRODUCTION: Management of transvenous leads in patients with congenital heart disease (CHD) can be complicated by venous obstructions and residual shunts. We present our experience performing concurrent lead extraction and dilation/stenting of venous pathways, including patients with complete venous obstruction. METHODS: All cases of concurrent lead extraction and recanalization of vena cavae/baffles between 2017 and 2021 at Boston Children's Hospital were retrospectively included and reviewed for safety and efficacy. RESULTS: Eight patients, 4 female, median 38.5 years of age (range 16.7-49 years) and 81.6 kg weight (range 41.3-97.8 kg) at time of procedure were included. All patients had CHD, a majority (n = 7) having transposition of the great arteries palliated via atrial switch. All leads were removed in their entirety, with most patients having two leads extracted (n = 7). Median lead dwell time was 13.8 years (range 3.6-35.3 years). Three patients had complete obstructions, three required stenting of their innominate veins and three required recanalization of their femoral vessels. Median procedure time was 9.8 h (range 5.4-12.8 h). Complications included blood transfusion (n = 2), arrhythmia (n = 3), pleural effusion (n = 1), and pressure ulcer (n = 1). There were no cardiac perforations, venous tears, or deaths. CONCLUSION: Lead extraction along with dilation and stenting of venous anomalies, though long in duration, proved effective with minimal complications. This combined procedure can safely and effectively resolve complete obstructions secondary to transvenous leads.

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.

Hypertrophic Cardiomyopathy and Ventricular Preexcitation in the Young: Cause and Accessory Pathway Characteristics.

BACKGROUND: The cause of hypertrophic cardiomyopathy (HCM) in the young is highly varied. Ventricular preexcitation (preexcitation) is well recognized, yet little is known about the specificity for any cause and the characteristics of the responsible accessory pathways (AP). METHODS: Retrospective cohort study of patients <21 years of age with HCM/preexcitation from 2000 to 2022. The cause of HCM was defined as isolated HCM, storage disorder, metabolic disease, or genetic syndrome. Atrioventricular AP (true AP) were distinguished from fasciculoventricular fibers (FVF) using standard invasive electrophysiology study criteria. AP were defined as high risk if any of the following were <250 ms: shortest preexcited RR interval in atrial fibrillation, shortest paced preexcited cycle length, or anterograde AP effective refractory period. RESULTS: We identified 345 patients with HCM and 28 (8%) had preexcitation (isolated HCM, 10/220; storage disorder, 8/17; metabolic disease, 5/19; and genetic syndrome, 5/89). Six (21%) patients had clinical atrial fibrillation (1 with shortest preexcited RR interval <250 ms). Twenty-two patients underwent electrophysiology study which identified 23 true AP and 16 FVF. Preexcitation was exclusively FVF mediated in 8 (36%) patients. Five (23%) patients had AP with high-risk conduction properties (including ≥1 patient in each etiologic group). Multiple AP were seen in 8 (36%) and AP plus FVF in 10 (45%) patients. Ablation was acutely successful in 13 of 14 patients with recurrence in 3. One procedure was complicated by complete heart block after ablation of a high-risk midseptal AP. There were significant differences in QRS amplitude and delta wave amplitude between groups. There were no surface ECG features that differentiated AP from FVF. CONCLUSIONS: Young patients with HCM and preexcitation have a high likelihood of underlying storage disease or metabolic disease. Nonisolated HCM should be suspected in young patients with large QRS and delta wave amplitudes. Surface ECG is not adequate to discriminate preexcitation from a benign FVF from that secondary to potentially life-threatening AP.

A multifunctional soft robot for cardiac interventions.

In minimally invasive endovascular procedures, surgeons rely on catheters with low dexterity and high aspect ratios to reach an anatomical target. However, the environment inside the beating heart presents a combination of challenges unique to few anatomic locations, making it difficult for interventional tools to maneuver dexterously and apply substantial forces on an intracardiac target. We demonstrate a millimeter-scale soft robotic platform that can deploy and self-stabilize at the entrance to the heart, and guide existing interventional tools toward a target site. In two exemplar intracardiac procedures within the right atrium, the robotic platform provides enough dexterity to reach multiple anatomical targets, enough stability to maintain constant contact on motile targets, and enough mechanical leverage to generate newton-level forces. Because the device addresses ongoing challenges in minimally invasive intracardiac intervention, it may enable the further development of catheter-based interventions.

Ventricular Arrhythmias in Adults With Congenital Heart Disease, Part I: JACC State-of-the-Art Review.

Patients with congenital heart disease associated with a higher risk for ventricular arrhythmias (VA) and sudden cardiac death (SCD) can be divided conceptually into those with discrete mechanisms for reentrant monomorphic ventricular tachycardia (VT) (Group A) and those with more diffuse substrates (Group B). Part I of this review addresses Group A lesions, which predominantly consist of tetralogy of Fallot and related variants. Well-defined anatomic isthmuses for reentrant monomorphic VT are interposed between surgical scars and the pulmonary or tricuspid annulus. The most commonly implicated critical isthmus for VT is the conal septum that divides subpulmonary from subaortic outlets. Programmed ventricular stimulation can be helpful in risk stratification. Although catheter ablation is not generally considered an alternative to the implantable cardioverter-defibrillator (ICD) for prevention of SCD, emerging data suggest that there is a subset of carefully selected patients who may not require ICDs after successful monomorphic VT ablation.

Ventricular Arrhythmias in Adults With Congenital Heart Disease, Part II: JACC State-of-the-Art Review.

There are marked variations in the incidence of sudden cardiac death (SCD) and in the substrates for ventricular arrhythmias (VAs) across the gamut of congenital heart defects. In this 2-part review, patients with higher-risk forms of congenital heart disease (CHD) were conceptually categorized into those with discrete anatomic isthmuses for macro-reentrant ventricular tachycardia (VT) (Group A) and those with more diffuse or less well-defined substrates (Group B) that include patchy or extensive myocardial fibrosis. The latter category encompasses CHD lesions such as Ebstein anomaly, transposition of the great arteries with a systemic right ventricle (RV), and congenital aortic stenosis. For Group B patients, polymorphic VT and ventricular fibrillation account for a higher proportion of VA. The prognostic value of programmed ventricular stimulation is less well established, and catheter ablation plays a less prominent role. As cardiomyopathies evolve over time, pathophysiological mechanisms for VA among Groups A and B become increasingly blurred.

Retroflexed catheter course reduces the risk of right free wall accessory pathway recurrence.

INTRODUCTION: 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. METHODS AND RESULTS: Retrospective chart review of patients who underwent catheter ablation of a right free wall AP from January 1, 2008 through June 1, 2021 with >2 months follow up. Cox proportional hazards regression was used to identify relationships between predictor variables and AP recurrence. We identified 95 patients who underwent ablation of 98 right free wall APs. Median age was 13.1 years and median weight at ablation was 52.3 kg. Overall, 23/98 (23%) APs recurred. Use of a retroflexed catheter course approaching the atrioventricular groove from the ventricular aspect was associated with reduced risk of AP recurrence with (univariable hazard ratio of 0.10 [95% confidence interval: 0.01-0.78]), which remained significant in multiple two variable Cox proportional hazards models. CONCLUSION: Use of a retroflexed catheter course is associated with a reduced likelihood of AP recurrence. This approach results in improved catheter stability and should be considered for ablation of right free wall APs.

Pacemaker lead insertion sites contribute to abnormalities of myocardial function and histopathology.

BACKGROUND: Ventricular pacing can cause myocardial dysfunction, but how lead anchoring to the myocardium affects function has not been studied. OBJECTIVE: The purpose of this study was to evaluate patterns of regional and global ventricular function in patients with a ventricular lead using cine cardiac computed tomography (CCT) and histology. METHODS: This was a single-center retrospective study with 2 groups of patients with a ventricular lead: (1) those who underwent cine CCT from September 2020 to June 2021 and (2) those whose cardiac specimen was analyzed histologically. Regional wall motion abnormalities on CCT were assessed in relation to lead characteristics. RESULTS: For the CCT group, 122 ventricular lead insertion sites were analyzed in 43 patients (47% female; median age 19 years; range 3-57 years). Regional wall motion abnormalities were present at 51 of 122 lead insertion sites (42%) in 23 of 43 patients (53%). The prevalence of a lead insertion-associated regional wall motion abnormality was higher with active pacing (55% vs 18%; P < .001). Patients with lead insertion-associated regional wall motion abnormalities had a lower systemic ventricular ejection fraction (median 38% vs 53%; P < .001) than did those without regional wall motion abnormalities. For the histology group, 3 patients with 10 epicardial lead insertion sites were studied. Myocardial compression, fibrosis, and calcifications were commonly present directly under active leads. CONCLUSION: Lead insertion site-associated regional wall motion abnormalities are common and associated with systemic ventricular dysfunction. Histopathological alterations including myocardial compression, fibrosis, and calcifications beneath active leads may explain this finding.

Heart sounds: Past, present, and future from a technological and clinical perspective - a systematic review.

The high prevalence of cardiac diseases around the world has created a need for quick, easy and cost effective approaches to diagnose heart disease. The auscultation and interpretation of heart sounds using the stethoscope is relatively inexpensive, requires minimal to advanced training, and is widely available and easily carried by healthcare providers working in urban environments or medically underserved rural areas. Since René-Théophile-Hyacinthe Laennec's simple, monoaural design, the capabilities of modern-day, commercially available stethoscopes and stethoscope systems have radically advanced with the integration of electronic hardware and software tools, however these systems are largely confined to the metropolitan medical centers. The purpose of this paper is to review the history of stethoscopes, compare commercially available stethoscope products and analytical software, and discuss future directions. Our review includes a description of heart sounds and how modern software enables the measurement and analysis of time intervals, teaching auscultation, remote cardiac examination (telemedicine) and, more recently, spectrographic evaluation and electronic storage. The basic methodologies behind modern software algorithms and techniques for heart sound preprocessing, segmentation and classification are described to provide awareness.

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 System Pacing Versus Conventional Cardiac Resynchronization Therapy in Congenital Heart Disease.

BACKGROUND: Dyssynchrony-associated left ventricular systolic dysfunction is a major contributor to heart failure in congenital heart disease (CHD). Although conventional cardiac resynchronization therapy (CRT) has shown benefit, the comparative efficacy of cardiac conduction system pacing (CSP) is unknown. OBJECTIVES: The purpose of this study was compare the clinical outcomes of CSP vs conventional CRT in CHD with biventricular, systemic left ventricular anatomy. METHODS: Retrospective CSP data from 7 centers were compared with propensity score-matched conventional CRT control subjects. Outcomes were lead performance, change in left ventricular ejection fraction (LVEF), and QRS duration at 12 months. RESULTS: A total of 65 CSP cases were identified (mean age 37 ± 21 years, 46% men). The most common CHDs were tetralogy of Fallot (n = 12 [19%]) and ventricular septal defect (n = 12 [19%]). CSP was achieved after a mean of 2.5 ± 1.6 attempts per procedure (38 patients with left bundle branch pacing, 17 with HBP, 10 with left ventricular septal myocardial). Left bundle branch area pacing [LBBAP] vs HBP was associated with a smaller increase in pacing threshold (Δ pacing threshold 0.2 V vs 0.8 V; P = 0.05) and similar sensing parameters at follow-up. For 25 CSP cases and control subjects with baseline left ventricular systolic dysfunction, improvement in LVEF was non-inferior (Δ LVEF 9.0% vs 6.0%; P = 0.30; 95% confidence limits: -2.9% to 10.0%) and narrowing of QRS duration was more pronounced for CSP (Δ QRS duration 35 ms vs 14 ms; P = 0.04). Complications were similar (3 [12%] CSP, 4 [16%] conventional CRT; P = 1.00). CONCLUSIONS: CSP can be reliably achieved in biventricular, systemic left ventricular CHD patients with similar improvement in LVEF and greater QRS narrowing for CSP vs conventional CRT at 1 year. Among CSP patients, pacing electrical parameters were superior for LBBAP vs HBP.

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.

Ventricular arrhythmias after fibroma resection: Are patients still at risk?

BACKGROUND: Ventricular fibromas frequently present with life-threatening ventricular tachycardia (VT) or ventricular fibrillation (VF) in children. The long-term risk of sustained ventricular arrhythmias after surgical resection is unknown. OBJECTIVES: The aims of this study were to quantify the VT/VF risk after surgical resection and to examine the results of early (during index surgical hospitalization) and late (≥3 months after surgery) postoperative ventricular stimulation (V-stim) studies. METHODS: We performed a retrospective cohort study of all patients with ventricular fibromas who underwent surgical resection at our institution (2000-2020). The primary outcome was defined as recurrent VT/VF ≥3 months after index surgical resection. RESULTS: Forty-six patients with a median age at surgery of 2 years (range 0.3-18.9 years) formed our study cohort. Indications for surgery included cardiac arrest in 11 (24%), sustained VT in 16 (35%), premature ventricular contractions/nonsustained VT in 10 (22%), and hemodynamic abnormalities in 9 (20%). Of the 11 patients who presented with cardiac arrest, 4 underwent pre-resection implantable cardioverter-defibrillator (ICD) implantation, all of which were explanted at the time of surgery. An early postoperative V-stim study was performed in 26 (57%) patients, and all were negative for inducible VT/VF. Of the 13 late postoperative V-stim studies, 3 were positive: 2 underwent ICD implantation and 1 was initiated on amiodarone and underwent loop recorder implantation. At the time of last follow-up (median 1.5 years; range 0.3-16.5 years), 45 (98%) were free of clinical VT/VF and no patient with an ICD has received an appropriate shock. CONCLUSION: Surgical resection of ventricular fibromas significantly reduces the risk of life-threatening arrhythmias in children; however, a small number of patients remain vulnerable.

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.

First-in-Human Computational Preprocedural Planning of Left Main Interventions Using a New Everolimus-Eluting Stent.

Left main coronary artery stenting requires rigorous planning and optimal execution. This case series presents a new approach to left main stenting guided by preprocedural patient-specific computational simulations. Three patients with significant left main artery disease underwent simulation-guided intervention using a novel stent scaffold purpose-built for large coronary arteries. (Level of Difficulty: Advanced.).