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Background Tricuspid valve (TV) surgery is often required for adult congenital heart disease (ACHD), but may hinder catheter ablation when an artificial material or imbricated tissue covers the tricuspid annulus. Objective The purpose of this study was to determine the outcomes of catheter ablation after TV surgery in a large ACHD cohort. Methods An international retrospective study involving 7 centers was conducted. Patients who did and did not undergo TV surgery were matched for age, lesion classification, and postsurgical duration. TV operations were classified as valve ring/replacement vs repair. Results One hundred thirty-six patients (42 ring/replacement, 39 repair, and 55 no TV surgery; median 32 years [IQR 20 - 46]) underwent 180 procedures targeting 239 tachycardias (cavotricuspid-isthmus dependent intraatrial reentrant tachycardia 36%, other intraatrial reentrant tachycardia 29%, focal atrial tachycardia 18%, and other supraventricular tachyarrhythmia 17%). Post-TV surgery, procedures were longer (4.3 hours vs 3.3 hours; P = .003) and required longer fluoroscopy time (31 minutes vs 18 minutes; P = .001). At least partial acute success was achieved in 81% of procedures in the TV ring/replacement group vs 94% in both TV repair and no TV surgery groups (P = .03). The difference was driven mainly by ablation of annular substrates, with acute success in 73% of TV ring/replacement, 92% of TV repair, and 94% of no TV surgery groups (P = .01). Over a median of 3.0 years, tachycardia recurred after 26% of procedures. TV ring/replacement predicted recurrence in the multivariable analysis (hazard ratio 2.4; 95% confidence interval 1.2–5.2; P = .009). Conclusion After surgery for ACHD, catheter ablation success was lower and tachycardia recurrence was higher after TV valve ring/replacement surgery. The findings of this retrospective report support future larger multicenter series and prospective evaluation to determine the role of empirical annular substrate ablation.

Background Children at high risk for sudden cardiac death (SCD) (>6% over 5 years) receive an implantable cardioverter–defibrillator (ICD), but no guidelines are available for those at lower risk. For children at intermediate risk for SCD (4%–6% over 5 years), the utility and cost-effectiveness of in-home automated external defibrillators (AEDs) are unclear. Objective The purpose of this study was to assess the cost-effectiveness of in-home AED for children at intermediate risk for SCD. Methods Using hypertrophic cardiomyopathy (HCM) as the proxy disease, a theoretical cohort of 1550 ten-year-old children with HCM was followed for 69 years. Baseline annual risk of SCD was 0.8%. Outcomes were SCD, severe neurologic morbidity (SNM), cost, and quality-adjusted life-years (QALYs). Model inputs were derived from the literature, with a willingness-to-pay threshold of $100,000 per QALY. Results Among children at intermediate risk for SCD, in-home AED resulted in 31 fewer cases of SCD but 3 more cases of SNM. There were 319 QALYs gained. Although costs were higher by $28 million, the incremental cost-effectiveness ratio was $86,458, which is below the willingness-to-pay threshold. Conclusion For children at intermediate risk for SCD and HCM, in-home AED is cost-effective, resulting in fewer deaths and increased QALYS for a cost below the willingness-to-pay threshold. These findings highlight the economic benefits of in-home AED use in this population.

Predictors of risk of lethal arrhythmic events (LAE) is poorly understood and may differ from adults in children with hypertrophic cardiomyopathy (HCM).The purpose of this study was to determine predictors of LAE in children with HCM.A retrospective data collection was performed on 446 children and teenagers 20 years and younger (290 [65%] male; mean age 10.1 ± 5.7 years) with idiopathic HCM from 35 centers. Patients were classified as group 1 (HCM with LAE) if having a secondary prevention implantable cardioverter-defibrillator (ICD) or primary prevention ICD with appropriate interventions or group 2 (HCM without LAE) if having a primary prevention ICD without appropriate interventions.There were 152 children (34%) in group 1 and 294 (66%) in group 2. Risk factors for group 1 by univariate analysis were septal thickness, posterior left ventricular (LV) wall thickness, lower LV outflow gradient, and Q wave3 mm in inferior electrocardiographic leads. Factors not associated with LAE were family history of SCD, abnormal blood pressure response to exercise, and ventricular tachycardia on ambulatory electrocardiographic monitoring. Risk factors for SCD by multivariate analysis were age at ICD placement (hazard ratio [HR] 0.9; P = .0025), LV posterior wall thickness z score (HR 1.02; P.005), and LV outflow gradient30 mm Hg (HR 2.0; P.006). LV posterior wall thickness z score ≥ 5 was associated with LAE.Risk factors for LAE appear different in children compared to adults. Conventional adult risk factors were not significant in children. Further prospective studies are needed to improve risk stratification for LAE in children with HCM.

Subcutaneous implantable cardioverter-defibrillator (SICD) shows promise for select patients at risk of sudden cardiac death. However, patients need to pass an electrocardiographic (ECG) screening (ECG-S) test before they can receive an SICD. Predictors of ECG-S failure in children are unclear.The purpose of this study was to identify the incidence and predictive factors for failure of ECG-S in children.Patients 18 years and younger with a preexisting ICD underwent ECG-S for SICD. ECG and demographic data were analyzed for factors predictive of failure.Seventy-three patients (mean age 14.2 ± 3.3 years; range 5-18 years) with hypertrophic cardiomyopathy (n = 24, 33%), long QT syndrome (n =18, 25%), other inherited arrhythmia syndromes (n = 20, 27%), congenital heart disease (n = 9, 12%), and miscellaneous conditions (n = 2) with an existing transvenous ICD underwent prospective ECG-S. Nineteen (26%) failed ECG-S. Failed patients had a longer corrected QT (QTc) interval (457 ms vs 425 ms; P = .03), a longer QRS duration (120 ms vs 98 ms; P = .04), and a lower ratio of R-wave to T-wave amplitudes (R:T ratio) in lead aVF (4 vs 5; P = .001). Multivariable logistic regression identified QTc interval (odds ratio [OR] 4.31; P = .04), QRS duration (OR 4.93; P = .03), R:T ratio in lead aVF (OR 3.13; P = .08) as predictors of failure. A risk score with 1 point each for QTc interval440 ms, QRS duration120 ms, and R:T ratio6.5 in lead aVF was associated with probability of failure of 15.4% (1 point), 47.4% (2 points), and 88.6% (3 points), respectively.ECG-S failure for SICD occurred in 26% of children, which is higher than the reported incidence in adults. Factors predicting ECG-S failure included longer QTc interval, longer QRS duration, and lower R:T ratio in lead aVF.

Society Guidelines PACES/HRS Expert Consensus Statement on the Recognition and Management of Arrhythmias in Adult Congenital Heart Disease Developed in Partnership Between the Pediatric and Congenital Electrophysiology Society (PACES) and the Heart Rhythm Society (HRS). Endorsed by the Governing Bodies of PACES, HRS, the American College of Cardiology (ACC), the American Heart Association (AHA), the European Heart Rhythm Association (EHRA), the Canadian Heart Rhythm Society (CHRS), and the International Society for Adult Congenital Heart Disease (ISACHD) Paul Khairy, MD, PhD, FRCPC (Chair),* George F. Van Hare, MD, FACC, FHRS (Co-Chair),y Seshadri Balaji, MBBS, PhD,y Charles I. Berul, MD, FHRS,y Frank Cecchin, MD, FACC,z Mitchell I. Cohen, MD, FACC, FHRS,y Curt J. Daniels, MD, FACC,** Barbara J. Deal, MD, FACC,y Joseph A. Dearani, MD, FACC,* Natasja de Groot, MD, PhD,{ Anne M. Dubin, MD, FHRS,y Louise Harris, MBChB, FHRS, Jan Janousek, MD, PhD,{ Ronald J. Kanter, MD, FHRS,y Peter P. Karpawich, MD, FACC, FAHA, FHRS,y James C. Perry, MD, FACC, FHRS,* Stephen P. Seslar, MD, PhD,y Maully J. Shah, MBBS, FHRS,y Michael J. Silka, MD, FACC, FAHA,x John K. Triedman, MD, FACC, FHRS,y Edward P. Walsh, MD, FACC, FHRS,y and Carole A. Warnes, MD, FRCP, FACC, FAHA** Pediatric and Congenital Electrophysiology Society (PACES) representative; yHeart Rhythm Society (HRS) representative; zAmerican College of Cardiology (ACC) representative; xAmerican Heart Association (AHA) representative; {European Heart Rhythm Association (EHRA) representative; Canadian Heart Rhythm Society (CHRS) representative; International Society for Adult Congenital Heart Disease (ISACHD) representative

Recognition and Management of Arrhythmias in Adult Congenital Heart Disease: Executive Summary Developed in partnership between the Pediatric and Congenital Electrophysiology Society (PACES) and the Heart Rhythm Society (HRS). Endorsed by the governing bodies of PACES, HRS, the American College of Cardiology (ACC), the American Heart Association (AHA), the European Heart Rhythm Association (EHRA), the Canadian Heart Rhythm Society (CHRS), and the International Society for Adult Congenital Heart Disease (ISACHD)

Background Arrhythmia management has become the major treatment challenge in adult patients with congenital heart disease (ACHD). Objective We sought to investigate the utility and safety profile of dofetilide for atrial arrhythmias in ACHD. Methods A retrospective chart review was performed. We included patients (age ≥18 years) with congenital heart disease who had atrial fibrillation (AF) or intra-atrial reentrant tachycardia treated with dofetilide. Results We identified 64 patients with a mean age at initiation of 42 ± 14 years. ACHD type included single ventricle (n = 19, 30%), transposition of the great arteries (n = 14, 22%), atrial septal defect (n = 9, 14%), tetralogy of Fallot (n = 8, 12%), atrioventricular canal defect (n = 5, 8%), mitral/aortic stenosis (n = 7, 11%), and other (n = 2, 3%). Thirty-five (55%) had atrial fibrillation, and 29 (45%) had intra-atrial reentrant tachycardia. A total of 3 (4.7%) patients had major inpatient adverse events: torsades de pointes (n = 1, 1.5%), ventricular tachycardia (n = 1, 1.5%), and corrected QT prolongation requiring discontinuation (n = 1, 1.5%). Dofetilide was discontinued in 1 patient because of sinus node dysfunction, and another patient discontinued therapy before discharge because of persistent arrhythmia. Of the patients who were discharged on dofetilide (n = 59, 92%), 40 (68%) had adequate rhythm control and 19 (32%) had partial rhythm control. After a median follow-up of 3 years, 29 (49%) patients remained on dofetilide and 2 (3%) patients died. Reasons for discontinuation included waning effect (n = 16, 57%), side effects (n = 5, 18%), noncompliance (n = 2, 7%), successful ablation (n = 3, 11%), high cost (n = 1, 3.5%), and unknown (n = 1, 3.5%). Conclusion Dofetilide remains a viable antiarrhythmic drug option in this challenging population. At 3 years, 49% remained on dofetilide. Close monitoring of renal function, concomitant medications, and corrected QT interval is required.

Background Extracardiac total cavopulmonary connection (E-TCPC) is widely performed for single ventricle palliation, yet there is little experience with catheter ablation in this population. Objectives We hypothesized that atrial tachycardia substrates after primary E-TCPC would be similar to those in other forms of congenital heart disease and that catheter ablation could be performed effectively using a primarily transconduit approach. Methods Catheter ablation characteristics of patients with E-TCPC from 9 centers were collected. Acute procedural success was defined as elimination of all sustained supraventricular tachyarrhythmias. Procedural complications, acute success, and recurrences were assessed. Results Forty-six catheter ablation procedures were performed in 36 patients. Access to the atrium was by transconduit puncture in 29 procedures (63%). The most common supraventricular tachyarrhythmia mechanism was intra-atrial reentrant tachycardia (IART) in 21 patients (58%); and for all patients with primary E-TCPC and IART, an isthmus between the atrioventricular valve annulus and the oversewn inferior vena cava was critical for maintenance of tachycardia. Overall, acute success was achieved in 38 procedures (83%). There were 8 complications, with only 1 requiring intervention (epicardial pacemaker) and none related to conduit puncture. Recurrence after the final procedure occurred in 6 patients (17%) over a median follow-up duration of 0.4 years (interquartile range 0.1–1.5 years). Conclusion Catheter ablation could be performed effectively in this group of patients with E-TCPC, and the underlying IART substrate after primary E-TCPC appears to be reproducible. Catheter ablation may be a reasonable alternative to long-term antiarrhythmic therapy in this patient group.

There is a lack of prospective population-based data regarding sudden death in children.The purpose of this study was to assess the burden of sudden cardiac arrest (SCA) in the pediatric population in a 3-year community-wide study.During 2002-2005, all residents of Multnomah County, Oregon (population 660,486) who underwent SCA were ascertained from emergency medical services, the medical examiner, and emergency rooms of 16 area hospitals. A comprehensive evaluation was performed, including analysis of circumstances of death, medical records, and available autopsy data. Annual incidence rates were calculated for all residents age18 years using the 2000 U.S. Census data.A total of 33 children met the criteria for SCA (58% female, median age 0.37 years, range 0.03-12.3 years). The majority of SCAs (76%) occurred in children age1 year. At least 90% of this subgroup also met the criteria for the sudden infant death syndrome (SIDS). Pediatric SCAs constituted 2.8% of all SCAs. The pediatric annual incidence rate per 100,000 population was 1.7 (95% confidence interval [CI] 1.1-2.3), compared with 60/100,000 for all ages. The pediatric annual incidence rate per 100,000 children was 7.5 (95% CI 5.1-10.5). The annual incidence rate of SIDS was 0.8/1000 live births. In contrast to an adult survival rate of 8%, none of the children survived to be discharged from the hospital.The burden of pediatric sudden death was low (3% of all sudden deaths), but 90% occurred before the age of 1 year, and the majority were diagnosed as SIDS (70% of overall sudden deaths in children). Population education to prevent SIDS and enhanced postnatal diagnosis of occult heart disease are likely to have the greatest impact on the prevention of pediatric sudden death.

A multicenter prospective study was performed to assess the results and risks associated with radiofrequency ablation in children. This report focuses on recurrences following initially successful ablation.Patients recruited for the study were aged 0 to 16 years and had supraventricular tachycardia due to accessory pathways or atrioventricular nodal reentrant tachycardia (AVNRT), excluding patients with more than trivial congenital heart disease. A total of 481 patients were recruited into the prospective cohort and were followed at 2, 6, and 12 months following ablation.There were 517 successfully ablated substrates out of 540 attempted (95.7%). Loss to follow-up for individual substrates was 3.3%, 10.6%, and 21.2% at 2, 6, and 12 months, respectively. Recurrence was observed in 7.0%, 9.2%, and 10.7% of these substrates at 2, 6, and 12 months, respectively (adjusted for loss to follow-up as an independent source of data censoring). Recurrence rate varied by substrate location (24.6% for right septal, 15.8% for right free wall, 9.3% for left free wall, and 4.8% for left septal), as well as for AVNRT versus all others (4.8% vs 12.9%) at 12 months. The recurrence rate was higher for substrates ablated using power control but was not a function of whether isoproterenol was used for postablation testing.Recurrence after initially successful ablation occurs commonly in children. It is least common after AVNRT ablation and most common following ablation of right-sided pathways. These results serve as a benchmark for the time course of recurrence following initially successful ablation of supraventricular tachycardia in children.

Tachycardia-induced cardiomyopathy (TIC) carries significant risk of morbidity and mortality, although full recovery is possible. Little is known about the myocardial recovery pattern.The purpose of this study was to determine the time course and predictors of myocardial recovery in pediatric TIC.An international multicenter study of pediatric TIC was conducted. Children ≤18 years with incessant tachyarrhythmia, cardiac dysfunction (left ventricular ejection fraction [LVEF]50%), and left ventricular (LV) dilation (left ventricular end-diastolic dimension [LVEDD] z-score ≥2) were included. Children with congenital heart disease or suspected primary cardiomyopathy were excluded. Primary end-points were time to LV systolic functional recovery (LVEF ≥55%) and normal LV size (LVEDD z-score2).Eighty-one children from 17 centers met inclusion criteria: median age 4.0 years (range 0.0-17.5 years) and baseline LVEF 28% (interquartile range 19-39). The most common arrhythmias were ectopic atrial tachycardia (59%), permanent junctional reciprocating tachycardia (23%), and ventricular tachycardia (7%). Thirteen required extracorporeal membrane oxygenation (n = 11) or ventricular assist device (n = 2) support. Median time to recovery was 51 days for LVEF and 71 days for LVEDD. Two (4%) underwent heart transplantation, and 1 died (1%). Multivariate predictors of LV systolic functional recovery were age (hazard ratio [HR] 0.61, P = .040), standardized tachycardia rate (HR 1.16, P = .015), mechanical circulatory support (HR 2.61, P = .044), and LVEF (HR 1.33 per 10% increase, p=0.005). For normalization of LV size, only baseline LVEDD (HR 0.86, P = .008) was predictive.Pediatric TIC resolves in a predictable fashion. Factors associated with faster recovery include younger age, higher presenting heart rate, use of mechanical circulatory support, and higher LVEF, whereas only smaller baseline LV size predicts reverse remodeling. This knowledge may be useful for clinical evaluation and follow-up of affected children.

BACKGROUND: Children with catecholaminergic polymorphic ventricular tachycardia (CPVT) are at risk for sudden death, and a risk stratification tool does not exist. OBJECTIVE: The purpose of this study was to determine whether proband status, age at symptom onset, and/or sex are independent predictors of cardiac events. METHODS: A multicenter, ambispective, cohort of pediatric CPVT patients was categorized by sex, proband status, and age at symptom onset (D1: first decade of life [symptom onset