Transcatheter Leadless Pacing in Children: A PACES Collaborative Study in the Real-World Setting.

BACKGROUND: Transcatheter Leadless Pacemakers (TLP) are a safe and effective option for adults with pacing indications. These devices may be an alternative in pediatric patients and patients with congenital heart disease for whom repeated sternotomies, thoracotomies, or transvenous systems are unfavorable. However, exemption of children from clinical trials has created uncertainty over the indications, efficacy, and safety of TLP in the pediatric population. The objectives of this study are to evaluate clinical indications, procedural characteristics, electrical performance, and outcomes of TLP implantation in children. METHODS: Retrospective data were collected from patients enrolled in the Pediatric and Congenital Electrophysiology Society TLP registry involving 15 centers. Patients ≤21 years of age who underwent Micra (Medtronic Inc, Minneapolis, MN) TLP implantation and had follow-up of ≥1 week were included in the study. RESULTS: The device was successfully implanted in 62 of 63 registry patients (98%) at a mean age of 15±4.1 years and included 20 (32%) patients with congenital heart disease. The mean body weight at TLP implantation was 55±19 kg and included 8 patients ≤8 years of age and ≤30 kg in weight. TLP was implanted by femoral (n=55, 87%) and internal jugular (n=8, 12.6%) venous approaches. During a mean follow-up period of 9.5±5.3 months, there were 10 (16%) complications including one cardiac perforation/pericardial effusion, one nonocclusive femoral venous thrombus, and one retrieval and replacement of TLP due to high thresholds. There were no deaths, TLP infections, or device embolizations. Electrical parameters, including capture thresholds, R wave sensing, and pacing impedances, remained stable. CONCLUSIONS: Initial results from the Pediatric and Congenital Electrophysiology Society TLP registry demonstrated a high level of successful Micra device implants via femoral and internal venous jugular approaches with stable electrical parameters and infrequent major complications. Long-term prospective data are needed to confirm the reproducibility of these initial findings.

Electrophysiologic Management and Considerations for D-transposition of the Great Arteries After Atrial Baffle Repair.

This unique case highlights the electrophysiologic management and risk assessment of sudden cardiac death in a 35-year-old woman with a history of D-transposition of the great arteries status post-Mustard atrial switch repair.

Management and outcomes of atrial fibrillation in 241 healthy children and young adults: Revisiting "lone" atrial fibrillation-A multi-institutional PACES collaborative study.

BACKGROUND: Atrial fibrillation (AF) in healthy children and young adults is rare. Risk of recurrence and treatment efficacy are not well defined. OBJECTIVE: The purpose of this study was to assess recurrence patterns and treatment efficacy in AF. METHODS: A retrospective multicenter cohort study including 13 congenital heart centers was facilitated by the Pediatric & Congenital Electrophysiology Society (PACES). Patients ≤21 years of age with documented AF from January 2004 to December 2018 were included. Demographics, family and clinical history, medications, electrophysiological study parameters, and outcomes related to the treatment of AF were recorded and analyzed. Patients with contributory diseases were excluded. RESULTS: In 241 subjects (83% male; mean age at onset 16 years), AF recurred in 94 patients (39%) during 2.1 ± 2.6 years of follow-up. In multivariable analysis, predictors of AF recurrence were family history in a first-degree relative <50 years of age (odds ratio [OR] 1.9; P = .047) and longer PR interval in sinus rhythm (OR 1.1 per 10 ms; P = .037). AF recurrence was similar whether patients began no treatment (39/125 [31%]), began daily antiarrhythmic therapy (24/63 [38%]), or had an ablation at any time (14/53 [26%]; P = .39). Ablating non-AF substrate with supraventricular tachycardia improved freedom from AF recurrence (P = .013). CONCLUSION: Recurrence of AF in the pediatric population is common, and the incidence of recurrence was not impacted by "no treatment," "medication only," or "ablation" treatment strategy. Ablation of pathways and other reentrant targets was the only intervention that decreased AF recurrence in children and young adults.

Pulmonary Cusp Positioning of a Right Ventricular Outflow Tract Ventricular Tachycardia in a Pediatric Patient Identified Using Intracardiac Echocardiography.

Ventricular premature beats originating from the right ventricular outflow tract can have myocardial extensions to the pulmonary valve and pulmonary artery. Treatment may consist of catheter ablation combined with the use of three-dimensional mapping to determine the exact location of ectopy. The location of ectopy relative to the pulmonary valve may be hard to ascertain. Intracardiac echocardiography (ICE) is a noninvasive approach by which one can determine the relationship of the pulmonary valve relative to the ablation catheter prior to ablation. ICE has achieved increasing popularity during the ablation of other arrhythmias such as tricuspid valve arrhythmias and has been shown to be helpful in guiding catheter placement prior to ablation. The additional information gained from deploying ICE may ensure more precise ablation, prevent theoretical damage to the pulmonary valve, and alleviate the need for a repeat procedure. Here, we present a case involving the use of ICE during a pediatric patient's second ablation procedure to precisely determine the location of ectopy of nonsustained ventricular tachycardia originating from the distal pulmonary valve.

Desmoplakin Cardiomyopathy, a Fibrotic and Inflammatory Form of Cardiomyopathy Distinct From Typical Dilated or Arrhythmogenic Right Ventricular Cardiomyopathy.

BACKGROUND: Mutations in desmoplakin (DSP), the primary force transducer between cardiac desmosomes and intermediate filaments, cause an arrhythmogenic form of cardiomyopathy that has been variably associated with arrhythmogenic right ventricular cardiomyopathy. Clinical correlates of DSP cardiomyopathy have been limited to small case series. METHODS: Clinical and genetic data were collected on 107 patients with pathogenic DSP mutations and 81 patients with pathogenic plakophilin 2 (PKP2) mutations as a comparison cohort. A composite outcome of severe ventricular arrhythmia was assessed. RESULTS: DSP and PKP2 cohorts included similar proportions of probands (41% versus 42%) and patients with truncating mutations (98% versus 100%). Left ventricular (LV) predominant cardiomyopathy was exclusively present among patients with DSP (55% versus 0% for PKP2, P<0.001), whereas right ventricular cardiomyopathy was present in only 14% of patients with DSP versus 40% for PKP2 (P<0.001). Arrhythmogenic right ventricular cardiomyopathy diagnostic criteria had poor sensitivity for DSP cardiomyopathy. LV late gadolinium enhancement was present in a primarily subepicardial distribution in 40% of patients with DSP (23/57 with magnetic resonance images). LV late gadolinium enhancement occurred with normal LV systolic function in 35% (8/23) of patients with DSP. Episodes of acute myocardial injury (chest pain with troponin elevation and normal coronary angiography) occurred in 15% of patients with DSP and were strongly associated with LV late gadolinium enhancement (90%), even in cases of acute myocardial injury with normal ventricular function (4/5, 80% with late gadolinium enhancement). In 4 DSP cases with 18F-fluorodeoxyglucose positron emission tomography scans, acute LV myocardial injury was associated with myocardial inflammation misdiagnosed initially as cardiac sarcoidosis or myocarditis. Left ventricle ejection fraction <55% was strongly associated with severe ventricular arrhythmias for DSP cases (P<0.001, sensitivity 85%, specificity 53%). Right ventricular ejection fraction <45% was associated with severe arrhythmias for PKP2 cases (P<0.001) but was poorly associated for DSP cases (P=0.8). Frequent premature ventricular contractions were common among patients with severe arrhythmias for both DSP (80%) and PKP2 (91%) groups (P=non-significant). CONCLUSIONS: DSP cardiomyopathy is a distinct form of arrhythmogenic cardiomyopathy characterized by episodic myocardial injury, left ventricular fibrosis that precedes systolic dysfunction, and a high incidence of ventricular arrhythmias. A genotype-specific approach for diagnosis and risk stratification should be used.

Exercise-induced syncope and Brugada syndrome.

Brugada syndrome (BrS) is a hereditary condition that is characterized by ST elevation, ventricular tachycardia or fibrillation, and sudden cardiac death in otherwise healthy patients. Life-threatening arrhythmias generally occur, while at rest, with fever or during vagotonic states. Exercise is generally not considered a trigger for ventricular arrhythmias or syncope in patients with BrS. We describe a patient who presented with exercise-induced syncope, ventricular tachycardia during an exercise test, and was found to be both genotypically and phenotypically positive for BrS. This case highlights a potentially important role of exercise testing in diagnosing and risk stratifying certain patients with BrS.

Noninvasive predictors of perioperative atrial arrhythmias in patients with tetralogy of Fallot undergoing pulmonary valve replacement.

BACKGROUND: Patients with tetralogy of Fallot (TOF) have increased risk of atrial arrhythmias. HYPOTHESIS: A measure of atrial dispersion, the P-wave vector magnitude (Pvm), can identify patients at risk for perioperative atrial flutter (AFL) or intra-atrial re-entrant tachycardia (IART) in a large TOF cohort. METHODS: We performed a blinded, retrospective analysis of 158 TOF patients undergoing pulmonary valve replacement between 1997 and 2015. History of AFL/IART was documented using electrocardiogram, Holter monitor, exercise stress test, implanted cardiac device, and electrophysiology study. P-R intervals, Pvm, QRS duration, and QRS vector magnitude were assessed from resting sinus-rhythm 12-lead electrocardiograms and identification of those with AFL/IART was determined. RESULTS: Fourteen patients (8.9%) were found to have AFL/IART. Pvm, QRS duration, and QRS vector magnitude significantly differentiated those with AFL/IART from those without on univariate analysis: 0.09 ± 0.04 vs 0.18 ± 0.07 mV, 161.3 ± 21.9 vs 137.7 ± 31.4 ms, and 1.2 (interquartile range, 1.0-1.2) vs 1.6 mV (1.0-2.3), respectively (P < 0.05 for each). The Pvm had the highest area under the ROC curve (0.88) and was the only significant predictor on multivariate analysis, with odds ratio of 0.02 (95% confidence interval: 0.01-0.53). P-R duration, MRI volumes, and right-heart hemodynamics did not significantly differentiate those with vs those without AFL/IART. CONCLUSIONS: In TOF patients undergoing pulmonary valve replacement, Pvm has significant value in predicting those with perioperative AFL/IART. These clinical features may help further evaluate TOF patients at risk for perioperative atrial arrhythmias. Prospective studies are warranted.

Noninvasive Predictors of Ventricular Arrhythmias in Patients With Tetralogy of Fallot Undergoing Pulmonary Valve Replacement.

OBJECTIVES: This study sought to test the hypothesis that a vectorcardiographic parameter, the QRS vector magnitude (QRSVm), can risk stratify those patients at risk for sustained spontaneous ventricular arrhythmias (VAs) or ventricular arrhythmia inducibility (VAI) in a large cohort of patients with tetralogy of Fallot (TOF). BACKGROUND: Patients with TOF have an increased risk of VAs, but predicting those at risk can often be challenging. METHODS: Blinded retrospective analyses of 177 TOF patients undergoing pulmonary valve replacement (PVR) between 1997 and 2015 were performed. VAI was evaluated by programmed electrical stimulation in 48 patients. QRS intervals and QRSVm voltage measurements were assessed from resting 12-lead electrocardiograms, and risk of VA was determined. Clinical characteristics, including imaging and cardiac catheterizations, were used for other modality comparisons. RESULTS: Sustained spontaneous VA occurred in 12 patients and inducible VA in 18 patients. Age and QRSVm were significant univariate predictors of VA. QRSVm was the only independent predictor of VAI (p < 0.001). Using a root mean square QRS value of 1.24 mV, the positive and negative predictive values were 47.9% and 97.8%, respectively, for spontaneous sustained VA. For VAI, using a QRSVm cutoff of 1.31 mV, positive and negative predictive values were 63.0% and 95.3%, respectively. CONCLUSIONS: In TOF patients undergoing PVR, older age was associated with increased spontaneous VA risk. Lower QRSVm predicted spontaneous VA or VAI risk with high negative predictive values. QRSVm is the only independent predictor of VAI. These clinical features may help further risk stratify TOF patients requiring therapies to prevent sudden death.

Lower spatial QRS-T angle rules out sustained ventricular arrhythmias in children with hypertrophic cardiomyopathy.

Introduction The spatial peaks QRS-T angle accurately distinguishes children with hypertrophic cardiomyopathy from their healthy counterparts. The spatial peaks QRS-T angle is also useful in risk stratification for ventricular arrhythmias. We hypothesised that the spatial peaks QRS-T angle would be useful for the prediction of ventricular arrhythmias in hypertrophic cardiomyopathy patients under 23 years of age. METHODS: Corrected QT interval and spatial peaks QRS-T angles were retrospectively assessed in 133 paediatric hypertrophic cardiomyopathy patients (12.4±6.6 years) with versus without ventricular arrhythmias of 30 seconds or longer. Significance, positive/negative predictive values, and odds ratios were calculated based on receiver operating characteristic curve cut-off values. RESULTS: In total, 10 patients with ventricular arrhythmias were identified. Although the corrected QT interval did not differentiate those with versus without ventricular arrhythmias, the spatial peaks QRS-T angle did (151.4±19.0 versus 116.8±42.6 degrees, respectively, p<0.001). At an optimal cut-off value (124.1 degrees), the positive and negative predictive values of the spatial peaks QRS-T angle were 15.4 and 100.0%, respectively, with an odds ratio of 25.9 (95% CI 1.5-452.2). CONCLUSION: In children with hypertrophic cardiomyopathy, the spatial peaks QRS-T angle is associated with ventricular arrhythmia burden with high negative predictive value and odds ratio.

Repolarization Vector Magnitude Differentiates Kawasaki Disease from Normal Children.

INTRODUCTION: Kawasaki disease (KD) is the leading cause of acquired heart disease in children. The 12-lead electrocardiogram (ECG) changes in patients during the acute phase of KD include flattened T waves and prolonged corrected QT intervals (QTc). We set out to determine the 12-lead ECG and vectorcardiography predictors for identification of patients with KD and which of these predictors would be clinically useful for early identification of those with coronary artery anomalies (CAA). METHODS: A blinded, retrospective case-control study of patients with KD and age-matched controls was performed. Deep Q waves, QTc, spatial QRS-T angles, and T-wave vector magnitude (root mean square of the T wave, RMS-T) were assessed. Comparisons between groups were performed to test for significant differences. RESULTS: Fifty patients with KD (mean age 3.1 ± 3.1 years, 26% female) were compared to 50 previously healthy control patients (mean age 3.8 ± 2.9 years, 44% female). Of the KD patients, 32 (64%) were diagnosed as incomplete KD and 28 (56%) of them had CAA. When compared to the control group, KD patients had abnormal Q waves (72% vs 44% P = 0.005), shorter QTc values (395.1 ± 24.7 ms vs 410.4 ± 34.7 ms, P = 0.013), and lower RMS-T (0.42 ± 0.02 mV vs 0.63 ± 0.03 mV P < 0.001), respectively. Incomplete KD was also discriminated from controls by the same parameters. No differences were noted between KD patients with versus without CAA. CONCLUSION: The RMS-T differentiates complete and incomplete KD from controls. KD patients with CAA were not differentiated from those without CAA.

Intermittent versus Persistent Wolff-Parkinson-White Syndrome in Children: Electrophysiologic Properties and Clinical Outcomes.

BACKGROUND: Intermittent Wolff-Parkinson-White (WPW) syndrome is considered to have a lower risk of sudden death. Fewer data exist regarding electrophysiologic (EP) characteristics and the natural history of intermittent WPW in children. METHODS: All patients with WPW age 1-18 years at a single institution (1996-2013) were reviewed. Patients with intermittent preexcitation were compared to those with loss of preexcitation on Holter/exercise testing and those with persistent preexcitation. High-risk accessory pathway (AP) was defined as AP effective refractory period (APERP), block cycle length, or shortest preexcited RR interval during atrial fibrillation ≤250 ms. RESULTS: A total of 295 patients were included: 226 (76.6%) persistent, 39 (13.2%) intermittent, and 30 (10.2%) loss of preexcitation Holter/exercise. There were no differences in symptoms between groups. Median interquartile range APERP was significantly longer in intermittent WPW (380 [320, 488] ms vs 320 [300, 350] ms persistent, 310 [290, 330] ms loss of preexcitation Holter/exercise; P = 0.0008). At baseline, there was no difference between groups in frequency of high-risk pathways. However, when isoproterenol values were included, high-risk pathways were more frequent among patients with loss of preexcitation on Holter/exercise (54% vs 16% persistent, 11% intermittent; P = 0.005). There was one death in a patient with loss of preexcitation on exercise testing, no EP study, and prior drug use. A second patient with persistent WPW and APERP 270 ms required resuscitation following a methadone overdose. CONCLUSION: Intermittent preexcitation in children does not connote a lower risk AP by EP criteria or reduced symptoms. The low number of pediatric WPW patients who develop preexcited atrial fibrillation or sudden death warrants larger studies to investigate these outcomes.

The spatial QRS-T angle outperforms the Italian and Seattle ECG-based criteria for detection of hypertrophic cardiomyopathy in pediatric patients.

INTRODUCTION: The spatial peaks QRS-T angle has been shown to differentiate adult patients with hypertrophic cardiomyopathy (HCM) from controls. We hypothesized that the spatial peaks QRS-T angle would, in isolation, be more accurate than the Italian 12-lead ECG Pre-participation Screening criteria or the Seattle criteria for detecting hypertrophic cardiomyopathy (HCM) in pediatric patients. METHODS: A retrospective study of pediatric patients with HCM compared to age and gender-matched control patients was undertaken. Significance, odds ratios, sensitivity and specificity of HCM detection of the visually derived spatial peaks QRS-T angle were compared to those of traditional 12-lead ECG criteria using: 1) Italy's National Pre-participation Screening Programme criteria; and 2) described criteria from Seattle. RESULTS: ECG results from 130 pediatric HCM patients (14.2±4.4years) were compared to 470 control patients (normal echocardiograms, mean age 13.4±4.6years). Mean±standard deviation (SD) values for spatial peaks QRS-T angles were 120.4±40.7 and 21.3±13.7 degrees for HCM and controls, respectively (P<0.001). A spatial peaks QRS-T angle cutoff value of >54.9 degrees yielded greater sensitivity and specificity (93.1% and 98.7%, respectively) for detecting HCM over ECG criteria from Italy (68.5% and 48.1%, respectively) or Seattle (64.6% and 78.9%, respectively) with odds ratios at 1039.70 (95% CI 363.03 to 2977.67), 2.01 (95% CI 1.33 to 3.04) and 6.84 (4.49-10.44), respectively. CONCLUSION: In our cohort, a visually derived spatial peaks QRS-T angle has increased sensitivity and specificity for detection of HCM in pediatric patients compared to currently utilized Italian or Seattle ECG criteria.

Vectorcardiographic predictors of ventricular arrhythmia inducibility in patients with tetralogy of Fallot.

INTRODUCTION: Vectorcardiography (VCG) may have predictive value in Tetralogy of Fallot (TOF) patients undergoing ventricular arrhythmia inducibility (VAI) electrophysiology studies (EPs). MATERIALS AND METHODS: Blinded, retrospective analyses of 37 adult TOF patients undergoing EPs prior to pulmonary valve replacements were performed (21 female, median age 37years). VAI was evaluated from EPs and resting 12-lead electrocardiograms, respectively using QRS and heart rate adjusted Q-T intervals, spatial QRS-T angles (peaks), T-wave and QRS-wave (QRSwave vc) component vector root mean squares. Differences were assessed (Student t-tests, Mann Whitney U-tests, Analysis of Variance). Relative risks were calculated. RESULTS: 16 patients had VAI (6 monomorphic, 10 polymorphic). Only the QRSwave vc showed significant differences between those with and without VAI, 10.5±2.4 dmV vs. 13.9±4.5dmV, respectively (p=0.002), area under the ROC curve of 0.78 and relative risk of 2.52. CONCLUSION: VCG evidence of depolarization differences was significant between TOF patients with and without inducible VA.

Predictors of myocardial recovery in pediatric tachycardia-induced cardiomyopathy.

BACKGROUND: Tachycardia-induced cardiomyopathy (TIC) carries significant risk of morbidity and mortality, although full recovery is possible. Little is known about the myocardial recovery pattern. OBJECTIVE: The purpose of this study was to determine the time course and predictors of myocardial recovery in pediatric TIC. METHODS: 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-score <2). RESULTS: 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. CONCLUSION: 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.

Tachyarrhythmia following Norwood operation: a single-center experience.

BACKGROUND: The purpose of this study was to characterize tachyarrhythmias in children following the Norwood procedure. METHODS: This is a single-center retrospective study including all children who underwent stage I Norwood procedure (n = 98; January 2003-September 2011). The primary outcome measure is the development of tachyarrhythmia during hospitalization after the Norwood procedure. Secondary aims include quantification of mortality in patients with tachyarrhythmias and evaluation of potential risk factors for the development of tachyarrhythmia. RESULTS: Tachyarrhythmia occurred in 33 (34%) of 98 patients. The median time to onset of tachyarrhythmia was ten days (0-47 days). Tachyarrhythmia conferred no increase in overall mortality (P = .45), including operative mortality (P = .37) or interstage mortality (P = 1.00). There was no significant difference in the incidence of arrhythmia based on demographic, anatomic, or surgical variables, including shunt type (P = .23) except that patients with tachyarrhythmias were slightly larger (median weight 3.2 kg) at the time of stage I than those without tachyarrhythmia (median weight 2.93 kg; P = .02]. The odds of arrhythmia in males were 8.7 times higher than that in females (95% confidence interval 2.9-31.3; P < .0001). CONCLUSIONS: Postoperative tachyarrhythmia is common, occurring in 34% of patients after the Norwood operation. Onset of tachyarrhythmia occurred later after the Norwood operation than reported previously, and male gender is a risk factor. Further studies to elucidate the etiology and the timing of tachyarrhythmias after the Norwood procedure are necessary.

The fate of nontargeted endocardial leads during the extraction of one or more targeted leads in pediatrics and congenital heart disease.

INTRODUCTION: Extraction of targeted endocardial leads can lead to inadvertent damage or dislodgement of nontargeted leads, though the frequency of this has not been reported in pediatrics and congenital heart disease (CHD). METHODS: This is a retrospective review of lead extraction procedures from 2002 to 2010 from two pediatric and CHD centers evaluating unplanned interventions on nontargeted leads during the extraction of one or more targeted leads. RESULTS: Nontargeted leads were present in the 22 lead extraction procedures performed on 20 patients with median age 15 years (interquartile range, 11.5-18.5 years): 11 (55%) with structurally normal hearts and nine (45%) with CHD. Twenty of 23 targeted leads (86%) were extracted with complete success. Of the 22 nontargeted leads, including 17 atrial leads and five ventricular leads, seven (32%) required further intervention including: five extracted due to damage, dislodgement, or change in device location; one abandoned due to damage; and one dislodged requiring a second procedure for repositioning. The remaining 15 nontargeted leads (68%) were unharmed. Nontargeted leads requiring further intervention had a shorter lead duration in situ (median 2 years, interquartile range 0.5-3.5 years) than unharmed nontargeted leads (median 6.6 years, interquartile range 4.1-9.1 years; P = 0.01). Age at extraction, CHD, implantable cardioverter defibrillator leads, atrial lead position, or primary extraction modality did not predict further intervention for nontargeted leads. Major complications occurred in one procedure (4.5%) with no deaths. CONCLUSIONS: In pediatrics and CHD, nontargeted leads are frequently damaged or dislodged during the extraction of targeted leads. The risk of lead damage or dislodgement has implications for procedural planning and counseling for patients and families of pediatric and CHD patients requiring lead extraction.