Anomalous coronary artery in Tetralogy of Fallot-Feasibility of right ventricular outflow tract stenting as initial palliation.

This study addresses the outcome of right ventricle outflow tract (RVOT) stenting in Tetralogy of Fallot (ToF) with anomalous coronaries crossing the RVOT. RVOT stenting in ToF patients has emerged as an alternative to Blalock Taussig shunting. This is a single center study of patients who underwent RVOT stenting for symptomatic ToF at Birmingham Children's Hospital between 2005 and 2020. A total of 122 patients underwent RVOT stenting as initial palliation over a 15-year period, 10 patients had anomalous coronaries crossing the RVOT (study group) and 112 not (comparative group). Median age of the study group was 72.5 days (interquartile range [IQR]: 28-103) with a weight of 4.7 kg (IQR: 3.5-4.9). No significant differences were found between the two groups regarding the patients' weights and ages, procedure and screening times, or hospital stay. Four had valve sparing stenting. Oxygen saturations increased from a median of 75.5% (IQR: 70-82) to 94.5% (IQR: 90-95), p < 0.002. Postprocedure median hospital stay was 3 days (IQR: 2-6). Six patients underwent interstage catheterization reintervention and one needed early surgical palliation due to stent suboptimal position. Complete repair could be delayed for a median of 11.1 months (IQR: 5.6-19.2). At surgical repair, the patients had a median age of 12.3 months (IQR: 7.5-25.6) and weight of 7.7 kg (IQR: 6.8-10.8). There were no deaths. RVOT stenting in ToF with anomalous coronaries is safe and effective. Dilatable stents should be used when two-stage delayed conduit repair is the default approach.

Supravalvular pulmonary stenosis: A risk factor for reintervention in Noonan syndrome with pulmonary valve stenosis.

OBJECTIVES: To assess the short- and long-term outcomes of balloon pulmonary valvuloplasty (BPV) in children with Noonan syndrome (NS). BACKGROUND: Pulmonary stenosis (PS) is the most common congenital heart lesion in NS. BPV is the accepted first line treatment in PS. However, BPV in NS patients has been reported to be less effective, without specific factors for the need for reintervention being identified. METHODS: Retrospective case-note review of all patients with NS who underwent BPV between 1985 and 2020. Patients were divided into 2 groups: those with supravalvular pulmonary stenosis (SPS) in addition to valvar PS, and those with isolated valvar PS. RESULTS: A cohort of 54 patients with NS underwent BPV at a median of 275 (interquartile range [IQR]: 108-575) days of age. SPS was present in 32 (59%) patients whereas 22 had (41) isolated PS. The preprocedural invasive gradient was 47 (IQR: 35-69) mmHg, and 44 (IQR: 35-48) mmHg in those with SPS and those without respectively (p = 0.88). Reintervention was required in 22 patients (41%): 17 (77%) with SPS and 5 (23%) without (p = 0.017). Fourteen patients (11 with SPS) required surgical reintervention and 8 (6 with SPS) required further BPV. There was no significant difference in the age at initial BPV, pre- and postprocedural gradients and interval until reintervention between groups. CONCLUSION: This is the largest reported cohort of patients with NS undergoing BPV. Although BPV is often successful, the reintervention rates are high. SPS was a risk factor for reintervention.

Clinical outcomes and programming strategies of implantable cardioverter-defibrillator devices in paediatric hypertrophic cardiomyopathy: a UK National Cohort Study.

AIMS: Sudden cardiac death (SCD) is the most common mode of death in paediatric hypertrophic cardiomyopathy (HCM). This study describes the implant and programming strategies with clinical outcomes following implantable cardioverter-defibrillator (ICD) insertion in a well-characterized national paediatric HCM cohort. METHODS AND RESULTS: Data from 90 patients undergoing ICD insertion at a median age 13 (±3.5) for primary (n = 67, 74%) or secondary prevention (n = 23, 26%) were collected from a retrospective, longitudinal multi-centre cohort of children (<16 years) with HCM from the UK. Seventy-six (84%) had an endovascular system [14 (18%) dual coil], 3 (3%) epicardial, and 11 (12%) subcutaneous system. Defibrillation threshold (DFT) testing was performed at implant in 68 (76%). Inadequate DFT in four led to implant adjustment in three patients. Over a median follow-up of 54 months (interquartile range 28-111), 25 (28%) patients had 53 appropriate therapies [ICD shock n = 45, anti-tachycardia pacing (ATP) n = 8], incidence rate 4.7 per 100 patient years (95% CI 2.9-7.6). Eight inappropriate therapies occurred in 7 (8%) patients (ICD shock n = 4, ATP n = 4), incidence rate 1.1/100 patient years (95% CI 0.4-2.5). Three patients (3%) died following arrhythmic events, despite a functioning device. Other device complications were seen in 28 patients (31%), including lead-related complications (n = 15) and infection (n = 10). No clinical, device, or programming characteristics predicted time to inappropriate therapy or lead complication. CONCLUSION: In a large national cohort of paediatric HCM patients with an ICD, device and programming strategies varied widely. No particular strategy was associated with inappropriate therapies, missed/delayed therapies, or lead complications.

Stenting of the right ventricular outflow tract as an initial intervention in Tetralogy of Fallot with pulmonary stenosis and major aortopulmonary collateral arteries.

OBJECTIVES: To assess the role of right ventricular outflow tract stenting as the primary intervention in Tetralogy of Fallot with pulmonary stenosis and major aortopulmonary collateral arteries. BACKGROUND: The management of a subset of infants with Tetralogy of Fallot with pulmonary stenosis and major aortopulmonary collateral arteries requires a staged approach including rehabilitation of diminutive native pulmonary arteries, conventionally using an aortopulmonary shunt. We share our experience of pulmonary artery rehabilitation with right ventricular outflow tract stenting. METHODS: Retrospective review of all patients with Tetralogy of Fallot with pulmonary stenosis who underwent right ventricular outflow tract stenting as primary intervention over an 8-year period. RESULTS: Ten patients underwent right ventricular outflow tract stent insertion at a median age of 61 days (interquartile range (IQR) 8.3-155 days). Median weight at stent deployment was 4.2 kg (IQR 3.2-5.7 kg). Oxygen saturations improved from a median of 79% (IQR 76-80%) to 92% (IQR 90-95%), p = 0.012. The median right and left pulmonary artery z score increased from -3.51 (IQR -4.59 to -2.80) and -2.07 (IQR -3.72 to 0.15) to a median of -1.17 (IQR -2.26 to 0.16) p < 0.05, and 0.24 (IQR -1.09 to 1.84) p < 0.05, respectively, at subsequent angiogram. Nine patients underwent further catheterisation. Four patients underwent complete anatomical repair. Only one patient required unifocalisation, as most patients had a native supply to all-important lung segments. CONCLUSION: Right ventricular outflow tract stenting is a useful procedure in the subset of patients with Tetralogy of Fallot with pulmonary stenosis and major aortopulmonary collateral arteries, where native pulmonary arterial growth is required to facilitate repair.

Clinical presentation and survival of childhood hypertrophic cardiomyopathy: a retrospective study in United Kingdom.

AIMS: Understanding the spectrum of disease, symptom burden and natural history are essential for the management of children with hypertrophic cardiomyopathy (HCM). The effect of changing screening practices over time has not previously been studied. This study describes the clinical characteristics and outcomes of childhood HCM over four decades in a well-characterized United Kingdom cohort. METHODS AND RESULTS: Six hundred and eighty-seven patients with HCM presented at a median age of 5.2 years (range 0-16). Aetiology was: non-syndromic (n = 433, 63%), RASopathy (n = 126, 18.3%), Friedreich's ataxia (n = 59, 8.6%) or inborn errors of metabolism (IEM) (n = 64, 9%). In infants (n = 159, 23%) underlying aetiology was more commonly a RASopathy (42% vs. 11.2%, P < 0.0001) or IEM (18.9% vs. 6.4% P < 0.0001). In those with familial disease, median age of presentation was higher (11 years vs. 6 years, P < 0.0001), 141 (58%) presented <12 years. Freedom from death or transplantation was 90.6% (87.9-92.7%) at 5 years (1.5 per 100 patient years) with no era effect. Mortality was most frequently sudden cardiac death (SCD) (n = 20, 2.9%). Children diagnosed during infancy or with an IEM had a worse prognosis (5-year survival 80.5% or 66.4%). Arrhythmic events occurred at a rate of 1.2 per 100 patient years and were more likely in non-syndromic patients (n = 51, 88%). CONCLUSION: This national study describes a heterogeneous disease whose outcomes depend on the age of presentation and aetiology. Overall mortality and SCD rates have not changed over time, but they remain higher than in adults with HCM, with events occurring in syndromic and non-syndromic patients.

A validation study of the European Society of Cardiology guidelines for risk stratification of sudden cardiac death in childhood hypertrophic cardiomyopathy.

AIMS: Sudden cardiac death (SCD) is the most common cause of death in children with hypertrophic cardiomyopathy (HCM). The European Society of Cardiology (ESC) recommends consideration of an implantable cardioverter-defibrillator (ICD) if two or more clinical risk factors (RFs) are present, but this approach to risk stratification has not been formally validated. METHODS AND RESULTS: Four hundred and eleven paediatric HCM patients were assessed for four clinical RFs in accordance with current ESC recommendations: severe left ventricular hypertrophy, unexplained syncope, non-sustained ventricular tachycardia, and family history of SCD. The primary endpoint was a composite outcome of SCD or an equivalent event (aborted cardiac arrest, appropriate ICD therapy, or sustained ventricular tachycardia), defined as a major arrhythmic cardiac event (MACE). Over a follow-up period of 2890 patient years (median 5.5 years), MACE occurred in 21 patients (7.5%) with 0 RFs, 19 (16.8%) with 1 RFs, and 3 (18.8%) with 2 or more RFs. Corresponding incidence rates were 1.13 [95% confidence interval (CI) 0.7-1.73], 2.07 (95% CI 1.25-3.23), and 2.52 (95% CI 0.53-7.35) per 100 patient years at risk. Patients with two or more RFs did not have a higher incidence of MACE (log-rank test P = 0.34), with a positive and negative predictive value of 19% and 90%, respectively. The C-statistic was 0.62 (95% CI 0.52-0.72) at 5 years. CONCLUSIONS: The incidence of MACE is higher for patients with increasing numbers of clinical RFs. However, the current ESC guidelines have a low ability to discriminate between high- and low-risk individuals.

Stenting and overdilating small Gore-Tex vascular grafts in complex congenital heart disease.

BACKGROUND: Gore-Tex® grafts are integral in the management of congenital heart disease. Issues of graft stenosis or somatic outgrowth may precipitate high-risk early surgery, and catheter intervention is a relatively under-reported management option. OBJECTIVES: To assess efficacy, safety, and outcomes of stenting and overdilating small Gore-Tex® vascular grafts with the aim of optimizing surgical timing. METHODS: Retrospective analysis of single-center, 13-year experience of 93 graft stenting interventions or reintervention in 80 patients, with the aim of relieving stenosis ± overdilation, to depose surgical graft revision or optimize surgical timing and candidacy. RESULTS: Median preintervention graft diameter was 52% (IQR 43-63) of nominal size, postintervention this increased to median 102% (IQR 96-120) [P < 0.001]. Overdilation was achieved in 54%; of these, the median final internal lumen was 126% (IQR 113-132) [P < 0.001]. Mean oxygen saturations increased from 69% to 82% [P < 0.001]. Adverse event rate was 14.9%; this includes mortality (3.2%) and atrioventricular conduction block (8.5%). Univariate analysis and logistic regression showed a significant relationship between adverse events and young age [P < 0.01], low weight [P < 0.01], univentricular physiology [P < 0.001], use of femoral venous access alone [P = 0.03], and intervention on a right ventricle to pulmonary artery conduit [P = 0.03]. Within respective indication groups, 74% were bridged to elective cavopulmonary shunt, 95% were bridged to biventricular surgery, and 78% of long-term palliative care patients continue under follow-up. CONCLUSIONS: Gore-Tex® vascular grafts can be stented effectively and expanded beyond nominal diameters by around +26%. This improves oxygen saturations, providing excellent palliation and optimized surgical timing. Adverse events are most frequent in precavopulmonary shunt patients. CONDENSED ABSTRACT: Gore-Tex® grafts are widely used in the palliation of cyanotic congenital heart disease. Grafts may become stenosed and do not allow for somatic growth. Over a 13 year period, graft stenting was performed in 80 patients (93 technically successful interventions, 4 unsuccessful.) Median internal lumen change was +50% (of nominal graft size), mean oxygen saturation change +13%. Over-dilation was performed in more than half of the cohort, with a median gain of +26% on nominal graft size. In precavopulmonary shunt patients, there was a moderate incidence of serious complications. Clinically useful deferral of surgery was achieved for the majority.

Outcome after transcatheter occlusion of patent ductus arteriosus in infants less than 6 kg: A national study from United Kingdom and Ireland.

OBJECTIVES: This study aimed to report our national experience with transcatheter patent ductus arteriosus (PDA) occlusion in infants weighing <6 kg. BACKGROUND: The technique of transcatheter PDA closure has evolved in the past two decades and is increasingly used in smaller patients but data on safety and efficacy are limited. METHODS: Patients weighing < 6 kg in whom transcatheter PDA occlusion was attempted in 13 tertiary paediatric cardiology units in the United Kingdom and Ireland were retrospectively analyzed to review the outcome and complications. RESULTS: A total of 408 patients underwent attempted transcatheter PDA closure between January 2004 and December 2014. The mean weight at catheterization was 4.9 ± 1.0 kg and mean age was 5.7 ± 3.0 months. Successful device implantation was achieved in 374 (92%) patients without major complication and of these, complete occlusion was achieved in 356 (95%) patients at last available follow-up. Device embolization occurred in 20 cases (5%). The incidence of device related obstruction to the left pulmonary artery or aorta and access related peripheral vascular injury were low. There were no deaths related to the procedure. CONCLUSIONS: Transcatheter closure of PDA can be accomplished in selected infants weighing <6 kg despite the manufacturer's recommended weight limit of 6 kg for most ductal occluders. The embolization rate is higher than previously reported in larger patients. Retrievability of the occluder and duct morphology needs careful consideration before deciding whether surgical ligation or transcatheter therapy is the better treatment option.

Transcatheter Retrieval of Cardiovascular Foreign Bodies in Children: A 15-Year Single Centre Experience.

There has been a rapid increase in the practice of interventional catheter treatment of congenital heart disease. Catheter retrieval of embolized cardiac devices and other foreign bodies is essential, yet no large studies have been reported in the paediatric population. Retrospective 15-year review of all children who underwent transcatheter foreign body retrieval in a tertiary cardiac centre from January 1997 to September 2012. Transcatheter retrieval of foreign bodies from the cardiovascular system was attempted in 78 patients [median age 4 (0.02-16) years and median weight 15 (1.7-74) kg] including 46 embolized devices. Transcatheter retrieval was successful in 70/78 (90%), surgical retrieval was required in 6. In two patients, small embolized coils were left in situ. Gooseneck snare was the most commonly used retrieval device. Median procedure and screening times were 90 (15-316) and 31 (2-161) min, respectively. There were no procedural deaths. Transient loss of foot pulses occurred in 5 and 2 patients required blood transfusion. Transcatheter retrieval of cardiovascular foreign bodies can be performed safely in the majority of children thus obviating the need for surgery. It is essential to have a comprehensive inventory of retrieval equipment and interventional staff conversant with its use.

Initial experience with the cook formula balloon expandable stent in congenital heart disease.

INTRODUCTION: Balloon expandable stents are an integral part in the catheter treatment of congenital heart disease. In the growing child, stents require dilatation to greater diameters over time. The Cook Formula stent is a recent 316 stainless steel open-cell design licensed for peripheral vascular work. METHODS: Following extensive ex vivo studies, 112 stents were implanted in 97 children [median age 3.9 (0.01-17.6) years; median weight 13.7 (2.4-62.8) kg] over a 27-month (Oct 2011-Dec 2013) period. RESULTS: Bench testing revealed that there was no stent shortening for dilatation to nominal diameter and beyond. The 5 mm stents could be dilated up to 10 mm, and the 10 mm stents to 20 mm. Stents were implanted through 4-7F sheaths or guide catheters over appropriate wires. Stent tracking and delivery was excellent. Twenty-three stents were implanted in the right ventricular outflow tract in Fallot-type lesions, 53 for branch pulmonary artery stenosis (22 post cavopulmonary shunt/Fontan), 14 conduit stenosis, 13 Fontan fenestrations, 3 PDA in hybrid stage I Norwood, 5 in coarctation, and 1 for SVC obstruction. Sixty-one stents (54%) were overdilated. There were no stent fractures. Radial strength was very good, whereas stent conformability was limited. CONCLUSIONS: The Cook Formula stent is a premounted balloon-expandable stent that can be significantly overdilated with virtually no shortening allowing for precise placement and minimal protrusion into adjacent vessels. The Formula stent is a very versatile addition to the range of stents for use in the catheter treatment of complex congenital heart disease in children. © 2014 Wiley Periodicals, Inc.

Successful emergency cardiac pacing and permanent pacemaker insertion in a preterm 29-week gestation hydropic baby with congenital complete heart block.

A preterm 29-week gestation baby was delivered because of gross foetal hydrops secondary to congenital complete heart block. Despite a poor prognosis, she survived stabilisation and received emergency epicardial pacing followed by permanent pacemaker insertion on day 13, weighing 1.2 kg.

Catheter interventions in the staged management of hypoplastic left heart syndrome.

AIM: To analyse the current practice and contribution of catheter interventions in the staged management of patients with hypoplastic left heart syndrome. METHODS: This study is a retrospective case note review of 527 patients undergoing staged Norwood/Fontan palliation at a single centre between 1993 and 2010. Indications and type of catheter interventions were reviewed over a median follow-up period of 7.5 years. RESULTS: A staged Norwood/Fontan palliation for hypoplastic left heart syndrome was performed in 527 patients. The 30-day survival rate after individual stages was 76.5% at Stage I, 96.3% at Stage II, and 99.4% at Stage III. A total of 348 interventions were performed in 189 out of 527 patients. Freedom from catheter intervention in survivors was 58.2% before Stage II and 46.7% before Stage III. Kaplan-Meier freedom from intervention post Fontan completion was 55% at 10.8 years of follow-up. Post-stage I interventions were mostly directed to relieve aortic arch obstruction--84 balloon angioplasties--and augment pulmonary blood flow--15 right ventricle-to-pulmonary conduit interventions; post-Stage II interventions centred on augmenting size of the left pulmonary artery--73 procedures and abolishing systemic venous collaterals--32 procedures. After Stage III, the focus was on manipulating the size of the fenestration--42 interventions--and the left pulmonary artery -31 procedures. CONCLUSION: Interventional cardiac catheterisation constitutes an integral part in the staged palliative management of patients with hypoplastic left heart syndrome. Over one-third (37%) of patients undergoing staged palliation required catheter intervention over the follow-up period.

Natural history and outcomes in paediatric RASopathy-associated hypertrophic cardiomyopathy.

AIMS: This study aimed to describe the natural history and predictors of all-cause mortality and sudden cardiac death (SCD)/equivalent events in children with a RASopathy syndrome and hypertrophic cardiomyopathy (HCM). METHODS AND RESULTS: This is a retrospective cohort study from 14 paediatric cardiology centres in the United Kingdom and Ireland. We included children <18 years with HCM and a clinical and/or genetic diagnosis of a RASopathy syndrome [Noonan syndrome (NS), NS with multiple lentigines (NSML), Costello syndrome (CS), cardiofaciocutaneous syndrome (CFCS), and NS with loose anagen hair (NS-LAH)]. One hundred forty-nine patients were recruited [111 (74.5%) NS, 12 (8.05%) NSML, 6 (4.03%) CS, 6 (4.03%) CFCS, 11 (7.4%) Noonan-like syndrome, and 3 (2%) NS-LAH]. NSML patients had higher left ventricular outflow tract (LVOT) gradient values [60 (36-80) mmHg, P = 0.004]. Over a median follow-up of 197.5 [inter-quartile range (IQR) 93.58-370] months, 23 patients (15.43%) died at a median age of 24.1 (IQR 5.6-175.9) months. Survival was 96.45% [95% confidence interval (CI) 91.69-98.51], 90.42% (95% CI 84.04-94.33), and 84.12% (95% CI 75.42-89.94) at 1, 5, and 10 years, respectively, but this varied by RASopathy syndrome. RASopathy syndrome, symptoms at baseline, congestive cardiac failure (CCF), non-sustained ventricular tachycardia (NSVT), and maximal left ventricular wall thickness were identified as predictors of all-cause mortality on univariate analysis, and CCF, NSVT, and LVOT gradient were predictors for SCD or equivalent event. CONCLUSIONS: These findings highlight a distinct category of patients with Noonan-like syndrome with a milder HCM phenotype but significantly worse survival and identify potential predictors of adverse outcome in patients with RASopathy-related HCM.

Sudden cardiac death in childhood RASopathy-associated hypertrophic cardiomyopathy: Validation of the HCM risk-kids model and predictors of events.

BACKGROUND: RASopathies account for nearly 20% of cases of childhood hypertrophic cardiomyopathy (HCM). Sudden cardiac death (SCD) occurs in patients with RASopathy-associated HCM, but the risk factors for SCD have not been systematically evaluated. AIM: To validate the HCM Risk-Kids SCD risk prediction model in children with RASopathy-associated HCM and investigate potential specific SCD predictors in this population. METHODS: Validation of HCM Risk-Kids was performed in a retrospective cohort of 169 patients with a RASopathy-associated HCM from 15 international paediatric cardiology centres. Multiple imputation by chained equations was used for missing values related to the HCM Risk-Kids parameters. RESULTS: Eleven patients (6.5%) experienced a SCD or equivalent event at a median age of 12.5 months (IQR 7.7-28.64). The calculated SCD/equivalent event incidence was 0.78 (95% CI 0.43-1.41) per 100 patient years. Six patients (54.54%) with an event were in the low-risk category according to the HCM Risk-Kids model. Harrell's C index was 0.60, with a sensitivity of 9.09%, specificity of 63.92%, positive predictive value of 1.72%, and negative predictive value of 91%; with a poor distinction between the different risk groups. Unexplained syncope (HR 42.17, 95% CI 10.49-169.56, p < 0.001) and non-sustained ventricular tachycardia (HR 5.48, 95% CI 1.58-19.03, p < 0.007) were predictors of SCD on univariate analysis. CONCLUSION: Unexplained syncope and the presence of NSVT emerge as predictors for SCD in children with RASopathy-associated HCM. The HCM Risk-Kids model may not be appropriate to use in this population, but larger multicentre collaborative studies are required to investigate this further.

Friedreich's ataxia-associated childhood hypertrophic cardiomyopathy: a national cohort study.

OBJECTIVE: Hypertrophic cardiomyopathy (HCM) is an important predictor of long-term outcomes in Friedreich's ataxia (FA), but the clinical spectrum and survival in childhood is poorly described. This study aimed to describe the clinical characteristics of children with FA-HCM. DESIGN AND SETTING: Retrospective, longitudinal cohort study of children with FA-HCM from the UK. PATIENTS: 78 children (<18 years) with FA-HCM diagnosed over four decades. INTERVENTION: Anonymised retrospective demographic and clinical data were collected from baseline evaluation and follow-up. MAIN OUTCOME MEASURES: The primary study end-point was all-cause mortality (sudden cardiac death, atrial arrhythmia-related death, heart failure-related death, non-cardiac death) or cardiac transplantation. RESULTS: The mean age at diagnosis of FA-HCM was 10.9 (±3.1) years. Diagnosis was within 1 year of cardiac referral in 34 (65.0%) patients, but preceded the diagnosis of FA in 4 (5.3%). At baseline, 65 (90.3%) had concentric left ventricular hypertrophy and 6 (12.5%) had systolic impairment. Over a median follow-up of 5.1 years (IQR 2.4-7.3), 8 (10.5%) had documented supraventricular arrhythmias and 8 (10.5%) died (atrial arrhythmia-related n=2; heart failure-related n=1; non-cardiac n=2; or unknown cause n=3), but there were no sudden cardiac deaths. Freedom from death or transplantation at 10 years was 80.8% (95% CI 62.5 to 90.8). CONCLUSIONS: This is the largest cohort of childhood FA-HCM reported to date and describes a high prevalence of atrial arrhythmias and impaired systolic function in childhood, suggesting early progression to end-stage disease. Overall mortality is similar to that reported in non-syndromic childhood HCM, but no patients died suddenly.

Clinical Features and Natural History of Preadolescent Nonsyndromic Hypertrophic Cardiomyopathy.

BACKGROUND: Up to one-half of childhood sarcomeric hypertrophic cardiomyopathy (HCM) presents before the age of 12 years, but this patient group has not been systematically characterized. OBJECTIVES: The aim of this study was to describe the clinical presentation and natural history of patients presenting with nonsyndromic HCM before the age of 12 years. METHODS: Data from the International Paediatric Hypertrophic Cardiomyopathy Consortium on 639 children diagnosed with HCM younger than 12 years were collected and compared with those from 568 children diagnosed between 12 and 16 years. RESULTS: At baseline, 339 patients (53.6%) had family histories of HCM, 132 (20.9%) had heart failure symptoms, and 250 (39.2%) were prescribed cardiac medications. The median maximal left ventricular wall thickness z-score was 8.7 (IQR: 5.3-14.4), and 145 patients (27.2%) had left ventricular outflow tract obstruction. Over a median follow-up period of 5.6 years (IQR: 2.3-10.0 years), 42 patients (6.6%) died, 21 (3.3%) underwent cardiac transplantation, and 69 (10.8%) had life-threatening arrhythmic events. Compared with those presenting after 12 years, a higher proportion of younger patients underwent myectomy (10.5% vs 7.2%; P = 0.045), but fewer received primary prevention implantable cardioverter-defibrillators (18.9% vs 30.1%; P = 0.041). The incidence of mortality or life-threatening arrhythmic events did not differ, but events occurred at a younger age. CONCLUSIONS: Early-onset childhood HCM is associated with a comparable symptom burden and cardiac phenotype as in patients presenting later in childhood. Long-term outcomes including mortality did not differ by age of presentation, but patients presenting at younger than 12 years experienced adverse events at younger ages.

Relationship Between Maximal Left Ventricular Wall Thickness and Sudden Cardiac Death in Childhood Onset Hypertrophic Cardiomyopathy.

BACKGROUND: Maximal left ventricular wall thickness (MLVWT) is a risk factor for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). In adults, the severity of left ventricular hypertrophy has a nonlinear relationship with SCD, but it is not known whether the same complex relationship is seen in childhood. The aim of this study was to describe the relationship between left ventricular hypertrophy and SCD risk in a large international pediatric HCM cohort. METHODS: The study cohort comprised 1075 children (mean age, 10.2 years [±4.4]) diagnosed with HCM (1-16 years) from the International Paediatric Hypertrophic Cardiomyopathy Consortium. Anonymized, noninvasive clinical data were collected from baseline evaluation and follow-up, and 5-year estimated SCD risk was calculated (HCM Risk-Kids). RESULTS: MLVWT Z score was <10 in 598 (58.1%), ≥10 to <20 in 334 (31.1%), and ≥20 in 143 (13.3%). Higher MLVWT Z scores were associated with heart failure symptoms, unexplained syncope, left ventricular outflow tract obstruction, left atrial dilatation, and nonsustained ventricular tachycardia. One hundred twenty-two patients (71.3%) with MLVWT Z score ≥20 had coexisting risk factors for SCD. Over a median follow-up of 4.9 years (interquartile range, 2.3-9.3), 115 (10.7%) had an SCD event. Freedom from SCD event at 5 years for those with MLVWT Z scores <10, ≥10 to <20, and ≥20 was 95.6%, 87.4%, and 86.0, respectively. The estimated SCD risk at 5 years had a nonlinear, inverted U-shaped relationship with MLVWT Z score, peaking at Z score +23. The presence of coexisting risk factors had a summative effect on risk. CONCLUSIONS: In children with HCM, an inverted U-shaped relationship exists between left ventricular hypertrophy and estimated SCD risk. The presence of additional risk factors has a summative effect on risk. While MLVWT is important for risk stratification, it should not be used either as a binary variable or in isolation to guide implantable cardioverter defibrillator implantation decisions in children with HCM.

A novel technique for stenting pulmonary artery and conduit bifurcation stenosis.

BACKGROUND: Distal conduit obstruction is a recognized complication after surgery for congenital heart disease requiring implantation of a conduit from the right ventricle to the pulmonary arteries. Endovascular stenting of distal conduit obstruction can be challenging due to the proximity to the pulmonary artery bifurcation. OBJECTIVE: A technique is described, whereby a single stent is mounted onto two balloon angioplasty catheters in tandem. This ensemble was delivered to the distal conduit/pulmonary artery via a large Mullins sheath on two guidewires, one placed in each of the branch pulmonary arteries. The aim was to assess safety and efficacy of this novel technique. MATERIALS AND RESULTS: Seven patients (mean age 13.4 (6.7-23.4) years, mean weight 44.2 (23-69) kg were treated with this method. The pressure gradient was reduced from 36 (26-52) mm Hg to 11 (8-15) mm Hg [P< 0.05]. RV/LV pressure ratio decreased from 0.85 (0.6-0.95) to 0.42 (0.35-0.5) [P < 0.05]. There were no significant complications. During follow-up over a median of 2.6 (0.3-6.7) years no patient required re-intervention or surgery. CONCLUSION: This novel technique appears to be safe and effective for stenting stenoses just proximal to pulmonary artery bifurcation.

Transcatheter interventions in the early postoperative period after the Fontan procedure.

OBJECTIVE: To analyze the safety and clinical impact of interventional cardiac catheter procedures in the management of early postoperative problems after completion of an extracardiac Fontan procedure. BACKGROUND: The mortality after Fontan procedure has consistently decreased over the last decade. The role of interventional catheterization to address early postoperative problems in this setting has not been studied systematically. METHODS: Over a 9.7-year period, 289 patients underwent an extracardiac fenestrated Fontan procedure with two early deaths (0.7%) and takedown in four (1.4%). Twenty-seven patients (9.3%) underwent 32 interventional cardiac catheter procedures at a median interval of 12.2 (1-30) days. The median weight was 14.5 (13.5-25) kg. The case notes and procedure records were reviewed retrospectively. RESULTS: Fontan pathway obstructions were treated in 11 patients with stent implantation with good results and no complications. Stent fenestration of the Fontan circulation was performed in 16 patients with one episode of transient hemiparesis and one episode of pericardial effusion. Three patients underwent initial balloon dilatation of branch pulmonary arteries or fenestration with little effect and underwent stent treatment 6 (5-9) days later. One patient had device closure of a large atrial fenestration. In one patient, residual anterograde pulmonary blood flow was occluded using a device. There were no deaths and in-hospital course was improved in all. CONCLUSION: Interventional cardiac catheter procedures can be performed safely and effectively in the early postoperative period after Fontan completion to address hemodynamic problems. These techniques contribute significantly to achieve a very low mortality and address morbidity after Fontan completion.

Outcomes From Pediatric Ablation: A Review of 20 Years of National Data.

OBJECTIVES: This study set out to examine outcomes from pediatric supraventricular tachycardia ablations over a 20-year period. This study sought to examine success rates and repeat ablations over time and to evaluate whether modalities such as 3-dimensional (3D) mapping, contact force, and cryotherapy have improved outcomes. BACKGROUND: Ablation of supraventricular tachycardia in pediatric patients is commonly performed in most congenital heart centers with excellent long-term results. METHODS: Data were retrieved from the NICOR (National Institute of Clinical Outcomes Research) database in the United Kingdom. Outcomes over time were evaluated, and procedure-related details were compared. RESULTS: There were 7,069 ablations performed from January 1, 1999, to December 31, 2018, at 10 centers. Overall, ablation success rates were 92% for accessory pathways, 97% for atrioventricular node re-entry tachycardia, and 89% for atrial tachycardia. There was an improvement in procedural success rates over time (p < 0.01). The use of 3D mapping did not alter success or need for repeat ablation but was associated with a higher proportion of lower fluoroscopy cases; 55% of 3D mapping cases used <5 min of fluoroscopy (p < 0.01). Patients needing a repeat ablation were 341 (12%) for accessory pathways, 128 (7%) for atrioventricular node re-entry tachycardia, and 35 (7%) for atrial tachycardia. Overall, the risk of complete heart block was low (n = 12, <0.01%). The use of cryotherapy was associated with an increased risk of needing a repeat ablation. CONCLUSIONS: Overall success rates from pediatric ablations are excellent and compare favorably to other registries. Introduction of newer technologies have likely made procedures safer and reduced radiation exposure, but they have not changed success rates or the need for a repeat procedure.