Empiric Slow Pathway Cryoablation in Symptomatic Children Without Documented Supraventricular Tachycardia

In symptomatic children without documented supraventricular tachycardia (SVT) and non-inducible atrioventricular nodal reentry tachycardia (AVNRT) the benefit of empiric slow pathway (SP) ablation is unknown. We evaluated 62 symptomatic patients without documented SVT that underwent electrophysiology study (EPS). The purpose of this study was to determine if symptoms improved after empiric SP ablation in children without documented SVT and without inducible AVNRT. Sixty-two symptomatic patients without previously documented SVT underwent EPS; 31 (50%) had inducible AVNRT and underwent SP ablation, 20 (32%) were non-inducible and underwent empiric SP ablation, 11 (18%) were non-inducible and had no ablation. After a mean follow-up of 23 ± 18 months there was no significant difference in freedom from symptoms within the non-inducible cohort regardless of whether empiric SP ablation was performed (p = 0.135). There was a significant improvement in symptoms at follow-up after SP ablation when comparing inducible and non-inducible patients (p = 0.020). During follow-up no patients had documented SVT. Symptomatic children without documented SVT do not benefit from empiric SP ablation when AVNRT cannot be induced.

Utility of routine follow-up defibrillation safety margin testing in young patients with epicardial implantable cardioverter-defibrillators

BACKGROUND

Routine defibrillation threshold testing (DFT) of transvenous implantable defibrillators (ICDs) has largely been in decline. In patients with non-transvenous ICDs that utilize subcutaneous and pleural ICD leads, serial DFT testing can detect a significant number of failures. Data about the utility of follow-up defibrillation safety margin testing (DSM) testing in pediatric patients and young adults with an epicardial ICD are lacking.

METHODS

Patients aged < 25 years old who underwent epicardial ICD placement at Mayo Clinic from 2014 to 2023 with at least one follow-up DSM test were included. The patients were divided into a "routine" (R) and "clinically indicated" (CI) group based on the index of clinical concern. Inadequate DSM was defined as unsuccessful defibrillation at an output of less than 10 J below the maximum output of the device. The purpose of this study was to assess the utility of follow-up DSM testing.

RESULTS

An epicardial ICD system was placed in 122 patients. A total of 26 patients met inclusion criteria and underwent a total of 47 DSM follow up tests. Inadequate DSM occurred in 1/33 (3%) in the R group and 2/14 (14%) DSM tests in the CI group. The median follow-up period was 54 and 36 months for the R and CI group, respectively.

CONCLUSIONS

Our data suggest that epicardial ICDs are reliable and routine follow-up DSM testing may not be necessary for all patients. DSM testing should be performed in individuals with epicardial ICD systems when there is clinical concern about lead or coil performance.

Septal Myectomy Outcomes in Children and Adolescents With Obstructive Hypertrophic Cardiomyopathy

BACKGROUND

Little data exist regarding characteristics and outcomes of pediatric patients undergoing septal myectomy. We evaluated this in a large referral population.

METHODS

Septal myectomy was performed in 199 consecutive patients aged ≤18 years with obstructive hypertrophic cardiomyopathy from January 1, 1976, to June 30, 2021.

RESULTS

Median age was 13 years (interquartile range [IQR], 8-15 years). Left ventricular myectomy approaches included transaortic (163 of 198 [82%]), transapical (16 of 198 [8%]), and combined (19 of 198 [10%]). Right ventricular interventions included myectomy (13 of 199 [7%]) and patch reconstruction of the outflow tract (15 of 199 [8%]). Maximum left ventricular outflow tract gradients decreased after myectomy (prebypass: 50 mm Hg [IQR, 31-73 mm Hg] vs postbypass: 4 mm Hg [IQR, 0-9 mm Hg], P < .001), and this was sustained long-term (5 mm Hg [IQR, 5-10 mm Hg] at 10 years). Iatrogenic aortic and mitral valve injuries occurred in 13 of 199 (7%) and 1 of 199 (1%), respectively; however, all were successfully repaired. Operative mortality was 2 of 199 (1%). The cumulative incidence of redo myectomy was low, at 5.8% at 5 and 8.3% at 10 years. Redo myectomy patients had higher maximum left ventricular outflow tract gradients on echocardiography at predischarge and 1 year and were younger at the index operation (8 years [IQR, 2.5-10 years] vs 13 years [IQR, 9-16 years], P < .001). Overall survival at 10 years was 90%, relative to 47% in a previously reported pediatric nonoperative cohort.

CONCLUSIONS

Pediatric septal myectomy provides safe, effective, and durable relief of ventricular outflow tract obstruction. Iatrogenic valve injury remains a low but nonnegligible risk. Recurrent obstruction requiring redo myectomy is infrequent and can be identified early. Long-term survival in this pediatric septal myectomy cohort appears to fare better than pediatric hypertrophic cardiomyopathy cohorts managed nonoperatively.

Pediatric Epicardial Devices: Early and Midterm Outcomes

BACKGROUND

Lead performance is suboptimal in young patients and a main cause of device system failure. Our objective was to assess early and midterm outcomes after epicardial device implantation in a contemporary pediatric cohort.

METHODS

A total of 116 consecutive pediatric patients underwent 137 epicardial device implantations from 2010 to 2019. Forty pacemakers and 97 implantable cardioverter defibrillators (ICDs) were implanted. Lead failure was defined as leads repaired, replaced, or abandoned due to fracture, dislodgement, or dysfunction. Freedom from device system failure was determined using Kaplan-Meier analysis.

RESULTS

Mean age at implantation was 10 ± 5 years, 46 (34%) were younger than 8 years old, 41 (30%) had prior cardiac surgery, and 38 (28%) had prior devices. Main indications were acquired heart block (17/40 [43%]), sinus node dysfunction (14/40 [35%]), and congenital heart block (7/40 [18%]) for pacemakers, and hypertrophic cardiomyopathy (46/97 [47%]), long QT syndrome (31/97 [32%]), and ventricular arrhythmia (17/97 [18%]) for ICDs. There were no early deaths. Three-year freedom from device system failure was 80% (95% CI 73%, 88%) for all patients and 88% (95% CI 79%, 99%) for patients <8 years old. Device system failure causes included lead fracture (20/34 [59%]), lead dysfunction (5/34 [15%]), lead dislodgement (5/34 [15%]), infection (3/34 [9%]), and pericarditis (1/34 [3%]). Reintervention was required in 26/34 (76%) device system failures.

CONCLUSIONS

Epicardial device implantation is safe, shows acceptable midterm outcomes in children, and is an effective option in patients younger than 8 years old. Close device surveillance continues to be essential to detect lead failure early and ensure timely reintervention.

Contemporary Early Postoperative Cone Repair Outcomes for Patients With Ebstein Anomaly

OBJECTIVE

To describe the early postoperative outcomes after cone repair (CR) for Ebstein anomaly (EA) across the age spectrum.

PATIENTS AND METHODS

For this study, 284 patients from 1 to 73 years of age who underwent CR at Mayo Clinic from June 1, 2007, to December 21, 2018, were separated by age group (1-<4, 4-<19, 19-<40, and 40+ years) and by disease severity for analysis. Outcomes of interest included death, reoperation, readmission, early postoperative complications, cardiac intensive care unit and hospital length of stay, and need for superior cavopulmonary anastomosis.

RESULTS

Mortality within 30 days was 0%. The reoperation rate was 4.9% (n=14) and the median hospital length of stay was 5 days, with no statistical difference between ages at time of CR or severity groups. The readmission rate was 2% (n=6). Postoperative complications were seen in 8.8% (n=25) of cases overall, with higher rates in the youngest age group (21%, P<.001). Superior cavopulmonary anastomosis was most common in the youngest age group (37% vs 17% overall, P<.001) and in those with severe disease (35%, P<.001).

CONCLUSION

Children and adults with Ebstein anomaly have very good early postoperative outcomes with a less than 10% complication and reoperation rate and very low mortality following cone reconstruction. In the setting of good and stable right ventricle function and no symptoms of heart failure or cyanosis, waiting for CR until 4 years of age may minimize early postoperative complications and need for superior cavopulmonary anastomosis.

2021 PACES Expert Consensus Statement on the Indications and Management of Cardiovascular Implantable Electronic Devices in Pediatric Patients: Developed in collaboration with and endorsed by the Heart Rhythm Society (HRS), the American College of Cardiology (ACC), the American Heart Association (AHA), and the Association for European Paediatric and Congenital Cardiology (AEPC) Endorsed by the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS)

In view of the increasing complexity of both cardiovascular implantable electronic devices (CIEDs) and patients in the current era, practice guidelines, by necessity, have become increasingly specific. This document is an expert consensus statement that has been developed to update and further delineate indications and management of CIEDs in pediatric patients, defined as ≤21 years of age, and is intended to focus primarily on the indications for CIEDs in the setting of specific disease categories. The document also highlights variations between previously published adult and pediatric CIED recommendations and provides rationale for underlying important differences. The document addresses some of the deterrents to CIED access in low- and middle-income countries and strategies to circumvent them. The document sections were divided up and drafted by the writing committee members according to their expertise. The recommendations represent the consensus opinion of the entire writing committee, graded by class of recommendation and level of evidence. Several questions addressed in this document either do not lend themselves to clinical trials or are rare disease entities, and in these instances recommendations are based on consensus expert opinion. Furthermore, specific recommendations, even when supported by substantial data, do not replace the need for clinical judgment and patient-specific decision-making. The recommendations were opened for public comment to Pediatric and Congenital Electrophysiology Society (PACES) members and underwent external review by the scientific and clinical document committee of the Heart Rhythm Society (HRS), the science advisory and coordinating committee of the American Heart Association (AHA), the American College of Cardiology (ACC), and the Association for European Paediatric and Congenital Cardiology (AEPC). The document received endorsement by all the collaborators and the Asia Pacific Heart Rhythm Society (APHRS), the Indian Heart Rhythm Society (IHRS), and the Latin American Heart Rhythm Society (LAHRS). This document is expected to provide support for clinicians and patients to allow for appropriate CIED use, appropriate CIED management, and appropriate CIED follow-up in pediatric patients.

Unconventional 2:1 Ventricular Pacing in a Neonate with Congenital Heart Block and Biventricular Noncompaction

Congenital complete heart block with concomitant biventricular noncompaction cardiomyopathy has been reported once previously. Although not universal, when restrictive physiology is present, impaired diastolic filling may pose a distinct challenge to pacing during the neonatal period. We present the case of a neonate with congenital complete heart block and biventricular noncompaction that resulted in severe diastolic dysfunction and atrioventricular dyssynchrony. We intentionally used 2:1 ventricular pacing to provide atrioventricular synchrony with every paced beat, and this resulted in hemodynamic and clinical improvement. This unconventional pacing technique may be beneficial in other neonates who have complete heart block and diastolic dysfunction.

What is the role of apical ventriculotomy in children and young adults with hypertrophic cardiomyopathy?

BACKGROUND

The transapical approach has been utilized in adult HCM patients with either midventricular obstruction or a small LV cavity; however, there are little data on its use in children.

METHODS

We retrospectively reviewed all patients (age <21 years) with HCM who underwent a transapical myectomy from January 2002 to December 2016. Indication for surgery was midventricular obstruction in 19/23 (83%) and small LV cavity in 4 (17%). Preoperative symptoms included: dyspnea (96%), chest pain (65%), presyncope (61%), and syncope (35%). The mean age at the time of operation was 14 ± 4.0 years (range, 4-20).

RESULTS

Overall, 23 patients (12 males) underwent transapical myectomy. A concomitant transaortic approach was performed in 16/19 (84%) with obstruction. The intraventricular gradient decreased from 71 mm Hg (IQR 44-92 mm Hg) preoperatively to 18 mm Hg (IQR 8-34 mm Hg, P < .0001) after myectomy. In patients with a small LV cavity, the mean left ventricular end diastolic dimension (LVEDD) increased from 40 ± 3 mm to 46 ± 3 mm (P = .05) after myectomy. There were no early deaths. Postoperative morbidity included complete heart block in 3 patients, 2 of which required pacemakers. Median follow up was 3.5 years (IQR 1.6-5.6). Symptoms improved in 95% of patients; the number of patients in NYHA class 3 or 4 heart failure decreased from 10/23 (43%) preoperatively to 3/23 (13%) postoperatively (P < .0001). Overall survival at 5 years postsurgery was 100%. Transplant-free survival was 91% and 87% at 1 and 5 years, respectively.

CONCLUSION

In children with HCM, transapical myectomy is an effective adjunct to a transaortic approach to abolish midventricular obstruction and it effectively increases LV stroke volume in patients with small LV cavities and nonobstructive HCM. It may be beneficial for these patients with significant symptoms and who have failed medical therapy as a treatment alternative to cardiac transplantation.

Left Axis Deviation in Children Without Previously Known Heart Disease

BACKGROUND

Left axis deviation (LAD) discovered in children via electrocardiogram (ECG) is uncommon but can be associated with heart disease (HD). The optimal diagnostic approach in a seemingly healthy child with LAD is unclear. We sought to better stratify which patients with LAD but without previously known HD may warrant additional workup.

METHODS

A retrospective chart review was performed to identify patients ≥1 to <18 years of age with LAD (QRS frontal plane axis 0 to -90) on an ECG between January 2002 and December 2014. Patients with known HD before their initial ECG were excluded.

RESULTS

Overall, 296 patients were identified (n = 181 [61%] male; mean age: 10.8 ± 4.6 years; mean QRS axis: -24 ± 22°). An echocardiogram was performed in 158 (53%) patients, with 24 (15%) having HD. Compared with those with an echocardiogram but without HD (n = 134), patients with HD had a more negative mean QRS axis (-42 vs -27°; P = .002) and were more likely to have a QRS axis ≤-42° (58% vs 26%; P = .003), ECG chamber enlargement or hypertrophy (38% vs 5%; P < .0001), and abnormal cardiac physical examination findings (75% vs 8%; P < .0001).

CONCLUSIONS

LAD discovered in isolation in the asymptomatic pediatric patient may not necessitate further cardiovascular investigation. Clinicians should consider obtaining an echocardiogram in patients with LAD and ECG cardiac chamber enlargement or hypertrophy, a QRS axis ≤-42°, and/or the presence of abnormal cardiac physical examination findings.

Radiofrequency Ablation in the Sinus of Valsalva for Ventricular Arrhythmia in Pediatric Patients

The need to perform catheter ablation of ventricular arrhythmia from within the sinuses of Valsalva in a pediatric patient is uncommon. This has been reported in adults, but there are little data about the feasibility, safety or efficacy of catheter ablation in the sinuses of Valsalva in the pediatric patients. This is a retrospective review of all patients aged 18 years or less, at two separate institutions with no structural heart disease that underwent an ablation procedure for ventricular arrhythmia mapped to the sinus of Valsalva from 2010 to 2015. We identified 8 total patients meeting inclusion criteria. Median age was 16 years and the median weight was 61 kg. All patients were symptomatic or had developed arrhythmia-induced ventricular dysfunction. Ablation was performed in the left sinus in 4 patients and the right sinus in 4 patients. No ablations were required in the non-coronary sinus. All 8 patients had an acutely successful ablation using radiofrequency energy. There were no complications. At a mean follow-up of 7 months (4-15 months), all patients were known to be living. Follow-up data regarding arrhythmia were available in 6 of the 8 patients, and none had recurrence of their ventricular arrhythmia off of all antiarrhythmic medications. Radiofrequency catheter ablation of ventricular arrhythmia in the sinus of Valsalva can be done safely and effectively in pediatric patients.

Electrocardiographic abnormalities in elite high school athletes: comparison to adolescent hypertrophic cardiomyopathy

BACKGROUND

In athletes, ECG changes from physiological cardiac remodelling are common but can overlap with findings from a pathological disorder. We compared ECG findings in a group of elite high school athletes to a cohort of adolescents with hypertrophic cardiomyopathy (HCM).

METHODS/RESULTS

We prospectively performed 15-lead ECGs and echocardiograms in 147 elite high school athletes. Student-athlete ECGs were compared in blinded fashion to ECGs of 148 adolescents with HCM of similar age and ethnicity. Standard ECG hypertrophy criteria and established expert opinion guidelines (European Society of Cardiology, ESC and Seattle criteria) were analysed. All student-athletes had normal echocardiograms. Overall, 77/147 (52%) of student-athletes met standard ECG criteria for ventricular hypertrophy compared to 126/148 (85%) adolescents with HCM (p<0.0001). There were 112/148 (76%) adolescents with HCM who had pathological Q-waves, T-wave inversion and/or ST-segment depression compared to 1/147 (1%) athletes (p<0.0001). Most patients with HCM (84%, 124/148) had ≥1 abnormal ECG finding(s) according to Seattle criteria, compared to 1% of student-athletes (2/147). Similarly, 130/148 (88%) patients with HCM met group-2 ESC criteria (abnormal), compared to 36/147 (24%) student-athletes (p<0.0001).

CONCLUSIONS

Over 50% of elite high school athletes with echocardiographically confirmed normal hearts satisfied standard voltage criteria for ventricular hypertrophy. Pathological Q-waves, T-wave inversion or ST-segment depression were most helpful in distinguishing adolescents with HCM from normals. Both ESC and Seattle criteria successfully stratified the student-athlete and HCM cohorts, however each had a false-negative rate >10% for the HCM cohort. The Seattle criteria demonstrated a significantly lower false-positive rate (1%) than the ESC criteria (24%).