PACES/HRS expert consensus statement on the evaluation and management of ventricular arrhythmias in the child with a structurally normal heart

Advancements in the diagnosis and management of premature ventricular contractions in pediatric patients

Background

Premature ventricular contractions (PVCs) are relatively common arrhythmias in the pediatric population, with implications that range from benign to potentially life-threatening. The management of PVCs in children poses unique challenges, and recent advancements in diagnostic and therapeutic options call for a comprehensive review of current practices.

Methods

This review synthesizes the latest literature on pediatric PVCs, focusing on publications from the past decade. We evaluate studies addressing the epidemiology, pathophysiology, diagnosis, and treatment of PVCs in children, including pharmacological, non-pharmacological, and invasive strategies.

Results

The review identifies key advancements in the non-invasive detection of PVCs, the growing understanding of their genetic underpinnings, and the evolving landscape of management options. We discuss the clinical decision-making process, considering the variable significance of PVCs in different pediatric patient subgroups, and highlight the importance of individualized care. Current guidelines and consensus statements are examined, and areas of controversy or limited evidence are identified.

Conclusions

Our review underscores the need for a nuanced approach to PVCs in children, integrating the latest diagnostic techniques with a tailored therapeutic strategy. We call for further research into long-term outcomes and the development of risk stratification tools to guide treatment. The potential of emerging technologies and the importance of multidisciplinary care are also emphasized to improve prognoses for pediatric patients with PVCs.

Wide complex rhythm in a well neonate: Where are the P waves?

A neonate was seen for an evolving broad QRS complex rhythm initially captured at birth as intermittent escape beats on electrocardiogram. Continuous monitoring recorded features mimicking pre-excitation, but closer analysis revealed a regular broad QRS complex rhythm with isorhythmic atrioventricular dissociation, favouring a ventricular source. Treatment with flecainide and propranolol achieved successful control of the incessant arrhythmia with improvement in cardiac function on echocardiogram.

Diastolic function evaluation in children with ventricular arrhythmia

Premature ventricular contractions (PVC) are frequently seen in children. We evaluated left ventricular diastolic function in PVC children with normal left ventricular systolic function to detect whether diastolic function disturbances affect physical performance. The study group consisted of 36 PVC children, and the control group comprised 33 healthy volunteers. Echocardiographic diastolic function parameters such as left atrial volume index (LAVI), left atrial strains (AC-R, AC-CT, AC-CD), E wave, E deceleration time (Edt), E/E' ratio, and isovolumic relaxation time (IVRT) were measured. In the cardiopulmonary exercise test (CPET), oxygen uptake (VO_{2 max}) was registered. Evaluation of diastolic function parameters revealed statically significant differences between the patients and controls regarding Edt (176.58 ± 54.8 ms vs. 136.94 ± 27.8 ms, p < 0.01), E/E' (12.6 ± 3.0 vs. 6.7 ± 1.0, p < 0.01), and IVRT (96.6 ± 19.09 ms. vs. 72.86 ± 13.67 ms, p < 0.01). Left atrial function was impaired in the study group compared to controls: LAVI (25.3 ± 8.2 ml/m² vs. 19.2 ± 7.5 ml/m², p < 0.01), AC-CT (34.8 ± 8.6% vs. 44.8 ± 11.8%, p < 0.01), and AC-R-(6.0 ± 4.9% vs. -11.5 ± 3.5%, p < 0.01), respectively. VO2 max in the study group reached 33.1 ± 6.2 ml/min/kg. A statistically significant, moderate, negative correlation between VO2 max and E/E' (r = -0.33, p = 0.02) was found. Left ventricular diastolic function is impaired and deteriorates with the arrhythmia burden increase in PVC children. Ventricular arrhythmia in young individuals may be related to the filling pressure elevation and drive to exercise capacity deterioration.

Younger postnatal age is associated with a lower heart rate on Holter monitoring during the first week of life

To evaluate heart rate (HR), the presence of extrasystoles and other Holter findings among healthy newborns, and to collect data for new normal limits for Holter parameters in newborns. For this cross-sectional study, 70 healthy term newborns were recruited to undergo 24-h Holter monitoring. Linear regression analysis was used in HR analyses. The age-specific limits for HRs were calculated using linear regression analysis coefficients and residuals. The mean (SD) age of the infants was 6.4 (1.7) days during the recording. Each consecutive day of age raised the minimum and mean HR by 3.8 beats per minute (bpm) (95% CI: 2.4, 5.2; P < .001) and 4.0 bpm (95% CI: 2.8, 5.2; P < .001), respectively. Age did not correlate with maximum HR. The lowest calculated limit for minimum HR ranged from 56 bpm (aged 3 days) to 78 bpm (aged 9 days). A small number of atrial extrasystoles and ventricular extrasystoles were observed in 54 (77%) and 28 (40%) recordings, respectively. Short supraventricular or ventricular tachycardias were found in 6 newborns (9%).

CONCLUSION

 The present study shows an increase of 20 bpm in both the minimum and mean HRs of healthy term newborns between the 3rd and 9th days of life. Daily reference values for HR could be adopted in the interpretation of HR monitoring results in newborns. A small number of extrasystoles are common in healthy newborns, and isolated short tachycardias may be normal in this age group.

WHAT IS KNOWN

• The current definition of bradycardia in newborns is 80 beats per minute. • This definition does not fit into the modern clinical setting of continuously monitored newborns, where benign bradycardias are commonly observed.

WHAT IS NEW

• A linear and clinically significant increase in heart rate was observed in infants between the ages of 3 and 9 days. • It appears as though lower normal limits for heart rate could be applied to the youngest newborns.

Frequent accelerated idioventricular rhythm in an otherwise healthy child: a case report and review of literature

BACKGROUND

Accelerated idioventricular rhythm (AIVR) is a wide QRS complex dysrhythmia that, as far as pediatric population is concerned, occurs mostly in children with underlying systemic or heart disease. Its clinical course is thought to be typically benign in otherwise healthy children and treatment to be completely needless. Existing guidelines/recommendations are based entirely on cases that had low daily burden of AIVR, and those referring to treatment itself are very unspecific. Pharmacologic therapy has been mostly unsuccessful and catheter ablation as a way of treatment has been only sporadically reported. This article is a case report with a literature review that aims to practically separate the age groups into newborn and older children and to emphasize the different clinical outcomes of children with occasional and frequent AIVR. There are only a few cases so far describing undesirable outcomes of this condition, and most of these patients had high daily burden of AIVR. To be more specific, among 38 healthy children older than 1 year reported in total, 6 had undesirable outcomes, short-term in terms of developing malignant arrhythmia or long-term in terms of developing cardiomyopathy/heart failure.

CASE PRESENTATION

An 11-year-old boy had been referred to our center for a workup of incidentally discovered wide-complex arrhythmia. He was asymptomatic, with no underlying cardiac or systemic diseases. Continuous heart rate monitoring detected AIVR during most time of monitoring. In 24-h Holter-ECG, wide QRS complexes accounted for 73%. With parental consent, we conducted an electrophysiological study accompanied by radiofrequent ablation of ectopic focus, which lead to an instantaneous sinus rhythm that continued during the entire follow-up.

CONCLUSION

AIVR is a rare dysrhythmia in the pediatric population, typically considered benign. Nevertheless, more than a few cases evidence its harmful potential, short-term in terms of developing malignant arrhythmia or long-term in terms of developing cardiomyopathy. Gathering more knowledge and experience along with conducting further studies is essential for the enhancement of understanding this condition, and selecting potentially vulnerable patients as well as their treatment.

Cardiopulmonary capacity is reduced in children with ventricular arrhythmia

BACKGROUND

Premature ventricular contractions (PVCs) are frequently seen in children and are considered benign. A substantial group of adolescents with PVCs complain about a broad range of clinical symptoms, including low exertion tolerance.

OBJECTIVE

The purpose of this study was to evaluate prospectively whether ventricular arrhythmia affects physical performance in adolescents with normal left ventricular function, using a cardiopulmonary exercise test (CPET) and evaluating the electrocardiographic (ECG) characteristics of patients with PVCs with regard to exercise capacity.

METHODS

The study group consisted of 49 children with PVCs and normal left ventricular function. The control group consisted of 36 healthy volunteers. Standard ECG, 24-hour Holter ECG, and CPET were performed. PVCs were analyzed for QRS duration, bundle branch block pattern, QRS axis, and coupling interval (CInt). For CPET, heart rate (HR), oxygen uptake (VO_2max), predicted VO_2max, and VO_2max expressed as a percentage of the predicted value (%VO₂) were measured.

RESULTS

In 37 patients (76%), arrhythmia subsided during exercise. Patients achieved lower VO_2max (32.9 ± 6.3 mL/min/kg) than controls (40.4 ± 6.7 mL/min/kg; P <.01). %VO₂ was 71.0 ± 13.7 in patients and 79.3 ± 12.2 in controls (P <.01). Exercise HR at which PVCs subsided correlated with VO_2max (r = 0.3; P = .07). Patients with persisting arrhythmia performed worse than those in whom arrhythmia subsided during exercise (VO_2max, P <.01; %VO_2,P <.01). No correlation between QRS and CInt parameters and VO_2max was observed.

CONCLUSION

Patients with PVCs have lower aerobic capacity than their healthy peers. Further worsening of exercise capacity is present when PVCs are preserved during effort.

Extrasystoles or short bradycardias of the newborn seldom require subsequent 24-hour electrocardiographic monitoring

AIM

To retrospectively assess the indications for and findings on 24-hour electrocardiographic (Holter) monitoring in newborns, focussing on bradycardias and extrasystoles.

METHODS

Data included 337 term-born infants. Holter indications were categorised into bradycardias below 80 beats per minute, extrasystoles, any tachycardia and other. Heart rate below 60 beats per minute, pathological atrioventricular conduction, supraventricular or ventricular tachycardia, or either atrial premature contractions over 10% or ventricular premature contractions over 5% of total beats were defined as significant arrhythmia on Holter.

RESULTS

The median age was 6 days (range: 2-62 days). Bradycardia (42%) or extrasystoles (32%) were the most common Holter indications. Fifty-three infants (16%) had significant arrhythmia on Holter. Heart disease or 12-lead electrocardiogram expressing extrasystoles or conduction abnormalities were associated with significant arrhythmias (p = 0.046 and p < 0.001, respectively). Twenty-seven of 109 infants (25%) with extrasystoles as a Holter indication had abnormal Holter results, but only seven (6.4%) had significant arrhythmia on Holter if the 12-lead electrocardiogram was normal. No pathology was found behind bradycardias below 80 beats per minute in the absence of heart disease.

CONCLUSION

Among term newborns with extrasystoles or bradycardias, Holter monitoring could be targeted to infants with heart disease or abnormal electrocardiograms.

Approach to Wide Complex Tachycardia in Paediatric Patients

Wide complex tachycardia (WCT) is an infrequently encountered condition in paediatric patients and may be due to a variety of causes including supraventricular tachycardia with aberrant conduction, ventricular activation via an accessory pathway, ventricular pacing, or ventricular tachycardia. Immediate tachycardia termination is required in haemodynamically unstable patients. After stabilization or in those with haemodynamically tolerated WCT, a careful review of electrocardiographic tracings and diagnostic manoeuvres are essential to help elucidate the cause. Subacute and chronic management for WCT will depend on the underlying cause as well as features of the patient and the tachycardia presentation. This article will review the epidemiology, potential causes, and management of WCT in children. A detailed review of the pathophysiology, differential diagnosis, and diagnostic and treatment options is provided to enable the reader to develop a practical approach to managing this condition in young patients.

Accelerated idioventricular rhythm in a healthy newborn: frightening but non-threatening

Accelerated idioventricular rhythm is a rare but benign form of ventricular tachycardia which might be challenging to differentiate from other more worrisome forms. We present the case of a healthy newborn diagnosed with an accelerated idioventricular rhythm which is spontaneously terminated without the need for medical therapy.

Diagnostic Value of the TpTe Interval in Children with Ventricular Arrhythmias

BACKGROUND

The changes in the period of ventricular repolarization, i.e., QT interval, QTp (Q-Tpeak) and TpTe interval (Tpeak-Tend), make it possible to assess the electrical instability of the heart muscle, which may lead to the development of life-threatening ventricular arrhythmia. The aim of the study was to determine and evaluate the use of differences in T-wave morphology and durations of repolarization period parameters (QT, TpTe) in resting ECGs for children with ventricular arrhythmias.

METHODS

The retrospective analysis was made of the disease histories of 80 examined children with resting ECGs, which were admitted to the Children's Cardiology Department. The study group consisted of 46 children aged 4 to 18 with ventricular arrhythmias and the control group consisted of 34 healthy children between 4 and 18 years of age, with no arrhythmias.

RESULTS

The duration of the TpTe interval was significantly (p < 0.001) longer in the group of children with ventricular arrhythmia with abnormal T-wave (bactrian/bifid, humid/biphasic) compared to the TpTe interval in children with ventricular arrhythmia with the normal repolarization period. The duration of the TpTe (p < 0.001), QTcB (p < 0.001) and QTcF (p < 0.001) intervals were significantly longer in the group of children with ventricular arrhythmias and with abnormal T-wave compared to the values of the TpTe, QTcB, and QTcF intervals of the control group with normal morphology of the repolarization period. Only the duration of the TpTe interval was significantly (p = 0.020) longer in the group of children with ventricular arrhythmia without clinical symptoms.

CONCLUSIONS

Children with benign ventricular arrhythmias recorded on a standard ECG with prolonged TpTe and QT intervals and abnormal T-wave morphology require systematic and frequent cardiac check up with long term ECG recordings due to the possibility of future more severe ventricular arrhythmias. Further follow-up studies in even larger groups of patients are necessary to confirm the values of these repolarization parameters in clinical practice.

Clinical characteristics and therapeutic strategy of frequent accelerated idioventricular rhythm

Background

Accelerated idioventricular rhythm (AIVR) is often transient, considered benign and requires no treatment. This observational study aims to investigate the clinical manifestations, treatment, and prognosis of frequent AIVR.

Methods

Twenty-seven patients (20 male; mean age 32.2 ± 17.0 years) diagnosed with frequent AIVR were enrolled in our study. Inclusion criteria were as follows: (1) at least three recordings of AIVR on 24-h Holter monitoring with an interval of over one month between each recording; and (2) resting ectopic ventricular rate between 50 to 110 bpm on ECG. Electrophysiological study (EPS) and catheter ablation were performed in patients with distinct indications.

Results

All 27 patients experienced palpitation or chest discomfort, and two had syncope or presyncope on exertion. Impaired left ventricular ejection fraction (LVEF) was identified in 5 patients, and LVEF was negatively correlated with AIVR burden (P < 0.001). AIVR burden of over 73.8%/day could predict impaired LVEF with a sensitivity of 100% and specificity of 94.1%. Seventeen patients received EPS and ablation, five of whom had decreased LVEF. During a median follow-up of 60 (32, 84) months, LVEF of patients with impaired LV function returned to normal levels 6 months post-discharge, except one with dilated cardiomyopathy (DCM). Two patients died during follow-up. The DCM patient died due to late stage of heart failure, and another patient who refused ablation died of AIVR over-acceleration under fever.

Conclusions

Frequent AIVR has unique clinical manifestations. AIVR patients with burden of over 70%, impaired LVEF, and/or symptoms of syncope or presyncope due to over-response to sympathetic tone should be considered for catheter ablation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02221-0.

Etiology is a predictor of recurrence after catheter ablation of ventricular arrhythmias in pediatric patients

BACKGROUND

Ventricular arrhythmias (VAs) are rare in pediatric patients, especially in absence of structural heart disease (SHD). Few data are available regarding the invasive VAs treatment with catheter ablation (CA) in pediatric patients and predictors of outcomes have not been fully investigated.

OBJECTIVE

To describe the clinical presentation, procedural characteristics, and outcomes in pediatric patients undergoing CA for VAs.

METHODS

Eighty-one consecutive pediatric patients (58 male [72%], 15.5 ± 2.2 years) treated by CA for ventricular tachycardia (VT) or premature ventricular beats (PVBs) were retrospectively evaluated. Study endpoints were VAs recurrence and mortality for any cause.

RESULTS

Ninety-five procedures were performed in 81 patients, 52 (55%) PVBs and 43 (45%) VT ablations. During a follow-up of 35.0 months (interquartile range = 13.0-71.0), 14 patients (14.7%) had a VA recurrence: 11 (33.3%) patients treated with CA for VT and 3 (6.2%) patients treated for PVBs (p < .001). One patient (1%) died 26 months after the procedure during an electrical storm. Patients with SHD had higher VAs recurrence rate, as compared with idiopathic VAs (pairwise log-rank p < .001). Patients treated with CA for VT had higher VA recurrence rate, as compared with PVB patients (pairwise log-rank p = .002). At Cox multivariate analysis only SHD was an independent predictor of VAs recurrence (hazard ratio = 5.56, 95% confidence interval = 2.68-11.54, p < .001).

CONCLUSION

CA of VAs is effective and safe in a pediatric population. CA of idiopathic and fascicular VAs are associated with lower recurrence rate, than VAs in the setting of SHD.

Evaluation of Galectin-3 Plasma Concentration in Adolescents with Ventricular Arrhythmia

Galectin-3 (G3) is a biomarker known as an inflammatory state exponent. The aim of this paper was to analyze the G3 in adolescents with ventricular arrhythmia (VES) in order to evaluate its impact on myocardial tissue preservation. The study group (SG) consisted of 25 VES adolescents. The control group (CG) was 21 healthy children. G3 was assessed in the SG and CG. In the SG electrocardiography, Holter monitoring, echocardiography and CMR were performed. The G3 in SG was 13.45 ± 11.4 ng/mL and in CG 7.2 ± 2.0 ng/mL, p < 0.001. Moderate positive correlation between the G3 and z-score of the left ventricular diameter (r = 0.47, p = 0.041) and moderate negative correlation between the G3 and the left ventricular ejection fraction in cardiac magnetic resonance (CMR EF) (-0.49, p = 0.032) were found. According to the multiple linear regression analysis, CMR EF and VES were independent predictors for G3 elevation. Conclusion: Galectin-3 plasma concentration is elevated and correlates with the chosen left ventricular dysfunction parameters in adolescents suffering from ventricular arrhythmia. Further investigation is necessary to establish if elevated G3 is a useful biomarker for screening young individuals with ventricular arrhythmia who are at risk of structural cardiovascular pathology.

Into a Fluoroless Future: an Appraisal of Fluoroscopy-Free Techniques in Clinical Cardiac Electrophysiology

Purpose of Review

There are risks to both patients and electrophysiology providers from radiation exposure from fluoroscopic imaging, and there is increased interest in fluoroscopic reduction. We review the imaging tools, their applications, and current uses to eliminate fluoroscopy.

Recent Findings

Multiple recent studies provide supporting evidence for the transition to fluoroscopy-free techniques for both ablations and device implantation. The most frequently used alternative imaging approaches include intracardiac echocardiography, cardiac MRI guidance, and 3D electroanatomic mapping systems. Electroanatomic mapping and intracardiac echocardiography originally used to augment fluoroscopy imaging are now replacing the older imaging technique. The data supports that the future of electrophysiology can be fluoroscopy-free or very low fluoroscopy for the vast majority of cases.

Summary

As provider and institution experience grows with these techniques, many EP labs may choose to completely forego the use of fluoroscopy. Trainees will benefit from early experience with these techniques.

Does Premature Ventricular Contractions Affect Exercise Capacity in Teenagers with Normal Hearts?

Premature ventricular contractions (PVCs) are common in teenagers even in the absence of structural heart disease or channelopathy. The suppression of PVCs with exercise is a favorable prognostic indicator. There is a paucity of data regarding the relationship between exercise capacity and PVC burden in this population. Our objective was to evaluate the association between various exercise stress parameters and PVC burden ascertained with a 24 h Holter in children without structural heart disease and/or channelopathy. In this retrospective study, 447 patient's charts with a diagnosis of PVC were reviewed at a single tertiary center. The study cohort consisted of ninety one patients with no structural heart disease or channelopathy who underwent an echocardiogram, maximal stress test, and 24 h Holter monitor. The cohort was divided into two groups based on PVC burden by 24-h Holter monitoring: < 10% and ≥ 10%. Peak oxygen uptake (VO₂ in ml/kg/min), an indicator of maximal aerobic capacity, was collected. Other exercise parameters included a) percentage of predicted VO₂ (%VO₂) based on age, weight, height, and gender b) percent oxygen pulse, c) Anaerobic threshold (AT), and d) Metabolic equivalents. Demographic and exercise stress test-derived parameters were compared between the two groups using student t test and a p value < 0.05 was considered significant. In our cohort of 91 patients, the mean (SD) age at exercise was 14.5 (3.2) years with 56 (62%) males. Left ventricle shortening fraction (LVFS) was ≥ 28% in all enrolled patients. PVCs were monomorphic in 72(80%) patients. The mean (SD) PVC burden was 14.43% (12.3) ranging from 0.1 to 49.8%. PVC burden was ≥ 10% in 48 (53%) patients. Eighty eight (97%) patients in the study cohort had suppression of PVCs with exercise. There were no significant differences between the two groups (< 10% vs. ≥ 10% PVC burden) with respect to demographic or exercise test-derived parameters. Univariate regression between PVC burden and %VO₂ did not show significant correlation (r = - 0.04, p = 0.75). Children even with ≥ 10% PVC burden did not demonstrate any objective decrease in their exercise capacity. A plausible reason for no difference in exercise capacity in our cohort may be due to lower PVC load or shorter duration of PVCs compared to adults.

Belhassen Ventricular Tachycardia in a Child

First reported in 1981, idiopathic left ventricular tachycardia (VT) of the Belhassen type is characterized during electrocardiography (ECG) by a right bundle branch pattern and left axis deviation. We report the case of a 15-year-old Hispanic male who, during a routine evaluation ECG to support sports participation, was found to have nonsustained monomorphic VT. Prior to his exercise treadmill test, his physical examination and echocardiogram were normal. Then, during preparation for the exercise treadmill test, the ECG showed sustained monomorphic VT with a right bundle branch block pattern and superior QRS axis, suggesting a diagnosis of Belhassen VT.

Accelerated Idioventricular Rhythm: A Rare Case of Wide-Complex Dysrhythmia in a Teenager

BACKGROUND

Accelerated idioventricular rhythm (AIVR) is an uncommon and typically benign dysrhythmia with similarities to more malignant forms of ventricular tachycardia (VT). It is often seen in adults after myocardial infarctions, although it also arises in the newborn period, as well as in children with and without congenital heart disease.

CASE REPORT

We describe a presentation of AIVR in an otherwise healthy 13-year-old girl, discovered on arrival to the pediatric emergency department in the setting of post-tonsillectomy bleeding. The case reviews the diagnostic criteria of AIVR, associated symptoms, the pathophysiologic origin of AIVR, and potential treatment strategies. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Given its morphologic similarities to life-threatening forms of VT, AIVR can be misdiagnosed in the emergency department or primary care settings. With an understanding of the dysrhythmia's unique features, emergency physicians can avoid unnecessary interventions and provide the correct diagnosis, workup, and management of AIVR for pediatric patients.

The Efficacy of Anti-Arrhythmic Drugs in Children With Idiopathic Frequent Symptomatic or Asymptomatic Premature Ventricular Complexes With or Without Asymptomatic Ventricular Tachycardia: a Retrospective Multi-Center Study

The aim of the study is to compare the efficacy of flecainide, beta-blockers, sotalol, and verapamil in children with frequent PVCs, with or without asymptomatic VT. Frequent premature ventricular complexes (PVCs) and asymptomatic ventricular tachycardia (VT) in children with structurally normal hearts require anti-arrhythmic drug (AAD) therapy depending on the severity of symptoms or ventricular dysfunction; however, data on efficacy in children are scarce. Both symptomatic and asymptomatic children (≥ 1 year and < 18 years of age) with a PVC burden of 5% or more, with or without asymptomatic runs of VT, who had consecutive Holter recordings, were included in this retrospective multi-center study. The groups of patients receiving AAD therapy were compared to an untreated control group. A medication episode was defined as a timeframe in which the highest dosage at a fixed level of a single drug was used in a patient. A total of 35 children and 46 medication episodes were included, with an overall change in PVC burden on Holter of -4.4 percentage points, compared to -4.2 in the control group of 14 patients. The mean reduction in PVC burden was only significant in patients receiving flecainide (- 13.8 percentage points; N = 10; p = 0.032), compared to the control group and other groups receiving beta-blockers (- 1.7 percentage points; N = 18), sotalol (+ 1.0 percentage points; N = 7), or verapamil (- 3.9 percentage points; N = 11). The efficacy of anti-arrhythmic drug therapy on frequent PVCs or asymptomatic VTs in children is very limited. Only flecainide appears to be effective in lowering the PVC burden.

Speckle Tracking Echocardiography in Pediatric Patients with Premature Ventricular Contractions

Premature ventricular contractions (PVCs) in pediatric patients without structural heart disease and normal left ventricular systolic function rarely require therapy, though it is unknown whether these patients have subclinical cardiac dysfunction. Speckle tracking echocardiography is an additional means of evaluating cardiac function in asymptomatic pediatric PVC patients with normal standard measures of left ventricular (LV) function. Asymptomatic pediatric patients (< 21 years) without congenital heart disease, LV ejection fraction (LVEF) ≥ 55% and PVC burden ≥ 5% on 24-h Holter monitor were included. Demographic information, exercise stress test results, standard echocardiographic measures of LV systolic function and PVC morphology by 12-lead ECG were collected. Peak global systolic longitudinal strain (GLS) from apical four-chamber view was analyzed offline. 29 patients were identified (mean age 11.7 ± 5.8 years, 49.2 ± 25.3 kg, 59% male). Mean PVC burden was 12.0 ± 7.0% (range 5-37.5%). 14/29 (48%) had exercise stress testing with evidence of PVCs; 9/14 (64%) had PVC suppression at a mean heart rate (HR) of 160 ± 23 bpm and 5/14 (36%) did not suppress at a mean maximum HR of 188 ± 9 bpm. All patients had normal strain values by speckle tracking echocardiography (mean LV GLS - 22.5 ± 2.0%, LV global circumferential strain - 25.3 ± 3.9 and RV GLS - 24.1 ± 3.0%). There was no correlation between PVC burden and cardiac function parameters. Asymptomatic pediatric patients without structural heart disease, preserved LVEF/shortening fraction and PVC burden ≥ 5% demonstrated normal cardiac function including strain patterns indicating no evidence of subclinical cardiac dysfunction. Larger scale studies and longitudinal evaluation of left ventricular function using speckle tracking echocardiography is warranted in this population.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

Risk Factors for Left Ventricle Enlargement in Children With Frequent Ventricular Premature Complexes

We aimed to assess the risk factors for left ventricle (LV) enlargement in children with idiopathic frequent ventricular premature complexes (VPC) and discuss the clinical features and treatment strategies. Children diagnosed with idiopathic frequent VPC at Xinhua Hospital affiliated to the Shanghai Jiao Tong University during 2013 to 2019 were retrospectively evaluated. Gender, age, body mass index, weight, number and sources of frequent VPC, and changes in the LV structure were analyzed and compared. A total of 29 patient showed changes in LV enlargement at diagnosis [age 7.3 ± 4.0 years, 8 (24.1%) had symptoms such as syncope, palpitations, fatigue, and dizziness], whereas 220 showed a normal LV structure [age 7.2 ± 4.5 years, 77 (32.3%) with symptoms]. Patients with LV enlargement showed a higher percentage of VPC on Holter recordings (30.2 ± 10.7 versus 9.4 ± 6.9, p < 0.05), higher prevalence of ventricular tachycardia [22 (75.9%) vs 36 (16.4%), p < 0.0001], higher number of couplets [26 (96.7%) vs 132 (60.0%), p = 0.002], higher number of trigeminy [27 (97.8%) vs 133 (83.2%), p < 0.001], higher QRS wave width [80.0 ± 5.9 vs 77.8 ± 6.8, p = 0.021], and higher incidence of right bundle branch block [11 (37.9%) vs 2 (0.9%), p < 0.001]. Multivariate analysis suggested that right bundle branch block (Odds Ratio = 143.9 p <0.001) and VPC burden (>20%) (Odds Ratio = 132.6, p <0.001) were the risk factors for LV enlargement in children with idiopathic frequent VPC. In conclusion, frequent VPC can induce prominent enlargement or LV dysfunction in children. LV enlargement are reversible after catheter ablation or medication.

Evaluation and Management of Common Neonatal Arrhythmias

Neonates can have different types of arrhythmias that range from benign to life-threatening. The evaluation, approach to acute presentation, and long-term management depend on correct identification of the arrhythmia. A systematic approach to analyzing the electrocardiogram and the telemetry monitor, if available, is often sufficient to diagnose the type of arrhythmia.

Benign arrhythmias in pediatric patients

An irregular heart rhythm is a common concern among children. Recognizing the cause of the irregular rhythm is crucial for the proper diagnosis and management by primary physicians as well as pediatric specialists. The cause of pediatric arrhythmias can be identified based on the clinical history, physical examination, presenting symptoms, and electrocardiogram. Pediatric arrhythmias are classified as benign and non-benign. Both benign and non-benign arrhythmias can originate from the sinoatrial node, atrial myocardium, atrioventricular node, and ventricle myocardium. The common form of benign arrhythmias, including sinus arrhythmia, premature atrial contraction, premature ventricular contraction, and Wenckebach atrioventricular block, have no clinical significance or need for therapy. On the other hand, non-benign arrhythmias, such as supraventricular tachycardia, ventricular tachycardia, high-degree atrioventricular conduction abnormalities, and genetic arrhythmia, can affect the hemodynamic state and may cause a serious condition in pediatric patients. Most cases of benign arrhythmia are asymptomatic, and the prognosis is favorable for the normal heart. In this article, we review our current understanding of the electrocardiographic characteristics, clinical presentation, etiology, and natural history of benign arrhythmias in pediatric patients.

Incidence of arrhythmias and electrocardiographic abnormalities in symptomatic pediatric patients with PCR-positive SARS-CoV-2 infection, including drug-induced changes in the corrected QT interval

Background

There is limited data regarding the electrophysiological abnormalities and arrhythmias in children with COVID-19, including those associated with treatment using potentially proarrhythmic hydroxychloroquine (HCQ) and azithromycin (AZN).

Objectives

To describe the electrophysiologic findings and arrhythmias associated with pediatric COVID-19 and its treatment.

Methods

A single-center retrospective chart review was undertaken and included all patients with (1) symptoms of COVID-19 and (2) PCR-positive nasopharyngeal swabs for SARS-CoV-2 who were placed on continuous telemetry for the duration of their hospitalization during March through May, 2020.

Results

Thirty-six patients were included in the study. Significant arrhythmias were found in 6 (nonsustained ventricular tachycardia in 5 and sustained atrial tachycardia in 1). All were self-resolving and half prompted prophylactic antiarrhythmic therapy. Patients with significant arrhythmias were likely to have noncardiac comorbidities (4/6), but these were not more common than in patients without arrhythmias (20/30, P = 1). The use of HCQ was associated with statistically significant QTc prolongation (413 ± 19 ms vs 425 ± 16 ms, P =.005). QTc was not statistically different in patients with and without arrhythmias (425 ± 15 ms vs 425 ± 15 ms, P = 1).

Conclusions

In pediatric patients with PCR-positive active COVID-19 infection, significant arrhythmias are infrequent, but are more common than expected in a general pediatric population. Comorbidities are not more common in patients with arrhythmias than in patients without arrhythmias. COVID-19 treatment using HCQ is associated with QTc prolongation but was not associated with arrhythmias in pediatric patients.

Incessant fascicular ventricular tachycardia in an infant with heart failure

We report an eight month old infant who presented with incessant Fascicular tachycardia and heart failure which was refractory to drugs and cardioversion. Sinus rhythm was restored by radio frequency ablation and this resulted in improvement in clinical status and cardiac function. Role of catheter ablation in this situation is discussed.

Accelerated idioventricular rhythm resulting in torsades de pointes and cardiac arrest in a child: successfully cryoablated in left'coronary cusp

Known as a benign arrhythmia and normally requiring no specific treatment, accelerated idioventricular rhythm can rarely degenerate to a life-threatening arrhythmia. Here, we present a child with left coronary cusp-originating accelerated idioventricular rhythm, degenerating into torsades de pointes and resulting in cardiac arrest, which was ablated with a cryocatheter. An 11-year-old boy, followed due to asymptomatic accelerated idioventricular rhythm before, was referred to our department because he had experienced an aborted cardiac arrest during sleep. He had been resuscitated for 5 minutes. Twenty-four-hour Holter-ECG revealed incessant accelerated idioventricular rhythm, consisting up to 90% of the whole record and two torsades de pointes attacks, triggered by accelerated idioventricular rhythm-induced "R on T" phenomenon, and resulting in syncope and cardiac arrest. Transthoracic echocardiography revealed no structural cardiac defect but mild left ventricular systolic dysfunction with an ejection fraction of 45% and shortening fraction 23%. An electrophysiologic study was conducted, and accelerated idioventricular rhythm focus was mapped to left aortic coronary cusp. A cryocatheter with an 8-mm tip was preferred for successful ablation of the accelerated idioventricular rhythm focus, due to close neighbourhood to coronary ostium. The patient was discharged in 3 days without any premature ventricular contractions or accelerated idioventricular rhythm and with normalised cardiac functions. After 9 months on follow-up, he was still asymptomatic, without any premature ventricular contractions or accelerated idioventricular rhythm and with normal cardiac functions. Although the clinical course of accelerated idioventricular rhythm is known as benign, accelerated idioventricular rhythm can rarely degenerate to a life-threatening arrhythmia. In such cases, electrophysiologic study and catheter ablation are a good option in such cases with accelerated idioventricular rhythm for an ultimate cure.

Can the 12-lead ECG distinguish RVOT from aortic cusp PVCs in pediatric patients?

BACKGROUND

The ability to differentiate right ventricular outflow tract (RVOT) from coronary cusp (CC) site of origin (SOO) by 12-lead ECG in pediatric patients may impact efficacy and procedural time. The objective of this study was to predict RVOT versus CC SOO by ECG in pediatric patients.

METHODS

Pediatric patients (<21 years) without structural heart disease with RVOT or CC premature ventricular contraction (PVC) ablations performed (2014-2018) were evaluated through multi-institution retrospective review. Demographics, ECG PVC parameters, ablation site, recurrence, and repeat procedures were collected.

RESULTS

Thirty-seven patients were evaluated (mean age 14.6 years, weight 60.6 kg): 11 CC and 26 RVOT PVC SOO. CC PVCs were less likely to exhibit left bundle branch block (64% vs 100%, P = .005), had larger R-wave amplitude in V1 (0.27 vs 0.11 mV, P = .03), larger R/S ratio in V1 (0.37 vs 0.09, P = .003), and had precordial transition in V3 or earlier (73% vs 15%, P = .002). A composite score was created with the following variables: isodiphasic or positive QRS in V1, R/S ratio in V1 > 0.05, S wave in V1 < 0.9 mV, and precordial transition at or before V3. Composite score ≥ 2 was associated with a CC SOO (OR 42.0, P = .001, and AUC 0.86).

CONCLUSIONS

12-lead ECG of PVCs from the CC was associated with larger V1 R-wave amplitude, larger R/S ratio in V1, and precordial transition at or before V3. A composite score may help predict PVC/VT arising from the CC.

Risk factors for development of ventricular tachycardia in patients with ventricular premature contraction with a structurally normal heart

BACKGROUND

We examined risk factors for development of ventricular tachycardia (VT) in pediatric patients with ventricular premature contractions (VPCs) and a structurally normal heart.

METHODS

The subjects were 81 844 first graders and 88 244 seventh graders of Kagoshima City School-based cardiovascular screening (SCV-screening) between 2001 and 2015. We retrospectively reviewed the clinical data of students who were diagnosed as having VPC.

RESULTS

Ventricular premature contractions were observed in 134 first graders (0.16%) and 270 seventh graders (0.31%). On the screening electrocardiograms (ECGs), 43 patients (11%) showed bi-/trigemini, three patients (0.7%) showed a couplet, and one patient showed VT. We obtained 166 patients' follow-up information and evaluated 59 patients (36%) as improved, 97 patients (58%) as no change, and 10 patients (6%) as worsened (couplets, five; triplets, two; VT, three). We assumed that these worsened patients have risk factors for development of VT. Comparing the findings of SCV-screening ECGs of risk patients with the others, a significant difference was observed only in the number of VPCs (per 10 seconds) (mean ± SD; 4.3 ± 2.6 vs 1.8 ± 1.4, P < .0001). A logistic regression analysis revealed that the number of VPCs was significant (P < .001, odds ratio; 2.01, 95% confidence intervals; 1.46-2.93). Receiver operating characteristics analysis showed an adequate cut-off number of three VPCs for the risk, the sensitivity was 89% and the specificity was 77%.

CONCLUSIONS

Of the patients with VPC and a structurally normal heart, a few patients developed VT. Careful observation is important in patients who had three or more VPCs on SCV-screening ECG.

Ventricular Tachycardia in an Infant Without Congenital Anomaly: A Case Report

Ventricular tachycardia (VT) is a serious form of arrhythmia that can be life-threatening; that’s why diagnosis and treatment are very important in order to avoid serious complications. We are reporting this case of VT which is a rare entity, especially, in healthy infants. This infant, without cardiac pathology known from birth, presented with poor food intake and grunting with hepatomegaly on clinical examination, and a heartbeat at 200/ min. The electrocardiogram (ECG) showed wide QRS complex tachycardia, and the echocardiogram showed a dilated and hypokinetic cardiomyopathy. The clinical signs and chest X-ray changes were consistent with mild cardiac failure. This presentation makes the diagnosis challenging, therefore, it is important to take a good history of the case with a complete clinical exam to achieve the correct diagnosis, and to avoid potential complications. VT of an infant may be benign but should not be diagnosed as such before eliminating serious causes.

Frequent Ventricular Premature Beats in Children and Adolescents: Natural History and Relationship with Sport Activity in a Long-Term Follow-Up

Premature ventricular complexes (PVCs) are frequently documented in children. To date, few studies report long-term follow-up in pediatric cohorts presenting with frequent PVCs. The aim of this study is to assess the clinical relevance and long-term outcomes of frequent PVCs (≥ 500/24 h) in a large pediatric cohort. From 1996 to 2016, we enrolled all consecutive patients evaluated at Anna Meyer Children Hospital for frequent PVCs. Symptomatic children were excluded together with those patients with known underlying heart diseases; thus, our final cohort of study included 103 patients (male 66%; mean age 11 ± 3.4 years), with a mean follow-up of 9.5 ± 5.5 years. All patients were submitted to complete non-invasive cardiologic evaluation. The mean number of PVCs at Holter Monitoring (HM) was 11,479 ± 13,147/24 h; couplets and/or triplets were observed in 5/103 (4.8%) cases; 3 patients (2.9%) presented runs of non-sustained ventricular tachycardia (NSVT). High-burden PVCs (> 30,000/24 h) was confirmed in 11/103 (10.6%) patients. During the follow-up, only five patients (4.8%) developed clinical symptoms (3 for palpitations, 1 myocardial dysfunction due to frequent PVCs and NTSV; 1 arrhythmogenic cardiomyopathy); no deaths occurred. Basal PVCs were still present in 45/103 (43.7%) patients. Our data suggest that frequent PVCs may be addressed as a benign condition and should not preclude sport participation if not associated with cardiac malformations, heart dysfunction, or cardiomyopathy. This seems to be true also in presence of very frequent/high-burden PVCs. Otherwise, a careful follow-up is mandatory since sport eligibility should be reconsidered in case of onset of symptoms and/or ECG/echocardiographic changes.

High burden of premature ventricular contractions in structurally normal hearts: To worry or not in pediatric patients?

BACKGROUND

There is paucity of data regarding the significance of high percentage of premature ventricular contractions (PVCs) in healthy children and their impact on left ventricular (LV) function and the risk of ventricular arrhythmias. The purpose of this study was to assess the prevalence of LV systolic dysfunction in children with frequent PVCs and determine whether PVC characteristics were predictive of LV dysfunction.

METHODS

We performed a single-center retrospective review to examine the prevalence of PVC-induced cardiomyopathy and natural history of PVC burden in children with frequent PVCs. Children aged 6 months-21 years with PVCs noted on 24-hr Holter monitoring studies were enrolled. The four categories included those with a PVC burden of >10%, 10%-20%, and those with more than 20% PVC burden.

RESULTS

A total of 134 children were included, 65 with more than 10% PVCs and 31 with more than 20% PVCs. Median age of the patients was 10.5 years (IQR 6.1-14.8 years), with 79 males (54.5%). Median PVC burden was 8.7% (IQR 4.2%-16.9%) with median follow-up of 2.8 years (IQR 1.2-4.6 years). During 2.8 years (1.3-4.3 years) of follow-up, the PVC burden decreased by 67% of baseline PVC burden in those who did not undergo any intervention. There were no deaths.

CONCLUSION

PVCs in children with structurally normal hearts are associated with a relatively benign course, with trend toward spontaneous resolution.

2019 HRS/EHRA/APHRS/LAHRS expert consensus statement on catheter ablation of ventricular arrhythmias

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

Catheter Ablation of Ventricular Arrhythmias Originating From the Pulmonary Sinus Cusp in Pediatric Patients: A Single-Center Retrospective Study

Objective: There are few reports of ventricular arrhythmias (VAs) originating from the pulmonary sinus cusp (PSC) in pediatric patients. Thus, we investigated the ablation of PSC-VAs in pediatric patients. Study Design: Clinical, echocardiographic, and ablation data were reviewed in 10 consecutive symptomatic children who underwent successful ablation of VAs of PSC origin at our center between March 2014 and June 2018. Results: The 10 patients' weights ranged from 29 to 63.5 kg, and all had structurally normal hearts and VAs with left bundle branch block (LBBB) morphologies and inferior axes. The initial ablation was performed in the right ventricular outflow tract (RVOT) or the aortic sinus cusp, which failed to terminate the VAs in nine patients. The successful ablation site was in the right cusp (RC) in seven patients, the anterior cusp in two patients, and the left cusp (LC) in one patient. The earliest potential recorded at the PSC ablation site preceded the onset of the QRS complex during VAs by 29.4 ± 4.9 ms. Conclusions: VAs with a LBBB morphologies and inferior axes may originate within the PSC of children. Ablation was effective and safe for the eradication of VAs originating from the PSCs in children. Due to the particularity of ablations in pediatric patients, mapping of PSCs should be considered when ablation fails in the RVOT.

Incidence and effect of early postoperative ventricular arrhythmias after congenital heart surgery

BACKGROUND

Postoperative arrhythmias after pediatric congenital heart disease (CHD) surgery are a known cause of morbidity and are associated with mortality. A comprehensive evaluation of early postoperative ventricular arrhythmias (VAs) after CHD surgery has not been reported.

OBJECTIVES

We sought to determine the incidence of in-hospital VAs after CHD surgery and assess the clinical relevance of this arrhythmia during the postoperative hospital course.

METHODS

Patients undergoing CHD surgery at our center from September 2007 through December 2016 were prospectively enrolled. Univariate and multivariate analysis was used to assess the association between postoperative VAs and in-hospital mortality, adjusting for postoperative extracorporeal membrane oxygenation and stage 1 single ventricle palliation operations.

RESULTS

A total of 2503 postoperative courses in 1835 patients were included. In all, 464 (18.5%) had VAs, of whom 135 (29.1%) received treatment. Monomorphic ventricular tachycardia was the most frequently treated ventricular arrhythmia (TVA; n=91 [62.3%]). TVAs were associated with increased postoperative extracorporeal membrane oxygenation (13.3% vs 5.5%; P < .001) and in-hospital mortality (14.9% vs 4.0%; P < .001). In multivariate analysis, TVA was an independent risk factor for in-hospital mortality (adjusted odds ratio 2.44; 95% confidence interval 1.21-4.92).

CONCLUSION

Early postoperative VAs after CHD surgery are more common than previously reported. Postoperative VAs are associated with increased in-hospital mortality, and the subgroup of TVAs is an independent risk factor for in-hospital mortality.

Structured inpatient evaluation of neonatal cardiac ectopy

OBJECTIVE(S)

In well-appearing newborns with suspected cardiac ectopy, we sought to evaluate our practice and test whether initial electrocardiogram (ECG) findings were associated with neonatal arrhythmias (NA).

STUDY DESIGN

We identified well-appearing, non-anomalous infants >34 weeks' gestation with suspected ectopy over 3.5 years. NA was defined as ≥10% premature atrial contractions (PAC), ≥5 beats of atrial tachycardia, ≥2% premature ventricular contractions (PVCs), or ≥3 beats of ventricular tachycardia. The unadjusted associations between initial ECG findings and NA are reported.

RESULT

Among 126 infants with ECGs and Holters performed, NA was observed in 38 patients (30%) and was similar whether PACs were present or not on the initial ECG (33% vs. no PACs: 29%, p = 0.6). However, NAs were identified more frequently based on the presence of PVCs on the initial ECG (83% vs. 25%, p < 0.01).

CONCLUSION

NAs were prevalent and both their etiologies and impact on infants warrant future study.

Right ventricular endomyocardial biopsy in children and adolescents with drug-refractory arrhythmia

Purpose This study aimed to assess the results of endomyocardial biopsy from the right ventricle to establish the possible cause for drug-refractory arrhythmias in children. Materials and methods We enrolled 19 consecutive young patients with drug-refractory arrhythmia, from 2010 to 2013, who underwent endomyocardial biopsy. Inclusion criteria were as follows: age <18 years with a structurally normal heart or mild changes in a structure of the heart initially diagnosed as arrhythmia-induced cardiomyopathy. Overall, 86 biopsies were performed in 19 patients. Histopathological analysis, immunohistochemistry, and polymerase chain reaction were used for the interpretation of the endomyocardial biopsy.

RESULTS

The mean age of the patient population was 14.1±2.9 year (range from 7 to 17 years). All these patients had a history of drug-refractory arrhythmia for >5 months (mean 30 months). Patients underwent a complete history investigation, physical examination, laboratory studies, echocardiography, electrocardiography, treadmill test, and Holter monitoring before endomyocardial biopsy; two patients with arrhythmogenic right ventricular dysplasia had implantable cardioverter defibrillator implantation and further appropriate successful device shocks. Myocarditis was diagnosed based on histopathological and immunohistological analyses in nine (47.4%) patients. Polymerase chain reaction was positive for viral genome in four of them; five patients had active myocarditis. Radiofrequency ablation was performed in 17 patients; five out of six (83%) endomyocardial biopsy-proved myocarditis patients had successful radiofrequency ablation. No significant complication was reported during ablation and endomyocardial biopsy.

CONCLUSIONS

Approximately half of the children with drug-refractory arrhythmia had unsuspected myocarditis according to the results of the endomyocardial biopsy.