Flecainide Is Associated With a Lower Incidence of Arrhythmic Events in a Large Cohort of Patients With Catecholaminergic Polymorphic Ventricular Tachycardia.

BACKGROUND: In severely affected patients with catecholaminergic polymorphic ventricular tachycardia, beta-blockers are often insufficiently protective. The purpose of this study was to evaluate whether flecainide is associated with a lower incidence of arrhythmic events (AEs) when added to beta-blockers in a large cohort of patients with catecholaminergic polymorphic ventricular tachycardia. METHODS: From 2 international registries, this multicenter case cross-over study included patients with a clinical or genetic diagnosis of catecholaminergic polymorphic ventricular tachycardia in whom flecainide was added to beta-blocker therapy. The study period was defined as the period in which background therapy (ie, beta-blocker type [beta1-selective or nonselective]), left cardiac sympathetic denervation, and implantable cardioverter defibrillator treatment status, remained unchanged within individual patients and was divided into pre-flecainide and on-flecainide periods. The primary end point was AEs, defined as sudden cardiac death, sudden cardiac arrest, appropriate implantable cardioverter defibrillator shock, and arrhythmic syncope. The association of flecainide with AE rates was assessed using a generalized linear mixed model assuming negative binomial distribution and random effects for patients. RESULTS: A total of 247 patients (123 [50%] females; median age at start of flecainide, 18 years [interquartile range, 14-29]; median flecainide dose, 2.2 mg/kg per day [interquartile range, 1.7-3.1]) were included. At baseline, all patients used a beta-blocker, 70 (28%) had an implantable cardioverter defibrillator, and 21 (9%) had a left cardiac sympathetic denervation. During a median pre-flecainide follow-up of 2.1 years (interquartile range, 0.4-7.2), 41 patients (17%) experienced 58 AEs (annual event rate, 5.6%). During a median on-flecainide follow-up of 2.9 years (interquartile range, 1.0-6.0), 23 patients (9%) experienced 38 AEs (annual event rate, 4.0%). There were significantly fewer AEs after initiation of flecainide (incidence rate ratio, 0.55 [95% CI, 0.38-0.83]; P=0.007). Among patients who were symptomatic before diagnosis or during the pre-flecainide period (n=167), flecainide was associated with significantly fewer AEs (incidence rate ratio, 0.49 [95% CI, 0.31-0.77]; P=0.002). Among patients with ≥1 AE on beta-blocker therapy (n=41), adding flecainide was also associated with significantly fewer AEs (incidence rate ratio, 0.25 [95% CI, 0.14-0.45]; P<0.001). CONCLUSIONS: For patients with catecholaminergic polymorphic ventricular tachycardia, adding flecainide to beta-blocker therapy was associated with a lower incidence of AEs in the overall cohort, in symptomatic patients, and particularly in patients with breakthrough AEs while on beta-blocker therapy.

Safety of maximal cardiopulmonary exercise testing in individuals with sickle cell disease: a systematic review.

OBJECTIVE: We evaluated the safety of maximal cardiopulmonary exercise testing (CPET) in individuals with sickle cell disease (SCD). Maximal CPET using gas exchange analysis is the gold standard for measuring cardiopulmonary fitness in the laboratory, yet its safety in the SCD population is unclear. DESIGN: Systematic review. DATA SOURCES: Systematic search of Medline (PubMed), EMBASE, Cochrane, ClinicalTrials.gov and professional society websites for all published studies and abstracts through December 2020. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Two reviewers independently extracted data of interest from studies that assessed safety outcomes of maximal CPET in children and adults with SCD. A modified version of the Newcastle-Ottawa Scale was used to assess for risk of bias in studies included. RESULTS: In total, 24 studies met inclusion/exclusion criteria. Adverse events were reported separately or as part of study results in 36 (3.8%) of 939 participants with SCD undergoing maximal CPET in studies included. Most adverse events were related to transient ischaemic changes on ECG monitoring or oxygen desaturation during testing, which did not result in arrhythmias or other complications. Only 4 (0.43%) of 939 participants experienced pain events due to maximal CPET. CONCLUSION: Maximal CPET appears to be a safe testing modality in children and adults with SCD and can be used to better understand the physiological basis of reduced exercise capacity and guide exercise prescription in this population. Some studies did not focus on reporting adverse events related to exercise testing or failed to mention safety monitoring, which contributed to risk of bias.

Exercise Recommendations in Pediatric HCM: Variation and Influence of Provider Characteristics.

Pediatric Hypertrophic Cardiomyopathy (HCM) is associated with sudden cardiac death (SCD) that can be related to physical activity. Without pediatric specific guidelines, recommendations for activity restriction may be varied. Therefore, our aim is to determine the current practice and variability surrounding exercise clearance recommendations (ER) in pediatric HCM referral centers as well as provider and patient characteristics that influence them. We designed a survey that was distributed to the Pediatric Heart Transplant Study (PHTS) providers and members of the Pediatric and Adult Congenital Electrophysiology Society (PACES) querying provider demographics and patient variables from 2 patient vignettes. The study is a multicenter survey of current practice of specialized providers caring for pediatric HCM patients. Survey of PHTS and PACES providers via email to the respective listservs with a response rate of 28% and 91 overall completing the entire survey after self-identifying as providers for pediatric HCM patients at their center. ER varies for pediatric HCM and is associated with provider training background as well as personal and professional history. Of the 91 providers who completed the survey, 42% (N = 38) trained in pediatric electrophysiology (EP), and 40% (N = 36) in pediatric heart failure (HF). Responses varied and only 53% of providers cleared for mild to moderate activity for the patient in Vignette 1, which is more in line with recent published adult guidelines. ER in both vignettes was significantly associated with type of training background. EP providers were more likely to recommend no restriction (27.8% vs 5.9%) than HF providers even when controlling for provider age and time out of training. Syncope with exercise was deemed "Most Important" by 81% of providers when making ER. ER for pediatric HCM are variable and the majority of providers make ER outside of previously published adult guidelines. Furthermore, ER are influenced by provider background and experience. Further study is needed for risks and benefits of physical activity in this population to inform the development of pediatric specific guidelines.

An International Multicenter Evaluation of Type 5 Long QT Syndrome: A Low Penetrant Primary Arrhythmic Condition.

BACKGROUND: Insight into type 5 long QT syndrome (LQT5) has been limited to case reports and small family series. Improved understanding of the clinical phenotype and genetic features associated with rare KCNE1 variants implicated in LQT5 was sought through an international multicenter collaboration. METHODS: Patients with either presumed autosomal dominant LQT5 (N = 229) or the recessive Type 2 Jervell and Lange-Nielsen syndrome (N = 19) were enrolled from 22 genetic arrhythmia clinics and 4 registries from 9 countries. KCNE1 variants were evaluated for ECG penetrance (defined as QTc >460 ms on presenting ECG) and genotype-phenotype segregation. Multivariable Cox regression was used to compare the associations between clinical and genetic variables with a composite primary outcome of definite arrhythmic events, including appropriate implantable cardioverter-defibrillator shocks, aborted cardiac arrest, and sudden cardiac death. RESULTS: A total of 32 distinct KCNE1 rare variants were identified in 89 probands and 140 genotype positive family members with presumed LQT5 and an additional 19 Type 2 Jervell and Lange-Nielsen syndrome patients. Among presumed LQT5 patients, the mean QTc on presenting ECG was significantly longer in probands (476.9±38.6 ms) compared with genotype positive family members (441.8±30.9 ms, P<0.001). ECG penetrance for heterozygous genotype positive family members was 20.7% (29/140). A definite arrhythmic event was experienced in 16.9% (15/89) of heterozygous probands in comparison with 1.4% (2/140) of family members (adjusted hazard ratio [HR] 11.6 [95% CI, 2.6-52.2]; P=0.001). Event incidence did not differ significantly for Type 2 Jervell and Lange-Nielsen syndrome patients relative to the overall heterozygous cohort (10.5% [2/19]; HR 1.7 [95% CI, 0.3-10.8], P=0.590). The cumulative prevalence of the 32 KCNE1 variants in the Genome Aggregation Database, which is a human database of exome and genome sequencing data from now over 140 000 individuals, was 238-fold greater than the anticipated prevalence of all LQT5 combined (0.238% vs 0.001%). CONCLUSIONS: The present study suggests that putative/confirmed loss-of-function KCNE1 variants predispose to QT prolongation, however, the low ECG penetrance observed suggests they do not manifest clinically in the majority of individuals, aligning with the mild phenotype observed for Type 2 Jervell and Lange-Nielsen syndrome patients.

An International Multicenter Evaluation of Inheritance Patterns, Arrhythmic Risks, and Underlying Mechanisms of CASQ2-Catecholaminergic Polymorphic Ventricular Tachycardia.

BACKGROUND: Genetic variants in calsequestrin-2 (CASQ2) cause an autosomal recessive form of catecholaminergic polymorphic ventricular tachycardia (CPVT), although isolated reports have identified arrhythmic phenotypes among heterozygotes. Improved insight into the inheritance patterns, arrhythmic risks, and molecular mechanisms of CASQ2-CPVT was sought through an international multicenter collaboration. METHODS: Genotype-phenotype segregation in CASQ2-CPVT families was assessed, and the impact of genotype on arrhythmic risk was evaluated using Cox regression models. Putative dominant CASQ2 missense variants and the established recessive CASQ2-p.R33Q variant were evaluated using oligomerization assays and their locations mapped to a recent CASQ2 filament structure. RESULTS: A total of 112 individuals, including 36 CPVT probands (24 homozygotes/compound heterozygotes and 12 heterozygotes) and 76 family members possessing at least 1 presumed pathogenic CASQ2 variant, were identified. Among CASQ2 homozygotes and compound heterozygotes, clinical penetrance was 97.1% and 26 of 34 (76.5%) individuals had experienced a potentially fatal arrhythmic event with a median age of onset of 7 years (95% CI, 6-11). Fifty-one of 66 CASQ2 heterozygous family members had undergone clinical evaluation, and 17 of 51 (33.3%) met diagnostic criteria for CPVT. Relative to CASQ2 heterozygotes, CASQ2 homozygote/compound heterozygote genotype status in probands was associated with a 3.2-fold (95% CI, 1.3-8.0; P=0.013) increased hazard of a composite of cardiac syncope, aborted cardiac arrest, and sudden cardiac death, but a 38.8-fold (95% CI, 5.6-269.1; P<0.001) increased hazard in genotype-positive family members. In vitro turbidity assays revealed that p.R33Q and all 6 candidate dominant CASQ2 missense variants evaluated exhibited filamentation defects, but only p.R33Q convincingly failed to dimerize. Structural analysis revealed that 3 of these 6 putative dominant negative missense variants localized to an electronegative pocket considered critical for back-to-back binding of dimers. CONCLUSIONS: This international multicenter study of CASQ2-CPVT redefines its heritability and confirms that pathogenic heterozygous CASQ2 variants may manifest with a CPVT phenotype, indicating a need to clinically screen these individuals. A dominant mode of inheritance appears intrinsic to certain missense variants because of their location and function within the CASQ2 filament structure.

Myocardial deformation as a predictor of right ventricular pacing-induced cardiomyopathy in the pediatric population.

INTRODUCTION: Right ventricular pacing is associated with pacemaker induced cardiomyopathy and lesser degrees of pacing-induced LV dysfunction (PIVD) manifested by a reduction in left ventricular ejection fraction (LVEF). Our objective was to determine whether apical 4 chamber strain (A4C) by echocardiography can identify patients at risk of PIVD before LVEF declines. METHODS AND RESULTS: A retrospective chart review of patients (0-21 years) who had a pacemaker with a ventricular lead placed between 2011 and 2017 was performed. Patients were divided into group A (LVEF <55% and/or >10% decline in LVEF within 12 months of pacemaker placement) and group B. Data have collected before and 1 and 12 months postpacemaker implantation. There were 30 patients in the group A and 60 in group B. At 1 and 12 months postpacemaker implantation, the LVEF was significantly lower while the A4C and QRS duration on electrocardiogram were significantly higher in the group A. While the LVEF and A4C became markedly abnormal in group A as early as 1 month, the A4C did not seem to demonstrate such marked abnormalities in group B. However, a sub-analysis of patients in the group A with preserved LVEF at 1 month demonstrated significant worsening in their A4C at that time. CONCLUSION: Myocardial deformation imaging may be a clinically useful tool for the prediction of a decline in LV systolic function following pacemaker implantation. Abnormalities in A4C seem to appear before LVEF decline and as soon as 1-month postpacemaker implantation.

Chemical cardioversion of atrial flutter and fibrillation in the pediatric population with Ibutilide.

INTRODUCTION: Atrial flutter (AFL) and atrial fibrillation (AF) are common in pediatric patients with congenital heart disease and structurally normal hearts as well. Chemical cardioversion is attractive for patients with AFL/AF for a short period of time because of the ability to avoid sedation. We review a single center's experience with Ibutilide in pediatric patients in an effort to report on its safety and efficacy. METHODS: We performed a retrospective chart review of pediatric patients (0-21 years) who underwent chemical cardioversion for AFL/AF with Ibutilide (January 2011-February 2019). Patients on another antiarrhythmic medication or attempted chemical cardioversion with another drug were excluded. RESULTS: There were 21 patients who met inclusion criteria. Thirteen of the 21 (62%) patients were successfully cardioverted with Ibutilide (10 out of 13 had AF and four out of 13 required a second dose). There were no significant differences in baseline characteristics between those who were successfully cardioverted compared to those who were not. Administration of magnesium prior to administration did not appear to have an effect on the success rate. There was a significant increase in rate corrected QT interval (QTc) post Ibutilide administration, which returned to baseline prior to discharge. One patient had symptomatic bradycardia needing intravenous fluids and another had torsades requiring electrical cardioversion during Ibutilide administration. CONCLUSIONS: The success rate of chemical cardioversion with Ibutilide was similar in our experience as compared to studies in the adult population and the other lone pediatric study. Although adverse events were uncommon, Ibutilide administration warrants close monitoring and fully defining its efficacy warrants further pediatric experience.

Recurrent single echo beats after cryoablation of atrioventricular nodal reentrant tachycardia: The pediatric population.

BACKGROUND: Cryoablation for atrioventricular nodal reentrant tachycardia (AVNRT) is effective and safe with a reported limitation of lower success and higher recurrence rates. We have observed cases in which slow pathway conduction was eliminated as demonstrated by atrial extra-stimulus testing within 1 min of cryo-energy delivery but returned following tissue rewarming. Frequently, slow pathway conduction persisted despite multiple acutely successful lesions over a broad anatomic region. We aimed to determine if return of slow pathway conduction after elimination during cryoablation represents a risk for recurrent AVNRT with the same intermediate term results as slow pathway ablation. We hypothesize that remnant single echo beats in the absence of sustained slow pathway conduction and inducible AVNRT is an acceptable end point after clear slow pathway elimination during cryoablation. METHODS: Retrospective chart review of patients undergoing attempted slow pathway ablation for AVNRT using solely cryoablation between January 2015-January 2018. RESULTS: Forty-four patients met inclusion criteria with at-least 2 features of dual AVN physiology. 19 patients had return of slow pathway conduction shortly after clear elimination during cryoablation (Group A) while 25 did not (Group B). All in Group A had recurrent single echo beats but none had sustained slow pathway conduction at the end of the procedure nor AVNRT recurrence at 1 year. CONCLUSION: Recurrent single echo beats with absent sustained slow pathway conduction and non-inducible AVNRT may be an acceptable endpoint for slow pathway ablation of AVNRT using cryoablation when there is elimination of slow pathway demonstrated during energy delivery.

Voltage mapping to guide pacemaker placement in patients with CHD.

Transvenous pacemaker implantation for sinus node dysfunction in patients with Fontan palliation presents the difficulty of finding suitable pacing tissue and the potential of causing vascular obstruction in a low-flow circuit. We describe a patient who underwent electro-anatomic voltage mapping to guide a transvenous single chamber lead within her Fontan baffle. This highlights the use of advanced mapping technologies for pacemaker implantation in complex cyanotic heart disease.

Genetic Testing in Pediatric Cardiomyopathy.

Genetic testing is recommended in patients with dilated cardiomyopathy (DCM); however, limited studies demonstrate high yields of genetic testing in non-hypertrophic (HCM) patients. Furthermore, there is sparse genotype-phenotype data in pediatric DCM patients. We performed a retrospective review of 70 consecutive probands with cardiomyopathy (non-HCM) who underwent genetic evaluation. Mean age at presentation was 5.48 years. Echocardiography revealed mean ejection fraction of 32.4%. The LVEDd z score ranged from - 5.7 to + 15.9. Cardiomyopathy was classified as dilated in 56, 10 with non-compaction, 2 with restrictive, and 2 with ARVC. TTN gene mutations were the most common gene involved. Genetic testing was negative in 16/70 (23%) giving a yield of 77% including VUS. 33% (23/70) of probands had a positive family history among whom the diagnostic yield was 57% (13/23) for pathogenic mutations. Yield for positive genetic testing in the DCM with positive family history group was 9/18 (50%). There were 6 deaths (9%) and 26/70 (37%) underwent transplantation. More frequent cardiac transplantations (48 vs. 34%) and deaths (17 vs. 2%) were seen in mutation-positive vs. mutation-negative subgroups. This study demonstrates an increasing yield of genetic testing in DCM although with a high rate of VUS detection. Use of genetic information for better management and prognostication will require big data analysis.

The role of illicit drug use in sudden death in the young.

The recreational use of illicit drugs remains an enormous and growing problem throughout the United States of America and around the world. Cocaine is most frequently thought of when considering the cardiovascular toxicity of illicit drugs. The association of cocaine use with sudden death due to myocardial ischaemia and infarction is well recognised, and this risk appears to be amplified by concomitant cigarette smoking and alcohol consumption. Like cocaine, amphetamine and its derivatives lead to indirect stimulation of the autonomic nervous system through the release of norepinephrine, dopamine, and serotonin in nerve terminals of the central and autonomic nervous systems. However, amphetamine lacks the ion channel-blocking properties of cocaine. Also similar to cocaine, coronary artery spasm may be induced in individuals with or without atherosclerotic disease and may lead to myocardial infarction. With the movement across the United States of America to legalise marijuana, or cannabis, for medicinal and recreational purposes, it is important to consider its potential deleterious effects. Marijuana has long been thought to have very few adverse effects with the exception of long-term dependence. There are, however, scattered reports of acute adverse events up to and including sudden death. These appear to be due to myocardial infarction. In conclusion, the incidence of sudden death associated with the use of these drugs varies from rare in the case of marijuana use to not infrequent with some drugs such as cocaine. It is important for care providers to recognise the potential for drug abuse when caring for a sudden cardiac arrest survivor.

Short QT syndrome manifesting with neonatal atrial fibrillation and bradycardia.

OBJECTIVES: Atrial fibrillation (AF) is rare during childhood and usually associated with other cardiovascular pathology. In lone AF, the ventricular response rate is usually rapid. We sought to describe a subset of children who present with early-onset AF and a slow ventricular response rate who were found to have the short QT syndrome (SQTS). METHODS: Using a MEDLINE/PubMed search, children with AF, a structurally normal heart and bradycardia were identified. Demographics, clinical presentation, electrocardiographic (ECG) findings, electrophysiologic testing, genetic analysis and follow-up assessment were collected on each child for analysis. RESULTS: Four children were identified in the literature and combined with 2 other children followed by the authors. All had a short QT interval and those who were tested were found to have a gain-of-function mutation in the KCNQ1 gene. CONCLUSIONS: We describe a subclass of children with SQTS who present with AF and a slow ventricular response. Medical therapy has not been effective in maintaining sinus rhythm. The long-term outcome remains unknown for these children. This condition may present in utero as persistent bradycardia with postnatal ECG showing a very short QT interval.

Safety of same-day discharge without anticoagulation for left-sided radiofrequency catheter ablations in pediatrics.

BACKGROUND: For left-sided radiofrequency catheter ablation (LCA) in pediatrics, significant practice variability exists regarding anticoagulation and discharge practices. Given the lack of data in pediatric patients, the risks and benefits of these practices are not well defined. OBJECTIVE: The purpose of this study was to evaluate the safety of same-day discharge and use of aspirin (ASA) in pediatric patients following LCA. METHODS: We performed a retrospective cohort study of pediatric patients who underwent LCA from 2010 to 2020 at our institution. Discharge timing and ASA usage were based on operator preference. The primary outcome was incidence of postablation anticoagulation complications reported within 1 month of the procedure. RESULTS: Three hundred seventy-six patients underwent LCA and met inclusion criteria. Median [25th, 75th percentiles] age was 13.9 [10.5, 16.2] years; 18 (4.7%) had a history of structural heart disease. The most common substrates for ablation were Wolff-Parkinson-White syndrome (183 patients [48.7%]), concealed accessory pathway (159 patients [42.3%]), and ectopic atrial tachycardia (10 patients [2.7%]). Three hundred thirty-eight patients (89.9%) were discharged on the day of LCA. Seventy-six patients (20.2%) were prescribed ASA at discharge. Of those who underwent follow-up (273 patients [72.6%]), 7 (2.7%) reported an anticoagulation complication (5 with hematoma, 2 with headache). One of these patients was prescribed ASA; none required readmission. There was no correlation between anticoagulation complications and same-day discharge or with ASA usage. CONCLUSION: Given the rare incidence of anticoagulation complications in pediatric patients undergoing LCAs, same-day discharge from the electrophysiology laboratory without anticoagulation should be considered.

An international multicenter cohort study on implantable cardioverter-defibrillators for the treatment of symptomatic children with catecholaminergic polymorphic ventricular tachycardia.

BACKGROUND: Catecholaminergic polymorphic ventricular tachycardia (CPVT) may cause sudden cardiac death (SCD) despite medical therapy. Therefore, implantable cardioverter-defibrillators (ICDs) are commonly advised. However, there is limited data on the outcomes of ICD use in children. OBJECTIVE: The purpose of this study was to compare the risk of arrhythmic events in pediatric patients with CPVT with and without an ICD. METHODS: We compared the risk of SCD in patients with RYR2 (ryanodine receptor 2) variants and phenotype-positive symptomatic CPVT patients with and without an ICD who were younger than 19 years and had no history of sudden cardiac arrest at phenotype diagnosis. The primary outcome was SCD; secondary outcomes were composite end points of SCD, sudden cardiac arrest, or appropriate ICD shocks with or without arrhythmic syncope. RESULTS: The study included 235 patients, 73 with an ICD (31.1%) and 162 without an ICD (68.9%). Over a median follow-up of 8.0 years (interquartile range 4.3-13.4 years), SCD occurred in 7 patients (3.0%), of whom 4 (57.1%) were noncompliant with medications and none had an ICD. Patients with ICD had a higher risk of both secondary composite outcomes (without syncope: hazard ratio 5.85; 95% confidence interval 3.40-10.09; P < .0001; with syncope: hazard ratio 2.55; 95% confidence interval 1.50-4.34; P = .0005). Thirty-one patients with ICD (42.5%) experienced appropriate shocks, 18 (24.7%) inappropriate shocks, and 21 (28.8%) device-related complications. CONCLUSION: SCD events occurred only in patients without an ICD and mostly in those not on optimal medical therapy. Patients with an ICD had a high risk of appropriate and inappropriate shocks, which may be reduced with appropriate device programming. Severe ICD complications were common, and risks vs benefits of ICDs need to be considered.

Normal electrocardiographic findings: recognising physiological adaptations in athletes.

Electrocardiographic changes in athletes are common and usually reflect benign structural and electrical remodelling of the heart as a physiological adaptation to regular and sustained physical training (athlete's heart). The ability to identify an abnormality on the 12-lead ECG, suggestive of underlying cardiac disease associated with sudden cardiac death (SCD), is based on a sound working knowledge of the normal ECG characteristics within the athletic population. This document will assist physicians in identifying normal ECG patterns commonly found in athletes. The ECG findings presented as normal in athletes were established by an international consensus panel of experts in sports cardiology and sports medicine.

Electrocardiographic interpretation in athletes: the 'Seattle criteria'.

Sudden cardiac death (SCD) is the leading cause of death in athletes during sport. Whether obtained for screening or diagnostic purposes, an ECG increases the ability to detect underlying cardiovascular conditions that may increase the risk for SCD. In most countries, there is a shortage of physician expertise in the interpretation of an athlete's ECG. A critical need exists for physician education in modern ECG interpretation that distinguishes normal physiological adaptations in athletes from abnormal findings suggestive of pathology. On 13-14 February 2012, an international group of experts in sports cardiology and sports medicine convened in Seattle, Washington, to define contemporary standards for ECG interpretation in athletes. The objective of the meeting was to develop a comprehensive training resource to help physicians distinguish normal ECG alterations in athletes from abnormal ECG findings that require additional evaluation for conditions associated with SCD.

Abnormal electrocardiographic findings in athletes: recognising changes suggestive of cardiomyopathy.

Cardiomyopathies are a heterogeneous group of heart muscle diseases and collectively are the leading cause of sudden cardiac death (SCD) in young athletes. The 12-lead ECG is utilised as both a screening and diagnostic tool for detecting conditions associated with SCD. Fundamental to the appropriate evaluation of athletes undergoing ECG is an understanding of the ECG findings that may indicate the presence of an underlying pathological cardiac disorder. This article describes ECG findings present in cardiomyopathies afflicting young athletes and outlines appropriate steps for further evaluation of these ECG abnormalities. The ECG findings defined as abnormal in athletes were established by an international consensus panel of experts in sports cardiology and sports medicine.

Abnormal electrocardiographic findings in athletes: recognising changes suggestive of primary electrical disease.

Cardiac channelopathies are potentially lethal inherited arrhythmia syndromes and an important cause of sudden cardiac death (SCD) in young athletes. Other cardiac rhythm and conduction disturbances also may indicate the presence of an underlying cardiac disorder. The 12-lead ECG is utilised as both a screening and a diagnostic tool for detecting conditions associated with SCD. Fundamental to the appropriate evaluation of athletes undergoing ECG is an understanding of the ECG findings that may indicate the presence of a pathological cardiac disease. This article describes ECG findings present in primary electrical diseases afflicting young athletes and outlines appropriate steps for further evaluation of these ECG abnormalities. The ECG findings defined as abnormal in athletes were established by an international consensus panel of experts in sports cardiology and sports medicine.

Junctional ectopic tachycardia after congenital heart surgery in the current surgical era.

To determine the incidence of postoperative junctional ectopic tachycardia (JET) in a modern cohort of pediatric patients, evaluate possible risk factors for JET, and examine the effects of JET on postoperative morbidity and mortality. JET is common after congenital heart surgery. JET-related mortality has been a rare event at our center, which is different from previous reports. We reviewed records for pediatric patients who had postoperative arrhythmias between January 2006 and June 2010 at a large tertiary-care children's hospital. We performed a matched case-control study to identify risk factors for JET and a matched-cohort study to compare outcomes between patients and controls. Whenever possible, each JET case was randomly matched to two controls on the basis of lesion, repair, and surgical period. We identified 54 patients with JET (incidence = 1.4 %). After multivariate logistic regression analysis, low operative weight, cardiopulmonary bypass (CPB) duration >100 min, and immediate postoperative serum lactic acid level >20 mg/dl were associated with increased odds of developing JET. Patients with JET had longer mechanical ventilation time, cardiac intensive care unit (CICU) stay, and hospital stay. There was only one death in JET group (1.8 %) with no significant difference compared with the control group. JET remains a relatively common postoperative arrhythmia, but it is less frequent than previously reported. JET occurs more commonly in smaller patients with longer CPB runs and significant postoperative lactic acidosis levels. Mortality associated with JET is lower than historically reported, but morbidity remains high.

Cryoablation therapy for atrioventricular nodal reentrant tachycardia in children: a multicenter experience of efficacy.

Atrioventricular nodal reentrant tachycardia (AVNRT), a common tachycardia in children, is routinely treated by catheter ablation using radiofrequency or cryothermal energy. Acute success rates of 95-97 % are reported for cryoablation, similar to those achieved with radiofrequency ablation (RFA). However, early studies reported higher recurrence rates after cryoablation for treatment of AVNRT than those reported for RFA. This study evaluated the success and recurrence rates for cryoablation in a current cohort of pediatric patients across several institutions. Patients 21 years old or younger with AVNRT who underwent cryoablation at five participating centers between 2004 and 2009 were retrospectively reviewed. Patient demographics and procedural data were extracted from patient records and analyzed. A total of 434 patients with AVNRT who underwent cryoablation were identified. Cryoablation was used as the exclusive ablation method for 379 patients. For 97 % (368/379) of these patients, cryoablation was acutely successful. A higher acute success rate was found with the 6-mm-tip catheter (99 %) than with the 4-mm-tip catheter (91 %) (p < 0.01). Recurrence was experienced by 7.3 % of the patients. Recurrence was more likely for those treated with the 4-mm-tip catheter (6/42, 14 %) than for those who had the larger catheters (12/204, 6 %) No patient experienced permanent heart block. Success and recurrence rates for this cohort of patients were similar to those reported for RFA used to treat AVNRT in pediatric patients. The findings show a higher success rate and a lower recurrence rate after cryoablation with a 6-mm-tip catheter than after use of the 4-mm-tip catheter, with an associated excellent safety profile.