Increased incidence of cavotricuspid isthmus atrial flutter following slow pathway ablation.

PURPOSE: The incidence of atrial flutter following radiofrequency ablation of supraventricular tachycardias is poorly understood. Ablation of atrioventricular nodal reentry tachycardia may place patients at risk of flutter because ablation of the slow pathway is in close proximity to the cavotricuspid isthmus. This study aims to evaluate the risk of atrial flutter following ablation of atrioventricular nodal reentry tachycardia relative to ablation of other supraventricular tachycardias. METHODS: A single-center retrospective analysis was completed for all supraventricular tachycardia ablations performed between July 2006 and July 2016. Patient and procedural details were collected for 544 patients who underwent atrioventricular nodal reentry tachycardia ablation (n = 342), atrioventricular reentry tachycardia ablation (n = 125), or atrial tachycardia ablation (n = 60). Follow-up for flutter after ablation of their incident arrhythmia was assessed. RESULTS: Patients who underwent atrioventricular nodal reentry tachycardia ablation were more likely to develop CTI-dependent flutter than patients who underwent ablation of other supraventricular tachycardias (4.97% vs. 0%; p = 0.002). Compared with patients who did not develop flutter, patients who developed flutter after atrioventricular nodal reentry tachycardia ablation were more likely to have undergone ablation of atypical atrioventricular nodal reentry tachycardia (11.8% vs. 2.15%; p = 0.016). CONCLUSIONS: We identified an association between atrioventricular nodal reentry tachycardia ablation and development of CTI-dependent atrial flutter. This finding may have implications for the management and follow-up after atrioventricular nodal reentry tachycardia ablation.

Association of age with clinical features and ablation outcomes of paroxysmal supraventricular tachycardias.

OBJECTIVE: The role of age in clinical characteristics and catheter ablation outcomes of atrioventricular nodal re-entrant tachycardia (AVNRT) or orthodromic atrioventricular re-entrant tachycardia (AVRT) has been assessed in retrospective studies categorising age by arbitrary cut-offs, but contemporary analyses of age-related trends are lacking. We aimed to study the relationship of age with epidemiological, clinical features and catheter ablation outcomes of AVNRT and AVRT. METHODS: We recruited 600 patients (median age 56 years, 60% female) with a confirmed diagnosis of AVNRT (n=455) or AVRT (n=145) by means of an electrophysiological study. They were interrogated for arrhythmia-related symptoms with a structured questionnaire and followed up to 1 year. We analysed age as a continuous variable using regression models and adjusting for relevant covariables. RESULTS: Both typical and atypical forms of AVNRT upraised with age while AVRT decreased (p<0.001 by regression). Female sex predominance in AVNRT was not observed in older patients. Overall, these tachycardias became more symptomatic with ageing despite a longer tachycardia cycle length (p<0.001) and regardless of the presence of structural heart disease, with a higher proportion of dizziness, syncope, chest pain or dyspnoea (p<0.005 for all) and a lower presence of palpitations or neck pounding (p<0.001 for both). Age was not associated with catheter ablation acute success, periprocedural complications or 1-year recurrence rates (p>0.05 for all). CONCLUSIONS: Age, evaluated as a continuous variable, had a significant association with the clinical profile of patients with AVNRT and AVRT. Nevertheless, catheter ablation outcomes and complications were not significantly related to patients' age.

Association between the geographic region and the risk of familial atrioventricular nodal reentrant tachycardia in the Polish population.

Introduction: Atrioventricular nodal reentrant tachycardia (AVNRT) is one of the most common regular supraventricular arrhythmias referred for catheter ablation (CA). In Poland, several families with familial AVNRT (FAVNRT) were reported in Podkarpacie Province (PP). Objectives: We aimed to determine the frequency of FAVNRT in PP compared with other south-eastern provinces of Poland. Patients and methods: Clinical data of 1544 patients with AVNRT diagnosed by invasive electrophysiological study between 2010 and 2019 were screened for FAVNRT. From January 2017 to June 2019, patients were asked to provide details on family history and origin to obtain 3-generation pedigrees. Families with at least 2 members with previous CA of AVNRT were divided into those from south-eastern provinces (SEPs; including PP and bordering provinces [BPs]) and the remaining parts of Poland (RPP). Results: There were 932 patients from SEPs and 612 from RPP. FAVNRT was reported in 45 patients (2.91%) from 27 families, with a higher frequency in SEPs than RPP (4.02% vs 1.17%; P = 0.002) and the highest frequency in PP (6.33% vs 2.47% in BPs; P = 0.004). The risk of FAVNRT was higher in PP compared with BPs (odds ratio, 2.67; 95% CI, 1.36­5.23; P = 0.004) and similar in BPs compared with RPP (odds ratio, 2.14; 95% CI, 0.86­5.34; P = 0.1). Conclusions: A relationship exists between the geographic region and frequency of FAVNRT. A greater distance from PP was associated with less frequent FAVNRT. International cooperation and genetic testing are needed to confirm the genetic impact of FAVNRT in this part of Central Europe.

Characteristics of a large-scale cohort with accessory pathway(s): A cross-sectional retrospective study highlighting over a twenty-year experience.

OBJECTIVE: Catheter ablation following electrophysiologic study (EPS) is the mainstay of diagnosis and treatment for patients with atrioventricular reentrant tachycardia (AVRT), demonstrating excellent long-term outcome and a low rate of complications. In this study, our aim was to assess our experience in patients with accessory pathway (AP) and to compare our data with the literature. METHODS: We included 1,437 patients who were diagnosed and treated for AP in our hospital between 1998 and 2020. The demographic data of all the patients, AP location, and periprocedural results were recorded. RESULTS: Of the 1,437 patients, 1,299 (90.4%) were men; and the mean age of the population was 26.67 years. The location of 1,418 APs were along the left free wall (647 [45.6%] patients), in the posteroseptal region (366 [25.3%] patients), in the anteroseptal region (290 [20.4%] patients), and along the right free wall (115 [8.1%] patients). The ratio of the second AP existence was 3.0% and AVNRT co-existence was 2.0%. A total of 55 (3.8%) patients had recurrent sessions for relapse. Our center's total success rate was 95.5%, and total complication rate was 0.26%. CONCLUSION: According to our retrospective analysis, EPS is a highly functional tool in the diagnosis and management of arrhythmias such as AVRT for high-risk patient groups like military personnel with the aim of risk stratification and medical management.

Gender associated disparities in atrioventricular nodal reentrant tachycardia: A review article.

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common sustained supraventricular arrhythmias. An understanding of gender-related differences in AVNRT epidemiology, diagnosis, treatment, outcome, and complications can help guide a more effective diagnosis and treatment of the condition. The study aimed to perform a review of the available literature regarding all aspects of gender-related differences of AVNRT. We focused on all aspects of gender-related differences regarding AVNRT between men and women. A literature search was performed using Google Scholar, PubMed, Springer, Ovid, and Science Direct. Many investigations have demonstrated that the prevalence of AVNRT exhibited a twofold women-to-men predominance. The potential mechanism behind this difference due to sex hormones and autonomic tone. Despite being more common in women, there is a delay in offering and performing the first-line therapy (catheter ablation) compared to men. There were no significant gender-related discrepancies in patients who underwent ablation therapy for AVNRT, regarding the acute success rate of the procedure, long-term success rate, and recurrence of AVNRT. AVNRT is more common in women due to physiological factors such as sex hormones and autonomic tone. Catheter ablation is equally safe and efficacious in men and women; however, the time between the onset of symptoms and ablation is significantly prolonged in women. It is important for the medical community to be aware of this discrepancy and to strive to eliminate such disparities that are not related to patients' choices.

Organization and procedures in contemporary catheter ablation centres: data from the 2018 Italian Catheter Ablation Registry.

AIMS: This report describes the findings of the 2018 Italian Catheter Ablation Registry of the Italian Association of Arrhythmology and Cardiac Pacing (AIAC). METHODS: The Italian Catheter Ablation Registry systematically collects data on the ablation procedures performed in Italy. Data collection was retrospective. A standardized questionnaire was completed by participating centres. RESULTS: We collected data on 15 714 catheter ablation procedures performed in Italy during 2018 in 94 electrophysiology centres. In most centres (75/94, 80%), a single electrophysiology laboratory was available, and a hybrid electrophysiology laboratory was available in 15% (14/94) of centres. In most (93%) centres, at least two electrophysiologists were involved in the catheter ablation procedures. In only 13 out of 94 (14%) electrophysiology laboratories, an anaesthesiologist assists every electrophysiology procedure; in most cases (74/94, 79%), an on-demand anaesthesiology service was available. On-site cardiothoracic surgery was reported in 43 out of 94 (46%) centres.Nonfluoroscopic navigation systems were available in most centres (88/94, 93%). Intracardiac echocardiography was used in 59 out of 94 (63%) electrophysiology laboratories. Atrial fibrillation (31%) was the most frequently treated ablation target, followed by atrioventricular nodal re-entrant tachycardia (20%) and cavo-tricuspid isthmus (15%). In 61.7% of all procedures, a 3D mapping system was used. In about one-third of procedures, a near-zero approach was performed. CONCLUSION: In most Italian electrophysiology centres, a single electrophysiology laboratory was available and at least two electrophysiologists were involved in the ablation procedures. An increasing number of procedures were performed by means of a nonfluoroscopic mapping system with a near-zero approach.

Long-term outcomes of arrhythmia and distinct electrophysiological features in congenitally corrected transposition of the great arteries in an Asian cohort.

Congenitally corrected transposition of the great arteries (ccTGA) is associated with various types of arrhythmia, including supraventricular tachycardia (SVT) and complete atrioventricular block (cAVB). Our study aims to characterize the arrhythmia burden, associated risk factors, arrhythmia mechanisms, and the long-term follow-up results in patients with ccTGA in a large Asian cohort. METHODS: We enrolled 104 patients (43 women and 61 men) diagnosed with ccTGA at our institution. The mean age at last follow-up was 20.8 years. RESULTS: For 40 patients (38%) with tachyarrhythmia, paroxysmal SVT (PSVT) and atrial arrhythmia were observed in 17 (16%) and 27 (26%) patients, respectively, with 4 patients (4%) having both types of SVT. The 20-year and 30-year SVT-free survival rates were 68% and 54%, respectively. Seven patients (7%) developed cAVB: 2 (2%) developed spontaneously, and the other 5 (5%) was surgically complicated (surgical risk of cAVB: 7%, all associated with ventricular septal defect repair surgery). PSVT was mostly associated with accessory pathways (5/9) but also related to twin atrioventricular nodal reentry tachycardia (3/9) and atrioventricular nodal reentry tachycardia (1/9). Most of the accessory pathways were located at tricuspid valve (9/10). Catheter ablation successfully eliminated all PSVT substrates (10/10) and most of the atrial arrhythmia substrates (3/5), with low recurrence rate. CONCLUSIONS: The arrhythmia burden in patients with ccTGA is high and increases over time. However, cAVB incidence was relatively low and kept stationary in this Asian cohort. The mechanisms of SVT are complicated and can be controlled through catheter ablation.

Endpoints for Successful Slow Pathway Catheter Ablation in Typical and Atypical Atrioventricular Nodal Re-Entrant Tachycardia: A Contemporary, Multicenter Study.

OBJECTIVES: This study sought to investigate markers of success following slow pathway ablation for atrioventricular nodal re-entrant tachycardia (AVNRT). BACKGROUND: Published data are conflicting. METHODS: The authors studied 1,007 patients with typical AVNRT and 77 patients with atypical AVNRT. RESULTS: Following ablation, tachycardia was rendered not inducible in all patients. One case of transient (0.09%) and 1 of permanent (0.09%) atrioventricular (AV) block were encountered. At a 3-month follow-up, arrhythmia recurrence was noted in 21 (2.10%) patients in the typical and 3 (3.90%) patients in the atypical group (odds ratio: 0.525; 95% confidence interval [CI]: 0.153 to 1.802; p = 0.298). To predict absence of recurrence in 3 months, the induction of junctional rhythm (95.70% in typical and 96.10% in atypical groups) had sensitivity of 95.9% (95% CI: 94.6% to 97.0%) and specificity of 4.20% (95% CI: 0.11% to 21.10%), while the absence of dual AV nodal conduction post-ablation had sensitivity of 65.2% (95% CI: 62.2% to 68.1%) and specificity of 33.30% (95% CI: 15.60% to 55.30%). Neither junctional rhythm nor residual dual AV nodal pathway conduction were predictive of arrhythmia recurrence by univariate analysis. In long-term follow-up data available for 239 patients, arrhythmia-free survival was not associated with the induction of junctional rhythm or the absence of residual dual AV nodal conduction (log-rank test, p = 0.819 and p = 0.226, respectively). CONCLUSIONS: Induction of a junctional rhythm during ablation is a sensitive but not a specific marker of success. Residual dual AV nodal conduction is not predictive of recurrence. Noninducibility of the arrhythmia, usually after ablation-induced junctional rhythm, and despite isoproterenol challenge, is the most credible endpoint for success.

Predictors and rates of recurrence of atrial arrhythmias following catheter ablation in adults with congenital heart disease.

BACKGROUND: Catheter ablation is commonly performed to treat atrial arrhythmias in adult congenital heart disease (ACHD). Despite the frequency of ablations in the ACHD population, predictors of recurrence remain poorly defined. OBJECTIVE: We sought to determine predictors of arrhythmia recurrence in ACHD patients following catheter ablation for atrial arrhythmias. METHODS: We performed a retrospective study of all catheter ablations for atrial arrhythmias performed in ACHD patients between January 12, 2005 and February 11, 2015 at our institution. Prespecified exposures of interest and time from ablation to recurrence were determined via chart review. RESULTS: Among 124 patients (mean age: 45 years) who underwent catheter ablation, 96 (77%) were treated for macro-reentrant atrial tachycardia, 10 (7%) for focal atrial tachycardia, 9 (7%) for atrial fibrillation, 7 (6%) for atrioventricular nodal reentrant tachycardia, and 2 (2%) for atrioventricular reentrant tachycardia. 15 (12%) required transseptal/transbaffle puncture. Fifty-one percent of patients recurred with a median time to recurrence of 1639 days. By univariate and multivariable analysis, body mass index (BMI) and Fontan status were the only variables associated with recurrence. Dose-dependent effect was observed with overweight (HR = 2.37, P = .012), obese (HR = 2.67, P = .009), and morbidly obese (HR = 4.23, P = .003) patients demonstrating an increasing risk for arrhythmia recurrence postablation. There was no significant different in recurrence rates by gender, age, non-Fontan diagnosis, or need for transseptal puncture. CONCLUSIONS: In our cohort of ACHD patients, BMI was a significant risk factor for arrhythmia recurrence postablation, independent of Fontan status. These findings may help guide treatment decisions for persistent arrhythmias in the ACHD population.

Prevalence and predictors of atrial arrhythmias in patients with sinus node dysfunction and atrial pacing.

PURPOSE: This study aimed to determine the incidence, prevalence, and predictors of atrial arrhythmias (AAs) in patients with symptomatic sinus node dysfunction (SND) who required permanent pacemaker implantation. Also, we evaluated the impact of atrial pacing (AP) on AAs. METHODS: All consecutive patients who underwent pacemaker implantation from 2005 to 2011 were included. Atrial fibrillation (AF), atrial flutter (AFL), atrial tachycardia (AT), and AV nodal reentrant tachycardia (AVNRT) were detected via pacemaker interrogation and clinical documentation. RESULTS: The study group included 322 patients (44% male) with mean age 68.8 ± 15 years and followed for an average of 5.6 ± 2.2 years (median 5.7 years). Overall, 61.8% were found to have any AA at follow-up. Individual prevalence of AAs was high as follows: AF 43.5%, AFL 6.5%, AT 25%, and AVNRT 6.8%. AF was documented in 23% of patients (n = 74) prior to pacemaker; among those, 15% (n = 11) had no recurrence of AF with average AP of 74%. The incidence of new-onset AF after pacemaker was 15.8%. In subgroup analysis, prevalence of AF was increased by 16% with high rate of AP (81-100%) and 17% with lower rate of AP (0-20%). Incidence of new-onset AF was not affected by AP. Diabetes, hypertension, and left atrial enlargement were predictors of AAs. White men and women had higher prevalence of AF. CONCLUSIONS: AAs are highly prevalent in SND, particularly in white patients. Paroxysmal AF is suppressed with AP in minority, but there is no impact of AP on new-onset AF. Patients with diabetes, hypertension, and dilated atria must be monitored closely for early detection of AAs.

A contemporary view of atrioventricular nodal physiology.

In delaying transmission of the cardiac impulse from the atria to the ventricles, the atrioventricular (AV) node serves a critical function in augmenting ventricular filling during diastole and limiting the ventricular response during atrial tachyarrhythmias. The complex structure of the nodal region, however, also provides the substrate for reentrant rhythms. Recent discoveries have elucidated the cellular basis and anatomical determinants of slow conduction in the node. Based on analysis of gap junction proteins, distinct structural components of the AV node have been defined, including the compact node, right and left inferior nodal extensions, the lower nodal bundle, and transitional tissue. Emerging evidence supports the role of the inferior nodal extensions in mediating slow pathway conduction. The most common form of reentry involving the node, slow-fast AV nodal reentrant tachycardia (AVNRT), utilizes the inferior nodal extensions for anterograde slow pathway conduction; the structures responsible for retrograde fast pathway activation in the superior septum are less well defined and likely heterogeneous. Atypical forms of AVNRT arise from circuits that activate at least one of the inferior extensions in the retrograde direction.

The prevalence and characteristics of coexisted atrioventricular nodal reentrant tachycardia and idiopathic left fascicular ventricular tachycardia.

BACKGROUND: Coexistence of idiopathic left fascicular ventricular tachycardia (ILFVT) and atrioventricular nodal reentrant tachycardia (AVNRT) has been rarely reported. OBJECTIVES: The study aimed at elucidating the prevalence of coexisted AVNRT in patients with ILFVT during longitudinal follow-up. The electrophysiological properties and clinical predictors of coexisted ILFVT and AVNRT were investigated. METHODS: From 1999 to 2017, a total of 108 patients (age: 33.7 ± 14.3, 84 male) with ILFVT from one tertiary center were consecutively enrolled. The prevalence of coexisted arrhythmias was explored during a longitudinal follow-up and the electrophysiological parameters from the index procedure were compared. RESULTS: During a mean follow-up period of 106.8 ± 69.5 months, 21 of 108 patients (19.4%) had coexisted AVNRT. The electrophysiological study demonstrated patients with coexisted ILFVT and AVNRT were characterized by more antegrade dual AV node conduction (52.4% vs. 19.5%, P = 0.002; 9.5%), shorter antegrade slow pathway effective refractory period (285.1 ± 34.1 ms vs. 329.2 ± 69.2 ms, P = 0.034), longer retrograde fast pathway effective refractory period (368.9 ± 56.7 ms vs. 312.5 ± 95.2, P = 0.036), and less VA dissociation (19.0% vs. 60.9%, P = 0.001) than those without a coexisted AVNRT. Multivariate logistic analysis showed that presence of antegrade dual AV nodal physiology and retrograde VA conduction could predict a coexisted AVNRT in patients with ILFVT (P = 0.005, OR: 4.80, 95% CI: 1.65-14.37 and P = 0.002, OR: 0.14, 95% CI: 0.04-0.49, respectively). CONCLUSION: There was a high prevalence of coexisted AVNRT in patients with ILFVT during longitudinal follow-up. The presence of antegrade dual AV nodal physiology and retrograde VA conduction can predict the coexisted AVNRT in patients with ILFVT.

Right atrial dual-loop reentrant tachycardia after cardiac surgery: Prevalence, electrophysiological characteristics, and ablation outcomes.

BACKGROUND: Right atrial (RA) dual-loop reentrant tachycardia has been described in patients who have undergone open heart surgery. However, the prevalence, electrophysiological (EP) substrate, and ablation outcomes have been poorly characterized. OBJECTIVE: The purpose of this study was to investigate the prevalence, EP substrate, and ablation outcomes for RA dual-loop reentrant tachycardia after cardiac surgery. METHODS: We identified all patients with atrial tachycardia (AT) after cardiac surgery. We compared EP findings and outcomes of those with RA dual-loop reentrant tachycardia to a control group of patients with RA macroreentrant arrhythmias in the setting of linear RA free-wall (FW) scar. RESULTS: Of the 127 patients with 152 postsurgical ATs, 28 of the ATs (18.4%) had RA dual-loop reentry and 24 of 28 (85.7%) had tricuspid annular reentry combined with FW incisional reentry. An incision length >51.5 mm along the FW predicted the substrate for a second loop. In 22 of 23 patients (95.7%) with initial ablation in the cavotricuspid isthmus, a change in the interval between Halod to CSp could be recorded, and 15 of 23 patients (65.2%) had coronary sinus activation pattern change. Complete success was achieved in 25 of 28 patients (89.3%) in the dual-loop reentry group and in 64 of 69 patients (92.8%) in the control group. After mean follow-up of 33.9 ± 24.2 months, 24 of 28 patients (85.7%) and 60 of 69 patients (86.95%) were free of arrhythmias after the initial procedure in the 2 groups, respectively. CONCLUSION: The prevalence of RA dual-loop reentry is 18.4% of ATs with prior atriotomy scar. A long incision should alert physicians to the possibility of a second loop at the FW. Halo and coronary sinus activation patterns provide important clues to circuit transformation.

Junctional ectopic rhythm after AVNRT ablation: An underrecognized complication.

BACKGROUND: Ablation is an effective treatment for atrioventricular nodal reentrant tachycardia (AVNRT). The occurrence of junctional ectopic rhythm (JER), including junctional ectopic tachycardia, following AVNRT ablation has been described as an extremely rare phenomenon, but may be underestimated. We aimed to determine the incidence of JER following AVNRT ablation within our institution, as well as that reported in the literature via an extensive review. METHODS: We reviewed our adult ablation institutional experience for the occurrence of JER after AVNRT ablation from 2009 to 2016. Additionally, we conducted an extensive literature search using different databases looking for AVNRT ablation case series. The individually reported complications of these studies were reviewed, with a primary endpoint defined as the occurrence of JER shortly after AVNRT ablation. The study was approved by our institutional review board. RESULTS: Our institutional data revealed 6/126 patients (prevalence 4.8%) developed non-preexisting JER post-AVNRT ablation. Four patients were asymptomatic. Two patients had persistent symptoms lasting over a year, with one patient requiring repeat ablation. The literature review included 149 adult and pediatric studies. There were three cases of reported JER, out of a total of 37,541 patients (31,768 adults and 5,773 pediatric; prevalence 0.008%). The three JER patients were pediatric, and all required further therapeutic intervention. CONCLUSION: JER might be an underreported complication of AVNRT ablation. It seems most often to be transient and self-limited, occurring days to weeks after ablation, but may also be debilitating, requiring more aggressive management.

The athlete's heart is a proarrhythmic heart, and what that means for clinical decision making.

Recurring questions when dealing with arrhythmias in athletes are about the cause of the arrhythmia and, more importantly, about the eligibility of the athlete to continue sports activities. In essence, the relation between sports and arrhythmias can be understood along three lines: sports as arrhythmia trigger on top of an underlying problem, sports as arrhythmic substrate promotor, or sports as substrate inducer. Often, there is no sharp divider line between these entities. The athlete's heart, a heart that adapts so magically to cope with the demands of exercise, harbours many structural and functional changes that by themselves predispose to arrhythmia development, at the atrial, nodal and ventricular levels. In essence, the athlete's heart is a proarrhythmic heart. This review describes the changes in the athlete's heart that are related to arrhythmic expression and focuses on what this concept means for clinical decision making. The concept of the athlete's heart as a proarrhythmic heart creates a framework for evaluation and counselling of athletes, yet also highlights the difficulty in predicting the magnitude of associated risk. The management uncertainties are discussed for specific conditions like extreme bradycardic remodelling, atrioventricular nodal reentrant tachycardia, atrial fibrillation and flutter, and ventricular arrhythmias.

Therapy Of Cardiac Arrhythmias In Children: An Emerging Role Of Electroanatomical Mapping Systems.

INTRODUCTION: Cardiac arrhythmias are challenging diseases in childhood. Most of them in pediatric subjects (90.2%) are atrioventricular reentrant tachycardias and atrioventricular nodal reentrant tachycardias. The standard 12-lead ECG is a highly accurate diagnostic tool but an invasive electrophysiological study is often required. The main concern about this kind of procedures is their invasive nature and the need of radiations, so antiarrhythmic agents are currently the first line therapy. However, they often show side effects and can be insufficient for the rate control. MATERIALS AND METHODS: We performed a systematic research on Embase and PubMed. We found 563 articles and selected the most representative 50. DISCUSSION: Management of cardiac arrhythmias could be very difficult in several scenarios, especially in children with body weight <15 kg and age <4 years. In general, pediatric subjects show a cumulative risk of malignancy greater than adults, having greater life expectancy. On this basis the guiding principle during radiation delivery in electrophysiological procedures is "as low as reasonably achievable" (acronym: ALARA). The development of 3-dimensional (3D) electroanatomical mapping systems allowed significant reduction of exposure. The most recently reported experiences demonstrate safety and feasibility of fluoroless ablation in the most common arrhythmias in children, even in challenging conditions. CONCLUSION: The first reasonable approach in cardiac arrhythmias involving younger patients seems to be pharmacological. However antiarrhythmic drugs pose problems both in terms of side effects and often have poor efficacy. Expertise in electrophysiological techniques is constantly increasing and the development of new technologies allow us to encourage the use of electroanatomical mapping systems in order to reduce the radiation exposure in children undergoing to catheter ablation, especially for accessory pathways.

Yield of 48-hour Holter monitoring in children with unexplained palpitations and significance of associated symptoms.

OBJECTIVE: To determine the yield of 48-hour Holter monitoring in children with unexplained palpitations and the significance of associated symptoms. METHODS: This descriptive study was conducted at the Children's Hospital and Institute of Child Health, Lahore, Pakistan, from January 1 to December 31, 2015. All children above 5 years of age with history of intermittent palpitations and normal basic cardiovascular workup were enrolled. A 48-hour Holter study was performed using Motara Holter Monitoring System. Frequency of various symptoms and abnormal Holter findings were analysed. SPSS 21 was used for data analysis. RESULTS: Of the 107 patients, 69(64.5%) were males and 38(34.5%) females. The median age was 10 years (interquartile range: 5-18 years). Most common concomitant symptoms with palpitation included syncope/pre-syncope in 35(32.7%) patients, chest pain 22(20.5%), shortness of breath 21(19.6%) and colour change/pallor 11(10.3%). Holter recording was positive in 40(37%) patients. Frequent premature ventricular contractions 12(11.2%) and atrial ectopic beats 9(8.4%) were the most common findings. Holter findings were significantly more common in patients with history of shortness of breath and colour change/pallor during palpitations (p=0.002). CONCLUSIONS: Extended 24-hour Holter monitoring in children with palpitations was an inexpensive, non-invasive investigation with a reasonably high diagnostic yield in detecting arrhythmias.

Catheter ablation of accessory pathway: 14-year trends in utilization and complications in adults in the United States.

BACKGROUND: The aim of this study was to determine the temporal trends in utilization of catheter ablation of accessory pathways in the United States. METHODS: All patients from the Nationwide Inpatient Sample (NIS) ≥18years of age with a primary diagnosis of anomalous atrioventricular excitation syndrome (International Classification of Diseases, Ninth Edition, Clinical Modification [ICD-9-CM] code 426.7) were included in the study. Patients who underwent catheter ablation were identified using ICD-9-CM procedure code 37.34. Patients with a concomitant diagnosis of atrial fibrillation, atrial flutter, atrial tachycardia or ventricular arrhythmias were excluded from the analysis. Annual hospital volume was identified using unique hospital identification number and was divided into tertiles for further analysis. RESULTS: A total of 11,601 catheter ablations for anomalous atrioventricular excitation syndrome were studied from 1998 to 2011. The mean length of stay was 1.8days (median 1day). The utilization trends of accessory pathway ablation have steadily declined from 3.9 ablation procedures/million US population in 1998-1999 to 2.5 ablation procedures/million US population in 2010-2011. The second tertile (adjusted OR 0.41; 95% CI 0.20-0.83, p=0.01) and third tertile (adjusted OR 0.39; 95% CI 0.18-0.85, p=0.02) of hospital volume were associated with reduction in cardiac complications as compared to first tertile of hospital volume. Advanced age (OR 1.02, 95% CI 1.01-1.04, p=0.002) was independent predictor of cardiac complications. There were no in-hospital deaths. CONCLUSION: Despite decline in ablation trends, it still remains a relatively safe procedure associated with low morbidity and no mortality.

Atrial Arrhythmias and Electroanatomical Remodeling in Patients With Left Ventricular Assist Devices.

BACKGROUND: The incidence, predictors, and impact of atrial arrhythmias along with left atrial structural changes in patients with left ventricular assist devices (LVADs) remain undetermined. METHODS AND RESULTS: All patients who underwent LVAD implantation from 2008 to 2015 at the University of Chicago Medical Center were included. Electronic medical records, electrocardiograms, echocardiograms, and cardiac electrical device interrogations were reviewed. The association of arrhythmias and clinical covariates with survival was evaluated by Kaplan-Meier and Cox proportional hazards analyses. A total of 331 patients were followed for a median of 330 days (range 0-2306 days). Mean age was 57.8±12.8 years, 256 participants (77.3%) were male, mean left ventricular ejection fraction was 20±6.6%, and 124 (37.5%) had ischemic cardiomyopathy. Atrial arrhythmias (53.8%) were highly prevalent and frequently coexisted before LVAD implantation: atrial fibrillation (AF) in 45.9%, atrial flutter in 13.9%, atrial tachycardia in 6.9%, and atrioventricular nodal reentrant tachycardia in 1.2%. New-onset AF was documented in 14 patients (7.8% of patients without prior AF) after the first 30 days with an LVAD. Increasing age, renal insufficiency, and lung disease were predictors of new-onset AF after LVAD implantation. Of patients with paroxysmal AF, 43% had no further AF after LVAD. Left atrial size and volume index improved with LVAD (P<0.005). History of persistent AF, atrial tachycardia, ventricular arrhythmia, coronary artery bypass, and low albumin were associated with decreased survival. CONCLUSIONS: Atrial arrhythmias are significantly prevalent in patients who require LVAD and are associated with increased mortality; however, LVADs induce favorable atrial structural and electrical remodeling.

Familial Occurrence of Atrioventricular Nodal Reentrant Tachycardia.

BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) is considered a sporadic disease occurring in ≈22.5 cases per 10 000 in the general population. We define the prevalence and characteristics of familial AVNRT among patients who underwent radiofrequency ablation. METHODS AND RESULTS: Ablation reports of all patients with familial AVNRT (at least 2 first-degree family members) who underwent radiofrequency ablation in our institution and in another hospital were reviewed. There were 1587 patients from our institution, of whom 20 had ≥1 first-degree relatives with AVNRT. This indicates a familial AVNRT prevalence of 127 cases per 10 000 (95% confidence interval, 82-196/10 000). First-degree relatives of patients with AVNRT presented a hazard ratio of at least 3.6 for exhibiting AVNRT compared with the general population. After inclusion of 4 families with familial AVNRT who underwent ablation at another hospital our population study comprised a total of 24 families (50 patients) with AVNRT. Patients at ablation were younger in the familial AVNRT group when compared with the sporadic AVNRT group (44.2±19 versus 54.8±18 years old, P=0.0001). The male/female ratio was similar, with female predominance. The supraventricular tachycardia mechanism was typical slow/fast reentry in most cases in both groups. The most common familial relationship in our 24 families included a parent and a child in 67% of cases and less often 2 siblings (29%). CONCLUSIONS: Familial AVNRT prevalence is higher than previously believed suggesting that this arrhythmia may have a genetic component. Autosomal dominance with incomplete penetrance is the most likely mode of inheritance.