Accessory Pathway Location Research Articles

Risk Factors Associated With Ventricular Dysfunction in Wolff-Parkinson-White Syndrome

BackgroundWolff-Parkinson-White (WPW) syndrome is associated with ventricular dysfunction in the absence of sustained tachyarrhythmias. Our aim was to determine the prevalence of ventricular dysfunction and to assess risk factors associated with this condition. MethodsA single-centre retrospective analysis of all patients <18 years of age with WPW syndrome and normal cardiac anatomy who underwent an electrophysiology study ablation over a 14-year period was performed. Patients with an ejection fraction <55% were defined as having ventricular dysfunction. ResultsAmong 305 patients, 14 cases (4.5%) with ventricular dysfunction were identified. In 4 of 14 cases (28%), the presenting symptom was heart failure, and only 6 of 14 (43%) had symptoms of palpitations or documented supraventricular tachycardia. The vast majority of patients with dysfunction had right-sided pathways, and only 2 patients had a left-sided pathway locations. Right anteroseptal, anterior, and anterolateral accessory pathway locations were more common in the dysfunction group. The presence of multiple pathways and pathway characteristics assessed during electrophysiology study were comparable between the 2 groups. ConclusionsThe prevalence of ventricular dysfunction in WPW syndrome in children was 4.5%, and this is seen more frequently with right anteroseptal, anterior, and anterolateral pathway locations. Risk analysis identified these pathway locations to be associated with a 4-fold risk of developing ventricular dysfunction (odds ratio: 4.32 [confidence interval: 1.38-14.18], P = 0.012). Because of this rare complication, serial assessment of ventricular function is recommended regardless of arrhythmia burden and an ablation should be considered in the presence of dysfunction.

A computational study on the influence of antegrade accessory pathway location on the 12-lead electrocardiogram in Wolff-Parkinson-White syndrome.

Wolff-Parkinson-White syndrome is a cardiovascular disease characterized by abnormal atrio-ventricular conduction facilitated by accessory pathways (APs). Invasive catheter ablation of the AP represents the primary treatment modality. Accurate localization of APs is crucial for successful ablation outcomes, but current diagnostic algorithms based on the 12 lead electrocardiogram (ECG) often struggle with precise determination of AP locations. In order to gain insight into the mechanisms underlying localization failures observed in current diagnostic algorithms, we employ a virtual cardiac model to elucidate the relationship between AP location and ECG morphology. We first introduce a cardiac model of electrophysiology that was specifically tailored to represent antegrade APs in the form of a short atrio-ventricular bypass tract. Locations of antegrade APs were then automatically swept across both ventricles in the virtual model to generate a synthetic ECG database consisting of 9271 signals. Regional grouping of antegrade APs revealed overarching morphological patterns originating from diverse cardiac regions. We then applied variance-based sensitivity analysis relying on polynomial chaos expansion on the ECG database to mathematically quantify how variation in AP location and timing relates to morphological variation in the 12 lead ECG. We utilized our mechanistic virtual model to showcase limitations of AP localization using standard ECG-based algorithms and provide mechanistic explanations through exemplary simulations. Our findings highlight the potential of virtual models of cardiac electrophysiology not only to deepen our understanding of the underlying mechanisms of Wolff-Parkinson-White syndrome but also to potentially enhance the diagnostic accuracy of ECG-based algorithms and facilitate personalized treatment planning.

Accuracy of Different Surface Electrocardiogram Algorithms for Localization of Accessory Pathway in Comparison to Invasive Electrophysiological Localization: An Observational Study

Introduction: Detection of accessory pathway (AP) on surface ECG in sinus rhythm helps in the diagnosis of Wolff-Parkinson-White Syndrome (WPW Syndrome), Catheter ablation of AP was indicated in symptomatic patients with preexcitation. Pre-ablation AP localization inferred from the 12-lead surface electrocardiogram (ECG) facilitates a tailored ablation strategy; there by specific risk can be properly assessed. As they are based on pre-excitation in the basal state, available algorithms can lead to complex and ambiguous analysis, mostly due to the variable influence of the AP over QRS morphology. Though various algorithms on surface ECG are available to predict the site of AP on surface ECG, but none of them are accurate. So, we have compared the accuracy of different algorithms in predicting the AP localization in comparison to electrophysiological study (EPS) diagnosis. Methodology: This retrospective observational study cohort consisted of 100 consecutive patients above 15 years of age presented to the tertiary care center with the history of palpitations or for assessment of a manifest AP. Accessory pathways were identified according to the site where successful radiofrequency energy was applied. Arruda algorithm, Milstein algorithm, Fitzpatrick algorithm and Pambrun algorithm were applied on a sinus rhythm manifest preexcited ECG to predict the AP localization by two independent investigators who are unaware of site of successful catheter ablation. Then those were compared with the EPS localization to test the accuracy of individual algorithm. Then Cohen’s Kappa was run to determine if there was agreement between any of the four different algorithms with EPS using SPSS version 20.0. Results: In the study population of 100 patients, male to female ratio of study population was 1.6:1, with a mean age of presentation 43.86 ± 11.4 years with the most common age group of 31 to 45 year. when the AP locations were categorized based on EP Study 56 percent of the AP were found on the left side while 43 percent of the AP were found on right side, 77 percent of the AP were septal pathways. Among the leftsided pathways, left anteroseptal constitutes majority followed by left posteroseptal pathway. On right side majority were in right posteroseptal location in our study. Based on 4 surface ECG algorithms AP was localized and each algorithm was compared with invasive EPS localization for accuracy using Cohen’s Kappa agreement analysis. As per agreement analysis the kappa value for Milstein, Pambrun algorithm, Fitzpatrik and Arruda were 0.188, 0.343, 0.441, and 0.645 respectively. It was found that Arruda algorithm had moderate strength of agreement with the findings of EPS (κ = 0.645). This is the proportion of agreement over and above chance agreement and which was statistically significant and the strongest among all the four algorithms. Conclusion: Our study has compared the accuracy of 4 surface ECG algorithms in predicting the accessory pathway localization with the EPS; it has demonstrated that the Arruda algorithm is more precise and accurate among the available algorithms followed by Fitzpatrik, Pambrun algorithm and Milstein algorithm, Knowing the pathway prior to ablation allows for optimal procedure preparation, mapping pathways that are difficult to find and finally may lessen the catheter-related injury and shortens the procedural time.

Is this an anteroseptal accessory pathway?

The ECG of a patient during sinus rhythm shows preexcited QRS pattern, with rS pattern in lead V1, transition in lead V2, and positive inferior leads. Following the stepwise algorithms, the location of accessory pathway (AP) was identified at anteroseptal region. However, the precordial transition in lead V2 indicates mid-septal or posteroseptal AP. The mismatch suggested multiple APs and 5 APs were identified by electrophysiologic study. This case highlights the importance of detailed analysis of ECG in order to achieve adequate ablation.

Evaluating the efficacy of pre-ablation algorithms in WPW syndrome localization: a retrospective study

Abstract Background and Objective Wolf-Parkinson-White (WPW) syndrome is a congenital condition that can be diagnosed at any age and may lead to dysrhythmias, most notably atrioventricular reentrant tachycardia (AVRT). Ablation of the accessory pathway responsible for the disorder has become a standard treatment approach. The success of ablation therapy is closely linked to accurately localizing the accessory pathway. Consequently, algorithms have been developed to predict the location of the accessory pathway using pre-ablation electrocardiography (ECG) parameters. This study aims to evaluate the predictive values of previously published algorithms. Method This study included 122 patients diagnosed with WPW syndrome who underwent successful ablation of a manifest accessory pathway at our university's cardiac electrophysiology laboratory between 2019 and 2023. We retrospectively examined these patients' baseline characteristics and their procedures' features. Additionally, a team analyzed their baseline electrocardiograms (ECGs) using the EASY-WPW, Pambrun, and St. George algorithms. The sensitivity, specificity, PPV, and NPV of these algorithms were then calculated based on the location of the accessory pathways identified during the patients’ ablation treatments. Results The median age of the patients in this study was 33 years (18 - 79). Among them, 65 patients (53.3%) were male (Table 1). Ablation treatment was conducted using a 3D mapping system for all included patients, considering only those who achieved acute procedural success for analysis. The most frequently observed accessory pathway localization was the posteroseptal region of the tricuspid annulus, found in 48 patients (39.3%). Regarding the accuracy of accessory pathway prediction, the EASY-WPW, Pambrun, and St. George algorithms demonstrated correct localization rates of 81%, 72%, and 62%, respectively. The efficacy of these predictions varied according to the specific localization of the accessory pathways (Table 2). Conclusion This study highlights the limitations of previously published algorithms in predicting the localization of accessory pathways in WPW syndrome. The notably lower success rates observed in our research, as compared to earlier studies, might be attributed to variations in how localization is defined across studies, differences in the interpretation of these algorithms by users, or evolving definitions of localization resulting from advancements in 3-dimensional mapping systems. Given these findings, there is a clear need for the development of new algorithms that incorporate current localization definitions and are validated in larger patient cohorts.

Accessory pathway localization with probabilistic density maps generated by a mobile application: Assessment of a full pre-excitation net-vector method.

Precise electrocardiographic localization of accessory pathways (AP) can be challenging. Seminal AP localization studies were limited by complexity of algorithms and sample size. We aimed to create a nonalgorithmic method for AP localization based on color-coded maps of AP distribution generated by a web-based application. APs were categorized into 19 regions/types based on invasive electrophysiologic mapping. Preexcited QRS complexes were categorized into 6 types based on polarity and notch/slur. For each QRS type in each lead the distribution of APs was visualized on a gradient map. The principle of common set was used to combine the single lead maps to create the distribution map for AP with any combination of QRS types in several leads. For the validation phase, a separate cohort of APs was obtained. A total of 800 patients with overt APs were studied. The application used the exploratory data set of 553 consecutive APs and the corresponding QRS complexes to generate AP localization maps for any possible combination of QRS types in 12 leads. Optimized approach (on average 3 steps) for evaluation of preexcited electrcardiogram was developed. The area of maximum probability of AP localization was pinpointed by providing the QRS type for the subsequent leads. The exploratory data set was validated with the separate cohort of APs (n = 256); p = .23 for difference in AP distribution. In the largest data set of APs to-date, a novel probabilistic and semi-automatic approach to electrocardiographic localization of APs was highly predictive for anatomic localization.

High-density open window mapping vs conventional mapping in accessory pathways ablation

Abstract Background and purpose High density (HD) mapping is associated with a reduction in fluoroscopy time compared to conventional mapping in accessory pathway (AP) ablation. The Open Window (OW) technique (CARTO 3, Biosense Webster) is a new tool that automatically uses conventional electrophysiology criteria for AP location, as shorter local EGM AV interval (extended early meets late tool), earliest local activation time (LAT) and annotation at unipolar signal (wavefront annotation). However, no studies comparing its feasibility to conventional mapping have been conducted. Therefore, the aim of the present study was to assess the feasibility and the clinical implications of high-density OW mapping when compared to conventional HD mapping. Methods A prospective, unicentric cohort study was conducted that included consecutive patients which were referred to our institution for AP ablation with OW mapping technique and compared to a recent retrospective cohort of patients who underwent conventional HD mapping. Total fluoroscopy time, total mapping time and the rate of recurrence of the AP were compared between groups. A schematic step by step graphic of the workflow procedure is represented in figure 1. Results A total of 33 consecutive patients (32.28 ± 18 years, 58% males) were included in the OW group and compared with a cohort of 29 patients (29.6 ± 18 years, 52% males) who underwent conventional HD mapping. An example of Right Superior AP ablation is showed in figure 2. No differences in the location of the AP were observed (p=NS). OW mapping was associated to a lower mapping time (29.3 vs 37.8 min; p=0.04), lower fluoroscopy time (14.3 vs 21.3 min; p= 0.04) and lower radiofrequency time (p=0.007). After a median follow up of6 months, there were no differences in the rate of recurrence of the AP conduction between groups (p=NS). Conclusions In our experience, OW mapping was a feasible tool for AP location associated to a lower mapping time, lower radiofrequency time and lower X-ray exposure time with no differences in recurrence rate when compared to conventional HD mapping. However, more studies should be performed to corroborate these conclusions.Step by Step WorkflowRight Superior AP ablation

A novel feature extraction method for the localization of accessory pathways in patients with Wolff-Parkinson-White syndrome

Background and objectiveThe localization of accessory pathways (APs) in patients with Wolff-Parkinson-White (WPW) syndrome using surface electrocardiogram (ECG) is often entirely subjective. This study aimed to develop a novel, more automated, and non-invasive localization method to differentiate right and left APs. Materials and methodsThe participants were 31 patients (aged 8–69 y, mean age: 31.19 ± 14.69 y, 32.3 % women) with manifest WPW syndrome who were treated successfully in the first ablation session. The novel localization of APs was based on feature extraction using McSharry’s model, and SFS-LOV, a combination of three methods (sequential forward selection (SFS), leave-one-subject-out cross-validation (LOSO), and majority voting). The k-nearest neighbor (KNN) and support vector machine (SVM) classifier were separately used in the SFS-LOV method. In this method, the features were extracted from three segments of the ECG signals. Each segment was started from the onset of the P-wave and terminated with the offset of the T-wave. The majority voting was applied to the results of the classifier on the segments of each participant. ResultsThe proposed method differentiated the right from the left APs with an accuracy of 87% (sensitivity: 80%, specificity: 94%). This was achieved by feeding four selected parameters of McSharry’s model into the KNN classifier. These selected parameters were estimated from the lead V4 of the ECG signals. ConclusionThe parameters of McSharry’s model can semi-automatically localize the right and left APs in patients with manifest WPW syndrome.

Utility of Right-Electrocardiogram Chest Leads in Localization of Accessory Pathways in Patients with Wolf-Parkinson-White Syndrome

Abstract Background Prediction of the precise location of an Accessory Pathway (AP) prior to the ablation procedure is of clinical importance. Several algorithms have been published to localize the AP on a surface 12-lead electrocardiogram (ECG). Most of them are based on analysis of delta wave morphology or QRS polarity. However, they are somewhat complicated, and an accurate determination of the delta wave morphology or QRS polarity are occasionally difficult, and their accuracy are still limited. Recently a new published algorithm using right-sided ECG chest leads for the prediction site of an AP is figured out and still under study for measuring its accuracy. Aim of the Work The aim of this study is to evaluate the accuracy of the utility of rightsided ECG Chest leads in the localization of APs in patients with manifest pre-excitation pattern in 12-lead ECG in prospective manner. Patients and Methods This study included 35 patients in whom successful ablation of manifest Wolff-Parkinson-White (WPW) syndrome was performed in prospective manner. Standard 12-lead ECG and right-sided chest ECG waveforms were recorded before the procedure. Results There were 13, 10, and 12 patients with left, right, and septal APs, respectively. All left AP patients had type A (RS morphology) in V1 and 12 of them in V4R leads, only 1 had type B in V4R lead. Of the 10 right AP patients, 5 had type B (rS morphology) in V1 while all 10 patients had type B in V4R. Of the 12 septal AP patients, 9 had type C (QS or Qr morphology) in V1, while 2 of the 12 patients had type B, and 1 of 12 patients had type A. All the 12 septal AP patients had type C in V4R. Conclusions The QRS morphology of V1 and V4R leads could predict the site of AP in patients with WPW syndrome with overall accuracy of 85.7% and 98%, respectively. Abbreviations AP: Accessory Pathway; ECG: Electrocardiogram; EPS: Electrophysiology study; RF: Radiofrequency; WPW: Wolff-Parkinson-White

Intermittent ventricular pre-excitation in symptomatic adults: Always a marker of low risk?

Intermittent ventricular pre-excitation was considered a low-risk marker for sudden death. However, to date, some studies do not exclude the existence of accessory pathways (APs) with high-risk intermittent antegrade conductive properties. According to current European Guidelines, high-risk features of APs are antegrade pathway conduction ≤250 ms in baseline or during the adrenergic stimulus, inducibility of atrioventricular reciprocating tachycardias (AVRT), inducibility of pre-excited atrial fibrillation (AF), and presence of multiple APs. For all of these transcatheter ablation is recommended. The aim of our study was to evaluate the existence of differences in risk characteristics between patients with intermittent pre-excitation (IPX) and those with persistent pre-excitation (PPX), from a sample of adults with ventricular pre-excitation and symptoms like palpitations. 293 adults [IPX: 51 (17.4%); PPX: 242 (82.6%)] underwent electrophysiological study and then catheter ablation of their APs if arrhythmia inducibility (AVRT/AF) was noted, or, conversely, if it was appreciated a fast AP antegrade conduction, in baseline or during intravenous isoproterenol infusion, or if multiple APs were detected. There were no statistically significant differences in demographic characteristics (age and gender), AVRT/AF inducibility, antegrade conductive properties, the prevalence of multiple APs, and APs locations between IPX and PPX patients. In our study, patients with IPX did not show significant differences in clinical and electrophysiological features versus PPX patients.

Utility of open-window mapping for catheter ablation of an accessory pathway in patients with Wolff-Parkinson-White syndrome.

Open-window mapping (OWM) is a novel automated mapping method for catheter ablation of an accessory pathway (AP), in which the local signal is annotated with window-of-interest parameters to analyze both atrial and ventricular signals. This study aimed to determine the utility of OWM in visualizing the location and width of APs in patients with Wolff-Parkinson-White syndrome. This two-center study enrolled 30 patients (20 males; mean age: 56 years, interquartile range [IQR]: 22-69 years) who underwent high-density OWM with the extended early-meets-late (EEML) algorithm using a 20-electrode, 5-spline catheter (PENTARAY, Biosense Webster). The lower threshold of the EEML was set to adjust the EEML gap to match the propagation mapping, and broad APs were defined as an EEML gap>1cm. The median mapping points, mapping time, and lower threshold of the EEML were 2482 (IQR: 1755-4000) points, 23 (IQR: 15-30) min, and 23 (IQR: 18-25), respectively. All 30 APs (24 in the mitral annulus and 6 in the tricuspid annulus) were successfully eliminated. Of these APs, 21 (70%) were eliminated by the first radio frequency (RF) application. OWM revealed broad APs in 11 patients (37%), in four of whom (36%) the first RF application achieved a loss of AP conduction (vs. 90% of patients without broad APs; p=.004). OWM facilitates the visualization of the location and width of APs, which may be particularly useful for predicting whether multiple RF applications are required for broad APs.

The effects of catheter choice on accessory pathway mapping efficiency

Abstract Funding Acknowledgements: Type of funding sources: None. Recent studies have assessed the use of a novel high density (HD) mapping catheter in pediatric patients, finding that the catheter is safe and effective in this population. However, there is a lack of understanding on use patterns of HD mapping technologies in this population and how these patterns affect intraprocedural workflows. The objective of this analysis was to assess the role of mapping catheter choice on the efficiency of accessory pathway localization and ablation in patients with structurally normal hearts treated in a pediatric EP setting. Acute data from 61 accessory pathway ablation cases in patients treated in a pediatric EP setting were prospectively collected from 14 hospitals in 6 countries in Europe and the US. Choice of mapping tools and strategy was left to physician discretion. Procedure data such as map collection duration and statistics were compared across three mapping catheter choices: Ablation Catheter (AC) (n=42), Linear Catheter (LC) (n=9), and HD Grid Catheter (HDC) (n=10). Of the 61 procedures, 16 cases were patients aged 0-12 years (26%), 34 aged 13-17 years (56%), and 5 aged 18+ years (18%). Distribution of catheter use was similar across age groups with HDC use of 13%, 15%, and 27%, respectively. Pathway location did not correlate with catheter choice. There was 0% incidence of congenital heart disease. Mean mapping times in the AC, LC, and HDC groups were 20.6±15.8, 18.8±12.9, and 14.2±13.8 minutes, respectively; differences in mapping times were not statistically significant but trended lower with higher density mapping. The mean number of mapping points used in each group was 44±46, 101±62, and 1521±908 points, respectively (p&amp;lt;.01). Ablation was attempted in 57 (93%) of cases with 100% acute success eliminating accessory pathway conduction. Ablation time was analyzed in patients receiving RF ablation (93% of treated; n=53); mean RF time was 526s in the AC group, 369s in the LC group, and 367s in the HDC group; differences were not statistically significant (p&amp;gt;.05). All groups had similar ablation target technique distributions including timing map and signal morphology. Mean procedure time was 2:11 (h:mm) in the AC group, 1:56 in the LC group, and 1:44 in the HDC group; differences were not statistically significant. Analysis of this cohort of pathways in a pediatric setting shows multipolar catheters may provide more mapping information in shorter times. RF ablation and procedure times also trend shorter in procedures with HD Grid used for mapping, regardless of anatomic location of pathway. Further analysis in a larger cohort may be warranted to validate these findings and explore use of open window mapping described elsewhere.

High-density open window mapping vs conventional mapping in accessory pathways ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background and purpose High density (HD) mapping is associated with a reduction in fluoroscopy time compared to conventional mapping in accessory pathway (AP) ablation. The Open Window (OW) technique (CARTO 3, Biosense Webster) is a new tool that automatically uses conventional electrophysiology criteria for AP location, as shorter local EGM AV interval (extended early meets late tool), earliest local activation time (LAT) and annotation at unipolar signal (wavefront annotation). However, no studies comparing its feasibility to conventional mapping have been conducted. Therefore, the aim of the present study was to assess the feasibility and the clinical implications of high-density OW mapping when compared to conventional HD mapping. Methods A prospective, unicentric cohort study was conducted. Consecutive patients which were referred to our institution for AP ablation with OW mapping technique were included and compared to a recent retrospective cohort of patients who underwent conventional HD mapping. Total fluoroscopy time, total mapping time and the rate of recurrence of the AP were compared between groups. Results A total of 29 consecutive patients (32.28 ± 18 years, 58% males) were included in the OW group and compared with a cohort of 29 patients (29.6 ± 18 years, 52% males) who underwent conventional HD mapping. An example of Right Superior AP ablation is showed in figure 1. No differences in the location of the AP were observed (p=NS). OW mapping was associated to a lower mapping time (29.3 vs 37.8 min; p=0.04), lower fluoroscopy time (14.3 vs 21.3 min; p= 0.04) and lower radiofrequency time (p=0.007). After a median follow up of 6 months, there were no differences in the rate of recurrence of the AP conduction between groups (p=NS). A schematic step by step graphic of the workflow procedure is represented in figure 2. Conclusions In our experience, OW mapping was a feasible tool for AP location associated to a lower mapping time, lower radiofrequency time and lower X-ray exposure time with no differences in recurrence rate when compared to conventional HD mapping. However, more studies should be performed to corroborate these conclusions.

Electrocardiographic features in Ebstein's disease

Ebstein's disease (ED) is a rare and heterogeneous congenital heart disease affecting the tricuspid valve and the right ventricle. Few studies have analyzed the electrocardiographic features of this disease. The purpose of our work is to describe the electrocardiographic features observed in ED. This was a retrospective descriptive study that enrolled 26 patients followed for ED. The mean age of discovery of the ED was 103.51 ± 99 months [0–31 years]. The diagnosis of ED is most often made between 5 and 10 years. We noted right atrial hypertrophy in 11 patients (42.3%), right ventricular hypertrophy in half of the patients. Right axial deviation was noted in 11 patients (42.3%). Eight patients (30.7%) had wide QRS ≥ 120 ms. Seven of these 8 patients (26.9%) had a fragmented QRS appearance. A right bandle block was noted in 22 patients (84.6%), it was a complete block in 7 cases (26.9%). A preexcitation was found in 6 patients (23.1%). The localization of accessory pathway was right postero-septal in all cases. Rhythmic disorders were noted in 9 patients (34.6%). It was a junctional tachycardia in 3 patients (11.5%), atrial flutter in 4 patients (15.4%) and atrial fibrillation in 2 patients (7.7%). A second degree atriventricular block was observed in one patient, it was Mobitz I type. Two cases of postoperative rhythm disturbances were recorded: paroxysmal atrial fibrillation and junctional tachycardia related to Wolf Parkinson White (WPW) syndrome. Surface ECG in the ED is often pathological with prevalence of rhythm disturbances related to WPW syndrome.

PO-04-004 UTILITY OF OPEN-WINDOW MAPPING FOR CATHETER ABLATION OF ACCESSORY PATHWAY

Open window mapping (OWM) is a novel automated mapping methods for catheter ablation of an accessory pathway (AP), in which the local signal is annotated with the windows of interest parameters set to analyze both atrial and ventricular signals. We sought to determine the utility of the OWM to identify the location of APs in patients with APs. In this two-center study, 28 patients (20 male, 55 years old: IQR 22-67) who underwent high-density OWM with extended early-meets-late (EEML) algorithm (CARTO 3, Biosense Webstar, USA) using a 20-electrode, 5-spline catheter (Pentaray, Biosense Webster) were enrolled. The lower threshold of the EEML was set to adjust the EEML gap to match propagation mapping (Figure A) and the EEML gap of > 1cm was defined as a wide AP (Figure B). The median mapping points, mapping time, and lower threshold of EEML were 2399 points (1736-3798), 24 minutes (16-30), and 22 (18-25), respectively. APs were successfully eliminated in all 28 patients (22 APs in mitral annulus and six APs in tricuspid annulus), in 19 of which were eliminated by the first radiofrequency (RF) application (68%). OWM revealed wide or multiple APs in 10 patients (36%), in all of whom multiple RF applications were required to eliminate the APs. OWM facilitates to visualize the location and width of APs, which is particularly useful to predict whether linear or cluster ablation lesion sets are required for wide APs.

Behavior of Retrograde Conduction Time at Supraventricular Tachycardia Induction and its Role in Differential Diagnosis

Background: Differential diagnosis between orthodromic reentrant tachycardia (ORT) and atypical nodal reentrant tachycardia (ANRT) can be challenging. Our hypothesis was that ANRT presents more variability in retrograde conduction time at tachycardia onset than ORT. Objectives: The objectives of this study were to assess retrograde conduction time variability at the start of tachycardia in ANRT and ORT, and postulate a new diagnostic tool to differentiate these two types of arrhythmias. Methods: The ventriculoatrial (VA) interval of the first beats after tachycardia induction was measured until stabilization. The difference between the maximum and minimum VA interval was defined as delta VA (ΔVA), and the number of beats needed for VA interval stabilization was also assessed. Atrial tachycardias were excluded. Results: In a total of 101 patients included in the study, ORT was diagnosed in 64 patients and ANRT in 37. ΔVA interval was 0 (interquartile range [IQR] 0-5) milliseconds (ms) in ORT vs. 40 (21-55) ms in ANRT (p &lt;0.001). The VA interval significantly stabilized earlier in ORT (1.5 [1-3] beats) than in ANRT (5 [4-7] beats) (p&lt;0.001). A ΔVA &lt;10 ms diagnosed ORT with 100% sensitivity, specificity, and positive and negative predictive values. Ventriculoatrial interval stabilization in less than 3 beats predicted ORT with good diagnostic accuracy. The results were similar considering only accessory septal pathways. Typical NRTs presented an intermediate variation. Conclusion: Presence of ΔVA &lt;10 ms is a simple criterion that accurately differentiates ORT from ANRT, independently of the accessory pathway localization.

Results of risk stratification and accessory pathway ablation in patients with asymptomatic Wolf-Parkinson-White pattern at 108 Military Central Hospital

Objective: To evaluate the electrophysiological characteristics, risk stratification and ablation outcomes in patients with asymptomatic Wolf-Parkinson-White pattern at 108 Military Central Hospital. Subject and method: A retrospective observational study on 45 asymptomatic Wolf-Parkinson-White patients underwent electrophysiology study and ablation by radiofrequency energy at Department of Cardiology, 108 Military Central Hospital, from December 2018 to December 2021. All patients were evaluated by electrophysiology study to stratify the risks. Indications of ablation was according to European Society of Cardiology guideline. Result: The average age of patients was 34.8 ± 15.1 years old. Majority of patients were men with the rate of 82.2%. The proportion of patients at high clinical risk was 31.1%. In electrophysiology study, the mean accessory pathway effective refractory period (APERP) was 215.5 ± 60.1 (in which 73.3% patients had APERP ≤ 240ms). Among patients with having spontaneous/ induced atrial fibrillation (22.2%), the mean shortest pre-excited R-R interval in atrial fibrillation (SPERRI) was 232 ± 81.2ms (80% of patients had SPERRI ≤ 250ms). The rate of patients with inducible atrioventricular reentrant tachycardia was 22.2%. There were 43 patients (95.55%) having indication for ablation (4.44% due to high-risk occupation and 91.11% due to high risk by electrophysiological study). The locations of accessory pathways included: 53.4% from left side (the most common region was anterior wall of mitral valve with 18.6%) and 46.6% from right side (14% from posterolateral wall of tricuspid valve). The mean number of attempt ablations before success was 3.1 times. The rate of successful ablation was 97.6%. There were no complications in our study sample. Conclusion: Among 45 patients with asymptomatic Wolf-Parkinson-White pattern, there were 95.55% patients having indication for ablation (4.44% due to high-risk occupation and 91.11% due to high risk by electrophysiological study). The locations of accessory pathways included: 53.4% from left side (18.6% from anterior wall of mitral valve) and 46.6% from right side (14% from posterolateral wall of tricuspid valve). The rate of successful ablation was 97.6%.

Association of Weight With AblationOutcomes in Pediatric Wolff-Parkinson-White: Analysis of the NCDR IMPACT Registry.

Guidelines for electrophysiology study (EPS) and catheter ablation in Wolff-Parkinson-White (WPW) are age based, but size may be a more relevant factor in determination of outcomes. The goal of this study was to evaluate the association of patient weight with outcomes of catheter ablation for pediatric WPW. A multicenter retrospective cohort study was performed on children aged 1 to 21 years with WPW and first-time EPS from April 2016 to December 2019 recorded in the IMPACT (Improving Pediatric and Adult Congenital Treatment) registry, excluding those with congenital heart disease, cardiomyopathy, and >1 ablation target. A weight threshold of 30kg was selected, representing 1 SD below the cohort mean. The primary outcome was major adverse events (MAEs); additional outcomes included deferred ablation, use of cryoablation, and ablation success. A total of 4,456 subjects from 84 centers were evaluated, with 14% weighing<30kg. Subjects weighing<30kg were more likely to have preprocedural supraventricular tachycardia (45% vs 29%; P< 0.001) and less likely to have right septal accessory pathways (25% vs 33%; P< 0.001). MAEs were rare, although with higher incidence in the<30kg cohort (0.3% vs 0.05%; P=0.04). No difference was seen in likelihood of deferred ablation (9% vs 12%; P=0.07) or use of cryoablation (11% vs 11%; P=0.70). Success was higher in the<30kg cohort: 95% vs 92% (P=0.009). This effect persisted after adjusting for covariates (odds ratio: 1.6; 95%CI: 1.01-2.70; P=0.046). Weight<30kg was associated with a small but elevated risk of MAEs. Rates of deferred ablation and cryoablation were similar. Adjusting for factors (including accessory pathway type and location), weight<30kg remained an independent predictor of acute success.

Advanced Mapping and Ablation Strategies for Redo Ablation of Accessory Pathway Conduction

Atrioventricular reentrant tachycardia (AVRT) is an integral part of the circuit for accessory pathways (APs), whose anatomical location and activation characteristics can influence ablation failure and arrhythmia recurrence. This manuscript describes a case of redo AVRT performed using the Rhythmia™ mapping system, while the index procedure was mapped through the CARTO 3™ system. The use of the automated Lumipoint™ algorithm, an innovative tool provided by Rhythmia™, allowed more rapid and precise identification of the AP location, leading to a successful ablation procedure.

Accuracy of Algorithms Predicting Accessory Pathway Localization in Pediatric Patients with Wolff-Parkinson-White Syndrome.

We aimed to assess the accuracy of determining accessory pathway (AP) localization from 12 lead ECG tracings by applying 12 different algorithms in pediatric patients diagnosed with Wolff-Parkinson-White syndrome. We compared algorithm accuracy in electrophysiologic study ECG tracings with full preexcitation and resting ECG tracings. The assessing pediatric cardiologists were blinded regarding EP study results on AP localization. For exact AP location, the algorithms published by D'Avila et al. and Boersma et al. yielded the highest accuracy (58%). Distinguishing laterality, the median accuracy for predicting left or right-sided APs was 74%, while for septal APs it was 68%. We conclude that algorithms predicting AP location in pediatric patients with Wolff-Parkinson-White syndrome show low accuracy for exact AP localization. For laterality, however, accuracy was significantly higher.