Accessory Pathway Location Research Articles

Identifying the Location of an Accessory Pathway in Pre-Excitation Syndromes Using an Artificial Intelligence-Based Algorithm.

(1) Background: The exact anatomic localization of the accessory pathway (AP) in patients with Wolff–Parkinson–White (WPW) syndrome still relies on an invasive electrophysiologic study, which has its own inherent risks. Determining the AP localization using a 12-lead ECG circumvents this risk but is of limited diagnostic accuracy. We developed and validated an artificial intelligence-based algorithm (location of accessory pathway artificial intelligence (locAP AI)) using a neural network to identify the AP location in WPW syndrome patients based on the delta-wave polarity in the 12-lead ECG. (2) Methods: The study included 357 consecutive WPW syndrome patients who underwent successful catheter ablation at our institution. Delta-wave polarity was assessed by four independent electrophysiologists, unaware of the site of successful catheter ablation. LocAP AI was trained and internally validated in 357 patients to identify the correct AP location among 14 possible locations. The AP location was also determined using three established tree-based, ECG-based algorithms (Arruda, Milstein, and Fitzpatrick), which provide limited resolutions of 10, 5, and 8 AP locations, respectively. (3) Results: LocAP AI identified the correct AP location with an accuracy of 85.7% (95% CI 79.6–90.5, p < 0.0001). The algorithms by Arruda, Milstein, and Fitzpatrick yielded a predictive accuracy of 53.2%, 65.6%, and 44.7%, respectively. At comparable resolutions, the locAP AI achieved a predictive accuracy of 95.0%, 94.9%, and 95.6%, respectively (p < 0.001 for differences). (4) Conclusions: Our AI-based algorithm provided excellent accuracy in predicting the correct AP location. Remarkably, this accuracy is achieved at an even higher resolution of possible anatomical locations compared to established tree-based algorithms.

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

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. 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. 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%. 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.

Radiofrequency catheter ablation of patients with permanent junctional reciprocating tachycardia and long-term follow-up results.

Permanent junctional reciprocating tachycardia (PJRT) is an infrequent form of atrioventricular re-entrant tachycardia. We report the clinical and electrophysiological properties of PJRT and outcomes of radiofrequency catheter ablation (RCA) in a large group of patients. We included 62 patients with the diagnosis of PJRT. Radiofrequency catheter ablation was performed in all. Location of accessory pathway was right posteroseptal in 37 (59,7%) cases, right midseptal in 3 (4,8%), left posterior in 7 (11,3%), left lateral in 5 (8,1%), left posterolateral in 3 (4,8%), left anterolateral in 2 (3,2%), left posteroseptal in 2 (3,2%), middle cardiac vein in 2 (3,2%), and left coronary cusp in 1 (1,6%). Single procedure success rate was 90.3%. None of patients had recurrence during follow-up after repeat ablations. Overall long-term success rate was 98.4%. Left ventricular systolic function recovered in all patients with tachycardia-induced cardiomyopathy (TIC). Retrograde decremental accessory pathways are mainly located in posteroseptal region. Radiofrequency catheter ablation is a safe and effective approach in patients with PJRT.

Wolff Parkinson White syndrome: Validation of an algorithm for identifying accessory pathway in children

Wolff Parkinson White syndrome is responsible of junctional tachycardia and potentially sudden death in children. Precise location of accessory pathway (AP) is crucial to increase safety and success rate of ablation procedures. Known ECG localization algorithms have limited accuracy in children close to 50%. The aim of study was to evaluate a new ECG algorithm relying on maximal pre-excitation (EMP) in children. ECG with EMP (ventricular activation secondary to AP without His bundle activation), induced by atrial pacing or adenosine test/vagal maneuver, was prospectively recorded during an electrophysiological study in 90 consecutive children under 16, in 3 tertiary centers between 2008 and 2020. 3 blinded investigators (1: expert rythmologist, 2: pediatric cardiologist and 3: pediatric cardiologist in training) tested a new algorithm based on EMP to predict AP location and 2 validated control algorithms, from Arruda and Min Baek , relying on basal pre-excitation. Predicted locations were matched with ablation-verified AP location. Sensibility, specificity, negative/positive predictive values and reproducibility, defined as level of agreement between investigators in determining AP location, were evaluated. AP were Left sided in 38%, septal in 47% and right sided in 16%. With the new algorithm, predictive accuracy for the 9 exact locations was 91%, 89% and 90% for investigator 1, 2 and 3, respectively. Sensibility was 80-100% for right sided, 95–100% for left sided and 62-100% for septal AP. Concordance between investigators was excellent (k ≥ 0,86). The accuracy for the reference algorithms remain poor (45% for Arruda and 51% for Min Baek ) with less concordance between investigators. Our new algorithm based on EMP allows accurate and easy to use localization of AP in children. This algorithm can be employed before cardiac catheterization and can allow better evaluation of the benefit/risk ratio of the intervention.

B-PO05-195 POST-EXCITATION: EARLY REPOLARIZATION IN WOLF-PARKINSON-WHITE SYNDROME

Life-threatening events (LTE) in Wolff-Parkinson White Syndrome (WPW) can occur pediatrics patients (pts) without high-risk accessory pathways (AP). Adults with WPW may have VF without atrial fibrillation. Early repolarization (ER) with specific patterns has been reported in adults with WPW, and has been associated with VF, but this has not been studied in children. Characterize ER in children with WPW and determine associations with clinical and electrophysiologic AP characteristics. All pts < 21 years with WPW who underwent ablation from 2017-2019 were included. ECGs were analyzed at baseline, maximal pre-excitation with adenosine, and post ablation. ER was defined by J point elevation ≥ 0.1 mV in 2 adjacent leads and notched vs. slurred pattern. ER lead distribution was characterized. 78 pts (mean age: 12 ± 3.7 yrs) with 13 AP locations were identified. ER was noted at baseline (26%), maximal pre-excitation (29%), and post ablation (45%). The predominant ER pattern at baseline was lateral (30%)/inferior (30%), inferior (52%) at maximal pre-excitation, and lateral (53%) post ablation. The predominant ER type was terminal QRS notching (see Table). Post-ablation ER appeared in 23% and disappeared in 4%. There was no association between ER and age, gender, symptoms, clinical arrhythmias, AP location, AP characteristics, inducible arrhythmias, or LTE. Of note, only 1 had a cardiac arrest. ER is more common in children with WPW pre and post ablation. There was no association between ER and electrophysiologic AP characteristics, suggesting ER is independent. Further evaluation is needed to determine if ER confers additional risk for LTE.

Explanation-visualised deep learning model for accessory pathway localisation using 12-lead electrocardiography

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): British Heart Foundation Imperial Centre of Research Excellence Background/Introduction ECG algorithms for identifying accessory pathway (AP) locations are inaccurate and difficult to use. Human expert interpretation is poorly reproducible. Artificial intelligence (AI) techniques such as machine learning can improve accuracy in classification tasks by eschewing theory-driven predictions. More reproducible and accurate AP localisation could shorten procedure time and personalise ablation consent. Purpose We developed a neural network to perform AP localisation using 12-lead ECGs. Its decision-making process was analysed to enable explainability of the neural network. Methods A convolutional neural network was trained on raw, digital, intra-procedural 12-lead ECGs of patients with manifest APs who underwent successful ablation. ECGs were labelled with AP locations as left-sided, septal or right-sided using procedure reports, fluoroscopy and electro-anatomical maps. Accuracy of the neural network was assessed via 4-fold cross-validation and was compared to the Arruda algorithm. Five cardiologists were also assessed for their accuracy in determining locations in sub-groups of cases. The neural network was retrospectively analysed to identify areas of ECGs most influential to its predictions using importance mapping. Results In 156 cases, accuracy of the neural network (92.9%) was significantly higher than the Arruda algorithm (76.9%; p &amp;lt; 0.0001) and all five cardiologists (37.5% to 65.9%; p = 0.0001 to 0.0290). Importance mapping demonstrated that the QRS complexes of leads aVL and V1 were perceived as most influential, indicating interrogation of the lateral and anterior-posterior axes respectively. The figure shows (A) architecture of the neural network, (B) accuracy of the neural network, Arruda algorithm and five cardiologists, (*, p = 0.05 – 0.01; **, p = 0.01 – 0.001; ***, p = 0.001 - 0.0001; ****, p &amp;lt; 0.0001; as compared to the neural network) and (C) example importance maps for 12-lead ECGs of left-sided, septal and right-sided APs (in order from left to right), with darker regions corresponding to greater relative importance. Conclusion AI ECG interpretation allows accurate, reproducible prediction of AP locations, superior to conventional algorithms and human interpretation. Although AI decision-making is thought of as a ‘black box’, explanation visualisation techniques such as importance mapping allow humans to understand aspects of how a neural network make decisions. A prospectively validated neural network could be integrated into clinical practice to improve pre-procedural AP localisation. Abstract Figure. Summary of results

Non-algorithmic approach to accessory pathway localization based on a mobile app

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Polish Cardiac Society - Section of Non-invasive Electrocardiology and Telemonitoring (PTK SENIT) Background. Electrocardiographical localization of accessory pathways (AP) in WPW syndrome remains an elusive goal. Despite several, often very complex algorithms that were developed over the last three decades, none of them is very accurate - as demonstrated by several independent validation studies. Moreover, algorithms are difficult to remember, which further limits their usefulness. The accessory pathway regions are arbitrary and transitions between them are smooth, not binary. The same applies to ECG features such as QRS polarity – they are not binary. Moreover, even the most careful ECG lead placement cannot compensate for the variability in heart position within the chest. Therefore, it is unrealistic to expect that any ECG feature or feature set will precisely identify a particular location in a 0 vs. 1 fashion. Aim We intend to create a mobile app / web based localizing application, that would support a novel method for AP localization: a colour density map generator - based on actual distribution of a sizable number of accessory pathway with a particular QRS features. Methods A total of 881 consecutive AP ablation procedures were reviewed and patients with successful ablation of an overt accessory pathway were included. ECG with baseline and full preexcitation obtained during incremental atrial pacing were obtained. AP localization was based on stored fluoroscopic images in several projections and procedure description. Each AP localization, as well as QRS polarity in all 12 leads, separately for full and baseline preexcitation patterns, were coded and introduced into the application database. An application web-based, optimized for mobile devices was developed. This application enabled to graphically show changing localization of AP with regard to the introduced, at each step, QRS polarity in a particular ECG lead. User can choose his/her own steps or criteria; there is no need to adhere to the proposed steps. Results A total of 604 patients/ ECGs were available for density map generation. With each additional lead QRS information introduced into the application the user can appreciate more and more precise localization of the AP. This quickly enables to pinpoint the area of maximum probability, i.e. the most likely/frequent location, followed by the immediate adjacent locations. Representative screen shots of to typical inital steps for left- and right-sided APs are provided below (Figure 1 and Figure 2). Limited prospective assessment was very favourable. Conclusions A novel method, easy to use, not requiring to remember any algorithmic steps, and based on an analysis of by far the largest cohort of over accessory pathways (in comparison with published algorithms) was developed. Prospective validation of the localization application seems warranted. Abstract Figure.

A new electrocardiographic marker with higher sensitivity and specificity for epicardial location of posteroseptal accessory pathway

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Catheter ablation of accessory pathways (AP) located in the posterior pyramidal space are often challenging due to its anatomical complexity. Scarce of data are available about the ECG features that might indicate when an epicardial approach is required in the ablation of the posteroseptal AP. Objective The purpose of this retrospective study was to describe the electrocardiographic features of posteroseptal AP which have been successfully ablated with epicardial approach and identify electrocardiographic predictors for epicardial AP location. Methods The 12 leads ECG of 75 patients with posteroseptal accessory pathways who were successfully ablated were retrospectively analyzed. ECG features for epicardial location described already in published studies have been considered (negative delta wave in DII, positive delta wave in aVR, high amplitude S wave in V6). Additionally the characteristics of the initial 40 ms of the delta wave in lead V1 (measured from the earliest QRS deflection in 12 leads) during full pre-excitation have been investigated. Results Of 75 patients with posteroseptal AP that undergone catheter ablation, 40 (53.3%) had successful epicardial ablation. An initial isoelectric or biphasic delta wave in lead V1 proved the highest sensitivity (82.5 %) respectively positive predictive value (97 %) and specificity (97 %) for an epicardial location of the AP. Deep S wave in V6 proved lower sensitivity (37.5%) and positive predictive value (68%) but higher specificity (80%) for epicardial location of AP. The specificity and sensitivity for epicardial location of AP of negative delta wave in DII were lower, however it failed to reach statistical significance. Conclusion This study shows that an initially isoelectric or biphasic delta wave aspect in lead V1 has a higher specificity, sensitivity and positive predictive value than previously described ECG markers for epicardial location of posteroseptal accessory pathways.

Deep insight into cardiac dysfunction in children and young adults with Wolff-Parkinson-White syndrome using speckle tracking imaging.

Although ventricular pre-excitation via accessory pathways (APs) causes cardiac dysfunction in children and young adults with Wolff-Parkinson-White (WPW) syndrome, the underlying cardiac dysfunction mechanisms are unclear. This study aimed to characterize cardiac dysfunction and clarify sensitive cardiac dysfunction indicators in WPW syndrome patients classified by the APs location with a layer-specific strain analysis. Twenty-four patients with WPW syndrome with a mean age of 14.1years (6.9-21.6years) (11 cases: type A with a left-sided AP [WA group], 13 cases: type B with a right-sided AP [WB group]), and 37 age-matched normal controls (N group) were examined. We measured the left ventricle (LV), base-, mid-, and apical-level of circumferential strain (CS), and longitudinal strain (LS) using a layer-specific strain with speckle tracking imaging. Dyssynchrony was also measured based on the timing of the radial strain at each segment. Peak endomyocardial base- and mid-level of CS was lower in both the WA and WB groups compared to the N group. Peak mid-myocardial and epimyocardial base-level of CS and peak mid-myocardial mid-level of CS were lower only in the WB group compared to the N group. Peak LS in all three layers was lower only in the WB group compared to the N group. There was a significant difference between the patient and normal groups for the dyssynchrony index only at the base-level, and there was no significant difference between the groups for LV ejection fraction (EF). Layer-specific strain decreased in more sites in the WB group despite the normal EF value. Layer-specific strains are sensitive indicators for the detection of the early stages of cardiac dysfunction.

The Correlation Between Gender and Accessory Pathways.

BackgroundAccessory pathways (APs) are muscular bundles capable of rapid conduction between atria and ventricles. They can be located anywhere along the atrioventricular groove or septum. The etiology of such pathways is generally unknown. This study aims to evaluate the correlation between gender, AP location, and clinical presentation.MethodsThis is a retrospective study of 139 patients who underwent radiofrequency ablations for newly diagnosed accessory pathways between years 2010 and 2016. Information extracted from the medical records included: age at the time of diagnosis, gender, characteristics, and anatomical location of the accessory pathways.ResultsA total of 139 patients with AP were enrolled in the study. The mean age of diagnosis was 32.2 ± 13.5 years. With regards to gender, APs were more common among men (p-value 0.04). Males were predominant in both the right and left AP groups (p-value 0.025), although, overall, most of the AP were left located. Also, males were more commonly diagnosed with right posteroseptal (RPS) accessory pathways while females with left lateral (LL) pathways. Concerning the clinical presentation, the manifest form was more frequent than concealed. Males were prevalent in both groups (p-value 0.38).ConclusionGender components might have a role in the pathogenesis of AP formation.

Conduction Properties and Ablation of Adenosine Sensitive Accessory Pathways in Children.

Block in accessory pathway (AP) conduction with adenosine has been previously described. However, conduction characteristics of these APs has not been well defined to date. All patients with APs </ = 21years old who underwent an EP study from 2014 to 2017 were included in our study. Patients with adenosine sensitive APs were identified (group 1). Demographic and AP conduction characteristics were compared between group 1 and the entire cohort of patients. Local atrioventricular (AV) or ventriculoatrial (VA) time, cycle length and need for isoproterenol were compared to a control group matched by age and AP location (group 2). Student's t test, Wilcoxon rank sum, χ2 and Fisher's exact were used for analysis. Fourteen (7%) out of 207 patients had an adenosine sensitive AP. The median age of patients with adenosine sensitive APs was 11.8 (IQR 8.5-13.5) years vs. 14 (IQR 10.6-16.7) for the rest of the cohort (p = 0.04). Three of the 134 patients with preexcitation had adenosine sensitive APs (2%) vs. 11 of the 73 patients with concealed APs (15%) (p = 0.001). The median local AV/VA time at the site of successful ablation was longer in group 1 vs group 2 [78ms, IQR 62-116 vs. 31ms, IQR 30-38; p < 0.001]. Antegrade AP effective refractory period and total procedure time were longer in patients with adenosine sensitive APs (p = 0.03 & p = 0.04, respectively). Adenosine sensitive APs which occur in children are more often concealed. These APs have a longer conduction time at the site of successful ablation.

Accessory pathway analysis using a multimodal deep learning model

Cardiac accessory pathways (APs) in Wolff–Parkinson–White (WPW) syndrome are conventionally diagnosed with decision tree algorithms; however, there are problems with clinical usage. We assessed the efficacy of the artificial intelligence model using electrocardiography (ECG) and chest X-rays to identify the location of APs. We retrospectively used ECG and chest X-rays to analyse 206 patients with WPW syndrome. Each AP location was defined by an electrophysiological study and divided into four classifications. We developed a deep learning model to classify AP locations and compared the accuracy with that of conventional algorithms. Moreover, 1519 chest X-ray samples from other datasets were used for prior learning, and the combined chest X-ray image and ECG data were put into the previous model to evaluate whether the accuracy improved. The convolutional neural network (CNN) model using ECG data was significantly more accurate than the conventional tree algorithm. In the multimodal model, which implemented input from the combined ECG and chest X-ray data, the accuracy was significantly improved. Deep learning with a combination of ECG and chest X-ray data could effectively identify the AP location, which may be a novel deep learning model for a multimodal model.

Ventricular pre-excitation in primary care patients: Evaluation of the risk of mortality.

Ventricular pre-excitation is characterized by the presence of atrioventricular accessory pathways, predisposing to arrhythmias. Although it is well established that risk stratification in symptomatic patients should be invasive, there is a lack of evidence of the benefit in asymptomatic. Evaluate ventricular pre-excitation in the electrocardiogram (ECG) as a risk factor for overall mortality in patients of Telehealth Network of Minas Gerais (TNMG), Brazil. This observational study was developed with the database of digital ECGs (2010-2017) from TNMG. The electronic cohort was obtained by linking data from ECG exams and those from the national mortality information system. Only the first ECG was considered. Clinical data were self-reported, and ECGs were interpreted manually by cardiologists and automatically by the Glasgow University Interpreter software. Hazard ratio (HR) for mortality was estimated using weighted Cox regression. Nearly1 665 667 patients were included (median age:50 [Q1: 34; Q3: 63] years; 41.4% were male). In a mean follow-up of 3.7 years, the overall mortality rate was 3.1%. The prevalence of ventricular pre-excitation was 0.07%. In multivariate analysis, adjusting for sex and age, ventricular pre-excitation was not associated with an increased risk of mortality (HR: 1.41; 95% confidence interval [CI]: 0.56-3.57; p = .47) when compared to the whole sample or to patients with normal ECG (HR: 1.41; 95% CI: 0.53-4.36; p = .43). In a subanalysis on accessory pathway location, there was no evidence of a higher risk of death related to any location. Ventricular pre-excitation was not associated with an increased risk of mortality in a primary care cohort.

The Effect of Accessory Pathway Location on Cardiac Function in Adult Patients with Wolff-Parkinson-White Syndrome.

Introduction The relationship between ventricular pre-excitation and left ventricular dysfunction has been described in the absence of sustained supraventricular tachycardia in a series of case reports. However, there have been no systematic studies about the effect of ventricular pre-excitation on cardiac function in adult patients with different accessory pathway locations. Methods and Results Patients were divided into four groups based on the type and location of their accessory pathway: septal, right free wall, left free wall, and concealed. N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, electrocardiogram recordings, electrophysiological properties, and transthoracic echocardiographic data (septal-to-posterior wall motion delay (SPWMD) and interventricular mechanical delay (IVMD) indicating intraventricular and interventricular dyssynchrony) were compared before and after successful ablation. Before radiofrequency catheter ablation, left ventricular ejection fraction (LVEF) was significantly lower in patients with septal and right free wall accessory pathways. Within three months after radiofrequency catheter ablation, NT-proBNP levels decreased, left ventricular function improved, and intraventricular left ventricular dyssynchrony disappeared. There was a negative correlation between initial LVEF with initial QRS duration and initial SPWMD. Notably, SPWMD had a stronger correlation with LVEF than initial QRS duration. Conclusions Anterograde conduction with a septal or right free wall accessory pathway may cause left ventricular dyssynchrony and impair left ventricular function. Intraventricular left ventricular dyssynchrony seems to be responsible for the pathogenesis of left ventricular dysfunction. Radiofrequency catheter ablation results in decreased NT-proBNP levels, normalized QRS duration, mechanical resynchronization, and improved left ventricular function.

The Vectorcardiogram and the Main Dromotropic Disturbances.

Until the mid-1980s, it was believed that the vectorcardiogram (VCG) presented a greater specificity, sensitivity and accuracy in comparison to the 12-lead electrocardiogram (ECG), in the cardiology diagnosis. Currently, the VCG still is superior to the ECG in specific situations, such as in the evaluation of myocardial infarctions when associated with intraventricular conduction disturbances, in the identification and location of accessory pathways in ventricular preexcitation, in the differential diagnosis of patterns varying from normal of electrical axis deviation, in the evaluation of particular aspects of Brugada syndrome, Brugada phenocopies, concealed form of arrhythmogenic right ventricular cardiomyopathy and zonal or fascicular blocks of the right bundle branch on right ventricular free wall.VCG allows us to analyze the presence of left septal fascicular block more accurately than ECG and in the diagnosis of the interatrial blocks and severity of some chambers enlargements. The three-dimensional spatial orientation of both the atrial and the ventricular activity provides a far more complete observation tool than the linear ECG. We believe that the ECG/VCG binomial simultaneously obtained by the technique called electro-vectorcardiography (ECG/VCG) brought a significant gain for the differential diagnosis of several pathologies. Finally, in the field of education and research, VCG provided a better and more rational tridimensional insight into the electrical phenomena that occurs spatially, and represented an important impact on the progress of electrocardiography.

Electocardiographic 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 Ebstein's disease. We conducted a retrospective descriptive study that enrolled 26 patients followed for ED. The mean age of discovery of the ME was 103.51 ± 99 months [0–31 years]. The diagnosis of ME 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.

Transcatheter cryo-ablation of septal accessory pathways, multicenter observational study in Japan

BackgroundAblation using radiofrequency energy has to be carefully performed when the arrhythmia substrate is located in close proximity to the atrioventricular (AV) node due to the risk of inadvertent permanent AV block. The aim of this study was to evaluate the efficacy and safety of catheter-based cryo-therapy for septal accessory pathways (APs). MethodsA total of eleven patients (median = 56.3 years, range 13–74 years) with septal APs underwent cryoablation. Ice-mapping was performed during sinus rhythm and an AV reciprocating tachycardia utilizing the APs as a requisite limb with cooling of the catheter tip temperature to a maximum of -30℃ for less than 45 s. Cryo-ablation was performed for 4 min at a temperature of -80℃ only if ice-mapping abolished the pre-excitation or retrograde conduction over the AP without injury to the AV nodal conduction. ResultsCryo-ablation was acutely successful in all eleven patients. No permanent cryo-related complications or adverse outcomes were reported. During the follow-up (range 14–26 months), no patients experienced any arrhythmia recurrences. ConclusionIce-mapping was a feasible and reliable method to determine the exact location of the APs owing to the possibility of validating the ablation site. Cryo-ablation of APs located near the AV junction is a safe and efficacious technique with a high success rate over the long term. IRB informationEthical Committee of Japan Red Cross Yokohama City Bay Hospital #2018−19.

Abstract 15563: Association of Weight With Ablation Outcomes in Pediatric Wolff-Parkinson-White Syndrome: Analysis of the NCDR® IMPACT Registry

Introduction: Guidelines for electrophysiology study (EPS) and catheter ablation in Wolff-Parkinson-White syndrome (WPW) are based on age. Size is an established factor in ablation risk and may be the more appropriate factor to consider when deciding timing of EPS. Hypothesis: Weight &lt;30 kg is associated with higher rates of major adverse events (MAE) and deferred ablation, and lower rates of success. Methods: A multicenter retrospective cohort study was performed on children age 1-21 years with WPW and first-time EPS data in IMPACT from 4/16-12/19, excluding those with congenital heart disease, cardiomyopathy, and &gt; 1 ablation target. MAE were defined as cardiac arrest, stroke, tamponade, permanent pacemaker, or unplanned cardiac / vascular surgery. Ablation success was evaluated in those with attempts. Multivariable logistic regression models were used to adjust for measurable confounders - accessory pathway (AP) type, AP location, and use of cryoablation (cryo). Results: 4456 subjects from 84 centers were evaluated, with 14% &lt;30 kg. Subjects &lt;30 kg were more likely to have pre-operative SVT (45% vs. 29%, p&lt;0.001) and inducible SVT (71% vs. 61%, p&lt;0.001), more likely to have left non-septal APs (46% vs. 37%, p&lt;0.001), and less likely to have right septal APs (25% vs. 33%, p&lt;0.001, Table). No difference was seen in the likelihood of deferred ablation based on weight (9.5% vs. 12%, p=0.07). Ablation success was higher in &lt;30 kg: 95% vs. 92% (p=0.009). This effect persisted after adjusting for measurable covariates (OR 1.7, 95% CI 1.03-2.7, p = 0.04). Left non-septal AP location was also associated with success (OR 2.9, CI 1.9-4.2, p &lt;0.0001), and cryo was negatively associated (OR 0.4, CI 0.3-0.5, p&lt;0.0001). MAE were rare, though with higher incidence in &lt;30 kg (0.3% vs. 0.05%, p=0.04). Conclusions: In this analysis of WPW patients with ablation data in IMPACT, weight &lt;30 kg was associated with increased ablation success; a higher incidence of MAE (which were rare) was observed.

Ultra-high resolution mapping and ablation of accessory pathway conduction.

Detailed mapping studies of accessory pathway (AP) conduction have not been previously performed using ultra-high resolution mapping systems. We sought to evaluate the clinical utility of ultra-high resolution mapping systems and the novel "Lumipoint" algorithm in AP ablation. This study included 17 patients who underwent AP mapping using minielectrode basket catheters and Rhythmia systems. Ablation was performed with 4-mm irrigated-tip catheters. Antegrade and retrograde AP conduction was observed in 6 and 16 patients. Atrial activation map was obtained during orthodromic tachycardia and ventricular pacing in 13 (76.5%) and 14 (82.3%) patients, and the earliest activation area was identical. Ventricular activation maps were created during atrial pacing in 3 patients. All maps showed focal activation patterns on global activation histograms, and the valley on the histogram highlighted the earliest activation area. "Complex activation" features further highlighted limited areas with continuous electrical activity during the time period in the majority. APs were located at the mitral and tricuspid annuli in 15 and 2 patients, and all were successfully eliminated with 3.4 ± 0.6s applications. No patients had recurrences during a median follow-up of 15 [10.5-22.5] months. At successful ablation sites, the local atrial and ventricular electrogram amplitudes and ratio tended to be greater, and fusion or continuous electrical activity between the atrial and ventricular components was more frequently observed on the minielectrode than ablation catheter (17/17 vs. 12/17, p = 0.005). Ultra-high resolution activation mapping and a novel algorithm facilitated the AP localization. The local electrogram characteristics differed between the minielectrode and ablation catheters.

Algorithms to Identify Accessory Pathways' Location on the 12-Lead Electrocardiogram.

The ability to estimate accessory pathway (AP) position enables pre-procedural planning, reduces mapping times, and improves risk estimates as part of the patient consent process. In this article, the nomenclature and important concepts of AP localization algorithms are outlined. An overview of three prominent algorithms is then provided. Each represents an era of invasive treatment of APs: surgical therapy, endocardial ablation, and contemporary electroanatomic mapping. In this manner, the premises, pitfalls, and evolution of AP localization algorithms are illustrated. In addition, the pertinent features of their work are distilled in a simplified topographic algorithm with the interventional electrophysiologist in mind.