Efficacy and safety of pulsed field ablation for accessory pathways: a pilot study.

AIMS: Radiofrequency ablation is used as a first-line therapy for accessory pathways (APs). However, data regarding the effects of pulsed field ablation (PFA) on APs are limited. We sought to evaluate the acute procedural and 6-month success and safety of PFA in a cohort of patients with APs. METHODS AND RESULTS: A focal contact force-sensing PFA catheter was used for patients with APs. Pulsed field ablation generator generated a bipolar and biphasic waveform (±1000 V) with a duration of 100 ms from the tip of the PFA catheter. A 100% acute procedural success was achieved in 10 conscious patients with APs (7 left anterolateral, 2 left inferolateral, and 1 right posteroseptal APs) including 6 (60%) patients after an initial application. The average total ablation time was 6.3 ± 4.9 s for 4.7 ± 1.8 ablation sites (ASs), including 3.1 ± 2.4 s at targets and 3.2 ± 2.9 s at 3.2 ± 2 bolus ASs. The mean skin-to-skin time was 59.3 ± 15.5 min, and PFA catheter dwell time was 29.4 ± 7.8 min. One patient encountered transient sinus arrest during PFA due to parasympathetic overexcitation. Sinus rhythm was restored in all patients without any significant adverse events during the short-term follow-up. CONCLUSION: Pulsed field ablation of APs was feasible, effective, and safe. Its efficiency was remarkable for its ultrarapid termination of AP conduction. Further studies are warranted to prove whether utilization of PFA with current parameters can extend to manifold AP ablation.

Case Report: Remote magnetic navigation and accessory pathways ablation in a single ventricle young adult with complex corrective surgeries.

Supraventricular arrhythmias have become an increasingly significant contributor to the risk of mortality and morbidity in adults with complex congenital heart disease (CHD), especially in light of recent advances in palliative corrective surgeries. Because of their unique characteristics, they demand specific treatment approaches. While pharmaco-logical interventions are an option, they have limited effectiveness and may lead to side effects. Although performing radiofrequency ablation (RFA) can be exceptionally challenging in patients with complex CHD, due to particular vascular access and also modified anatomy, it has paved the way to enhance comprehension of the underlying mechanisms of supraventricular arrhythmias. This, in turn, enables the provision of improved therapies and, ultimately, an enhancement in the quality of life and symptom management for these patients. The purpose of this case report is to highlight the benefits of utilizing advanced technologies such as three-dimensional electro-anatomical mapping systems, remote magnetic navigation, and highly flexible mapping and ablation catheters during RFA in a young adult with complex congenital heart disease. Although he lacked venous connections to the right atrium (RA) due to multiple corrective surgeries we, remarkably, were capable to advance a decapolar deflectable diagnostic catheter inside the Fontan tunnel and from there to record and stimulate the RA. Successful ablation of two accessory pathways was achieved with no arrhythmia recurrence during follow-up.

EPM algorithm: A stepwise approach to accessory pathway localization in ventricular pre-excitation.

BACKGROUND: Accurate estimation of accessory pathway (AP) localization in patients with ventricular pre-excitation or Wolff-Parkinson-White (WPW) syndrome remains a diagnostic challenge. Existing algorithms have contributed significantly to this area, but alternative algorithms can offer additional perspectives and approaches to AP localization. OBJECTIVE: This study introduces and evaluates the diagnostic accuracy of the EPM algorithm in AP localization, comparing it with established algorithms Arruda and EASY. METHODS: A retrospective analysis was conducted on 138 patients from Hospital São Paulo who underwent catheter ablation. Three blinded examiners assessed the EPM algorithm's diagnostic accuracy against the Arruda and EASY algorithms. The gold standard for comparison was the radioscopic position of the AP where radiofrequency ablation led to pre-excitation disappearance on the ECG. RESULTS: EPM showed a diagnostic accuracy of 51.45%, closely aligning with Arruda (53.29%) and EASY (44.69%). Adjacency accuracy for EPM was 70.67%, with Arruda at 66.18% and EASY at 72.22%. Sensitivity for EPM in distinguishing left vs. right APs was 95.73%, with a specificity of 74.33%. For identifying septal vs. lateral right APs, EPM sensitivity was 82.79% with a specificity of 46.15%. These measures were comparable to those of Arruda and EASY. Inter-observer variability was excellent for EPM, with Kappa statistics over 0.9. CONCLUSION: The EPM algorithm emerges as a reliable tool for AP localization, offering a systematic approach beneficial for therapeutic decision-making in electrophysiology. Its comparable diagnostic accuracy and excellent inter-observer variability underscore its potential clinical applicability. Future research may further validate its efficacy in a broader clinical setting.

Catheter ablation for an incessant arrhythmia in a preterm low-weight neonate.

A 15-day-old neonate weighing 1800 g presented with incessant long-RP tachycardia. Temporary cessation of the arrhythmia with adenosine confirmed the diagnosis of permanent junctional reciprocating tachycardia (PJRT). The arrhythmia was refractory to multiple drugs. An electrophysiological study confirmed diagnosis. The arrhythmia was successfully treated with radiofrequency. Learning objective: Transcatheter radiofrequency ablation can be done safely in infants who are unresponsive to medical therapy, regardless of age and body weight.

Wide QRS complex tachycardia with a mysterious mask-Tricuspid isthmus-dependent atrial flutter with preexcitation syndrome and dual atrioventricular nodal pathway conduction.

Key Clinical Message: Atrial flutter (AFL) and supraventricular tachycardia (SVT) are common arrhythmias in clinic. However, some AFL cases may present additional complexities, such as both accessory pathways (AP) and dual atrioventricular node pathways, putting on a mysterious mask and making it challenging to distinguish on electrocardiograms (ECGs). Abstract: A 60-year-old male patient had a sudden syncope, and an ECG showed wide QRS complex tachycardia. This diagnostic ambiguity is further compounded by the fact that SVT via AP conduction can exhibit wide QRS complex tachycardia characteristics resembling ventricular tachycardia (VT). Consequently, a definitive diagnosis through electrophysiological (EP) examination becomes imperative, as it dictates subsequent ablation strategies. In this article, we present a rare case involving three distinct arrhythmias including AFL, AP, and dual atrioventricular node pathways, and successfully treated through ablation.

Validation of qrs-polarity algorithm with special emphasis in parahisian pathways / Validación del algoritmo de la polaridad del qrs con especial énfasis en vías parahisianas

Abstract Background: In 1996 Iturralde et al. published an algorithm based on the QRS polarity to determine the location of the accessory pathways (AP), this algorithm was developed before the massive practice of invasive electrophysiology. Purpose: To validate the QRS-Polarity algorithm in a modern cohort of subjects submitted to radiofrequency catheter ablation (RFCA). Our objective was to determinate its global accuracy and its accuracy for parahisian AP. Methods: We conducted a retrospective analysis of patients with Wolff-Parkinson-White (WPW) syndrome who underwent an electrophysiological study (EPS) and RFCA. We employed the QRS-Polarity algorithm to predict the AP anatomical location and we compared this result with the real anatomic location determined in the EPS. To determine accuracy, the Cohen's kappa coefficient (k) and the Pearson correlation coefficient were used. Results: A total of 364 patients were included (mean age 30 years, 57% male). The global k score was 0.78 and the Pearson's coefficient was 0.90. The accuracy for each zone was also evaluated, the best correlation was for the left lateral AP (k of 0.97). There were 26 patients with a parahisian AP, who showed a great variability in the ECG features. Employing the QRS-Polarity algorithm, 34.6% patients had a correct anatomical location, 42.3% had an adjacent location and only 23% an incorrect location. Conclusion: The QRS-Polarity algorithm has a good global accuracy; its precision is high, especially for left lateral AP. This algorithm is also useful for the parahisian AP.

Resumen Antecedentes: En 1996 Iturralde y colaboradores publicaron un algoritmo basado en la polaridad del QRS para determinar la ubicación de las vías accesorias (VA), este algoritmo fue desarrollado antes de la práctica masiva de la electrofisiología invasiva. Objetivo: Validar el algoritmo de la polaridad del QRS en una cohorte moderna de sujetos sometidos a ablación con catéter por radiofrecuencia (ACRF). Nuestro objetivo fue determinar su precisión global y su precisión para las VA parahisianas. Métodos: Realizamos un análisis retrospectivo de pacientes con síndrome de Wolff-Parkinson-White (WPW) a los que se les realizó estudio electrofisiológico (EEF) y ACRF. Empleamos el algoritmo de la polaridad del QRS para predecir la ubicación anatómica de la VA y comparamos este resultado con la ubicación anatómica real determinada en el EEF. Para determinar la precisión se utilizaron el coeficiente kappa de Cohen (k) y el coeficiente de correlación de Pearson. Resultados: Se incluyeron un total de 364 pacientes (edad media 30 años, 57 % varones). La puntuación k global fue de 0,78 y el coeficiente de Pearson de 0,90. También se evaluó la precisión para cada zona, la mejor correlación fue para las VA laterales izquierdas (k de 0.97). Hubo 26 pacientes con VA parahisianas, que mostraron una gran variabilidad en las características del ECG. Empleando el algoritmo de la polaridad del QRS, el 34,6 % de los pacientes tenía una ubicación anatómica correcta, el 42,3 % tenía una ubicación adyacente y solo el 23 % una ubicación incorrecta. Conclusión: El algoritmo de la polaridad del QRS tiene una buena precisión global; su precisión es alta, especialmente para VA lateral izquierdo. Este algoritmo también es útil para la VA parahisiana.

Validation of qrs-polarity algorithm with special emphasis in parahisian pathways.

BACKGROUND: In 1996 Iturralde et al. published an algorithm based on the QRS polarity to determine the location of the accessory pathways (AP), this algorithm was developed before the massive practice of invasive electrophysiology. PURPOSE: To validate the QRS-Polarity algorithm in a modern cohort of subjects submitted to radiofrequency catheter ablation (RFCA). Our objective was to determinate its global accuracy and its accuracy for parahisian AP. METHODS: We conducted a retrospective analysis of patients with Wolff-Parkinson-White (WPW) syndrome who underwent an electrophysiological study (EPS) and RFCA. We employed the QRS-Polarity algorithm to predict the AP anatomical location and we compared this result with the real anatomic location determined in the EPS. To determine accuracy, the Cohen's kappa coefficient (k) and the Pearson correlation coefficient were used. RESULTS: A total of 364 patients were included (mean age 30 years, 57% male). The global k score was 0.78 and the Pearson's coefficient was 0.90. The accuracy for each zone was also evaluated, the best correlation was for the left lateral AP (k of 0.97). There were 26 patients with a parahisian AP, who showed a great variability in the ECG features. Employing the QRS-Polarity algorithm, 34.6% patients had a correct anatomical location, 42.3% had an adjacent location and only 23% an incorrect location. CONCLUSION: The QRS-Polarity algorithm has a good global accuracy; its precision is high, especially for left lateral AP. This algorithm is also useful for the parahisian AP.

ANTECEDENTES: En 1996 Iturralde y colaboradores publicaron un algoritmo basado en la polaridad del QRS para determinar la ubicación de las vías accesorias (VA), este algoritmo fue desarrollado antes de la práctica masiva de la electrofisiología invasiva. OBJETIVO: Validar el algoritmo de la polaridad del QRS en una cohorte moderna de sujetos sometidos a ablación con catéter por radiofrecuencia (ACRF). Nuestro objetivo fue determinar su precisión global y su precisión para las VA parahisianas. MÉTODOS: Realizamos un análisis retrospectivo de pacientes con síndrome de Wolff-Parkinson-White (WPW) a los que se les realizó estudio electrofisiológico (EEF) y ACRF. Empleamos el algoritmo de la polaridad del QRS para predecir la ubicación anatómica de la VA y comparamos este resultado con la ubicación anatómica real determinada en el EEF. Para determinar la precisión se utilizaron el coeficiente kappa de Cohen (k) y el coeficiente de correlación de Pearson. RESULTADOS: Se incluyeron un total de 364 pacientes (edad media 30 años, 57 % varones). La puntuación k global fue de 0,78 y el coeficiente de Pearson de 0,90. También se evaluó la precisión para cada zona, la mejor correlación fue para las VA laterales izquierdas (k de 0.97). Hubo 26 pacientes con VA parahisianas, que mostraron una gran variabilidad en las características del ECG. Empleando el algoritmo de la polaridad del QRS, el 34,6 % de los pacientes tenía una ubicación anatómica correcta, el 42,3 % tenía una ubicación adyacente y solo el 23 % una ubicación incorrecta. CONCLUSIÓN: El algoritmo de la polaridad del QRS tiene una buena precisión global; su precisión es alta, especialmente para VA lateral izquierdo. Este algoritmo también es útil para la VA parahisiana.

Multiple accessory pathways coexisting with a persistent left superior vena cava: a case report.

BACKGROUND: Wolff-Parkinson-White syndrome is characterized by a short PR interval (delta-wave), long QRS complex, and the appearance of paroxysmal supraventricular tachycardia. Patients with Wolff-Parkinson-White syndrome usually have one accessory pathway, whereas cases with multiple accessory pathways are rare. Persistent left superior vena cava is a vascular anomaly in which the vein drains into the right atrium through the coronary sinus at the junction of the left internal jugular and subclavian veins due to abnormal development of the left cardinal vein. The simultaneous presence of multiple accessory pathways and persistent left superior vena cava has not been reported before. CASE PRESENTATION: A 56-year-old Japanese man with a 5-year history of palpitations was referred for radiofrequency catheter ablation due to increased frequency of tachycardia episodes in the previous 2 months. Persistent left superior vena cava was confirmed by transthoracic echocardiography and computed tomography. An electrophysiological study revealed that the accessory pathways were located in the left lateral wall, anterolateral wall, and posteroseptal region. They were completely ablated with radiofrequency energy application. CONCLUSIONS: We reported an extremely rare case of a patient with multiple accessory pathways and persistent left superior vena cava. Our case may suggest a potential embryological relationship between the multiple accessory pathways and persistent left superior vena cava.

Accessory pathway properties are similar in symptomatic and asymptomatic preexcitation.

PURPOSE: Patients with WPW syndrome have an increased mortality rate compared to the general population. Although asymptomatic preexcitation has previously been considered benign, recent studies have found that also asymptomatic patients have clinical and electrophysiological factors associated with increased risk of sudden cardiac death. This study compares the baseline electrophysiological characteristics of accessory pathways in symptomatic and asymptomatic patients with preexcitation. We hypothesized that a significant proportion of asymptomatic patients has inducible orthodromic tachycardia during programmed electrical stimulation. METHODS: This retrospective study includes 1853 patients with preexcitation who underwent invasive electrophysiological testing in two Swedish University Hospitals between 1991 and 2018. The mean age was 36 ± 17 years with a range of 3-89 years. Thirty-nine percent was women. A total of 269 patients (15%) were children younger than 18 years. Electrophysiological data included effective refractory period of the accessory pathway (APERP, in 1069 patients), tachycardia cycle length, inducibility and type of tachycardia, and AP localization. RESULTS: A total of 1703 (93%) patients reported symptoms suggesting tachyarrhythmias before the study and 128 (7%) were asymptomatic. The proportion of potentially dangerous pathways with short APERP (≤ 250 ms) were similar in symptomatic and asymptomatic patients (187/949, 20% vs. 25/108, 23%) (P = 0.40) as was the mean APERP (303 ± 68 ms vs. 307 ± 75) (P = 0.61). The proportion of patients who had inducible arrhythmia was larger in the symptomatic group (64% vs. 31%) (P < 0.001). CONCLUSION: The results of this study strengthen the present guideline recommendation (IIA) to consider invasive risk assessment in patients with asymptomatic preexcitation.

Positive QRS complex in limb lead 2 with negative QRS in lead 3 on surface electrocardiogram: A novel predictor for anterior location of right-sided accessory pathways (10-1 o'clock on tricuspid annulus).

BACKGROUND: Localization of atrioventricular accessory pathways (AP) from Electrocardiogram (ECG) is crucial for successful ablation. We analyzed the value of limb lead 2 versus 3 QRS vector discordance on surface ECG among right-sided pathways. METHODS: Data from consecutive patients undergoing successful ablation of manifest AP were analyzed. They were categorized into two groups-Gr I: Endocardial ablation from anterior and anterolateral tricuspid annulus (TA, 10-1 o'clock, right anterolateral [RAL]); Gr II: Ablation outside this region (1-10 o'clock of TA). Inferior lead discordance (ILD) was defined as positive QRS complex (monophasic R, Rs) in lead 2 with negative/equiphasic QRS vector in lead 3 (rS, S, RS). Maximally pre-excited ECGs during electrophysiology study were compared for presence of ILD. RESULT: Among total 22 cases (Age 36 ± 18 years, 12 males), ILD was noted in 4/4 cases of Gr I. It was absent among 17/18 cases of right-sided AP in Gr II. The only case in Gr II having ILD was ablated near 8 o'clock (posterolateral). In contrast to the other four cases, aVF was negative, along with lead 3. A close differential was mid-septal AP (MSAP). However, the MSAP had absence of r in V1 and lead 2 having rS/RS complex in contrast to strongly positive QRS in RAL pathways. The sensitivity and specificity of ILD for RAL are 100% and 95%, respectively. The positive, negative predictive value, and accuracy are 80%, 100%, and 95%, respectively. CONCLUSION: Positive QRS complex in lead 2 with negative QRS in lead 3 in maximally pre-excited ECG is often predictive of anterior and anterolateral location among right-sided pathways.

Success rate and safety of catheter ablation in preexcitation syndrome: A comparison between adult and pediatric patients.

BACKGROUND: In contrast to adults, in whom cardiac rhythm disorders are mainly conditioned by coronary artery disease, in children, arrhythmias are most often associated with inherited heart disorders. Catheter ablation (CA) has an important role in the management of cardiac arrhythmias, in adults and children. The aim of the study was to assess and compare the efficacy and safety of CA in children and adults with preexcitation syndrome. METHODS: The study population comprised 43 adults and 43 children diagnosed with a Wolff-Parkinson-White syndrome (WPW). The mean age of the study population was 41 ± 15 years for adults and 14 ± 2.5 years for children. In all patients, an electrophysiological study and CA were performed. Analysis with respect to the procedure duration, fluoroscopy exposure time, location of accessory pathways (AP), immediate success rate and complications were performed. RESULTS: Electrophysiological study revealed the most frequent presence of left-sided AP (56% in children and 70% in adults). The mean procedure duration was 96 ± 36 min and 106 ± 51 min in children and adults, respectively (p = NS). The mean fluoroscopy duration was 8.5 ± 4.3 min and 5.9 ± 5.8 min in children and adults, respectively p < 0.05. The CA procedure was successful in 40 out of 43 (93%) adults and in 36 out of 43 (83.7%) children (p = NS). In 2 (4%) children minor complications occurred. CONCLUSIONS: Ablation in children and adults are equally effective with respect to short-term clinical observation.

V1r + DIIq is a novel and accurate criterion to predict right vs. left paraseptal accessory pathways.

PURPOSE: The correct estimation of accessory pathway (AP) localization from surface ECG is critical before the procedure. Our study aimed to detect the predictive value of the V1r + DIIq criterion for differentiating right- from left-sided paraseptal APs. METHODS: We retrospectively included 58 patients with (Wolff-Parkinson-White) WPW syndrome and paraseptal APs who underwent successful catheter ablation (37 male, 21 female; mean age 34.4 ± 13.6 years). The V1r + DIIq criterion was calculated using the following formula: V1r + DIIq (mV) = initial r wave amplitude in V1 + q wave amplitude in DII. The combined criterion included V1r + DIIq <2.05 mV and/or no initial r wave in V1. RESULTS: Right-sided paraseptal APs were detected in 36 patients (62.1%), left-sided paraseptal APs were detected in 21 patients (36.2%), and AP from CS was detected in 1 patient (1.7%). The initial r wave amplitude in V1 (mV), q wave amplitude in DII (mV) and V1r + DIIq criterion (mV) were lower in patients with right-sided paraseptal APs (p < 0.001). The percentage of patients with no initial r wave in V1 (36.1% vs. 0%) and those meeting the combined criterion (91.7% vs. 4.5%) were increased in patients with right-sided paraseptal APs. The cutoff value of the V1r + DIIq criterion obtained by ROC curve analysis was 2.05 mV for predicting right-sided paraseptal APs (sensitivity: 86.1%, specificity: 95.5%). The area under the curve (AUC) was 0.943 (95% CI = 0.881-1.000) (p < 0.001). The sensitivity and specificity values were 36.1% and 100%, respectively, for the no initial r wave criterion and 91.7% and 95.5%, respectively, for the combined criterion. CONCLUSION: The V1r + DIIq criterion and the combined criterion represent novel and simple electrocardiographic criteria for accurately differentiating right- from left-sided paraseptal APs. This simple ECG measurement can improve the accuracy of detection of paraseptal AP localization and could be beneficial for decreasing ablation duration and radiation exposure.

Administration of Adenosine Triphosphate Provides Additional Value Over Programmed Electrophysiologic Study in Confirmation of Successful Ablation of Atrioventricular Accessory Pathways.

Objectives: To study the benefit of adenosine triphosphate (ATP) in evaluating ablation endpoints of accessory pathways (AP) and subsequent long-term prognosis. Methods: We reviewed consecutive patients with supraventricular tachycardias due to APs that underwent radiofrequency catheter ablation (RFCA) from January 2016 to September 2018 in our center. The patients were divided into two groups: the ATP group (who had passed both the ATP test and PES after ablation as the endpoint) and the non-ATP group (who had passed PES only after ablation as the endpoint). We reviewed the patients' intra-cardiac electrograms and analyzed their long-term outcomes. Results: In total, 1,343 patients underwent successful RFCA. There were 215 patients in the ATP group with one lost to follow-up. There were 1,128 patients in the non-ATP group with 39 lost to follow-up. Twenty-three patients in the ATP group demonstrated additional electrophysiological entities due to ATP administration, including reappearance of the ablated APs in 16 patients, discovery of PES-undetected APs in 5, induction of atrial fibrillation in 5, premature atrial contractions in 1, and premature ventricular contractions in another. During the 7 to 39 months (average 24.4 ± 9.5 months) follow-up, the recurrence rate was 8.41% (18/214) in the ATP group and 6.80% (74/1,084) in the non-ATP group. In subjects with recurrence, 14 patients (14/18 = 77.8%) in the ATP group and 50 patients (50/74 = 67.6%) in the non-ATP group accepted redo ablations. Among the ATP-group, all the 14 redo APs were the old ones as before. Among the non-ATP-group, redo ablations confirmed that 39 APs were the old ones, while 20 APs were newly detected ones which had been missed previously. The difference in recurrent AP locations confirmed by redo procedures between the two groups was significant (p = 0.008). In the non-ATP group, 20 (40%) of redo cases were proven to have multiple APs, while 33 (3.3%) cases who did not suffer from recurrence had multiple APs. Existences of multiple APs in recurred cases were significantly higher than that in non-recurred ones in the non-ATP group (p < 0.001), while there was no such difference in the ATP group (p = 0.114). Conclusions: The existence of multiple APs was more common in recurrent cases if ATP was not used for confirmation of ablation endpoints. ATP probably has additional value over PES alone by detecting weak AP conductions. ATP can evoke atrial and ventricular arrhythmias.

Outcomes Of Manifest Right Free Wall Accessory Pathway Ablation: Data From A Single Center.

BACKGROUND: Right free wall (RFW) accessory pathways (AP) typically present anatomical challenges to ablation leading to high rates of procedural failure and recovery of AP conduction. METHODS: Patients with a diagnosis of Wolff-Parkinson-White Syndrome (WPW) and a manifest RFW AP undergoing an electrophysiology study (EPS) or an ablation at our center between 01/01/2008 and 08/01/2019 were identified from our databases using diagnosis codes and manual chart review. RESULTS: Twenty-one patients with manifest RFW AP underwent EPS, all of which were targeted for ablation. Single procedure success rate was 19 / 21 (90.5%). Of the 19 successful cases, 4 (17.4%) patients were found to have recurrent right free wall pathway conduction at follow-up and each underwent a successful 2nd procedure (9.5%). Fluoroscopic and 3D electroanatomic mapping software was used in all cases to guide ablation. A 4 mm or 8 mm non-irrigated radiofrequency (RF) ablation catheter was used in 76% of cases while an 8 mm cryo-catheter was used in one case. More than one type of ablation catheter was used in four cases (16%). A steerable sheath was used in 68% of cases. CONCLUSIONS: In a tertiary center, RFW AP ablation has high acute success (>90%) but approximately 21% of patients with initially successful ablation required a 2nd procedure for recurrence of pathway conduction. A combination of a large tip ablation catheter and a steerable sheath were used in most cases.

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.