Comprehensive assessment of Mahaim accessory pathways’ anatomic distribution

Objective To present the authors’ experience of Mahaim-type accessory pathways (MAPs), focusing on anatomic localizations. Methods Data from consecutive patients who underwent electrophysiological study (EPS) for MAP ablation in two tertiary centres, between January 1998 and June 2020, were retrospectively analysed. Results Of the 55 included patients, 27 (49.1%) were male, and the overall mean age was 29.5 ± 11.6 years (range, 12–66 years). MAPs were ablated at the tricuspid annulus in 43 patients (78.2%), mitral annulus in four patients (7.3%), paraseptal region in three patients (5.5%), and right ventricle mid-apical region in five patients (9.1%). Among 49 patients who planned for ablation therapy, the success rate was 91.8% (45 patients). Conclusion MAPs were most often ablated at the lateral aspect of the tricuspid annuli, sometimes at other sides of the tricuspid and mitral annuli, and infrequently in the right ventricle. The M potential mapping technique is likely to be a useful target for ablation of MAPs.

Orthodromic Atrioventricular Tachycardia in Wolff-Parkinson-White Syndrome with Two Accessory Pathways Participation during the Same AVT

Case report of a 49-year-old patient with Wolff-Parkinson-White syndrome, very symptomatic, with apparent parahisian pathway who, during an electrophysiological study, presented orthodromic atrioventricular tachycardia, featuring two accessory pathways, retrogradely, the parahisian pathway and a hidden left posterolateral pathway, during the same tachycardia, alternating the retrograde pathway of tachycardia without interruption.

707 Transvenous radiofrequency ablation of epicardial posterior-septal accessory pathways in children with WPW syndrome: can technology and imaging innovations improve the outcome?

Aims The aim of the study was to analyse our recent single-centre experience about epicardial posterior-septal accessory pathways transcatheter ablation in children and young patients using radiofrequency through the coronary sinus, in order to understand which mapping and ablation strategy is associated with higher success rate and safety. Methods and results We reviewed all the cases of ablation of overt accessory pathways (in Wolff–Parkinson–White syndrome) with epicardial posterior-septal localization performed in children or young patients at our institution in the last 5 years. Twenty-two paediatric patients (mean age: 13 ± 3 years) with epicardial posterior-septal accessory pathways (15 in coronary sinus and 7 in the Middle Cardiac Vein) underwent radiofrequency transcatheter ablation with CARTO 3TM. Acute success rate was 77%. No patient was lost to follow-up (mean time 14.4 ± 9 months). The recurrence rate was 18%. Two patients underwent a successful redo-procedure; the overall long-term success rate was 68%. NAVISTAR® catheter presented the highest acute success rate in the coronary sinus. NAVISTAR SMARTTOUCH® was the only catheter that did not present recurrences after the acute success and it was successfully used in two patients previously unsuccessfully treated with a NAVISTAR THERMOCOOL®. Integration with angio-CT of coronary sinus branches obtained with CARTOMERGE was associated with higher success rate in patients with a previous failed ablation attempt. Conclusions Epicardial posterior-septal accessory pathways can be successfully treated with transvenous radiofrequency ablation in more than half of the cases in children/young patients. Acute success rate does not seem to depend on catheters used but contact-force catheter seems to be useful in cases with recurrences. Image integration with cardiac-CT reconstruction of coronary sinus branches anatomy can be useful to better guide ablation in case of previously failed attempts.

547 Supernormal conduction of an accessory pathway: the case of a young sportsman

Aims Ventricular pre-excitation is defined by the presence of all of the following electrocardiographic criteria: PQ interval duration ≤120 ms, QRS duration ≥120 ms, and presence of δ wave (defined as initial ‘slurring’ of the QRS complex). Ventricular pre-excitation together with the presence of symptoms (orthodromic and/or antidromic atrioventricular reentry tachycardia, atrial fibrillation) defines Wolff–Parkinson–White (WPW) syndrome. The anatomical substrate of ventricular pre-excitation consists of an extranodal accessory atrio-ventricular connection: the so-called Kent bundle. Such pathways can have antegrade, retrograde, or mixed conductive properties. Accessory pathways endowed with anterograde conductive capability may be responsible for manifest, intermittent, or non-manifest ventricular pre-excitation depending on whether it is respectively always visible on the ECG, not always visible on the ECG and not visible on the ECG even though the pathway has the ability to antegrade conduction. The rare phenomenon of supernormal conduction of anomalous pathways is part of the manifest pre-excitation, which represents the topic of the case reported below. Methods and results We report the clinical case of a young not agonist sportsman undergoing an electrophysiological study (SEF) because of he is suffering from ventricular pre-excitation. The SEF did not showed the inducibility of arrhythmias and, at the same time, apparently it showed low risk characteristics of the pathway even during adrenergic stimulus. However, a careful study, performed with atrial stimulation with couplings up to refractoriness of the atrioventricular node revealed supernormal conduction properties of the Kent bundle which proved to have high risk characteristics according to current guidelines and, therefore, was effectively treated with catheter ablation. Conclusions This case invites us to careful studying of accessory pathways properties, especially since, although rare, they may possess supernormal conduction characteristics capable of determining high ventricular rates in the case of sustained atrial tachyarrhythmias, especially in conditions of adrenergic hyperactivity.

Redo accessory pathway ablation in the pediatric population

Background Literature reports 5% of recurrence/failure in paediatric accessory pathway ablations. Our aim was to investigate the reasons underlying this finding and share techniques to obtain long-term success. Methods Thirty-nine paediatric patients referred for a repeat procedure were analysed: characteristics of the pathways and the initial and redo procedures were identified. Results Mean age was 11.9 ± 3.3 years (59% males). Three patients (8%) had multiple accessory pathways. The most frequent location was left lateral (26%). Left sided pathway recurrence was caused mainly by poor contact (60%) and inadequate mapping (40%). For right lateral accessory pathways, poor contact accounted for 70% of failures. For antero-septal and para-Hisian locations, the use of cryoablation and choice of low radiofrequency energy delivery accounted for > 75% of failures. Long-term success strategies included choice of contact force catheters and radiofrequency applications at the ventricular insertion of the pathway and in the aortic coronary cusps. In postero-septal substrates, the main reason accounting for failure was deep or epicardial location of the pathway (37%), solved by using an irrigated tip catheter or applying lesions within the coronary sinus, or applications from both right and left postero-septal areas. Conclusion Acute failure and post-procedure recurrence in paediatric accessory pathway ablations have multiple reasons related to the characteristics of the pathway and the technology available. Accurate understanding of the anatomy, careful mapping and pacing manoeuvers, and incorporation of new technologies contribute to achieve a definitive success in > 98% of procedures.

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.

Dyssynchronous cardiomyopathy in patients with WPW syndrome and its reversibility after RFA of accessory pathway

Introduction In some cases accessory pathway-mediated ventricular preexcitation can be associated with electro-mechanical dyssynchrony and, consequently, with dyssynchrony-related dilated cardiomyopathy, even in the absence of supraventricular tachycardia (SVT). Sometimes rapid progression of ventricular dysfunction developed in such patients after birth. Methods and materials 8 patients with asymptomatic WPW and dyssynchronous cardiomyopathy were examined in our Institute from 2017 till 2019. Four patients of the group were observed in other clinics with dilated cardiomyopathy (DCM) and prescribed appropriate therapy without significant clinical effect. The absence of complaints of heartbeat and episodes of tachycardia at the scheduled Holter monitoring allowed eliminating incessant tachycardia as a possible cause of cardiomyopathy. After radiofrequency ablation (RFA) all patients were performed ECG to assess QRS duration, Holter monitoring, echocardiography (Echo) for assessment of heart chamber volume and left ventricle (LV) contractile function and Speckle tracking – Echo with LV longitudinal strain assessment. The average age of the patients was 9.5 years (from 2 to 14 years). 6 children had heart failure (NYHA Class II). Results According to Echo all patients had widened QRS complex. Dilatation and enlargement of LV volume were marked in 6 pts. According to Echo7 patients had decrease of LV contractile function. According to Speckle tracking – Echo all patients had intraventricular dyssynchrony, decrease of longitudinal strain indices. At intracardiac electrophysiology study right-sided accessory pathways was diagnosed in all patients, successful RFA was performed. Preexitation relapsed, and the repeated RFA was performed in 2 pts. Complications caused by RFA were not marked. After RFA all patients showed a regular normalization of QRS duration. At the 5th day after RFA Echo was performed to all patients. The patients with initially decreased LV ejection fraction had it increased. The patients with initial dilatation and LV volume enlargement had normalization of the given indices. According to Speckle tracking – Echo normalization of global and regional myocardial function, LV longitudinal strain, disappearance of intraventricular and interventricular dyssynchrony were marked in all patients. The index of longitudinal strain was 17,0±0,64% before RFA, after RFA - 23,75±0,92% (p=0,ehab724.035946). Conclusion As a result of RFA of accessory pathways electromechanical resynchronization causes LV demodeling and restoration of its contractile ability. The presented clinical examples are an additional indication for RFA of accessory pathways even in the absence of SVT in patients regardless of age. FUNDunding Acknowledgement Type of funding sources: None.