Ablation Of Atrioventricular Nodal Reentry Tachycardia Research Articles

Activation map of koch triangle: a novel approach to AVNRT ablation using CARTO 3 v7

Abstract Background Ablation of slow pathway (SP) is the standard approach for atrioventricular nodal reentry tachycardia (AVNRT) treatment (1). Low-voltage bridge is an optimal target during mapping using low x-ray exposure (2,3). Purpose We want to assess a new tool to identify SP by activation mapping of Koch’s triangle using CARTO PRIME V7 Methods Triangle of Koch 3D-activation map were obtained from intracardiac contact mapping during low x-ray CARTO 3 procedures (Figure 1). In 60 patients (39 % males, mean age 60.3 ± 14.7 years) undergoing ablation for AVNRT, an automatic activation map using a DECANAV mapping catheter and CARTO Confidense, Coherent, and FAM DX software modules were obtained. Results We indentified SP in all patients as the latest atrioventricular node activation area; RF catheter ablation (RFCA) elicited junctional beats. The mean dose-area product (DAP) was 16.5 ± 2.7 cGy/cm2, the mean fluoroscopy time exposure was 2.9 ± 2 min, the mean ablation index was 428.6 ± 96.6, and the mean contact force was 8 ± 2.8 g. There were no adverse event during the procedure and no AVNRT recurrences during a mean follow-up of 14.3 ± 8.3 months. Conclusions Ablation of the SP by automatic mapping using Confidense, Coherent, and FAM DX software modules is a new approach to AVNRT ablation. The CARTO3 V7 system defines a 3D map of the latest AV node activation area during sinus rhythm allowing a highly effective RFCA under low fluoroscopy time exposure without recurrences or AV blocks.Figure 1

Low voltage mapping in atrio-ventricular nodal reentry tachycardia ablation: safety and efficacy in a single center experience

Abstract Background Atrio-ventricular nodal reentry tachycardia (AVNRT) is one of the most common supraventricular arrhythmias. Transcatheter ablation is the first-choice strategy for its treatment. Despite various ablation techniques, using different signal analyses and different energy sources, the reported incidence rate of AVNRT recurrences and high-grade or complete atrioventricular block are about 5% and 1% respectively. Voltage mapping for slow pathway localization is a novel technique for the treatment of AVNRT, that may increase procedural safety and effectiveness, particularly in pediatric patients. Purpose To evaluate the safety and efficacy of ablation of slow conduction pathway identified via three-dimensional voltage mapping of Koch’s triangle. Methods 108 consecutive patients (45% male, mean age 58.6±15.4 years) scheduled for AVNRT ablation in our center underwent three-dimensional voltage mapping of the right atrial septum and Koch’s triangle. Voltage map was aimed at detecting an area of low voltage (voltage bridge) below the His bundle (adjusting the high-voltage slider to 1,5 mV), corresponding to the slow conduction pathway. Focusing on this target, we evaluated the number of radiofrequency (RF) pulses and RF time application for effective ablation of the slow conduction pathway defined by accelerated junctional rhythm (AJR) induction during RF delivery and absence of post-ablative AVNRT inducibility. After RF ablation, all patients underwent clinical evaluation every 3 months to identify AVNRT recurrences. Results Voltage mapping was performed in all patients. The mean duration of mapping was 5.7±3.8 minutes. In all patients, a low voltage bridge could be identified. Using this target, RF was delivered until AJR was elicited (mean number of RF pulses at 30W, 50°C = 1.5±1.1; mean time to AJR: 25±12 s). After successful ablation of the slow conduction pathway, AVNRT was no more inducible. No atrioventricular conduction defect (atrioventricular block of any grade) occurred after RF ablation in any patient (AH pre vs. AH post: 148.5±22.8 ms vs. 153.6±17.8 ms, p=n.s.; HV pre vs. HV post: 20.5±18.7 ms vs. 21.8±17.3 ms, p=n.s.; Wenkebach point pre vs. Wenkebach point post: 320.4±45.3 ms vs. 326.2±38.7 ms, p=n.s.). All patients were discharged without antiarrhythmic drug therapy. Overall, during a 2-year follow up, 4 patients had a recurrence of AVNRT (incidence rate of recurrences: 0.025/year). Conclusions Voltage mapping can easily identify the low voltage bridge area of Koch’s triangle as a target for slow pathway ablation. RF ablation of the slow pathway identified in this way is safe and effective. Success in slow pathway ablation can be achieved with a low number of very precise RF pulses. This approach can prevent the risk of ablation-related atrioventricular conduction defects and reduce the risk of AVNRT recurrences.

Atrioventricular nodal reentry tachycardia treatment using CARTO 3 V7 activation mapping: a new era of slow pathway radiofrequency ablation is under coming.

Slow pathway (SP) ablation is the cornerstone for atrioventricular nodal reentry tachycardia (AVNRT) treatment, and a low-voltage bridge offers a good target during mapping using low x-ray exposure. We aimed to assess a new tool to identify SP by activation mapping using the last CARTO3® version, i.e., CARTO PRIME® V7 (Biosense Webster, Diamond Bar, CA, USA). Right atrial septum and triangle of Koch 3D-activation map were obtained from intracardiac contact mapping during low x-ray CARTO 3® procedure. In 60 patients (mean age 60.3 ± 14.7, 61% females) undergoing ablation for AVNRT, an automatic activation map using a DECANAV® mapping catheter and CARTO® Confidense™, Coherent, and FAM DX software modules were obtained. The SP was identified in all patients as the latest atrioventricular node activation area; RF catheter ablation (RFCA) in that region elicited junctional beats. The mean procedural time was 150.3 ± 48.3 min, the mean fluoroscopy time exposure was 2.9 ± 2 min, the mean dose-area product (DAP) was 16.5 ± 2.7 cGy/cm2. The mean number of RF applications was 3.9 ± 2, the mean ablation index was 428.6 ± 96.6, and the mean contact force was 8 ± 2.8 g. There were no adverse event during the procedure, and no AVNRT recurrences occurred during a mean follow-up of 14.3 ± 8.3 months. Ablation of the SP by automatic mapping using Confidense™, Coherent, and FAM DX software modules is an innovative, safe, and effective approach to AVNRT ablation. The CARTO3® V7 system shows on a 3D map the latest AV node activation area during sinus rhythm allowing low fluoroscopy time and highly effective RFCA.

Electroanatomical Mapping System-Guided vs. Intracardiac Echocardiography-Guided Slow Pathway Ablation: A Randomized, Single-Center Trial.

Radiofrequency (RF) catheter ablation is an effective treatment option for targeting the slow pathway (SP) in atrioventricular nodal reentry tachycardia (AVNRT). Previous data suggested that using intracardiac echocardiography (ICE) guidance could improve procedural outcomes when compared to using fluoroscopy alone. In this prospective study, we aimed to compare the effectiveness of an electroanatomical mapping system (EAMS)-guided approach with an ICE-guided approach for SP ablation. Eighty patients undergoing SP ablation for AVNRT were randomly assigned to either the ICE-guided or EAMS-guided group. If the procedural endpoint was not achieved after 8 RF applications; patients were allowed to crossover to the ICE-guided group. The ICE-guided approach reduced the total procedure time (61.0 (56.0; 66.8) min vs. 71.5 (61.0; 80.8) min, p < 0.01). However, the total fluoroscopy time was shorter (0 (0-0) s vs. 83.5 (58.5-133.25) s, p < 0.001) and the radiation dose was lower (0 (0-0) mGy vs. 3.3 (2.0-4.7) mGy, p < 0.001) with EAMS-guidance. The ICE-guided group had a lower number of RF applications (4 (3-5) vs. 5 (3.0-7.8), p = 0.03) and total ablation time (98.5 (66.8-186) s vs. 136.5 (100.5-215.8) s, p = 0.02). Nine out of 40 patients (22.5%) in the EAMS-guided group crossed over to the ICE-guided group, and they were successfully treated with similar RF applications in terms of number, time, and energy compared to the ICE-guided group. There were no recurrences during the follow-up period. In conclusion, the utilization of ICE guidance during SP ablation has demonstrated notable reductions in procedural time and RF delivery when compared to procedures guided by EAMS. In challenging cases, an early switch to ICE-guided ablation may be the optimal choice for achieving successful treatment.

PO-05-232 SAFETY AND EFFICACY OF ATRIOVENTRICULAR NODAL REENTRY TACHYCARDIA ABLATION USING AN IRRIGATED CONTACT FORCE CATHETER

Atrioventricular Nodal Reentry Tachycardia (AVNRT) ablation is a common procedure in contemporary electrophysiology practice. Traditionally ablation for AVNRT has been performed with non-irrigated catheters, guided by fluoroscopy and intracardiac electrograms. Increasingly electroanatomic mapping systems are utilized to allow for low or zero fluoroscopy procedures. Contact force catheters can provide information on tissue contact and stability that can be helpful in patients with challenging anatomy. Available contact force catheters are irrigated and concern has existed for using irrigated tip ablation catheters for AVNRT ablation due to the potential to create lesions that are too deep and could increase the risk for AV block. To describe the safety and efficacy for the use of irrigated contact force catheters for ablation of AVNRT Review of procedural data from patients undergoing radiofrequency ablation for AVNRT using electroanatomical mapping combined with irrigated contact force catheter. Fifty patients from 4 regions across Australia were included. Procedures were performed by 9 experienced electrophysiologists. No periprocedural complications occurred. Procedural success was achieved in 96%. Median lesion contact force (25-75 centile) was 4.0(2-6)g. Peak power was set at 50W, median baseline irrigation was at 2ml/min and 6ml/min during ablation. Median number of lesions was 9(4.5-17.5); with total ablation time of 203(95-366) seconds. 60% of the cases were performed without fluoroscopy. Ablation of AVNRT using an irrigated contact force catheter on low irrigation setting is safe and effective. Contact force catheters using low irrigation settings may safely improve success rates in AVNRT with challenging anatomy or ablation of other substrate in close proximity to vital structures.

Randomized trial of intracardiac echocardiography-guided slow pathway ablation.

Radiofrequency (RF) catheter ablation of the slow pathway (SP) in atrioventricular nodal reentry tachycardia (AVNRT) is highly effective; however, it may require prolonged fluoroscopy and RF time. We postulated that visualization of the SP region with intracardiac echocardiography (ICE) could decrease ablation time, minimize radiation exposure, and facilitate SP ablation compared to the standard, fluoroscopy-guided approach. In our study, we randomized 91 patients undergoing electrophysiologic study and SP ablation for AVNRT into 2 groups: fluoroscopy-only (n = 48) or ICE-guided (n = 43) group. Crossover to ICE-guidance was allowed after 8 unsuccessful RF applications. Mapping plus ablation time (mean ± standard deviation: 18.8 ± 16.1min vs 11.6 ± 15.0min, p = 0.031), fluoroscopy time (median [interquartile range]: 4.9 [2.93-8.13] min vs. 1.8 [1.2-2.8] min, p < 0.001), and total ablation time (144 [104-196] s vs. 81 [60-159] s, p = 0.001) were significantly shorter in the ICE group. ICE-guidance was associated with reduced radiation exposure (13.2 [8.2-13.4] mGy vs. 3.7 [1.5-5.8] mGy, p < 0.001). The sum of delivered RF energy (3866 [2786-5656] Ws vs. 2283 [1694-4284] Ws, p = 0.002) and number of RF applications (8 [4.25-12.75] vs. 4 [2-7], p = 0.001) were also lower with ICE-guidance. Twelve (25%) patients crossed over to the ICE-guided group. All were treated successfully thereafter with similar number, time, and cumulative energy of RF applications compared to the ICE group. No recurrence occurred during the follow-up. ICE-guidance during SP ablation significantly reduces mapping and ablation time, radiation exposure, and RF delivery in comparison to fluoroscopy-only procedures. Moreover, early switching to ICE-guided ablation seems to be an optimal choice in challenging cases.

Abstract 14261: Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia: A Standardized Mapping System Protocol

Introduction: according to European guidelines, ablation has become the treatment of choice in patients with symptomatic atrioventricular nodal reentry tachycardia (AVNRT). Despite the high procedure success rate, anatomical variations can affect the outcome in terms of relapses and complications. As recently demonstrated, low-voltage bridge visualization allows low pathway identification and therefore a new ablation strategy. Hypothesis: our purpose was the validation of standardized ablation protocol within the low-voltage bridge area. Methods: 70 consecutive patients with inducible AVNRT were evaluated and a three-dimensional voltage map of the right atrial septum and Koch Triangle was constructed by means of contact mapping. Ablation site was identified as the low-voltage area below the His bundle, adjusting the high-voltage slider to 1,5 mV and dynamically adjusting the slider of low-voltage. Radio-frequency energy (with an average number of nine lesions per patient) was then delivered within this area until the appearance of junctional beats. The results were tested at the end of the procedures and during the observational period (the mean follow-up was 10,5 months). Results: the slow pathway was identified by the low-voltage bridge in 60 patients (85,6%) and in these patients, the target lesions in that area finally prevented induction of AVNRT in 100% of cases. A zero-fluoroscopy approach was possible for 50 patients (83%). Compared with standard AVNRT ablation, no complications as well as no statistical differences in terms of total procedure time were observed (p=0,056). 59 patients (98%) had no relapses during the follow-up. Conclusions: voltage gradient mapping successfully targeted the slow pathway in most of our cases. Lesions on the voltage bridge led to effective ablation of AVNRT and to a drastic x-ray exposure reduction in the absence of acute or long-term complications.

Remote magnetic navigation shows superior long-term outcomes in pediatric atrioventricular (nodal) tachycardia ablation compared to manual radiofrequency and cryoablation.

BackgroundCatheter ablation (CA) is the first-choice treatment for tachyarrhythmia in children. Currently available CA techniques differ in mechanism of catheter navigation and energy sources. There are no large studies comparing long-term outcomes between available CA techniques in a pediatric population with atrioventricular reentry tachycardia (AVRT) or atrioventricular nodal reentry tachycardia (AVNRT) mechanisms.ObjectiveThis study aimed to compare procedural and long-term outcomes of remote magnetic navigation-guided radiofrequency (RF) ablation (RMN), manual-guided RF ablation (MAN) and manual-guided cryoablation (CRYO).MethodsThis single-center, retrospective study included all first consecutive CA procedures for AVRT or AVNRT performed in children without structural heart disease from 2008 to 2019. Three study groups were defined by the ablation technique used: RMN, MAN or CRYO. Primary outcome was long-term recurrence of tachyarrhythmia.ResultsIn total, we included 223 patients, aged 14 (IQR 12–16) years; weighting 56 (IQR 47–65) kilograms. In total, 108 procedures were performed using RMN, 76 using MAN and 39 using CRYO. RMN had significantly lower recurrence rates compared to MAN and CRYO at mean follow-up of 5.5 ± 2.9 years (AVRT: 4.3% versus 15.6% versus 54.5%, P < 0.001; AVNRT: 7.7% versus 8.3% versus 35.7%, P = 0.008; for RMN versus MAN versus CRYO respectively). In AVNRT ablation, RMN had significantly lower fluoroscopy doses compared to CRYO [30 (IQR 20–41) versus 45 (IQR 29–65) mGy, P = 0.040).ConclusionIn pediatric patients without structural heart disease who underwent their first AV(N)RT ablation, RMN has superior long-term outcomes compared to MAN and CRYO, in addition to favorable fluoroscopy doses.

Cryoablation of atypical atrioventricular nodal reentry tachycardia.

Data on ablation for atypical recurrent atrioventricular nodal reentry tachycardia (AVNRT) and long-term follow-up are generally sparse. Furthermore, the rate of recurrence and safety of cryoablation for atypical AVNRT has not been established. We compared patients cryoablated for atypical AVNRT and typical AVNRT during long-term follow-up. All patients (n = 2612) who underwent catheter ablation for AVNRT at the Karolinska University Hospital between January 2009 and August 2019 were analyzed. A total of 91 patients undergoing first-time cryoablation for atypical AVNRT were included. A control group with first-time cryoablation for typical AVNRT was matched in a 1:1 ratio. Patients were followed-up for recurrences for a median of 5.0 years (interquartile range: 3.1-7.5 years). After 5 years, AVNRT recurrence occurred in 10 patients (11.0%) in the atypical AVNRT group and in 8 patients (8.8%) in the typical AVNRT group (hazard ratio: 1.31 [95% confidence interval: 0.52-3.32]; p = 0.568). The duration of the index procedure was significantly longer for atypical compared to typical AVNRT ablation (132.1 ± 49.2 min vs. 110.1 ± 38.8 min; p = 0.001). Transient AV blocks occurred in a similar fashion in the atypical compared to typical group (11 [12.1%] vs. 4 [4.9%]; p = 0.103). However, no ablation induced persistent AV block developed in either group. Cryoablation for atypical AVNRT showed similar rate of recurrences and safety compared to typical AVNRT during long-term follow-up.

Wenckebach cycle length: A novel predictor for AV block in AVNRT patients treated with ablation.

Radiofrequency catheter ablation remains the most effective management option for atrioventricular nodal reentry tachycardia (AVNRT). The risk of atrioventricular (AV) block requiring permanent pacemaker is substantial, but, currently, a reliable method to predict this complication is lacking. The electrophysiologic studies (EPS) and baseline characteristics of patients who underwent catheter ablation for the treatment of AVNRT were retrospectively analyzed to investigate predisposing factors for AV block after treatment. Patients were followed for AV block at one month and one year after hospital discharge. Among 784 patients treated with catheter ablation for AVNRT between 1999 to 2019, 15 developed AV block. Patients with AV block were older (p=.001). Among the recorded EPS parameters, patients with AV block had significantly higher Atrial His interval (120vs. 110 ms, p=.049), Wenckebach cycle length (WCL) (400vs. 353 ms, p<.001) and tachycardia CL (400vs. 387 ms, P=.01) during the ablation compared to their peers without AV block. Additionally, only WCL (OR=1.1, 95% CI 1.02-1.19, p=.017) remained significant after adjustment for age, gender, ERP, AH interval, and HR. This association was confirmed by comparing patients with (n=15) and without (n=15) AV block using propensity score-matching. A WCL≥400ms was associated with a 4-fold higher incidence of AV block (4.79% vs. 1.25%). Increased pre-procedural WCL was associated with a high risk for AV block after catheter ablation treatment for AVNRT. These findings suggest that this readily available EPS-derived parameter may be a novel marker of risk for severe complications in these patients.

Speckle-tracking echocardiography can predict atrial fibrillation in patients with supraventricular tachycardia.

Atrioventricular nodal reentry tachycardia (AVNRT) is the most common supraventriculer arrhythmia in daily clinical practice. Comorbidity of AVNRT and atrial fibrillation (AF) has been well documented in some patients and AF development has been observed more frequently in AVNRT patients during their long-term follow-up. This study was conducted in order to investigate the left atrial two-dimensional-speckle-tracking echocardiographic (STE) parametres as the predictors of the occurence of AF in long-term follow-up in patients with spontaneously developed AF during AVNRT ablation. Two hundred and thirty two consecutive AVNRT patients who developed spontaneous AF during ablation procedure were included in the study. The patients were followed up for a mean follow-up period of 6.2 ± 2.1 years. All patients were evaluated using the 2D-STE method. AF was developed in 34 patients during the follow-up period. Cox regression analysis was performed in order to identify the independent predictors of AF occurence. Left atrial LA-res, LA-pump, LA-SRs, LA-SRe, and LA-SRa values were found to be significantly decreased in the group of patients that developed AF during the follow-up period (p<.001 for all aforementioned values). Multivariate cox regression analysis revealed that LA-res (hazard ratio [HR], 0.367; 95% confidence interval [CI], 0.161-0.0.683, p<.001) and SRe (HR, 0.472; 95% CI, 0.346-0.825, p=.006) were independent risk factors associated with the occurrence of AF. In conclusion, it was demonstrated for the first time with this study that 2D-STE can effectively predict the development of AF in long-term follow-up in patients with spontaneously developed AF during AVNRT ablation.

Voltage bridge mapping in atrioventricular nodal reentry tachycardia ablation in adult population: results from a multicenter registry

Abstract Funding Acknowledgements Type of funding sources: None. Background The presence of Low Voltage Bridge (LVB) in Atrioventricular Nodal Reentry Tachycardia (AVNRT) ablation has been described in children populations. Slow pathway ablations visualizing and targeting the LVB has been described to be safe and effective. However, the incidence of LVB in AVNRT ablation has not been widely explored in adult population. Purpose We aim to investigate the presence of LVB in adult patients (pts) undergoing AVNRT ablation, and the relationship between the LVB and the successful ablation site. We have also investigated the correlations between the Koch’s triangle (KT) anatomy and biophysical pts data. Methods The observational registry prospectively collected data of 165 pts. undergoing AVNRT ablation guided by 3D electroanatomical mapping system (EnSite - Abott, St Paul, MN) in 6 EP centers. Gender: 90F – 75M (55% - 45%) - Age: 57 ± 17 ys (min 15 – max 87) - Weight: 73 ± 15 kgs (min 42 - max 150) Prior of ablation a voltage map of KT was created using diagnostic and ablation catheters. We define as Type I LVB a clear, long area of low voltage within the KT between the CS ostium and the AV node with the base on the edge of the tricuspid annulus and Type II LVB a narrow low voltage channel between normal-voltage regions with the base on the edge of the tricuspid annulus. The relationship between LVB and successful site was evaluated at the end of the procedure. KT anatomical data were correlated to gender, age and weight. Results The LVB was identified in 134 pts (81%) with a prevalence of type I (91 - 68%) over type II (33 - 25%). In 10 pts (7%) the LVB did not match type I nor type II. When an LVB was identified, the correspondence between the LVB and the successful ablation site was verified in 117 pts (87%). In addition, a shorter RF time was applied when an LVB was found (396s vs 298s; p = 0.03). Strong correlations between KT anatomy and biophysical pts data were not identified. The distance between His electrograms and the successful ablation site weakly correlated (ρ = -0.24, p &amp;lt; 0.01) with pts age suggesting a shortening in the distance with age progression. Conclusion The visualization of the Low Voltage Bridge may be a helpful tool to guide AVNRT ablation in a large cohort of pts; furthermore it is associated with reduced RF applications time. The KT characteristics are difficult to be predicted a priori according to patient gender, age or weight.

A minimally fluoroscopic approach in AVNRT ablation reduces radiation exposure and number of RF applications without compromising safety, effectiveness and procedural time

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Radiofrequency ablation (RF) of atrioventricular nodal reentry tachycardia (AVNRT) using conventional fluoroscopy is associated with a significant radiation exposure to both patients and operators. 3D electro-anatomical mapping systems (EAMS) can reduce radiation exposure, but specific clinical studies on their use in AVNRT ablation still lack. Purpose The aim of this study was to determine if EAMS use in AVNRT ablation can reduce radiation exposure and to analyse its effects on clinical and procedural outcomes. Methods We selected 277 patients who underwent AVNRT RF ablation in a single center in Belgium between July 2015 and November 2019 and performed a retrospective analysis of 136 and 141 patients who respectively and consecutively underwent AVNRT ablation with a conventional fluoroscopic approach (Conventional group) and a minimally fluoroscopic approach using a 3D electro-anatomical mapping system to guide the procedure (Minimal fluoroscopy group). Conventional fluoroscopy was used in both groups to confirm AVNRT induction to avoid costs related to the use of EAMS catheters in case of non-induction. We compared radiation dose, acute success/complication rates, procedural time and the number/time of RF applications in both groups. Results Radiation dose in the minimal fluoroscopy group was significantly lower compared to the conventional group (1179 vs. 2686 mgray.cm2, p &amp;lt; 0,0001) and fluoroscopic time was shorter (2,5 vs. 8,6 minutes, p &amp;lt; 0,0001). Procedural time (70 vs. 69 min, p = NS) and acute success rate (99% vs. 98%, p = NS) were not significantly different in the minimal fluoroscopy group compared to the conventional group, and no complications were observed in both groups. The number of RF applications was significantly lower when EAMS was used (6,2 ± 4,8 vs. 8,6 ± 7,6 RF application, p = 0,01) while the RF application time was not significantly different (56,8 ± 51,2 1 vs. 65,3 ± 86 seconds, p = NS). Conclusion AVNRT catheter ablation using a minimally fluoroscopic approach with 3D electro-anatomical mapping systems reduces radiation exposure without compromising safety, effectiveness and procedural time. EAMS use is associated with a reduction in the number of RF applications suggesting a higher precision and stability of ablation catheters during RF application.

Remote magnetic navigation shows superior long-term outcomes in pediatric atrioventricular (nodal) tachycardia ablation compared to manual radiofrequency and cryoablation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction – Catheter ablation (CA) is a first-choice treatment for tachyarrhythmia in pediatric patients. The currently available CA techniques differ in manner of catheter steering technique and energy sources. There are no large studies comparing long-term outcomes between the available CA techniques in pediatric patients with atrioventricular reentry (also known as accessory pathway mediated) tachycardia (AVRT) or atrioventricular nodal reentry tachycardia (AVNRT) mechanisms. Objective – The aim of this study was to compare procedural parameters and outcomes of remote magnetic navigation-guided radiofrequency (RF) ablation (RMN), manual-guided RF ablation (MAN) and manual-guided cryoablation (CRYO). Methods – This single-center, retrospective study included all first consecutive CA procedures for AVRT or AVNRT mechanisms performed in pediatric patients with no structural heart disease from January 2008 until June 2019. Three study groups were defined by the ablation technique used: RMN, MAN or CRYO. Primary outcome was recurrence of tachyarrhythmia and/or pre-excitation on ECG. Baseline clinical parameters, procedure times and complication rates were also evaluated. Results – In total, we included 223 patients, aged 13.8 ± 2.8 years, with a mean weight of 55.6 ± 14 kilograms. In total, 108 procedures were performed using RMN, 76 using MAN and 39 using Cryo. RMN had the lowest recurrence rates at a mean follow-up of 5.5 ± 2.9 years (AVRT ablation: 4% vs. 16% vs. 55%, P &amp;lt; 0.001; AVNRT ablation: 8% vs. 8% vs. 36%, P = 0.008; for RMN vs. MAN vs. CRYO respectively). In AVRT ablation, procedure and fluor times were comparable between groups. However, in AVNRT ablation, RMN and MAN had significantly lower fluoroscopy times compared to Cryo (10 (IQR 7-14) vs. 9 (IQR 6-26) vs. 15 (IQR 10-22) minutes respectively, P = 0.040). Moreover, procedure times were shortest in MAN and second in RMN ablation (101 (IQR 87-121) vs. 88 (IQR 62-99) vs. 120 (IQR 88-143) minutes respectively, P = 0.018). We observed minor complications in 3 patients (1%), which were comparable between groups and no major complications. Conclusion – In pediatric patients with no structural heart disease who underwent their first AV(N)RT ablation, RMN has the most favorable long-term outcomes, in addition to favorable fluoroscopy and procedure times. Abstract Figure. AVRT and AVNRT ablation recurrence rates

Radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia using standardized voltage mapping system protocol

Abstract Funding Acknowledgements Type of funding sources: None. Background according to European guidelines, ablation has become the treatment of choice in patients with symptomatic atrioventricular nodal reentry tachycardia (AVNRT). Despite the high procedure success rate, anatomical variations can affect the outcome in terms of relapses and complications. As recently demonstrated, low-voltage bridge visualization allows low pathway identification and therefore a new ablation strategy. Purpose our purpose was the validation of standardized ablation protocol within the low-voltage bridge area. Methods 70 consecutive patients with inducible AVNRT were evaluated and a three-dimensional voltage map of the right atrial septum and Koch Triangle was constructed by means of contact mapping. Ablation site was identified as the low-voltage area below the His bundle, adjusting the high-voltage slider to 1,5 mV and dynamically adjusting the slider of low-voltage. Radio-frequency energy (with an average number of nine lesions per patient) was then delivered within this area until the appearance of junctional beats. The results were tested at the end of the procedures and during the observational period (the mean follow-up was 10,5 months). Results the slow pathway was identified by the low-voltage bridge in 60 patients (85,6%) and in these patients, the target lesions in that area finally prevented induction of AVNRT in 100% of cases. A zero-fluoroscopy approach was possible for 50 patients (83%). Compared with standard AVNRT ablation, no complications as well as no statistical differences in terms of total procedure time were observed (p = 0,056). 59 patients (98%) had no relapses during the follow-up. Conclusions voltage gradient mapping successfully targeted the slow pathway in most of our cases. Lesions on the voltage bridge led to effective ablation of AVNRT and to a drastic x-ray exposure reduction in the absence of acute or long-term complications. Abstract Figure. Last lesion on low-voltage bridge.

Delayed radiofrequency ablation efficacy in slow pathway ablation: a case report.

BackgroundThe delayed effect of radiofrequency (RF) ablation was described in cases of accessory pathway and premature ventricular contraction ablation, as well as delayed atrioventricular (AV) block after slow pathway ablation.Case summaryWe report a case of a female patient with AV nodal re-entry tachycardia (AVNRT), in whom the first electrophysiology study ended with acute failure of slow pathway ablation, despite using long steerable sheath, both right and left-sided ablation with >15 min of RF energy application and repeatedly achieving junctional rhythm. Six weeks afterwards, during scheduled three-dimensional electroanatomical mapping procedure, there was no proof of dual AV nodal conduction nor could the tachycardia be induced. Also, the patient did not have palpitations between the two procedures nor during the 12-month follow-up period.DiscussionThis case illustrates that watchful waiting for delayed RF ablation efficacy in some cases of AVNRT ablation could be reasonable, in order to reduce the risk of complications associated with slow pathway ablation.

Trends in ablation procedures in Greece over the 2008-2018 period: Results from the Hellenic Cardiology Society Ablation Registry

ObjectiveIn 2008, the radiofrequency ablation (RFA) procedures registry of the Hellenic Society of Cardiology was created. This online database allowed electrophysiologists around the country to input data for all performed ablation procedures. The aim of this study is to provide a thorough report and interpretation of the data submitted to the registry between 2008 and 2018. MethodsIn 2008, a total of 27 centers/medical teams in 24 hospitals were licensed to perform RFA in Greece. By 2018, the number had risen to 31. Each center was tasked with inserting their own data into the registry, which included patient demographics (anonymized), type of procedure and technique, complications, and outcomes. ResultsA total of 18587 procedures in 17900 patients were recorded in the period of 2008-2018. By 2018, slightly more than 70% of procedures were performed in 7 high-volume centers (>100 cases/year). The most common procedure since 2014 was atrial fibrillation ablation, followed by atrioventricular nodal reentry tachycardia ablation. Complication rates were low, and success rates remained high, whereas the 6-month relapse rates declined steadily. ConclusionThis online RFA registry has proved that ablation procedures in Greece have reached a very high standard, with results and complication rates comparable to European and American standards. Ablation procedures for atrial fibrillation are increasing constantly, with it being the most common intervention over the last 6-year period, although the absolute number of procedures still remains low, compared to other European countries.

Periprocedural, early, and long-term risks of pacemaker implantation after atrioventricular nodal re-entry tachycardia ablation: a French nationwide cohort

Pacemaker implantation (PI) after atrioventricular nodal re-entry tachycardia (AVNRT) ablation is a dreadful complication. We aimed to assess periprocedural, early, and late risks for PI. All 27022 patients who underwent latest AVNRT ablation in France from 2009 to 2017, were identified in the nationwide medicalization database. A control group of 305152 patients hospitalized for arm, leg, or skin injuries with no history of AVNRT or supraventricular tachycardia were selected. After propensity score matching, both groups had mean age of 53 ± 18 years and were predominantly female (64%). During this 9-year period, 822 of 27022 (3.0%) AVNRT patients underwent PI, with significant higher risk in propensity-matched AVNRT patients compared to propensity-matched controls [2.9% vs. 0.9%; hazard ratio 3.4 (2.9-3.9), P < 0.0001]. This excess risk was significant during all follow-up, including periprocedural (1st month), early (1-6 months), and late (>6 months) risk periods. Annualized late risk per 100 AVNRT patients was 0.2%. In comparison to controls, excess risk was 0.2% in <30-year-old AVNRT patients; 0.7% in 30-50-year-old; 1.1% in 50-70-year-old and 6.5% over 70-year-olds. Risk for PI was also significantly different according to three procedural factors: centres, experience, and ablation date, with a 30% decrease since 2015. Periprocedural, early, and late risks for PI were higher after AVNRT ablation compared to propensity-matched controls. Longer follow-up is needed as the excess risk seems to persist late after AVNRT ablation.

Increased risk of late pacemaker implantation after ablation for atrioventricular nodal reentry tachycardia: A 10-year follow-up of a nationwide cohort

Catheter ablation of the slow pathway is the standard treatment of atrioventricular nodal reentry tachycardia (AVNRT) with a well described low risk of periprocedural atrioventricular block. Less is known about the risk of pacemaker implantation late after ablation. We aimed to quantify the risk of late pacemaker implantation in a countrywide cohort undergoing first-time ablation for AVNRT. All patients undergoing first-time ablation for AVNRT in Sweden from 2004 to 2014 were identified from the Swedish catheter ablation registry and matched against the Swedish Pacemaker and ICD registry. The cohort was compared to patients ablated for an accessory pathway (AP) and to matched controls. During follow-up of 2039 days, pacemaker was implanted later than 30 days after ablation in 96 of 6842 patients with AVNRT (1.4%), 29 of 4065 patients with AP (0.7%) (P = .001), and 124 of 33,270 controls (0.4%) (P < .00001). A periprocedural pacemaker (≤30 days postablation) was implanted in 32 of 6877 patients with AVNRT (0.5%) and 9 of 4079 patients with AP (0.2%) (P = .05). With cryoablation, 5 patients needed periprocedural pacemaker implantation. Pacemakers were implanted before ablation in 88 of 6977 patients with AVNRT (1.3%) and 11 of 4100 patients with AP (0.3%); the prevalence of pacemaker implants in controls was 124 of 33,270 (0.4%) (P < .00001 for both comparisons). The risk of late pacemaker implantation after AVNRT ablation was low but 3 times higher than that in the control population and 3 times higher than the risk of periprocedural pacemaker implantation. Similar results were observed with cryoablation and radiofrequency ablation. Ablation may not be the cause of increased late pacemaker implantation risk.

Troponin T release comparing manually or magnetically guided radiofrequency ablation for AVNRT- a MAGMA AVNRT substudy

Objectives. Catheter ablation is regarded as first-line therapy for symptomatic atrioventricular nodal reentry tachycardia (AVNRT). Ablation induces intended myocardial damage and the extent of myocardial damage may differ between ablation methods. The objective of this MAGMA AVNRT(NCT00875914) substudy was to compare high-sensitive cardiac troponin T (hs-cTnT) levels as a surrogate marker for myocardial damage after manually guided (MAN) AVNRT ablation versus AVNRT ablation using remote magnetic navigation (RMN). Design. In total, 70 patients (mean age 44 ± 14 years, 26% male) undergoing catheter ablation for AVNRT in the MagMa-AVNRT-Trial were randomized to remote magnetic navigation (n = 34, 49%) or manually guided catheter ablation (n = 36, 51%). hs-cTnT was measured the day after the procedure. Results. The median follow-up time was 6.2 ± 1.1 years. Acute success was 100% in both groups. hs-cTnT release was significantly lower in the remote magnetic navigation group (52 ng/L versus 95 ng/L, p < .01), even though the ablation time was longer and number of applications was higher with remote magnetic navigation (4.2 min vs 2.8 min, p = .017; 4.9 vs 3.3 applications, p = .01). hs-cTnT released per minute ablation time was also lower with remote magnetic navigation (12 ng/L versus 34 ng/L, p < .01). Both groups exhibited similar clinical long-term follow up regarding recurrence and complications. Conclusion. Remote magnetic navigation controlled catheter ablation of AVNRT has similar clinical outcome, but leads to less hs-cTnT release than manually guided catheter ablation. This might correspond to less unintended myocardial damage with RMN, which might be advantageous in complex ablation procedures.