Characteristics of Slow Pathway Conduction After Successful AVNRT Ablation

Three-dimensional electroanatomically guided slow pathway elimination is associated with procedural improvements and clinical benefit in atrioventricular node reentrant tachycardia patients

Background

Slow pathway (SP) ablation, in the context of atrioventricular node reentrant tachycardia (AVNRT) treatment could result in either complete elimination or only modification of the SP with ambiguity regarding associated benefits. Three-dimensional electroanatomical mapping (3D-EAM) may be used adjunctively aiming to complete SP elimination. Our purpose was to compare a 3D-EAM-based strategy targeting SP elimination to the conventional fluoroscopic approach with respect to clinical outcomes.

Methods

One hundred and two consecutive AVNRT patients (36 males, mean age 53.2 ± 13.7 years) underwent in two successive periods a conventional fluoroscopic ablation approach (n = 42) or a 3D-EAM-guided ablation focusing on complete SP elimination (n = 60).

Results

Several procedural parameters improved with 3D-EAM use, including fluoroscopy time (2.4 ± 4.7 min vs. 13 ± 4.5 min), dose-area product (1061 ± 3122 μGy × m2 vs. 5002 ± 3032 μGy × m2) and slow pathway elimination frequency (95% vs. 50%, all p < .001). Procedural time was slightly prolonged in the 3D-EAM group (101 ± 31 min vs. 87 ± 24 min, p = .013). Two major complications occurred in the conventional group. Altogether, over a mean follow-up of approximately 2.7 years, recurrence occurred in 6 of 42 (14.3%) in the conventional group as compared to 1 of 62 (1.7%) in the EAM-based group (p = .019). In the Kaplan-Meier analysis, time-to-event was significantly longer for the EAM-based patients (p < .030). Moreover, the EAM-based strategy was associated with less redo procedures' rates (9.5% in the non-EAM group vs. 0% in the EAM group, p = .026).

Conclusions

The present study showed that an EAM-based SP elimination strategy is not only feasible and safe but it is also accompanied by improved clinical outcomes in the setting of AVNRT ablation.

A prospective evaluation of the impact of individual RF applications for slow pathway ablation for AVNRT: Markers of acute success

BACKGROUND

Catheter ablation is highly effective for atrioventricular nodal re-entrant tachycardia (AVNRT). Generally junctional rhythm (JR) is an accepted requirement for successful ablation however there is a lack of detailed prospective studies to determine the characteristics of JR and the impact on slow pathway conduction.

METHODS

Multicentre prospective observational study evaluating the impact of individual radiofrequency (RF) applications in typical AVNRT (slow/fast). Characteristics of JR during ablation were documented and detailed testing was performed after every RF application to determine outcome. Procedural success was defined as ≤1 AV nodal echo.

RESULTS

Sixty-seven patients were included (mean age 53 ± 18years, 57% female and a history of SVT 2.9 ± 4.7 years). RF (50w, 60°) ablation for AVNRT was applied in 301 locations with JR in 178 (59%). Successful slow pathway modification was achieved in 66 (99%) patients with slow pathway block in 30 (46%). Success was associated with JR in all patients. Success was achieved in six patients with RF < 10 s. There was no significant difference in the CL of JR during RF between effective (587 ± 150 ms) versus ineffective (611 ± 193 ms, p = .4) applications. Inadvertent junctional beat-atrial (JA) block with immediate termination of RF was observed in 19 (28%) patients with AVNRT no longer inducible in 14 (74%). Freedom from SVT was achieved in 66 (99%) patients at a mean follow up of 15 ± 6 months.

CONCLUSION

In this prospective study, JR was required during RF for acute success in AVNRT. Cycle length of JR during RF was not predictive of success. Although unintended JA block during faster JR was associated with slow pathway block, this is a precursor to fast pathway block and should not be intentionally targeted.

Limitations of ventricular pacing maneuvers to differentiate orthodromic reciprocating tachycardia from atrioventricular nodal reentry tachycardia

PURPOSE

Various ventricular pacing maneuvers have been developed to differentiate orthodromic reciprocating tachycardia (ORT) from atrioventricular nodal reentry tachycardia (AVNRT). We aimed to evaluate the diagnostic value of ventricular pacing maneuvers in patients undergoing catheter ablation for AVNRT/ORT.

METHODS

Sixty patients with supraventricular tachycardia (SVT) undergoing invasive EP study were included (ORT: 31, typical AVNRT: 18, atypical AVNRT: 11). Ventricular overdrive pacing (VOP) and resetting by premature ventricular stimulation (PVS) during SVT were analyzed by 3 independent observers blinded to the ultimate diagnosis. We determined intraclass correlation coefficient (ICC) for interobserver agreement and the diagnostic accuracy of consensual results.

RESULTS

Although specificity of all parameters was high (96-100%) for ORT, semi-quantitative parameters of VOP (requiring the recognition of specific ECG patterns) had lower interobserver reliability (ICC: 0.32-0.66) and sensitivity (16.1-77.4%). In contrast, most quantitative measurements of VOP and PVS showed good reproducibility (ICC: 0.93-0.95) and sensitivity (74.2-89.3%), but post-pacing interval after VOP needed correction with AV nodal conduction slowing. False negative results for diagnosing ORT were more common with left free wall vs. right free wall or septal, and slowly vs. fast-conducting septal APs. False positivity was only seen with a bystander, concealed nodo-fascicular/nodo-ventricular (NF/NV) AP in a case of AVNRT.

CONCLUSIONS

No single maneuver is 100% sensitive for ORT. Semi-quantitative features have limited reproducibility and all parameters can be misleading in the case of rate-dependent delay during VOP/PVS, ORT circuits remote from the pacing site, or a bystander, concealed NF/NV AP.

Outcomes in patients with dual antegrade conduction in the atrioventricular node: insights from a multicentre observational study

BACKGROUND

Supraventricular tachycardias induced by dual antegrade conduction via the atrioventricular (AV) node are rare but often misdiagnosed with severe consequences for the affected patients. As long-term follow-up in these patients was not available so far, this study investigates outcomes in patients with dual antegrade conduction in the AV node.

METHODS AND RESULTS

In this multicentre observational study, patients from six European centres were studied. Catheter ablation was performed in 17 patients (52 ± 16 years) with dual antegrade conduction via both AV nodal pathways between 2012 and 2018. Patients with the final diagnosis of a manifest dual AV nodal non-re-entrant tachycardia had a mean delay of the correct diagnosis of over 1 year (range 2-31 months). Two patients received prescription of non-indicated oral anticoagulation, two further patients suffered from inappropriate shocks of an implantable cardioverter defibrillator. In 12 patients, a co-existence of dual antegrade and re-entry conduction in the AV node was present. Mean fast pathway conduction time was 138 ± 61 ms and mean slow pathway conduction time was 593 ± 134 ms. Successful radiofrequency catheter ablation was performed in all patients. Post-procedurally oral anticoagulation was discontinued, without detection of cerebrovascular events or atrial fibrillation during a long-term follow-up of median 17 months (range 6-72 months).

CONCLUSION

This first multicentre study investigating patients with supraventricular tachycardia and dual antegrade conduction in the AV node demonstrates that catheter ablation is safe and effective while long-term patient outcome is good. Autonomic tone dependent changes in ante- vs. retrograde conduction via slow and/or fast pathway can challenge the diagnosis and therapy in some patients.

AH jump duration is associated with elimination of slow pathway during ablation of atrioventricular nodal reentrant tachycardia

Introduction

Ablating the slow pathway (SP) is the superior treatment for atrioventricular nodal reentrant tachycardia (AVNRT) with a low complication rate. However, the ablation of the SP could result in either complete elimination or modification of the SP. We aimed to investigate whether the duration of AH jump pre-ablation associated with the outcome of elimination of SP.

Methods

We included 56 patients with typical AVNRT (slow-fast), 20 males and 36 females, aged 44.2 ± 15.1 years. Slow pathway ablation was performed using classical approach. Univariate and multivariate analysis was performed for potential predictors of SP elimination.

Results

Typical AVNRT was inducible in all patients. Post-ablation, non-inducibility of AVNRT was obtained in all 56 (100%) patients, with SP elimination in 33 (61%) patients and SP modification in 23 (39%) patients. Patients with SP elimination had significantly longer AH jump than patients with SP modification. Cox regression analysis showed that AH jump duration was the independent predictor of SP elimination, in which every 20 ms increase in AH jump duration was associated with 1.30 higher rate of SP elimination. Furthermore, ROC curve analysis indicated that the AH jump duration of ≥100 ms had 6.14 times higher probability for complete elimination of the SP with a sensitivity of 79%, specificity of 70%, PPV of 79% and NPV of 70%.

Conclusions

AH jump duration pre-ablation is associated with complete elimination of slow pathway during AVNRT ablation.

[Dual AV nodal nonreentry tachycardia (DAVNNT): unrecognized differential diagnosis with far-reaching consequences]

BACKGROUND

The dual atrioventricular nodal nonreentry tachycardia (DAVNNT) is a rare form of tachycardia which occurs due to a time delayed double antegrade conduction via the slow and fast atrioventricular nodal pathways. Its epidemiology is not known so far. The aim of this article is to present the clinical findings in a series of patients with DAVNNT.

MATERIALS AND METHODS

We retrospectively analyzed our database of patients who successfully underwent radiofrequency catheter ablation between January 2012 and March 2013 due to diagnosed supraventricular tachycardia.

RESULTS

In 3 out of 231 patients DAVNNT could be successfully treated by slow pathway modulation/ablation. Patients presented with widely varying symptoms including syncope, palpitations which had been mistaken as atrial fibrillation, and inappropriate defibrillator shocks due to suspected ventricular tachycardia.

CONCLUSIONS

The DAVNNT seems to be more common than previously thought. This important differential diagnosis needs to be taken into consideration as slow pathway modulation can be curative while a misdiagnosis, such as atrial fibrillation or ventricular tachycardia might result in over-treatment in patients with this arrhythmia.

Standardized review of atrial anatomy for cardiac electrophysiologists

Catheter ablation of cardiac arrhythmias has rapidly evolved from a highly experimental procedure to a standard form of therapy for various tachyarrhythmias. The advances in this field have included, first, the development of techniques of catheter ablation that often requires the precise destruction of minute amounts of arrhythmogenic tissues and, second, techniques of resynchronization therapy that require pacing different parts of the ventricles. A detailed prepocedural knowledge of cardiac anatomy can improve the safety of the procedure and its rate success. It helps the electrophysiologist to choose the appropiate region for ablation, shortening the procedural time. The atrial anatomy structures are usually localized before ablation by different imaging techniques such as fluoroscopy, electroanatomic mapping, intracardiac echocardiography or multidetector computed tomography. In this review, we describe the normal anatomy of the atria, highlighting the landmarks of interest to intervencional cardiologist, stressing their relationship to other structures. This article is part of a JCTR special issue on Cardiac Anatomy.

Post-ablation prolongation of atrioventricular nodal refractory period is correlated with long-term success of cryoablation for atrioventricular nodal reentrant tachycardia in the case of the persistence of a residual jump

PURPOSE

A residual slow pathway after successful cryoablation for atrioventricular nodal reentrant tachycardia (AVNRT) is correlated with a higher recurrence rate. We described determinants of recurrence in subjects with a residual jump.

METHODS

We analyzed the data of subjects with acute successful slow pathway cryoablation for AVNRT using a 6-mm-tip cryocatheter. Success was defined as AVNRT non-inducibility. Patients with no baseline elicitable jump, no inducible AVNRT, and transient first atrioventricular (AV) block at the last site were excluded.

RESULTS

From 371 patients who underwent cryoablation from May 2002 to March 2011, 303 fulfilled the entry criteria (mean age, 41 ± 16; 222 women). Baseline AV nodal effective refractory period (ERP) was 272 ± 57 ms, postprocedural 331 ± 64 (P < 0.001), and the mean of the difference (Δ ERP) 60 ± 41. At the end of the procedure, 64 patients (21 %) had a residual jump, of whom 22 with a single echo. At 12 months follow-up, the actuarial recurrence-free rate was 70.3 % in patients with a residual jump and 86 % in those without (P = 0.01). In patients with a jump, only Δ AV nodal ERP was correlated with recurrence (37 ± 41 vs. 68 ± 47 ms; P < 0.04) while a single echo was not. The actuarial rate of recurrence was 60.8 % in patients with a Δ AV nodal ERP ≤ 30 ms and 18.8 % in those with a Δ AV nodal ERP >30 ms (P < 0.01).

CONCLUSIONS

Suppression of slow pathway conduction is the optimal endpoint for AVNRT cryoablation. A residual jump can be tolerated if AV nodal ERP postcryoablation is prolonged >30 ms.

Effects of slow pathway ablation on fast pathway function in patients with atrioventricular nodal reentrant tachycardia: cryo- vs. radiofrequency ablation

BACKGROUND

In typical atrioventricular nodal reentrant tachycardia, radiofrequency (RF) ablation of the slow pathway (SP) is known to change the effective refractory period of the fast pathway (ERP(FP)) after successful RF ablation of the SP. The purpose of this study was to ascertain the mechanism of the ERP(FP) changes after SP ablation by comparing the results of both cryo- and RF ablation.

METHODS AND RESULTS

A total of 112 patients were enrolled prospectively and their electrophysiological properties analyzed before and after successful SP ablation. Patients were grouped into cryoablation (n=54) and RF ablation (n=58) groups and each group was subdivided into complete ablation (CG) and modification (MG) based on the presence of the SP after successful ablation. CG was performed in 64 patients: 30 by cryoablation and 34 by RF ablation. In patients who underwent complete SP ablation, the ERP(FP) was shortened significantly after cryoablation (375 ± 74 vs. 281 ± 39 ms, P<0.01), without significant change in the atrio-His (AH) or sinus cycle length (SCL) interval. Similarly, the ERP(FP) was shortened significantly (358 ± 106 vs. 289 ± 84 ms, P=0.01) also after RF ablation without change in AH or SCL interval.

CONCLUSIONS

ERP(FP) shortening was observed after complete SP ablation with both cryo- and RF ablation without significant changes in indices of autonomic activity.