Delta-wave automatic mapping of the manifest accessory pathway

Abstract

Background: Despite the high success rate of radiofrequency catheter ablation (RFCA) in Wolff-Parkinson-White Syndrome (WPW), localizing the successful ablation site can be challenging and may require multiple radiofrequency (RF) applications.

Objective: This study aims to evaluate the efficacy of a novel workflow for the automatic and precise identification of accessory pathway ablation site, named Delta Wave Automatic Mapping.

Methods: Patients undergoing a first procedure for RF ablation of a manifest accessory pathway were included. Electro-Anatomical Mapping (EAM) was performed with the CARTO 3 system (Biosense Webster, Johnson & Johnson Medical S.p.a., Irvine, CA) leveraging auto-acquisition algorithms already present in the CARTO 3 software. Mapping and ablation were performed with an irrigated tip catheter with contact force sensor. Procedure success was defined as loss of pathway function after ablation. The number of RF applications required and time to effect were measured for each patient. Recurrences were evaluated during follow-up visits. Additionally, at the end of each procedure, historical predictors of ablation success were measured offline to evaluate their relationship with the successful ablation site found with the novel workflow.

Results: A total of 50 patients were analysed (62% APs right and 38% APs left). All 50 APs were successfully eliminated in each procedure with a median Time-to-effect (TTE) of 2.0 (IQR 1.2-3.5) seconds. No AP recurrences during a median follow-up of 10 (IQR 6-13) months were recorded. Offline analysis of successful ablation site revealed a pre-ablation delta/ventricular interval of ≤-10 msec in 52% of the patients and in 100% of the patients the signal related to the Kent bundle was identified.

Conclusions: The novel workflow efficiently localizes APs without requiring manual annotations. Historical endocardial parameters predicting success were measured offline for each case and they corresponded to the ablation target automatically annotated by the proposed workflow. This novel mapping workflow holds promise in enhancing the efficacy of RFCA in the presence of manifest APs.

Keywords: 3D electro-anatomical mapping system; Wolff-Parkinson-White Syndrome; accessory pathway; activation map; automatic signal annotation; radiofrequency catheter ablation.

Figure 1

The new algorithm is based on the concomitant use of the confidense^TM module (automatic mapping, wavefront annotation, and pattern matching) and the CARTO prime^TM parallel mapping module integrated in the CARTO prime^TM software of the CARTO 3 system version 7 (biosense webster, Johnson & Johnson medical S.p.a., Irvine, CA). (A) The most stable QRS peak in one of the 12 ECG leads was chosen as reference for Pattern Matching (beat-to-beat analysis). (B) We set specific filters for the Confidense Module and these filters are the following: (a) pattern-matching should correlate at least 96% with the pre-excited QRS morphology (during Sinus rhythm, atrial pacing or antidromic tachycardia); (b) the mapping catheter should be stable in position and temporal activation (5 mm, 5 s); (c) the mapping catheter should have a contact force ≥3 grams with the endocardial tissue; (d) acquisition density should be set at the maximum level (<1 mm).

Figure 2

(A) Example of the location of accessory pathway (AP) being in the left postero-lateral region. For mapping and ablation of this left-sided AP an retro-aortic approach was performed. Atrial activation map was obtained during sinus rhythm with ventricular pre-excitation and a unipolar EGM with qS morphology and a continuous A-V EGM were recorded at the ablation point automatically marked by the system. (B) The acute success was 100% acutely with time to effect (TTE) was 2.0 s. In this case the AP block was achieved with just a single RF application.