Recurrent Wide Complex Tachycardia: Where is The Target for Ablation?

Funding Acknowledgements Type of funding sources: None. Introduction Approximately 18% of patients with atrial fibrillation (AF) undergo a repeat ablation within 12 months after their index ablation. Despite the high prevalence, comparative studies on non-pulmonary vein (PV) target strategies in repeat AF ablation are scarce. Purpose: This study aims to describe 12 months efficacy of non-PV and PV target ablations as a repeat ablation strategy. Methods A multicentre retrospective, descriptive study was conducted with data of 280 patients who underwent repeat AF ablation. Ablation strategy for repeat ablation was at the operators’ discretion. Non-PV target ablation (n=140) included posterior wall isolation, mitral line, roofline and/or complex fractionated atrial electrogram ablation. PV target ablation (n=140), included re-isolation and/or wide atrium circumferential ablation. Patients’ demographics and rhythm outcomes during 12-months follow-up were analysed. Results: Overall, the mean age was 63 ± 9 years, 64% were male, and body mass index was 27.1 ± 4.2. Patients undergoing non-PV target ablation had more frequently persistent AF (47.9% vs 14.3%, p < 0.001), and had a higher CHA2DS2 VASc (2.0 vs 1.3, p < 0.001). At 12 months, more atrial tachyarrhythmias were observed in the non-PV target group (48.6%) compared to the PV target group (29.3%, p=0.001). Similarly, a significantly higher AF and atrial tachycardia (AT) recurrence rate was observed after non-PV target ablation compared to PV target ablation (36.4% versus 22.1% and 22.9% versus 10.7%). After adjusting for several associated covariates, a significantly higher AT recurrence risk remained in the non-PV target group (adjusted OR 2.19 95% CI 1.18 – 4.42, p = 0.023) (Figure 1C). Sensitivity analysis was performed with inverse propensity weighting to assess the robustness of the multivariate model and demonstrated comparable outcomes. Both groups significantly de-escalated anti-arrhythmic drug use, de-escalation was more profound after PV target ablation. Patients with isolated PVs during non-PV target ablation had a significantly higher risk for AF recurrence than those with reconnected PVs (Figure 1B). Conclusion: Compared to PV target ablation, non-PV target repeat ablation did not improve outcomes after 12 months and was independently associated with a higher risk for AT recurrences.

Background We describe a technique to localize the ablation target in patients with an unusual variant of slow/fast atrioventricular nodal reentrant tachycardia (AVNRT) using a slow pathway connecting to the basal inferolateral left atrium. Methods Consecutive patients with slow/fast AVNRT were included. During stable slow/fast AVNRT, a single late atrial extrastimulus (AES) was delivered at the inferolateral left atrium near the mitral annulus. Advancing the next His bundle potential by ≥5 ms, followed by resetting of the tachycardia cycle length, indicated that the AES engaged the anterograde slow pathway. The latest AES resetting AVNRT was considered to be in close proximity to the atrial end of the anterograde slow pathway and was selected as the ablation target. Results In 10 of 843 (1.2%) patients, ablation at the inferolateral left atrium was required. All patients had had failed ablation at the inferior triangle of Koch and roof of the coronary sinus. In all 10 patients, a late AES advanced the His bundle potential by ≥10 ms and reset the tachycardia. Ablation at that site eliminated slow pathway conduction and terminated the tachycardia. Ablation was successful at the site of the latest AES, delivered 49±12 ms after the onset of the His bundle potential. No recurrent tachycardia was noted at 1 year of follow-up. Conclusions The inferolateral left atrium slow pathway is used in a small subset of patients with slow/fast AVNRT. Accurate localization of the ablation target can be achieved by delivering late AES during AVNRT (resetting response).

IntroductionApproximately 18% of patients with atrial fibrillation (AF) undergo a repeat ablation within 12 months after their index ablation. Despite the high prevalence, comparative studies on nonpulmonary vein (PV) target strategies in repeat AF ablation are scarce. Here, we describe 12 months efficacy of non‐PV and PV target ablations as a repeat ablation strategy.MethodsA multicentre retrospective, descriptive study was conducted with data of 280 patients who underwent repeat AF ablation. The ablation strategy for repeat ablation was at the operators' discretion. Non‐PV target ablation (n = 140) included PV reisolation, posterior wall isolation, mitral line, roofline, and/or complex fractionated atrial electrogram ablation. PV target ablation (n = 140), included reisolation and/or wide atrium circumferential ablation. Patients' demographics and rhythm outcomes during 12 months follow‐up were analyzed.ResultsAt 12 months, more atrial tachyarrhythmias were observed in the non‐PV target group (48.6%) compared to the PV target group (29.3%, p = .001). Similarly, a significantly higher AF and atrial tachycardia (AT) recurrence rate was observed after non‐PV target ablation compared to PV target ablation (36.4% vs. 22.1% and 22.9% vs. 10.7%). After adjustment, a significantly higher risk of AT recurrence remained in the non‐PV target group. Both groups significantly de‐escalated antiarrhythmic drug use; de‐escalation was more profound after PV target ablation. Patients with isolated PVs during non‐PV target ablation had a significantly higher risk for AF recurrence than those with reconnected PVs.ConclusionCompared to PV target ablation, non‐PV target repeat ablation did not improve outcomes after 12 months and was independently associated with an increased risk for AT recurrences.

Background Contact force catheter ablation is the gold standard for treatment of atrial fibrillation (AF). Local tissue impedance (LI) evaluation has been recently studied to evaluate lesion formation during radiofrequency ablation. Purpose Aim of the study was to assess the outcomes of an irrigated catether with LI alghorithm compared to contact force (CF)-sensing catheters in the treatment of symptomatic AF. Methods A prospective, single-center, nonrandomized study was conducted, to compare outcomes between CF-AF ablation (Group 1) and LI-AF ablation (Group 2). For Group 1 ablation was performed using the Carto 3© System with the SmartTouch SF catheter and, as ablation target, an ablation index value of 500 anterior and 400 posterior. For Group 2, ablation was performed using the Rhythmia™ System with novel ablation catheter with a dedicated algorithm (DirectSense) used to measure LI at the distal electrode of this catheter. An absolute impedance drop greater than 20Ω was used at each targeted. According to the Close Protocol, ablation included a point by point pulmonary vein isolation (PVI) with an Inter-lesion space ≤5 mm in both Groups. Procedural endpoint was PVI, with confirmed bidirectional block. Results A total of 116 patients were enrolled, 59 patients in Group 1 (CF) and 57 in Group 2 (LI), 65 (63%) with a paroxismal AF and 36 (37%) with a persistent AF. Baseline patients features were not different between groups (P=ns). LI-Group showed a comparable procedural time (180±89 vs 180±56, P=0.59) but with a longer fluoroscopy time (20±12 vs 13±9 min, P=0.002). Wide antral isolation was more often observed in CF-Group (95% vs 80%, P=0.022), while LI-Group 2 required frequently additional right or left carina ablation (28% vs 14%, P=0.013). The mean LI was 106±14Ω prior to ablation and 92.5±11Ω after ablation (mean LI drop of 13.5±8Ω) during a median RF time of 26 [19–34] sec for each ablation spot. No steam pops or complications during the procedures were reported. The acute procedural success was 100%, with all PVs successfully isolated in all study patients. Regarding safety, only minor vascular complications were observed (5%), without differences between groups (p=0.97). During follow up, 9-month freedom from atrial fibrillation/atrial flutter/atrial tachycardia recurrence was 86% in Group 1 and 75% in Group 2 (P=0.2). Conclusions An LI-guided PV ablation strategy seems to be safe and effective, with acute and mid-term outcomes comparable to the current contact force strategy. LI monitoring could be a promising complementary parameter to evaluate not only wall contact but also lesion formation during power delivery. Procedural Outcomes Funding Acknowledgement Type of funding source: None

Dextrocardia with situs inversus is a rare cardiac positional anomaly. Catheter ablation procedures performed in this set of patients have not been sufficiently reported. A total of 10 patients with dextrocardia and situs inversus who received catheter ablation for supraventricular tachycardia (SVT) were included from a cohort of over 20 000 cases of catheter ablation for SVT in three centers from 2005 to 2016. All patients underwent electrophysiologic study and catheter ablation of SVT. Ablation targets were selected based on different tachycardia mechanisms with the primary endpoint of noninduction of tachycardia. The average age was 32.4 ± 5.6 years. Congenitally corrected transposition of great arteries (TGA) with situs inversus and D-looping of the ventricles and aorta (congenitally corrected TGA {I,D,D}) was found in four patients, while the other six patients exhibited mirror-image dextrocardia {I,L,L}. The mechanisms of SVT were atrioventricular nodal reentrant tachycardia in four patients, atrioventricular reentrant tachycardia in three, typical atrial flutter in one, intra-atrial reentrant tachycardia in one, and focal atrial tachycardia in one. Immediate procedural success was achieved in 9 out of 10 patients with no procedural complications. During a follow-up period of 6.3 ± 3.5 years on average, all patients remained free from recurrent tachycardia. For patients with dextrocardia and situs inversus, catheter ablation of SVT is safe and feasible. Differences in catheter maneuver and fluroscopy projection, along with difficulties in distorted anatomy are major obstacles for successful ablation.

Recent studies suggest that atrial fibrillation (AF) is maintained by electrical activity arising from focal sources. We sought to test whether catheter ablation that targets focal sources can improve on current ablation protocols for persistent AF. In patients with persistent AF whose AF did not terminate with pulmonary vein (PV) isolation, the left atrium was mapped with a 20-pole high-density mapping catheter using CARTO® 3 navigation. If a site demonstrated centrifugal activation over at least three consecutive cycles, it was deemed a focal source and ablated. If AF remained, defragmentation was performed until AF was terminated. Freedom from atrial tachyarrhythmia was compared between the study patients and propensity score matched historical controls who had undergone conventional stepwise ablation. Of the 68 study patients, 2.9±1.9 focal sources were identified in 60 patients. Focal sources displayed transient centrifugal activation patterns for a median of six consecutive cycles. Total radiofrequency duration was shorter in the study group (62±16minutes vs. 75±24minutes, P=0.0003). During a 1-year follow-up period, 39 (57%) and 26 (38%) patients were free from atrial tachyarrhythmias in the absence of antiarrhythmic drugs in the study and control groups, respectively (hazard ratio: 1.85, 95% confidence interval: 1.17-2.96, P=0.009). Improvement of clinical outcome was mainly driven by a decrease in recurrence of atrial tachycardia in the study patients (22%vs. 40%, P=0.047). The results of this study suggest that focal sources are appropriate ablation targets in addition to the PVs in persistent AF.

Intraoperative mapping studies suggest that an isthmus of myocardium between the mitral valve annulus and the border of inferior myocardial infarction may play a role in the genesis of ventricular tachycardia. We examined the frequency with which a slow conduction zone within the mitral isthmus was critical to the maintenance of ventricular tachycardia associated with remote inferior infarction in patients undergoing catheter ablation. In 4 of 12 patients, a critical zone of slow conduction was identified within the mitral isthmus. In each of these patients, two characteristic and morphologically distinct tachycardias were induced: a left bundle (rS in V1, R in V6), left superior axis morphology and a right bundle (R in V1, QS in V6), right superior axis morphology (cycle length, 610 to 320 ms). In each patient, a zone of slow conduction, shared by both morphologies, was characterized by diastolic potentials with electrogram-QRS intervals of 85 to 161 ms (21% to 47% of tachycardia cycle length) and entrainment with concealed fusion during pacing associated with stimulus-QRS intervals of 81 to 400 ms (20% to 91% of tachycardia cycle length). In each patient, a single radiofrequency energy application at the shared site of slow conduction eliminated inducibility of both morphologies. During follow-up of 1 to 11 months, no patient had recurrent tachycardia. The mitral isthmus contains a critical region of slow conduction in some patients with ventricular tachycardia after inferior myocardial infarction, providing a vulnerable and anatomically localized target for catheter ablation. Characteristic tachycardia morphologies may provide clinical markers for this underlying mechanism.

A new era of atrial fibrillation (AF) treatment began in 1997–1998 with the discovery that triggers within the pulmonary veins initiate AF and reports that elimination of these triggers is successful in treating AF in its paroxysmal form.1–3 However, in patients with persistent AF, the success rate of exclusive pulmonary vein isolation is substantially lower.4,5 To improve the outcome of persistent AF ablation, different ablation strategies have been explored, but to date the optimal strategy has not been defined. Although some groups argue that limited ablation, including pulmonary vein isolation and, if present, ablation of nonpulmonary vein triggers, is sufficient for persistent AF ablation, other groups, including ours, favor more extensive, substrate-based ablation in addition to pulmonary vein isolation. In this review, we will discuss the rationale for a substrate-based ablation strategy to treat persistent AF and show why elimination of triggers is not sufficient in most patients with persistent AF. Response by Roten et al on p 1232 In a simple model, an electric impulse in AF can form because of abnormalities in impulse generation (triggers) or can result from abnormal impulse propagation (reentry). By a strict definition, a trigger is a focal source of new impulse generation. The mechanism by which a new impulse can form is either abnormal automaticity or triggered activity. Trigger-ablation protocols target these sources of new impulse generation. Abnormal impulse propagation, on the other hand, depends on altered substrate properties causing nonuniform or slowed conduction. This in turn causes multiple forms of wave reentry thought to be responsible for AF perpetuation: random reentry (multiple wavelets), macro- and microreentry, or functional reentry (rotors). Substrate-based ablation strategies aim to abate abnormal impulse propagation and interrupt any form of atrial reentry. Triggers of paroxysmal AF are mainly located in the pulmonary …

B-PO02-089 NON-PAROXYSMAL ATRIAL FIBRILLATION IN YOUNGER PATIENTS ARE REFRACTORY TO SPATIOTEMPORAL ELECTROGRAM DISPERSION ABLATION TARGETING ROTORS?

Post-infarct ventricular tachycardia is associated with channels of surviving myocardium within scar characterized by fractionated and low-amplitude signals usually occurring late during sinus rhythm. Conventional automated algorithms for 3-dimensional electro-anatomic mapping cannot differentiate the delayed local signal of conduction within the scar from the initial far-field signal generated by surrounding healthy tissue. Ripple mapping displays every deflection of an electrogram, thereby providing fully informative activation sequences. We prospectively used CARTO-based ripple maps to identify conducting channels as a target for ablation. High-density bipolar left ventricular endocardial electrograms were collected using CARTO3v4 in sinus rhythm or ventricular pacing and reviewed for ripple mapping conducting channel identification. Fifteen consecutive patients (median age 68 years, left ventricular ejection fraction 30%) were studied (6 month preprocedural implantable cardioverter defibrillator therapies: median 19 ATP events [Q1-Q3=4-93] and 1 shock [Q1-Q3=0-3]). Scar (<1.5 mV) occupied a median 29% of the total surface area (median 540 points collected within scar). A median of 2 ripple mapping conducting channels were seen within each scar (length 60 mm; initial component 0.44 mV; delayed component 0.20 mV; conduction 55 cm/s). Ablation was performed along all identified ripple mapping conducting channels (median 18 lesions) and any presumed interconnected late-activating sites (median 6 lesions; Q1-Q3=2-12). The diastolic isthmus in ventricular tachycardia was mapped in 3 patients and colocated within the ripple mapping conducting channels identified. Ventricular tachycardia was noninducible in 85% of patients post ablation, and 71% remain free of ventricular tachycardia recurrence at 6-month median follow-up. Ripple mapping can be used to identify conduction channels within scar to guide functional substrate ablation.

Objective Until now, whether left posterior fascicular block (LPFB) could predict the success of ablation for fascicular ventricular tachycardia (VT) is ongoing controversy.In this study, we investigated whether LPFB could be as the predictor of left posterior fascicle VT(LPF-VT) long term success after ablation. Methods From January 2010 to December 2012, consecutive patients (n=67) with LPF-VT underwent mapping and ablation by using three dimension mapping and ablation were enrolled in department of cardiology the First Affiliated Hospital of Nanjing Medical University.Burst and programmed stimulation at the right atrium and right ventricle apex were used for VT inducing.Activation mapping was performed to find the ablation target (earliest fascicular potential, PP) during VT.Pace mapping was used to locate the ablation target for patients in whom VT could not be induced.Ablation was performed by delivering radiofrequency energy in temperature-control mode.According to LPFB or not, patients were assigned to LPFB group (group A) and LPF not block group (group B), and with long-term follow-up. Results Among 67 patients (mean age 30.1±12.6, male 53) with LPF-VT, VT could not be induced in two cases, failed ablation in one case.Ablation target with earliest P potential was located by activation mapping during VT in 61 patients.Ablation target was disclosed by pace mapping in 3 patients.Altogether, ablation was succeeding in 64 cases without inducing of VT with isoproterenol infusion.After ablation, 46 patients were enrolled in group A, and 18 were in group B. During (55.8±10.4)months of follow-up, the long term success rate after a single procedure without anti-arrhythmic agents was 82.8%(53/64). VT reoccurred in 11 cases, 8 cases in group A, 3 cases in group B(P=0.94). The mean duration of reoccurred time was 1.4-54.9(9.2±16.1) months after the ablation.All reoccurred 11 cases and one failed case had repeated successful ablation.No complications were observed in these cases. Conclusions Activation mapping guided ablation is highly effective and associated with long term clinical outcomes in patients with LPF-VT.The reoccurred rate was not lower in LPFB group, indicating that LPFB could not predict long term success of ablation for LPF-VT. Key words: Fascicular ventricular tachycardia; Activation mapping; Left posterior fascicle block

Ventricular abnormal potentials are low-amplitude electrical signals that appear in intracardiac electrograms during a QRS or with an unpredictable delay with respect to it. Their spatial localization can be exploited by cardiologists for the identification of the ablation targets in substrate-guided mapping and ablation procedures. In this work, an automatic approach for a reliable detection of such potentials in intracardiac electrograms is proposed.To this aim, 86 intracardiac electrograms from five patients with post-ischemic ventricular tachycardia, acquired by the CARTO3 System, were retrospectively annotated by an expert cardiologist, to be used for a supervised classifier training and test.The automatic detection was based on a non-linear denoising followed by a time-scale decomposition based on the continuous wavelet transform. Then, different morphological features were extracted from both the time-scale domain and the time domain, and used to feed a support vector machine trained to discriminate between physiological and abnormal potentials. The recognition accuracy exceeded 93%, paving the way to further developments and more extensive studies.

B-PO02-139 MAPPING AND ABLATION OF INAPPROPRIATE SINUS TACHYCARDIA: BEST OF BOTH?

PO-02-042 SAFETY AND EFFICACY OF VERY HIGH-POWER SHORT-DURATION TEMPERATURE-CONTROLLED ABLATION FOR THE TREATMENT OF PERSISTENT ATRIAL FIBRILLATION

The impact of the His bundle location and distance from the ablation site on ablation efficacy and complication risk remains unexplored. We determined the correlation between age, height, body mass index (BMI), and the His bundle location, and whether the distance between the His bundle and ablation target (DHIS-ABL) affects ablation safety and efficacy. Overall, 346 patients with atrioventricular nodal re-entrant tachycardia (AVNRT) and 96 with atrioventricular re-entrant tachycardia (AVRT) were retrospectively analyzed. The distance between the His bundle and the coronary sinus ostium (DHis-CS), the height of the His bundle (HHIS), and DHIS-ABL were measured. Electrocardiograms were obtained 3 months post-ablation to assess recurrence and complications. Multiple linear regression showed that HHIS was negatively correlated with age in both groups. In AVNRT patients, DHIS-ABL was associated with age, height, and BMI; DHIS-CS was only negatively correlated with age. In AVRT patients, there was no significant correlation between the DHIS-ABL and age, height, or BMI. The recurrence rates in the AVNRT and AVRT groups were 0.9% and 8.7%, respectively. Subgroup analysis showed that patients with DHIS-ABL≤10mm had a higher recurrence rate than those with DHIS-ABL>10mm (p=.013). The incidence of third-degree atrioventricular block (AVB) complications was 0.2%. HHIS was negatively correlated with age but not with height and BMI. The DHIS-ABL correlated with age, height, and BMI in AVNRT patients. A short DHIS-ABL led to a higher rate of supraventricular tachycardia recurrence; whether this affects AVB risk warrants further studies with larger sample sizes.