Noninducibility Of Ventricular Tachycardia Research Articles

Systematic right ventricular electrophysiologic evaluation in patients with repaired tetralogy of Fallot before pulmonary valve replacement

Abstract Introduction Adults with repaired tetralogy of Fallot (rToF) are prone to develop ventricular tachycardia (VT) in adulthood, due to reentry related to slowly conducting anatomical isthmuses (SCAI). Pulmonary valve replacement (PVR) in patients without history of VT, may lead to obliteration of unrecognized SCAI with subsequent catheter ablation failure; electrophysiologic study is thus recommended before PVR. A systematic evaluation of the topology of SCAI in this population is, however, scant. Methods Consecutive rToF patients undergoing PVR with native right ventricular outflow tract were studied with pre-PVR EPS. Electroanatomical mapping with systematic evaluation of all possible anatomical isthmuses (AI) with pacemapping, activation mapping in sinus/paced rhythm and bipolar voltage mapping was performed (AI1: anterior scar/patch to tricuspid annulus; AI2: anterior scar to pulmonary annulus; AI3: pulmonary annulus to ventricular septal defect – VSD- patch; AI4: VSD to tricuspid annulus). Conduction velocity (CV) across all documented AI was calculated (ratio between the distance among the nearest point with bipolar voltage >1.5 mV and their difference in activation timing). Ventricular programmed stimulation was performed at 2 sites (apex and outflow tract) with drive train ad 600/400 ms, up to three extrastimuli until refractoriness or induction, during baseline and isoproterenol infusion. Radiofrequency catheter ablation (RFCA) was performed in all patients with inducible VT and/or SCAI, aiming at conduction block across the SCAI validated with differential pacing. Results Between May 2023 and November 2023, 10 patients with rToF and 1 double outlet right ventricle were studied (73% males, age 46±10 years; 54% with a previous shunt, 46% with a previous transannular patch, 27% pulmonary valvotomy and infundibular boring; median age at surgery 4 years, interquartile range 3-6). EPS was positive for inducible VT in 4 patients (mean cycle length 297 ms, 3 with left bundle branch morphology and 1 right bundle branch morphology, all inferior axis) and polymorphic VT in 1. AI1 was present in 5 patients, AI2 in 5, AI3 in 7, AI 4 in 2. At least 1 SCAI was present in 7 patients (64%), 2 SCAI in 3 patients (43% of patients with SCAI; in every patient SCAI3+SCAI2 in 2 and SCAI 4 in 1 patient). There were no SCAI1; there were 3 SCAI 2 (mean CV 0.43 m/s), 4 SCAI 3 (mean CV 0.3 m/s), 1 SCAI 4 (CV 0.4 m/s). RFCA was performed in 8 patients; acute success was achieved in all patients, achieving bidirectional conduction block across treated SCAI and non-inducibility of VT. Conclusions SCAI are often present in rToF candidate to PVR and without clinical history of spontaneous VT, involving prevalently SCAI3 and SCAI2. Inducible VT is not sufficient as a marker of arrhythmic risk and SCAI should be better sought for. RFCA of SCAI with bidirectional conduction block is acutely highly efficacious.

Ventricular tachycardia mapping and ablation using MIXture of well-established approaches. The MIX-VT study

Abstract Introduction Ablation for ventricular tachycardia (VT) is still challenging despite impressive technology development, especially in mid- or low-volume centers. The most frequently used approach is homogenization of scar area responsible for VT, combined with standard electrophysiological (EP) approaches such as VT inducibility and mapping. However, in real life long-term efficacy of VT ablation in such centers does not exceed 50%. We hypothesized that an approach consisting of the mixture of various well-established parameters would be more effective than scar homogenization and VT non-inducibility as the endpoints. Purpose To compare the outcome of VT ablation using the standard approach (scar homogenization) and a more complex approach, called the MIX-VT protocol, using late potential mapping + pace mapping with rapid change of VT morphology to localize the critical isthmus + core isolation. All procedures were performed using the 3D mapping system, Pentaray mapping catheter, Smart-Touch ablation catheter and intracardiac echocardiography (ICE). Methods 48 consecutive patients (41 male, mean age 71.5 years) with ischemic cardiopathy referred for urgent VT ablation were included: 23 patients underwent "standard" VT ablation between December 2018 and December 2019, whereas the next 25 patients underwent ablation using the MIX-VT protocol between January 2020 and December 2020. First step in the MIX-VT group was to perform ICE imaging of the scar area from the right ventricle. Next, left ventricular maps were created during rhythm at which spontaneous VT occurred (sinus or paced). Areas of late potentials were identified to localize the critical isthmus where the abrupt change in the paced-QRS axis was seen. Finally, areas delineated by these two above-mentioned maneuvers where ablated in order to achieve core isolation (Figure 1). The patients were followed for 12 months in the outpatient clinic during ICD examination. The composite end-point for follow-up was VT recurrences terminated by anty-tachycardia pacing (ATP) or shock, or death. Results Clinical and demographic variables were similar between the two groups (Figure 2), except for a higher prevalence of diabetes mellites and number of previous ablations in the standard group (4/25 [16%] vs 10/23 [43%], p=0.03 and 2/24 vs 8/23 [34.8], p=0.03, respectively). Three patients from the MixVT group and one patient from the standard group were lost to follow-up. During follow-up, VT recurrences were significantly less frequent in the MIX-VT group (3/22 [13.6] vs 10/22 [45.4]. p=0.02. It was mostly driven by less ATP therapy. (Figure 2). One patient from the standard approach groups died. Conclusion Ablation for VT in low- or medium volume centers using the combination of well-established various EP approaches resulted in the improvement in overall survival and arrythmia-free survival. The presented approach does not involve additional resource utilization.

Long-Term Freedom From Ventricular Arrhythmias in ARVC With Endocardial Only Ablation: Predictors of Success

BackgroundAlthough the epicardial predominance of substrate abnormalities has been well demonstrated in early stages of arrhythmogenic right ventricular cardiomyopathy (ARVC), endocardial (ENDO) ablation may suffice to eliminate ventricular tachycardia (VT) in some patients. ObjectivesThis study aimed to report the long-term outcomes of ENDO-only ablation in ARVC patients and factors that predict VT-free survival. MethodsWe included consecutive patients with Task Force Criteria diagnosis of ARVC undergoing a first ENDO-only VT ablation between 1998 and 2020. Ablation was predominantly guided by activation/entrainment mapping for mappable VTs and pace mapping/targeting abnormal electrograms for unmappable VTs. The primary endpoint was freedom from any recurrent sustained VT after the last ENDO-only ablation. ResultsSeventy-four ARVC patients underwent ENDO-only VT ablation. VT noninducibility was achieved in 49 (66%) patients. During median follow-up of 6.6 years (Q1-Q3: 3.4-11.2 years), 40 (54.1%) patients remained free from any VT recurrence with rare VT ≤2 episodes in additional 12.2%. Among patients with noninducibility, VT-free survival was 75.5% during long-term follow-up. In multivariable analysis, >45 y of age at diagnosis (HR: 0.41; 95% CI: 0.17-0.98) and VT noninducibility (HR: 0.36; 95% CI: 0.16-0.80) were predictors of VT-free survival. ConclusionsLong-term VT-free survival can be achieved in over half of ARVC patients following ENDO-only VT ablation, increasing to over 75% if VT noninducibility is achieved. Our results support consideration of a stepwise ENDO-only approach before proceeding to epicardial ablation if VT noninducibility can be achieved particularly in older patients.

Arrhythmia detection using an implantable loop recorder after a negative electrophysiology study in Brugada syndrome: Observations from a multicenter international registry

BackgroundRisk stratification in Brugada syndrome (BrS) remains controversial. In this respect, the role of the electrophysiology study (EPS) has been a subject of debate. In some centers, it is common practice to use an implantable loop recorder (ILR) after a negative EPS to help in risk stratification. However, the diagnostic value of this approach has never been specifically addressed. ObjectiveThe aim of this study was to describe the baseline characteristics and the main findings of a diagnostic workup strategy with an ILR after a negative EPS in BrS. MethodsWe conducted a retrospective international registry including patients with BrS and negative EPS (ie, noninducible ventricular tachycardia or ventricular fibrillation) before ILR monitoring. ResultsThe study included 65 patients from 8 referral hospitals in The Netherlands, Spain, and the United Kingdom (mean age, 39 ± 16 years; 72% male). The main indication for ILR monitoring was unexplained syncope/presyncope (66.2%). During a median follow-up of 39.0 months (Q1 25.0–Q3 47.6 months), 18 patients (27.7%) experienced 21 arrhythmic events (AEs). None of the patients died during follow-up. Bradyarrhythmias were the most common finding (47.6%), followed by atrial tachyarrhythmias (38.1%). Only 3 patients presented with ventricular arrhythmias. AEs were considered incidental in 12 patients (66.7%). In 11 patients (61.1%), AEs led to specific changes in treatment. ConclusionThe use of ILR after a negative EPS in BrS is a safe strategy that reflected the high negative predictive value of EPS for ventricular arrhythmia in this syndrome. In addition, it allowed the detection of AEs in a significant proportion of patients, with therapeutic implications in most of them.

Ventricular tachycardia ablation after myocardial infarction guided by cardiac magnetic resonance/multidetector computed tomography image integration

Abstract INTRODUCTION The persistent challenge of ventricular tachycardia (VT) ablation lies in the elevated morbidity and mortality due to the underlying disease progression and the complexity of the arrhythmogenic substrate. As imaging methods are evolving, substrate-based VT ablation is moving closer to the realm of precision medicine. CASE PRESENTATION A 52-year-old patient with a history of hypertension, type II diabetes mellitus, hyperlipidemia, and stage IIIB chronic kidney disease was referred to our hospital for sustained monomorphic VT. Upon admission, the patient was hemodynamically stable. Laboratory results indicated mild anemia, moderate renal dysfunction, and normal myocardial enzymes. ECG during sinus rhythm showed widespread repolarization abnormalities in the apical and postero-lateral leads. Echocardiography revealed mild left ventricular dysfunction and coronary angiography confirmed significant lesions in multiple coronary arteries that were treated with drug-eluting stents (DES). Cardiac MRI showed relatively limited areas of old myocardial infarctions in the left circumflex artery and left anterior descending artery territories, therefore we decided to perform VT ablation. We used a Carto 3 Biosense Webster electro-anatomical mapping system (EAM) guided by fusion imaging (cardiac MRI and multidetector computed tomography - MDCT) with the aid of ADAS 3D software. The voltage map created during sinus rhythm, was concordant with the lesions identified on LGE-CMR. Radiofrequency (RF) catheter ablation targeted abnormal signals from the EAM, which were identified based on conduction channels (CCs) from the fusion imaging. There was complete VT non-inducibility at programmed ventricular stimulation (PVS). At the 3-month follow-up, echocardiography showed a slight improvement in LVEF and repeated PVS proved persistent ventricular arrhythmia non-inducibility. CONCLUSION Substrate-based VT ablation in structural heart disease has greatly improved by high-resolution substrate imaging with detailed anatomy, allowing successful personalized treatment. There is room for further improvement in the near future with the contribution of artificial intelligence, possibly with a more targeted and automated VT ablation.

Ablation targets of scar-related ventricular tachycardia identified by dynamic functional substrate mapping

BackgroundDynamic functional substrate mapping of scar-related ventricular tachycardia offers better identification of ablation targets with limited ablation lesions. Several functional substrate mapping approaches have been proposed, including decrement-evoked potential (DEEP) mapping. The aim of our study was to compare the short- and long-term efficacy of a DEEP-guided versus a fixed-substrate-guided strategy for the ablation of scar-related ventricular tachycardia (VT).ResultsForty consecutive patients presenting for ablation of scar-related VT were randomized to either DEEP-guided or substrate-guided ablation. Late potentials were tagged and ablated in the non-DEEP group, while those in the DEEP group were subjected to RV extrastimulation after a drive train. Only potentials showing significant delay were ablated. Patients were followed for a median duration of 12 months. Twenty patients were allocated to the DEEP group, while the other 20 were allocated to the non-DEEP group. Twelve patients (60%) in the DEEP group had ischemic cardiomyopathy versus 10 patients (50%) in the non-DEEP group (P-value 0.525). Intraoperatively, the median percentage of points with LPs was 19% in the DEEP group and 20.6% in the non-DEEP group. The procedural time was longer in the DEEP group, approaching but missing statistical significance (P-value 0.059). VT non-inducibility was successfully accomplished in 16 patients (80%) in the DEEP group versus 17 patients (85%) in the non-DEEP group (P value 0.597). After a median follow-up duration of 12 months, the VT recurrence rate was 65% in both groups (P value 0.311), with a dropout rate of 10% in the DEEP group. As for the secondary endpoints, all-cause mortality rates were 20% and 25% in the DEEP and non-DEEP groups, respectively (P-value 0.342).ConclusionsDEEP-assisted ablation of scar-related ventricular tachycardia is a feasible strategy with comparable short- and long-term outcomes to a fixed-substrate-based strategy with more specific ablation targets, albeit relatively longer but non-significant procedural times and higher procedural deaths. The imbalance between the study groups in terms of epicardial versus endocardial mapping, although non-significant, warrants the prudent interpretation of our results. Further large-scale randomized trials are recommended. Trial registration: clinicaltrials.gov, registration number: NCT05086510, registered on 28th September 2021, record https://classic.clinicaltrials.gov/ct2/show/NCT05086510

Utility of Very High-Output Pacing to Identify VT Circuits in Patients Manifesting Traditionally Inexcitable Scar

BackgroundEntrainment and pace mapping are used to identify critical components (CCs) of ventricular tachycardia (VT) circuits. In patients with dense myocardial scarring, VT circuits may elude capture at standard high pacing outputs (up to 10 mA at a 2-millisecond pulse width). ObjectivesThe purpose of this study was to assess the utility of very high–output pacing (V-HOP, 50 mA at 2 milliseconds) for identifying CCs of VT circuits after standard high pacing output failed to elicit capture in densely scarred myocardial tissue. MethodsOur standard VT ablation approach included electroanatomic mapping for substrate characterization and entrainment and/or pace mapping to identify CCs of VT circuits. Patients that required V-HOP to capture sites of interest comprised the study cohort. Ablation endpoints were VT termination and noninducibility. ResultsTwenty-five patients (71 ± 10 years of age, all males) undergoing 26 VT ablations met the inclusion criteria. The mean left ventricular ejection fraction was 30% ± 14%, and 85% had ischemic cardiomyopathy. V-HOP was used to successfully entrain VT in 17 patients, yielding central isthmus sites in 10 and entrance/exit sites in 4. VT terminated with radiofrequency ablation at these sites in 15 patients. In 9 patients, V-HOP identified scar locations with a delayed exit. Acute procedural success was achieved in 24 patients without any adverse events. Over a follow-up period of 16 ± 21 months, 2 patients experienced VT recurrence requiring repeat ablation during which the same location was targeted successfully in 1 patient. ConclusionsIn VT patients with a dense scar that is traditionally inexcitable, V-HOP can identify CCs of the re-entrant circuit and guide successful ablation.

PO-05-094 LONG TERM OUTCOMES AFTER BIPOLAR RADIOFREQUENCY ABLATION FOR INTRASEPTAL VENTRICULAR TACHYCARDIAS IN NON-ISCHEMIC AND ISCHEMIC CARDIOMYOPATHY – A MULTI-CENTER EXPERIENCE

Ventricular tachycardia (VT) arising from mid-myocardial substrate of the interventricular septum (IVS) can be challenging for ablation. Bipolar radiofrequency ablation (B-RFA) is a potential option for treating VT of septal origin however there are limited data on outcomes of B-RFA for septal VT comparing individuals with non-ischemic cardiomyopathy (NICM) to those with ischemic cardiomyopathy (ICM). The purpose of this study is to describe the outcomes of B-RFA for septal VT in a multicenter study of patients with NICM and ICM. We included 46 patients (mean age 66 ± 10 years; 95% male; left ventricular ejection fraction 33% ± 12%; 50% with history of prior VT ablation) who underwent B-RFA for VT of septal origin. Septal VTs were determined after failed unipolar ablation or VT substrate mapped by electroanatomic mapping of IVS. Short-term outcomes including non-inducibility of VT after ablation as well as long-term outcomes including recurrent VT, repeat VT ablation and death were evaluated at mean follow-up (FU) of 37 ± 18 months. Of the 46 total patients, 30 patients (65%) had NICM and 16 (35%) had ICM. Noninducibility of the clinical VT immediately after B-RFA was achieved in 27 patients (90%) with NICM vs 16 patients (100%) with ICM. During FU, recurrent VT occurred in 17 patients (37%) overall. Recurrent VT occurred in 14 patients (47%) with NICM vs in 3 patients (19%) with ICM. For those with NICM, 11 patients (37%) underwent repeat VT ablations, including 5 patients (17%) who underwent repeat B-RFA. For those with ICM, 3 patients (19%) underwent repeat VT ablation, and no patients underwent repeat B-RFA. During FU, death occurred in 5 patients (17%) with NICM vs 3 patients (19%) with ICM. B-RFA is an effective strategy for terminating VT of septal origin with a high acute success rate. Recurrent VT after B-RFA and repeat ablations were more common in patients with NICM.

PO-05-037 EFFICACY AND CLINICAL CHARACTERISTICS OF AVERT-VT: ABLATION AT VIRTUAL-HEART PREDICTED VT

We have previously demonstrated the feasibility of virtual-heart simulations in determining noninvasively the optimal infarct-related ventricular tachycardia (VT) ablation targets and guiding the clinical ablation. We are now proceeding with AVERT-VT, an FDA-approved study for ten prospective patients. To develop the end-to-end personalized computational modeling prediction pipeline enabling AVERT-VT and to assess the corresponding clinical characteristics of the predicted virtual-heart ablation targets. We developed a comprehensive end-to-end computational pipeline enabling AVERT-VT (Fig). 3D LGE-MRI scans with 1.5x1.5mm in-plane spatial resolution and slice thickness <2mm were used to reconstruct the 3D left ventricular (LV) model incorporating deep scar, border (gray) zone, and non-infarcted tissue. In silico rapid pacing from 7 LV regions were performed to induce VTs. The optimal ablation targets were determined by thorough analyses of the wavefront propagation of the induced in silico VTs. A linear ablation connecting a VT ablation target to a transmural deep scar region, the basal region, or the other VT target was performed to eliminate the potential VT pathway formed by the target ablation. Potential emergent VTs in the post-ablation substrate were investigated by repeating the VT induction pacing protocol. This process was iterated until complete VT non-inducibility was achieved. The initial and repeat ablation targets, linear ablations, as well as the LV, right ventricle, infarct area, aortic arch, and left and right coronary cusp geometries, were exported as an ablation strategy plan compatible with the clinical mapping system. The figure presents results from one patient in the clinical study. The ablation plan was successfully imported and co-registered to the patient’s heart. The extent of the model infarct corresponded to the bipolar low-voltage regions. Abnormal electrograms were observed at the proposed targets. 2 VTs were observed during the procedure. Areas of latest activation in sinus rhythm and best pace maps, with a long stimulus to QRS, were found at 2 of the proposed targets. One of the seven proposed targets was not ablated due to the proximity to the left sided His potential. The patient was not inducible of any VT at the end of the procedure. AVERT-VT proposed targets corresponded to abnormal electrograms, and ablating at the targets led to VT non-inducibility.

PO-04-158 INTRACARDIAC ECHOCARDIOGRAPHY GUIDES ANATOMICAL ISTHMUS ABLATION IN PATIENTS WITH VENTRICULAR TACHYCARDIA AND REPAIRED TETRALOGY OF FALLOT

Successful catheter ablation of monomorphic ventricular tachycardia (VT) in patients with repaired Tetralogy of Fallot (TOF) can be achieved by targeting one or more of four common anatomical isthmuses. However, variability in the size and location of surgical patches means careful mapping is required to design ablation lines to block the critical isthmus. Intracardiac echocardiography (ICE) may assist ablation by accurate identification of individual TOF anatomy. To determine whether the routine use of ICE aids linear ablation of VT isthmuses in patients with repaired TOF. Retrospective study of repaired TOF patients undergoing VT ablation at our centre from January 2017 to November 2022. Cases were divided into those which used ICE to assist anatomical mapping versus those which used voltage mapping to identify patches and valve annuli. Once anatomy was defined, we started with a VT stimulation study where haemodynamically stable VTs were mapped. Non-inducible or unstable VTs underwent substrate mapping in sinus rhythm. All cases underwent ablation and had no inducible monomorphic VT as the endpoint. Data are presented as median and [interquartile range]. Twenty-six patients were identified, of which 15 were guided by ICE. The baseline demographic data is presented in the table and a representative figure shows the use of ICE to identify surgical patches. The use of ICE allowed linear ablation of the critical anatomical isthmus in 12/15 patients (80%) compared to 4/11 (36%) without ICE (p=0.023). The remaining patients without linear ablation underwent substrate-based ablation only to sites of local abnormal ventricular activity. There was no significant difference in overall procedure time (ICE: 165 [60] minutes versus no ICE: 145 [50] minutes; p=0.24), nor in fluoroscopy time (ICE: 25 [17] minutes versus no ICE: 31 [16] minutes; p=0.9). Over time, the introduction of ICE was associated with improved workflow. When comparing the first and last five cases using ICE, both median procedure times (from 196 to 160 minutes) and fluoroscopy times (from 35 to 20 minutes) were shorter. Intracardiac echocardiography improves targeted linear ablation of the critical anatomical isthmus for VT in patients with repaired TOF. ICE provides real-time individualised identification of surgical patches and valve anatomy to guide optimal linear lesion sets across isthmuses, with routine use over time showing a trend towards shorter procedural and fluoroscopy times.Tabled 1Baseline demographicsICE (n=15)No ICE (n=11)Age (years)53 [26]41 [23]Male10 (67%)7 (64%)Number of sternotomies2 [1]3 [2]History of syncope5 (33%)1 (9%)QRS width (milliseconds)176 [59]172 [54]Left ventricular ejection fraction (%)50 [25]54 [9]Right ventricular ejection fraction (%)29 [8]27 [7]Implantable cardiac defibrillator7 (47%)5 (45%)History of sustained VT12 (80%)8 (73%)VT ablation15 (100%)11 (100%)Inducible VT at electrophysiology study11 (73%)6 (55%)Linear anatomical isthmus ablation12 (80%)4 (36%)Procedure time (minutes)165 [60]145 [50]Fluoroscopy time (minutes)25 [17]31 [16] Open table in a new tab

The value of functional substrate mapping in ventricular tachycardia ablation.

In the setting of structural heart disease, ventricular tachycardia (VT) is typically associated with a re-entrant mechanism. In patients with hemodynamically tolerated VTs, activation and entrainment mapping remain the gold standard for the identification of the critical parts of the circuit. However, this is rarely accomplished, as most VTs are not hemodynamically tolerated to permit mapping during tachycardia. Other limitations include noninducibility of arrhythmia or nonsustained VT. This has led to the development of substrate mapping techniques during sinus rhythm, eliminating the need for prolonged periods of mapping during tachycardia. Recurrence rates following VT ablation are high; therefore, new mapping techniques for substrate characterization are required. Advances in catheter technology and especially multielectrode mapping of abnormal electrograms has increased the ability to identify the mechanism of scar-related VT. Several substrate-guided approaches have been developed to overcome this, including scar homogenization and late potential mapping. Dynamic substrate changes are mainly identified within regions of myocardial scar and can be identified as local abnormal ventricular activities. Furthermore, mapping strategies incorporating ventricular extrastimulation, including from different directions and coupling intervals, have been shown to increase the accuracy of substrate mapping. The implementation of extrastimulus substrate mapping and automated annotation require less extensive ablation and would make VT ablation procedures less cumbersome and accessible to more patients.

Matching Ablation Endpoints to Long-Term Outcome: The Prospective Multicenter Italian Ventricular Tachycardia Ablation Registry

BackgroundMulticenter ventricular tachycardia (VT) ablation studies have shown poorer outcomes compared with single-center experiences. This difference could be related to heterogeneous mapping and ablation strategies. ObjectivesThis study evaluated a homogenous simplified catheter ablation strategy for different substrates and compared the results with those of a single referral center. MethodsThis was a multicenter prospective VT ablation registry of patients with the following 4 causes of VT: previous myocardial infarction; previous myocarditis; arrhythmogenic right ventricular dysplasia; or idiopathic dilated cardiomyopathy. The procedural protocol included precise mapping and ablation steps with the combined endpoint of late potential (LP) abolition and noninducibility of VT. The long-term primary efficacy endpoint was freedom from VT. ResultsA total of 309 patients were enrolled. LPs were present in 70% of patients and were abolished in 83%. At the end of the procedure 74% of LPs were noninducible. The primary combined endpoint of LP abolition and noninducibility was achieved in 64% of patients with LPs at baseline. Freedom from VT at 12 months was observed in 67% of patients. In the overall study group, VT inducibility was the only predictor of freedom from VT (P = 0.013). In patients with LPs, the VT recurrence rate was lower both for patients with complete LP abolition (P = 0.040) and for patients meeting the composite endpoint (P = 0.035). ConclusionsA standardized VT mapping and ablation technique reproduced the procedural outcomes of a single referral center in a multicenter prospective study. LP abolition and noninducibility were effective in reducing VT recurrences in patients with 4 causes of cardiomyopathy. (Ventricular Tachycardia Ablation Registry; NCT03649022)

Impact of Amiodarone Therapy on the Ablation Outcome of Ventricular Tachycardia in Arrhythmogenic Right Ventricular Cardiomyopathy.

(1) Background: Catheter ablation (CA) is an accepted treatment option for drug-refractory ventricular tachycardia (VT) in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). This study investigates the effect of amiodarone on ablation outcomes in ARVC. (2) Methods: The study enrolled patients with ARVC undergoing CA of sustained VT. In all patients, substrate modification was performed to achieve non-inducible VT. The patients were categorized into two groups according to whether they had used amiodarone before CA. Baseline and electrophysiological characteristics, substrate, and outcomes were compared. (3) Results: A total of 72 ARVC patients were studied, including 29 (40.3%) "off" amiodarone and 43 (56.7%) "on" amiodarone. The scar area was similar between the two groups. Patients "off" amiodarone had smaller endocardial and epicardial areas with abnormal electrograms. Twenty of 43 patients (47.5%) "on" amiodarone discontinued it within 3 months after CA. During a mean follow-up period of 43.2 ± 29.5 months, higher VT recurrence was observed in patients "on" amiodarone. Patients "on" amiodarone who discontinued amiodarone after CA had a lower recurrence than those without. (4) Conclusions: Patients with ARVC "on" amiodarone before CA had distinct substrate characteristics and worse ablation outcomes than patients "off" amiodarone, especially in those who had used amiodarone continuously.

Predictors of recurrence in patients without non-inducibility of ventricular tachycardia at the end of ablation.

Ventricular tachycardia (VT) non-inducibility at the end of ablation is associated with a less likely VT recurrence. However, it is not clear whether we should use VT non-inducibility as a routine end point of VT ablation. The aim of this study was to evaluate VT recurrence in patients in whom VT non-inducibility was not achieved at the end of the radiofrequency (RF) ablation and the factors attributing to the VT recurrence. We analyzed that 62 patients in whom VT non-inducibility was not achieved at the end of the RF ablation were studied. Over 2 years, 22 (35%) of the cases had VT recurrences. A multivariate analysis showed that an LVEF ≥35% (HR: 0.19; 95% CI: 0.06-0.49; p < .01) and elimination of the clinical VT as an acute ablation efficacy (HR: 0.23; 95% CI: 0.04-0.81; p=.02) were independent predictors of fewer VT recurrences. RF ablation was associated with a 91.1% reduction in VT episodes. Even if VT non-inducibility was not achieved, patients with an LVEF ≥35% or in whom the clinical VT could be eliminated might be prevented from having VT recurrences. The validity of the VT non-inducibility of any VT should be evaluated considering each patient's background and the results of the procedure.

Substrate Characterization and Outcomes of Catheter Ablation of Ventricular Arrhythmias in Patients With Mitral Annular Disjunction.

Mitral annular disjunction (MAD) has recently been recognized as an arrhythmogenic entity. Data on the electrophysiological substrate as well as the outcomes of catheter ablation of ventricular arrhythmias in patients with MAD is limited. Forty patients with MAD (mean age 47±15 years; 70% female) underwent catheter ablation for ventricular arrhythmias. Detailed clinical, electrocardiographic, cardiac imaging, and procedural data were collected. Clinical outcomes were compared between patients who had substrate modification in the MAD area and those who did not. Twenty-three (57.5%) patients had ablation for premature ventricular contractions, 10 (25%) patients for sustained ventricular tachycardia, and 7 (17.5%) patients for premature ventricular contraction-triggered ventricular fibrillation. Mean end-systolic MAD length was 10.58±3.49 mm on transthoracic echocardiography. Seventeen (42.5%) patients had preprocedural cardiac magnetic resonance imaging, and 5 (29%) patients had late gadolinium enhancement. Among the 18 (45%) patients who had abnormal local electrograms (low voltage, long-duration, fractionated, isolated mid-diastolic potentials) during electroanatomical mapping, 10 (25%) patients had abnormal electrograms in the anterolateral mitral annulus and/or MAD area. Substrate modification was performed in 10 (25%) patients. Catheter ablation was acutely successful in 36 (90%) patients (elimination of premature ventricular contraction or noninducibility of ventricular tachycardia). After a median follow-up duration of 54.08 (interquartile range, 10.67-89.79) months, premature ventricular contraction burden decreased from a median of 9.75% (interquartile range, 3.25-14) before the ablation to a median of 4% (interquartile range, 1-7.75) after the ablation (P=0.03 [95% CI, 0.055-6.5]). Eight (20.5%) patients had repeat ablation for ventricular arrhythmias. Substrate modification of the MAD was associated with a trend toward lower rates of repeat ablation (0% versus 26.7%; P=0.16). Patients with MAD have a complex arrhythmogenic substrate, and catheter ablation is effective in reducing recurrence of ventricular arrhythmias. Substrate mapping and ablation may be considered in these patients.

Monomorphic VT Non-Inducibility after Electrical Storm Ablation Reduces Mortality and Recurrences.

Background: Electrical storm (ES) is defined by clustering episodes of ventricular tachycardia (VT) and is associated with severe long-term outcomes. We sought to evaluate the prognostic impact of radiofrequency catheter ablation (RFCA) in ES as assessed by aggressive programmed ventricular stimulation (PVS). Methods: Single-center retrospective longitudinal study with 82 consecutive ES patients referred for RFCA with a median follow-up (IQR 25–75%) of 45.43 months (15–69.86). All-cause mortality and VT recurrences were assessed in relation to RFCA outcomes defined by 4-extrastimuli PVS: Class 1—no ventricular arrhythmia; Class 2—no sustained monomorphic VTs (mVT) inducible, but non-sustained mVTs, polymorphic VTs, or VF inducible; Class 3—clinical VT non-inducible, other sustained mVTs inducible; and Class 4—clinical VT inducible. Results: Class 1, Class 2, Class 3, and Class 4 were achieved in 56.1%, 13.4%, 23.2%, and 7.4% of cases, respectively. The combined outcome of Class 1 + Class 2 (no sustained monomorphic VT inducible) led to improved survival (log-rank p < 0.001) and reduced VT recurrence (log-rank p < 0.001). Residual monomorphic VT inducibility (HR 6.262 (95% CI: 2.165–18.108, p = 0.001), NYHA IV heart failure symptoms (HR 20.519 (95% CI: 1.623–259.345), p = 0.02)), and age (HR 1.009 (95% CI: 1.041–1.160), p = 0.001)) independently predicted death during follow-up. LVEF was not predictive of death (HR 1.003 (95% CI: 0.946–1.063) or recurrences (HR 0.988 (95% CI: 0.955–1.021)). Conclusions: Non-inducibility for sustained mVTs after aggressive PVS post-RFCA leads to improved survival in ES, independently of LVEF.

Endocardial Scar-Homogenization With vs Without Epicardial Ablation in VT Patients With Ischemic Cardiomyopathy.

In this study, the authors investigated the ablation success of scar homogenization with combined (epicardial+ endocardial) vs endocardial-only approach for ventricular tachycardia (VT) in patients with ischemic cardiomyopathy (ICM) at 5 years of follow-up. Best ablation approach to achieve long-term success rate in VT patients with ICM is not known yet. Consecutive ICM patients undergoing VT ablation at our center were classified into group 1: endocardial+ epicardial scar homogenization and group 2: endocardial scar homogenization. Patients with previousopen heart surgery were excluded. Epicardial ablation was performed despite being noninducible after endocardial ablation in all group 1 patients. All patients underwent bipolar substrate mapping with standard scar settings defined as normal tissue >1.5mV and severe scar<0.5mV. Noninducibility of monomorphic VT was the procedural endpoint in both groups. Patients were followed up every 4months for 5 years with implantable device interrogations. A total of 361 patients (group 1: n=70 and group 2: n=291) were included in the study. At 5 years, 81.4% (n=57/70) patients from group 1 and 66.3% (n=193/291) from group 2 were arrhythmia-free (P = 0.01) Of those patients, 26 of 57 (45.6%) and 172 of 193 (89.1%) from group 1 and group 2 respectively were on anti-arrhythmic drugs (AAD) (log-rank P < 0.001). After adjusting for age, sex, and obstructive sleep apnea, endo-epicardial scar homogenization was associated with a significant reduction in arrhythmia-recurrence (HR: 0.48; 95%CI: 0.27-0.86; P = 0.02). In this series of patients with ICM and VT, epicardial substrate was detected in all group 1 patients despite being noninducible after endocardial ablation. Moreover, combined endo-epicardial scar homogenization wasassociated with a significantly higher success rate at 5 years of follow-up and a substantially lower need for antiarrhythmic drugs after the procedure compared with the endocardial ablation alone.

VT recurrence and predictors in patients with VT inducibility at the end of VT ablation

Abstract Background A successful Radiofrequency (RF) ablation of ventricular tachycardia (VT) can prevent VT recurrence. It has been reported that VT non-inducibility at the end of RF ablation is associated with less likely VT recurrence in ischemic cardiomyopathy (ICM) and non-ICM (NCIM). However, it is not clear whether we should use VT non-inducibility as routine end point in RF ablation of VT. Purpose The aim of this study was to evaluate VT recurrence in patients who couldn't be achieved VT non-inducibility at the end of RF ablation and the factors attributed to VT recurrence in ICM and NICM patients. Methods Between January 2009 and April 2020, 84 consecutive patients (ICM: 34, NICM: 50) underwent RF ablation for drug-resistant VT in our hospital. VT non-inducibility was defined as any ventricular tachy-arrhythmia, including clinical VT, non-clinical VT, and VF, was not induced by programed stimuli at the end of session. Non-inducibility was achieved in 37 patients but it was not achieved in 47 patients (ICM: 18, NICM: 29). To evaluate the validity of “non-inducibility” as an end point of VT ablation, 47 patients (male: 40, mean age: 66±15 years) in whom non-inducibility of any ventricular tachyarrhythmia was not achieved were studied. The primary endpoint was recurrence of any sustained VT and VF during follow up period (mean follow-up period was 1.4 (range, 0.0, 2.0) years.) Results Mean left ventricular ejection fraction (LVEF) was 36±13%. Epicardial ablation was required in 8 patients. 32 patients had electrical storm at the time of ablation. Among them, 21 patients had VT recurrence and 26 patients had non-VT recurrence during follow-up period. VT recurrence rate was significantly lower in patients with LVEF≥35% than those with LVEF&amp;lt;35% (HR=0.31, 95% CI 1.25–9.92). Multivariate survival analysis identified LVEF≥35% (HR=0.34, 95% CI 0.10–0.98) and ablation of VT isthmus (HR=0.18, 95% CI 0.02–0.78) as independent predictors of non-VT recurrence. Conclusions Even if non-inducibility of any ventricular tachyarrhythmia wasn't achieved at the end of ablation, the patients with LVEF≥35% or who had ablated of VT isthmus might prevent VT recurrence. The validity of non-inducibility of any ventricular tachyarrhythmia should be evaluated in each patient's background. Funding Acknowledgement Type of funding sources: Public hospital(s). Main funding source(s): Abbott, Medtronic

Long-term outcome of endocardial-only versus combined endocardial-epicardial homogenization of the scar for treatment of ventricular tachycardia in patients with ischemic cardiomyopathy

Abstract Introduction We investigated the ablation success of scar homogenization with combined (epicardial + endocardial) versus endocardial-only approach for ventricular tachycardia (VT) in patients with ischemic cardiomyopathy (ICM) at 5 years of follow-up. Method Consecutive ICM patients undergoing VT ablation at our center were classified into group 1: endocardial scar homogenization and group 2: endocardial +epicardial scar homogenization. Patients with previous open heart surgery were excluded. All patients underwent bipolar substrate mapping with standard scar settings defined as normal tissue &amp;gt;1.5 mV and severe scar &amp;lt;0.5 mV. Non-inducibility of monomorphic VT was the procedural endpoint in both groups. Patients were followed up twice a year for 5 years with implantable device interrogations. Results A total of 361 (Group 1: 291 and group 2: 70) patients were included in the study (mean age: 67 years, male: 88.4%). At 5 years, significantly higher number of patients from group 2 remained arrhythmia-free (figure 1). Of those patients, 87 (45%) and 51 (89%) from group 1 and 2 respectively were off-anti-arrhythmic drugs (AAD) (p&amp;lt;0.001). After adjusting for age, gender, hypertension, diabetes, and obstructive sleep apnea, scar homogenization using endo-epicardial approach was associated with 51% less recurrence compared to the endocardial ablation strategy (Hazard Ratio: 0.49, 95% CI: 0.27–0.89, p: 0.02). Conclusion In this series of patients with ischemic cardiomyopathy and VT, endo-epicardial scar homogenization was associated with a lower need for AAD and a significantly lower recurrence rate at 5-years of follow-up compared to the endocardial ablation alone. Funding Acknowledgement Type of funding sources: None. Figure 1

Gender differences in patients with structural heart disease undergoing VT ablation

This study sought to examine gender differences in patients with structural heart disease (SHD) referred for ablation of ventricular tachycardia (VT). Female patients are often underrepresented in large studies. Significant differences in the clinical presentation, treatment, and prognosis of female patients have been described in previous studies. We investigated 88 female patients with SHD undergoing VT ablation (mean age 59 years, 56% nonischemic cardiomyopathy, mean left ventricular ejection fraction 35%, 82% in electrical storm). A case-control study with 88 male patients was performed and the results regarding clinical and procedural characteristics, acute and long-term results of the two groups were compared. The female patients had more arrhythmogenic substrate, as they more commonly presented with electrical storm (p = .016) and had a higher number of inducible VT morphologies during the procedure (p = .018). Moreover, the female patients were less likely to have an optimized heart failure medical treatment at baseline (p = .030) and required more time from the first manifestation of the VT to ablation referral (p = .034). Although fewer epicardial ablations were performed in female patients (p = .019), the two groups showed similar results regarding VT noninducibility as ablation endpoint (p = .844), major procedure-related complications (p = .719) and freedom from VT during follow-up (p = .268). Moreover, the overall mortality in the two groups was similar (p = .176). Advanced NYHA class was associated with worse transplant and assist-device-free survival in the female group. Female patients presenting for VT ablation had more arrhythmogenic substrate and were less likely to have an optimized heart failure medical treatment. Nevertheless, the procedural acute and long-term outcomes between the two genders were similar.