Underwent VT Ablation Research Articles

Extracorporeal Membrane Oxygenation for Patients With Electrical Storm or Refractory Ventricular Arrhythmias: Management and Outcomes.

Patients on venoarterial extracorporeal membrane oxygenation (VA-ECMO) are at high risk for ventricular arrhythmias due to derangements in myocardial perfusion, hemodynamics, and heightened catecholamine states. Existing data on the management and outcomes of patients with electrical storm or refractory ventricular tachycardia/fibrillation (VT/VF) treated with VA-ECMO are primarily derived from retrospective observational studies. Typical survival rates are in the range of 40%-50%, with 15%-20% of patients undergoing VT ablation and 30%-40% of patients requiring advanced heart failure therapies (cardiac transplant or durable left ventricular assist device). Similarly, there is a paucity of published data on VT/VF management for patients while on VA-ECMO, as these data are largely extrapolated from patients with electrical storm. Although many of the treatment principles (identifying reversible causes, antiarrhythmic drugs, VT ablation, and reduction of adrenergic tone) are translatable, several aspects require special consideration when managing VT/VF in the VA-ECMO patient population. Among carefully selected patients on VA-ECMO who underwent VT ablation, reported recurrence rates were ∼ 30% and a sizeable proportion of them (30%-40%) required advanced heart failure therapy as an exit strategy. In addition, there are specific issues that require consideration for patients on VA-ECMO who undergo VT ablation, such as vascular access, ECMO access site complications, and bleeding due to systemic anticoagulation. Optimal management of VT/VF in this patient population requires ongoing reassessment and dialogue among electrophysiology, heart failure, and critical care specialists. Additional research is needed to better inform the care of this very high-risk patient population.

High-density mapping-guided ventricular tachycardia ablation in patients with ischemic cardiomyopathy: outcomes from a tertiary center cohort in Switzerland

Abstract Background Substrate-based ablation has emerged as a successful technique for VT ablation, especially in patients with ischemic cardiomyopathy with markedly reduced left ventricular function. High-density mapping catheters provide high-resolution electroanatomical maps and better discrimination of abnormal substrates and local activation in the heart chambers, making them a valuable and safe resource in the electrophysiology laboratory. Purpose The purpose of this study was to investigate differences in procedural characteristics and clinical outcomes of VT ablation with ischemic cardiomyopathy. VT ablations were guided by two mapping strategies: high-density mapping using a high-density mapping catheter and conventional mapping using an ablation catheter. Methods Patients with ischemic cardiomyopathy receiving VT ablation at our center between January 2018 and June 2023 were retrospectively included. Procedural characteristics and clinical outcomes were compared between patients receiving high-density mapping with a multielectrode-mapping catheter vs conventional mapping with a single-tip irrigated ablation catheter. Results Eighty-four patients with ischemic cardiomyopathy who underwent VT ablation were consecutively included (mean age 67 ± 12 years, mean LVEF 32 ± 11 %, 79 (94%) males). Fifty-seven (68 %) procedures were performed using high-density mapping, and 27 (32 %) conventional mapping. In the high-density mapping and conventional mapping group, the total procedure time was 256 ± 77 min vs. 232 ± 61 min (P < 0.05) and the total fluoroscopic dose was 1643 ± 204 μGy.m2 vs. 948 ± 105 μGy.m2 (P < 0.05), respectively,. However, there was no difference between the two groups in terms of acute success (84% vs 80%, P > 0.05) or major complications (5% vs 4%, P > 0.05). The mean duration of follow-up was 2.6 years (4 - 51 months). The 1-year mortality rates were 4% vs 7% in the high-density mapping and conventional mapping groups, respectively (P < 0.05). The 3-month and 1-year single-procedural sustained VT/VF-free rates were 77% vs 59% and 74% vs 63%, respectively (P < 0.05). The 1-year incidence of sustained VT/VF recurrence was 7.0 per 100 person-years in high-density mapping group, compared with 7.4 per 100 person-years in the conventional group. Conclusions VT ablation in patients with ischemic cardiomyopathy using high-density mapping appears to be superior to conventional mapping in terms of reducing postprocedural VT/VF recurrence and a subsequent reduction of overall mortality.Figure 1Figure 2

Catheter ablation of ventricular tachycardia: strategies to improve outcomes.

Catheter ablation of ventricular arrhythmias has evolved considerably since it was first described more than 3 decades ago. Advancements in understanding the underlying substrate, utilizing pre-procedural imaging, and evolving ablation techniques have improved the outcomes of catheter ablation. Ensuring safety and efficacy during catheter ablation requires adequate planning, including analysis of the 12 lead ECG and appropriate pre-procedural imaging. Defining the underlying arrhythmogenic substrate and disease eitology allow for the developed of tailored ablation strategies, especially for patients with non-ischemic cardiomyopathies. During ablation, the type of anesthesia can affect VT induction, the quality of the electro-anatomic map, and the stability of the catheter during ablation. For high risk patients, appropriate selection of hemodynamic support can increase the success of VT ablation. For patients in whom VT is hemodynamically unstable or difficult to induce, substrate modification strategies can aid in safe and successful ablation. Recently, there has been an several advancements in substrate mapping strategies that can be used to identify and differentiate local late potentials. The incorporation of high-definition mapping and contact-sense technologies have both had incremental benefits on the success of ablation procedures. It is crucial to harness newer technology and ablation strategies with the highest level of peri-procedural safety to achieve optimal long-term outcomes in patients undergoing VT ablation.

Machine learning based prediction of 1-year arrhythmia recurrence after ventricular tachycardia ablation in patients with structural heart disease

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Project no. NVKP_16-1–2016-0017 (’National Heart Program’) - National Research, Development and Innovation Fund of Hungary Thematic Excellence Programme (2020-4.1.1.-TKP2020) of the Ministry for Innovation and Technology in Hungary Background Ventricular tachycardia (VT) is a life-threatening condition. Catheter ablation treatment is often successful, however post procedural VT recurrence still remains an issue. Therefore, there is a demand for an accurate risk stratification system to assess the probability of arrhythmia recurrence after the procedure. Objective We aimed to implement a machine learning (ML) pipeline to predict 1-year VT recurrence in patients with structural heart disease (SHD) undergoing VT ablation. Methods For 297 patients who underwent VT ablation, we collected medical history, laboratory, echocardiography, and procedural data. Following manual and ML-based feature selection, we trained several supervised machine learning models to predict 1-month and 1-year recurrence. The area under the receiver operating characteristic curve (AUC) was calculated to quantify the models’ performance. Results 1-year VT recurrence was observed in 107 (36%) cases. The best predictions of VT recurrence were demonstrated by random forest models utilizing 7 input features [1-month AUC: 0.74; 1-year AUC: 0.76]. These models significantly outperformed a previously published risk score, the I-VT score [AUC: 0.63, p=0.024] on our data. The most important predictors of recurrence were the number of VT morphologies during the procedure, electrical storm, left ventricular ejection fraction, left ventricular end systolic diameter, and the severity of mitral regurgitation. Conclusion Our machine learning model can efficiently predict VT recurrence in SHD patients undergoing VT ablation. Thus, it could facilitate the prompt identification of high-risk patients and the personalization of treatment and follow-up strategies, ultimately leading to improved outcomes.

PO-03-090 NOVEL HIGH RESOLUTION MR IMAGING IMPROVES PRE-PROCEDURE IDENTIFICATION OF ABLATION TARGETS IN POST-INFARCT VENTRICULAR TACHYCARDIA

MRI-based personalized virtual heart models (VHM) are a useful tool for reconstructing scar distribution and identifying VT circuits for planning catheter ablation procedure, an effective therapy for preventing sudden cardiac death from VT in patients with myocardial infarction. However, the MRI resolution used to reconstruct VHMs may not be sufficient to accurately detect all VT circuits, possibly leading to erroneous predictions. To predict catheter ablation targets in the arrhythmogenic substrate using VHMs reconstructed from both clinical and high-resolution 2D MRI datasets and compare the predictions. High-resolution (1.352 x 3mm) short-axis cardiac MRI were acquired by combining two subsequent clinical resolution (1.352 x 6mm) short-axis MRI from nine post-infarct patients undergoing VT ablation. The high-resolution and two clinical MRI were used to reconstruct a total of three personalized VHMs for each patient that represented the patient-specific infarct remodeling. Rapid pacing was used to assess the VT circuits and identify ablation targets in each VHM. Differences in VT inducibility and location were assessed between the high and clinical resolution VHM reconstructions, as well as between the two clinical resolution VHM reconstructions. Virtual ablations were performed to identify emergent VTs and were also compared between the VHMs for each patient. The amount of fibrotic remodeling changed by 12.6 ± 3.3% between the high-resolution and two clinical MRI VHMs for each patient, while the distribution was only moderately affected (Fig 1). The heterogeneity of the myocardium and the fractal dimension (complexity) of the scar tissue was not statistically different between the VHMs for each patient (Fig 1). VT inducibility was observed in all VHMs with an average of 2.7 [1-4] unique VT morphologies induced in each VHM. In two patients, only one clinical VHM was able to identify all the unique VT morphologies observed in the high-resolution VHM. VT exit sites in the clinical MRI VHMs were within 5mm of the exit sites observed in the high-resolution VHMs in 72.2% of cases. Virtual ablations uncovered emergent VT circuits in two of the high-resolution VHMs, compared to only one of the corresponding clinical MRI VHMs. The distribution of ablation targets required to terminate VT was statistically different in 44.4% of cases (Fig 1). VHMs reconstructed from high-resolution MRI more accurately identify VT circuits and may improve catheter ablation outcomes.

PO-05-091 ACUTE AND MID-TERM CLINICAL OUTCOMES OF ISCHEMIC SCAR-RELATED VT ABLATION GUIDED BY REAL-TIME INTRAPROCEDURAL RAPID-VT SYSTEM FOR LOCALIZING VT EXIT SITES ON PATIENT-SPECIFIC 3D GEOMETRY: A PILOT CASE-CONTROL STUDY

We have previously developed an intraprocedural system to identify VT exit sites in real-time on the patient-specific CT/MRI geometry using 3-lead ECGs (leads III, V2, V6) during catheter ablation for ventricular tachycardia (RAPID-VT). To assess prospectively the localization performance and clinical outcomes of using the RAPID-VT system to guide catheter ablation. 8 consecutive consenting patients with ischemic cardiomyopathy undergoing VT ablation who had preprocedural CT/MRI scans were included. A reconstructed LV endocardial mesh surface was registered to the electroanatomic shell during the procedure and imported into the RAPID-VT program. During the procedure, predicted VT exit sites were used to guide mapping and ablation (Figure). The localization accuracy was quantified by comparing estimated sites against sites clinically identified using activation, entrainment, and pace mapping. Acute and mid-term clinical outcomes were compared to a control group of 8 consecutive patients with ischemic cardiomyopathy who underwent catheter ablation. Baseline clinical characteristics were similar between the 2 groups. The RAPID-VT system had localization accuracy of 8.6±3.2 mm. There were trends toward less RF time, RF applications and fluoroscopy times with RAPID-VT procedures. Overall procedure time and complications were similar. VT was noninducible in a higher proportion of patients in the RAPID-VT group. (7/8 vs. 1/8, p=0.01). A trend towards less VT recurrences or need for repeat ablations at 12 months was observed. (Table) In this pilot study, RAPID-VT system was feasibly used in real-time to guide VT mapping and ablation with exit site localization error <10 mm. Clinical outcomes compared favorably with control patients. Validation in larger studies is required.Tabled 1Comparison between the 2 groupsRAPID-VT (n=8)Control (n=8)BaselineAge (years)68±767±9LVEF (%)39±1136±8Amiodarone use prior to ablation75ProcedureProcedure duration (min)284±33288±65Total RF time (min)28.7±8.636.1±21.3Number of RF applications49±1557±38Fluoroscopy time (min) ¶12.7±3.521±10.1All clinical VTs interrupted with RF53Non-inducible at end of procedure§71Follow-upICD shocks @ 12 months13ICD therapies @ 12 months24VT recurrence @ 12 months36Time to recurrence (days)*70 (288)32.5 (302)* Median (range) § Fisher’s exact test p=0.01 ¶ Fisher’s exact test p=0.06 Open table in a new tab

PO-05-001 TARGETING WAVEFRONT DISCONTINUITY LINES FOR SCAR-RELATED VENTRICULAR TACHYCARDIA ABLATION

Late activation mapping can identify wavefront discontinuities during functional substrate mapping. Automated visualization of wavefront discontinuity lines (WaDLs) representing conduction block or delay may be a suitable target for a focused VT ablation. To describe WaDLs in multiple types of cardiomyopathy undergoing VT ablation, with correlation to critical VT circuit sites and bipolar low voltage scar. Patients who underwent high density substrate ablation with late activation mapping in sinus or paced wavefront were retrospectively analyzed. An automated mapping algorithm was used to visually demarcate WaDLs by identifying adjacent points where mapped activation times were greater than a certain timing threshold (CARTO®,Biosense Webster) Extended Early Meets Late module). Timing threshold was set to 25-35% of the mapped activation time. The number, total length, and distance to critical VT site of WaDLs was compared at each threshold 34 patients (20 post-infarct, 10 dilated, 1 Chagas, 1 sarcoid, 1 ARVC, 1 lamin) with 46 endocardial or epicardial surface substrate maps (10 epicardial, 36 endocardial; mean 1898 points) were included. WaDLs were present in each cardiomyopathy and surface, and represented average timing discontinuities of 50-61 ms (25%-35% WaDL threshold) with no difference in number or length of WaDLs by the mapped chamber, cardiomyopathy type, or wavefront. Parallel WaDLs forming putative channels were present in 37.2% of mapped chambers. In 15 patients with a critical VT site identified, the median distance from critical site to nearest WaDL was 7.4 mm (IQR 2.2-18.6 mm), with shorter distances on the epicardial surfaces compared to endocardial (1.4 vs 13.9 mm at 30% WaDL, P = 0.015). Functional substrate ablation in this cohort covered a mean 26% of the bipolar low voltage scar area (< 1.5 mV). Automated WaDLs represent easily visualized significant discontinuities that correlate with clinical VT circuits, are present in a wide variety of cardiomyopathy types and both epicardial and endocardial surfaces. Targeting WaDLs requires a smaller ablation area than low voltage homogenization.

PO-04-045 HOW TO VISUALIZE BIPOLAR ABLATION CATHETERS ON 3D MAPPING FOR BIPOLAR RADIOFREQUENCY CATHETER ABLATION AND MINIMIZE FLUOROSCOPY

Bipolar radiofrequency catheter ablation (RFCA) strategy using two ablation catheters may require prolonged fluoroscopy time because of challenges with catheter positioning. Intracardiac echocardiographic images may only offer limited views to help maneuver both ablation catheters. To simultaneously visualize both ablation catheters on the 3D mapping system for localizing the ablation target and minimizing fluoroscopy. A bipolar RFCA system was set up with connections to the grounding pad and two distal pins connected to the distal electrodes of the THERMOCOOL SMARTTOUCH® SF ablation catheter (Biosense Webster) with 1-6-2mm spacing (Figure A). Case 1: A 51-year-old male with familial HCM presented with VT storm for which he was externally cardioverted. The patient underwent VT ablation during which the VT was localized to LV summit. Due to difficulty achieving transmural lesions with unipolar ablation, bipolar RFCA with two ablation catheters on posteroseptal RVOT and below the RCC was performed with successful elimination of the clinical VT. The distal 3rd and 4th electrodes on the second ablation catheter was connected to our bipolar circuit, which was visualized on CARTO® 3D mapping (Biosense Webster) (Figure B). Case 2: A 62-year-old male with a CRT-D for cardiac sarcoidosis and non-ischemic cardiomyopathy, and a recent endocardial VT ablation in the setting of VT storm presented with multiple ICD shocks. Patient underwent repeat ablation with further endocardial substrate modification and epicardial ablation. With the second ablation catheter on the epicardium, the distal 3rd and 4th electrodes were visualized, and the dome of the catheter tip was created on CARTO® (Figure C). The patient underwent an extensive endocardial and epicardial ablation but remained inducible with slower VT for which he underwent further heart transplant evaluation. Utilizing a novel bipolar RFCA set-up that allows visualization of both ablation catheters on the 3D mapping system may offer better target localization and less fluoroscopy exposure.

CE-452773-3 ASSESSMENT OF OPTIMAL VOLTAGE THRESHOLDS FOR VENTRICULAR SCAR SUBSTRATE CHARACTERIZATION

Despite the advancement in technology, historic cut-offs of <0.5mV for dense scar and 0.5-1.5mV for scar borderzone continue to be used in contemporary electrophysiology. Modern multipolar mapping catheters employ smaller electrodes and interelectrode spacing that theoretically allows for mapping with increased resolution and reduced far-field electrogram (EGM) component. We aimed to assess the optimal voltage cut-offs for ventricular scar substrate characterization using HD Grid multipolar mapping catheter against cardiac MRI-derived scar. We compared optimal voltage cut-offs using conventional bipolar sampling,Best Duplicate Algorithm and HD wave solution plus best duplicate algorithm on. A multicenter study of 33 patients with ischaemic heart disease undergoing VT ablation. Substrate mapping was performed using the high-density HD-grid multipolar mapping catheter. Bipolar voltage maps were co-registered with cardiac MRI/CT obtained before the procedure to assess the voltage characteristics of the scar defined by the image. Pre-procedure contrast-enhanced MRI data were analysed using ADAS software (Galgo medical). Data points were collected in regions of scar during (1) HD wave mapping with best duplicate algorithm on(Waveon), (2) Mapping with HD wave off and best duplicate on (Waveoff) and (3) with conventional bipolar mapping (Alloff). 29,633 voltage points were analyzed and compared to their location with the fused MRI voltage map. The median bipolar voltage for regions of dense MRI/CT scar using (Waveon) HD wave solution and best duplicate algorithm was 0.24mV (IQR 0.12 – 0.43). The median voltage with (Waveoff) HD wave off was 0.29mV (0.15 – 0.45). The median voltage with (Alloff) HD wave off and best duplicate off was 0.32mV (0.19 – 0.5). ROC analysis using AUC suggested the optimal cut-off for endocardial dense scar using (Waveon) HD wave mapping and best duplicate algorithm was 0.31mV (sensitivity: 69.6%, specificity: 60.74%) (Figure), (Waveoff) cut-off with the best duplicate and without the HD wave mapping was 0.34mV (sensitivity: 88.0%, specificity: 42.96%) and (Alloff) without wave mapping or best duplication was 0.36mV (sensitivity: 84%, specificity: 52%). Ventricular substrate characterization with newer mapping technology using narrow electrode spacing and smaller electrode sizes suggests that traditional voltage cut-offs may need revision. The optimal cut-off for dense scar delineation with the HD Grid and wave technology is 0.31mV.

PO-04-200 ANALYSIS OF RELATIONSHIP BETWEEN PACING SITE AND EXIT SITE IN REGIONS WITH STIMULUS-QRS DELAY AND IMAGING DEFINED MYOCARDIAL FIBROSIS

Delay between ventricular pacing stimulus and QRS onset (S-QRS delay), often seen in regions of myocardial fibrosis, suggests conduction along a protected channel which often represents substrate for re-entrant arrhythmias. 1. To analyze the relationship between pacing stimulus site and myocardial exit site in regions with stimulus-QRS delay and imaging-defined myocardial fibrosis undergoing VT ablation and 2. To consider conduction time between these two locations. Six patients with structural heart disease who underwent VT catheter ablation with pre-procedural cardiac CT image processing (InHeart Models (Pessac, France)) and evidence of late-iodine enhancement were included. CT images were registered with electroanatomic mapping. At pacing sites with S-QRS delay >40 msec, catheter location was compared to the exit site, predicted using a previously validated algorithm (RAPID-VT). Imputed conduction velocity (CV) between stimulus site and exit site was calculated (stim-QRS time/Euclidian distance). Stimulus to QRS delay in regions of imaging derived fibrosis ranged 40 to 291.4 ms; At 9 pacing sites, multiple QRS morphologies were generated. Imputed CV was reduced in dense scar and borderzone compared to values seen in healthy myocardium and varied between 0.16 and 0.65 m/s. These results may under-estimate true tissue CV given complex routes between pacing and exit sites. In the same region, following delivery of RF, mean imputed CV was reduced, raising the possibility that conduction was altered, potentially diverted along a different path (0.21m/s vs 0.14m/s, p=0.024). Myocardial fibrosis defined on CT may be associated with slowed conduction through protected channels. Delivery of RF increases conduction time and results in different exit sites following pacing, indicating multiple and likely complex routes of conduction in regions of imaging-defined fibrosis. Visualization of predicted exit sites in real time could help focus RF to interrupt these conduction paths.Tabled 1Patient #Stim to QRS onset (ms)Imputed conduction velocity (m/s)166.8±15.20.18±0.09241.0±1.50.65±0.08351.0±9.10.30±0.10460.6±11.50.20±0.105103.7±0.160.16±0.10674.3±13.60.19±0.02 Open table in a new tab

Electrical Storm Has Worse Prognosis Compared to Sustained Ventricular Tachycardia after VT Ablation

Electrical storm (ES) represents a serious heart rhythm disorder. This study investigates the impact of ES on acute ablation success and long-term outcomes after VT ablation compared to non-ES patients. In this large single-centre study, patients presenting with ES and undergoing VT ablation from June 2018 to April 2021 were compared to patients undergoing VT ablation due to ventricular tachyarrhythmias but without ES. The primary prognostic outcome was VT recurrence, and secondary endpoints were rehospitalization rates and cardiovascular mortality, all after a median follow-up of 22 months. A total of 311 patients underwent a first VT ablation due to ventricular tachyarrhythmias and were included (63 ± 14 years; 86% male). Of these, 108 presented with ES. In the ES cohort, dilated cardiomyopathy as underlying heart disease was significantly higher (p = 0.008). Major complications were equal across both groups (all p > 0.05). Ablation of the clinical VT was achieved in 94% of all patients (p > 0.05). Noninducibility of any VT was achieved in 91% without ES and in 76% with ES (p = 0.001). Patients with ES revealed increased VT recurrence rates during follow-up (65% vs. 40%; log rank p = 0.001; HR 1.841, 95% CI 1.289-2.628; p = 0.001). Furthermore, ES patients suffered from increased rehospitalization rates (73% vs. 48%; log rank p = 0.001; HR 1.948, 95% CI 1.415-2.682; p = 0.001) and cardiovascular mortality (18% vs. 9%; log rank p = 0.045; HR 1.948, 95% CI 1.004-3.780; p = 0.049). After multivariable adjustment, ES was a strong independent predictor of VT recurrence and rehospitalization rates, but not for mortality. In a propensity score-matched cohort, patients with ES still had a higher risk of VT recurrences and rehospitalizations compared to non-ES patients. VT ablation in patients with ES is challenging and these patients reveal the highest risk for recurrent VTs, rehospitalization and cardiovascular mortality. These patients need close follow-ups and optimal guideline-directed therapy.

Abstract 10034: Novel Late-Gadolinium Enhanced Cardiac Magnetic Resonance (LGE-CMR)-Based Computational Heart Paradigm Predicts Optimal Ventricular Tachycardia (VT) Ablation Targets in Arrhythmogenic Right Ventricular (RV) Cardiomyopathy (ARVC)

Introduction: ARVC is an inherited cardiac disease that increases risk of life-threatening VTs in young adults. Catheter ablation, a mainstay of VT treatment in ARVC, remains challenging due to difficulties in identifying optimal VT ablation targets. Hypothesis: Right Ventricular Cardiomyopathy Ablation Targeting (RVCAT) is a novel digital-heart paradigm that accurately predicts the optimal VT ablation targets of ARVC patients. Methods: We retrospectively enrolled 11 ARVC patients; 8 presented with clinical VTs and underwent VT ablation. In all patients, RV hyperenhancement on LGE-CMR was identified. For this study, we developed RVCAT, the first computational heart model integrating RV personalized diffuse and dense fibrosis as VT substrates. Each region was assigned ARVC-specific electrophysiologic properties. VT inducibility was assessed via rapid pacing in each model. If inducible, optimal ablation targets, which rendered the RV substrate non-inducible for each VT, were determined. Targets were compared to electroanatomic voltage maps (EAM), locations of clinical ablations, and clinical records. Results: Personalized model predictions correlated well with clinical observations. All 8 models of the patients with a history of clinical VT had inducible VTs (Fig A). Furthermore, model VT circuit locations matched the clinical description. Substrate distribution in models matched low-voltage zones in EAM. The predicted ablation targets coincided with clinical ablations (Fig B). Results showed that the volume of model ablation lesions was significantly smaller than that of clinical ablations (1.02±0.68 versus 1.45±0.91, p&lt;0.05, Fig C). For the 3 patients who did not have VTs, their corresponding heart models correctly predicted that no VTs would be induced. Conclusions: RVCAT is a novel digital-heart technology for optimal ARVC VT ablation guidance that can be potentially integrated into clinical workflows for augmenting therapeutic precision.

Efficacy and safety of VT ablation of electrical storm

Abstract Funding Acknowledgements Type of funding sources: None. Background Data about VT ablation in patients with electrical storm (ES) is limited. This study sought to compare the prognostic outcome of patients with ES to those with ventricular tachyarrhythmias but without ES undergoing VT ablation on mortality, VT recurrence rates, rehospitalization rates and major adverse cardiac events (MACE). Methods In this large single-centre study patients presenting with ES and undergoing VT ablation from June 2018 to April 2021 were compared to patients undergoing VT ablation due to ventricular tachyarrhythmias but without ES. The primary prognostic outcome was cardiovascular mortality, secondary endpoints were VT recurrence rates, rehospitalization rates and MACE all after a median follow-up of 22 months. Results A total of 311 patients underwent a first VT ablation due to ventricular tachyarrhythmias and were included (63 ± 14 years; 86% male). Of them 108 presented with ES. In the ES cohort dilated cardiomyopathy as underlying heart disease was significantly increased (p=0.008), whereas all other cardiomyopathies were equally distributed. Major complications were equal among both groups (p&amp;gt;0.05). Ablation of the clinical VT was achieved in 95% of all patients without ES and in 94% of all patients with ES (p&amp;gt;0.05). Noninducibility of any VT was achieved in 91% without ES and in 76% with ES (p=0.001). This was also reflected in higher VT induction rates in non-invasive programmed stimulation before hospital discharge among ES patients (40% vs. 19%; p=0.031). After a median of 22 months of follow-up, patients with ES revealed slightly increased cardiovascular mortality rates (17% vs. 9%; log-rank p=0.061; HR 1.902; CI 95% 0.961 – 3.765; p=0.061). Furthermore, ES patients suffered from increased VT recurrence rates (59% vs. 40%; log rank p=0.006), rehospitalization rates (73% vs. 49%; log rank p=0.001) and MACE (71% vs. 45%; log rank p=0.001). ES patients displayed a 1.7-fold increased risk for VT recurrence (HR 1.701; CI 95% 1.160 – 2.493; p=0.006), a 1.9-fold increase for rehospitalization (HR 1.885; CI 95% 1.366 – 2.600; p=0.001) and a 1.9-fold increase for occurrence of MACE (HR 1.935; CI 95% 1.398 – 2.679; p=0.001). Presence of ES was the only independent predictors of VT recurrence and occurrence of MACE, whereas ES and decreased LVEF were independent predictors of rehospitalization. Conclusions VT ablation in patients with ES is challenging and these patients reveal highest risk for recurrent VTs, rehospitalization and MACE. These patients need close follow-ups and optimal guideline-directed therapy.

Prognosis of patients with and without septal substrate after VT ablation due to electrical storm

Abstract Funding Acknowledgements Type of funding sources: None. Background Data about VT ablation in patients with electrical storm (ES) is limited. This study sought to compare the prognostic outcome of patients undergoing VT ablation after electrical storm with and without a septal substrate on mortality, VT recurrence rates, rehospitalization rates and major adverse cardiac events (MACE). Methods In this large single-centre study patients presenting with ES and undergoing VT ablation were included from June 2018 to April 2021. Patients with septal substrate were compared to patients without septal substrate. The primary prognostic outcome was cardiovascular mortality, secondary endpoints were VT recurrence rates, rehospitalization rates and MACE all after a median follow-up of 22 months. Results A total of 108 patients underwent a first VT ablation due to electrical storm and were included (65 ± 13 years; 86% male; 45% ischemic cardiomyopathy). Cardiovascular risk factors were equally distributed among both groups (all p&amp;gt;0.05). Major complications occurred in 11% of all patients with increased postinterventional third degree AV blocks among patients with septal substrate (9% vs 0%; p=0.062). Noninducibility of the clinical VT was achieved in 98% of all patients without a septal substrate and in 91% of all patients with a septal substrate (p=0.136). Noninducibility of any VT was achieved in 88% without a septal substrate and in 66% with a septal substrate (p=0.011). However, in non-invasive programmed stimulation before hospital discharge VT inducibility did not differ among both groups (p&amp;gt;0.05). After 1 year and a median of 22 months follow-up, patients with septal substrate died significantly more often due to cardiovascular causes (25% vs. 7%; log-rank p=0.021). In univariate analysis cardiovascular mortality for ES patients with septal substrate was 3.9 fold higher (HR 3.979; CI 95% 1.124 – 14.092; p=0.032). Independent predictors of adverse outcome in multivariable regression analysis were presence of septal substrate (HR 4.836; p=0.026) and increased numbers of VTs inducible during VT ablation (HR 1.635; p=0.007). VT recurrence during follow-up was 59% and equally distributed among both groups (log rank p=0.911). Rehospitalization rates (log rank p=0.532) and rates of MACE (log rank p=0.463) were equal. Conclusions Presence of a septal substrate is associated with adverse long-term cardiovascular mortality in patients admitted for VT ablation after electrical storm. Despite decreased ablation success in these patients VT recurrence rates were not increased during follow-up.

Assessment of optimal thresholds for ventricular scar substrate characterization using the high density grid multipolar mapping catheter

Abstract Funding Acknowledgements Type of funding sources: None. Background Voltage thresholds for ventricular scar definition are based on historic data collected using catheters with widely spaced bipoles in the absence of contact force. Modern multipolar mapping catheters employ smaller electrodes and interelectrode spacing that theoretically allows for mapping with increased resolution and reduced far-field electrogram (EGM) component. Despite the advancement in technology, historic cut-offs of &amp;lt;0.5mV for dense scar and 0.5-1.5mV for scar borderzone continue to be used in contemporary electrophysiology. Purpose We aimed to assess the optimal voltage cut-offs for ventricular scar substrate characterization using the HD Grid multipolar mapping catheter. Voltage cut-offs were assessed against cardiac MRI derived scar. We compared optimal voltage cut-offs using conventional bipolar sampling, the Best Duplicate Algorithm and with the HD wave solution plus best duplicate algorithm on. Methods A multicentre study of twenty patients undergoing VT ablation was conducted. Substrate mapping was performed using the high-density HD-grid multipolar mapping catheter. Bipolar voltage maps were co-registered with cardiac MRI obtained prior to the procedure to assess the voltage characteristics of scar defined by cardiac MRI (CMR) (Figure 1). Pre-procedure contrast enhanced CMR data were analysed using ADAS software (Galgo medical). Data points were collected in regions of scar during (1) HD wave mapping with best duplicate algorithm on(Waveon), (2) Mapping with HD wave off and best duplicate on (Waveoff) and (3) with conventional bipolar mapping (Alloff). Results The median bipolar voltage for regions of dense CMR scar using (Waveon) HD wave solution and best duplicate algorithm was 0.27mV (IQR 0.14 – 0.46). The median voltage with (Waveoff) HD wave off was 0.29mV (0.15 – 0.45). The median voltage with (Alloff) HD wave off and best duplicate off was 0.32mV (0.19 – 0.5). ROC analysis using AUC suggested the optimal cut-off for endocardial dense scar using (Waveon) HD wave mapping and best duplicate algorithm was 0.30mV (sensitivity: 69.6%, specificity: 60.74%), (Waveoff) cut-off with the best duplicate and without the HD wave mapping was 0.34mV (sensitivity: 69.78%, specificity: 64.46%) and (Alloff) without wave mapping or best duplication was 0.36mV (sensitivity: 84%, specificity: 52%) Figure 2. Conclusion Ventricular substrate characterization with newer mapping technology using narrow electrode spacing and smaller electrode size suggests that traditional voltage cut-offs may need revision for delineation of scar characteristics. Additionally, the ability to repeat sample in a region to obtain the best signal (Best Duplicate), and the ability to obviate the effect of wavefront direction using the HD wave solution omnipolar technology, may further increase the fidelity of scar characterization. This has important implications for mapping VT and characterizing channels in order to identify VT circuits.

Differentiating border-zone tissue from post-infarct scar using ripple mapping during VT ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background Areas of post-infarct ventricular scar and border-zone slow conduction are often highlighted on a bipolar voltage map with generalized values 0.5mV–1.5mV. The true voltage that differentiates regions of conducting from non-conducting tissue is unknown. Ripple Mapping (RM)displays allows conducting tissue to be seen as areas supporting Ripple activation, and non-conducting tissue as areas devoid of Ripple activation. Purpose We describe application of Ripple Maps to differentiate areas of scar from conducting tissue during ischemic VT ablation. Methods Dense bipolar voltage maps were created (Pentaray catheter, pacing 80-100bpm) and presented as a single value (e.g. 0.5mV-0.5mV) to binarize the color display (red and purple). RMs were superimposed on the voltage map and played above a pre-set noise threshold (&amp;gt;0.05mV). The voltage map mV limit was sequentially reduced ("border-zone threshold") until only those areas devoid of Ripple bars appeared red. The surrounding border-zone supporting ripple activation thus appeared purple. We performed off-line analysis of border-zone voltage thresholds from a series of RM guided VT ablations. Results 10 consecutive patients (LVEF 32.3±7.5%) with remote myocardial infarction underwent VT ablation (median 19days (IQR 8-33) since last VT). Bipolar voltage mapping (5873±2841 points, median shell area 224cm2), revealed voltages&amp;lt;0.5mV covered a median 11% (IQR 7-17%) of the shell. The border-zone voltage threshold was median 0.2mV (range 0.12mV - 0.3mV). Non-conducting tissue below this value covered only median 5% (IQR 3-7%) of the entire shell. VT was mappable in 4 patients, and the isthmus was bordered by tissue below the same border-zone threshold as found in normal rhythm. The border-zone was homogenized with ablation(40-50W, median 29 mins (IQR 22-33), and clinical VT was non-inducible in all, and 9 pts (91%) remain sustained VT-free at median 90-day follow-up (IQR 23-139), 2-weeks blanking period). Picture 1 presents an infero-lateral LV infarct collected in an RV paced rhythm (7340points) and displayed at conventional bipolar voltage settings 0.5-1.5mV. Tissue with voltages&amp;lt;0.5mV appear red and cover 30% of the total area. In this case, this border-zone voltage threshold was defined as 0.25mV. Non-conducting tissue, seen as areas devoid of ripple bars below this value, now appeared as red, and covered only 11% of the total area. Picture 2 demonstrates the morphologies of 4 poorly tolerated induced VTs during this case. Each had near perfect pacemaps to the exit sites of border-zone tissue defined using this approach, and were targets for ablation resulting in complete non-inducibility and no VT recurrence in early follow-up. Conclusion The bipolar voltage that differentiates putative scar from bordering conducting tissue is unique to each patient, and far lower than 0.5mV-1.5mV. RM presents a practical approach to visualize the border-zone activation to guide ablation.

PO-665-06 ROLE OF WALL THICKNESS CHANNELS IN FUNCTIONAL SUBSTRATE ABLATION OF SCAR-RELATED VENTRICULAR TACHYCARDIA

In patients with scar-related VT from ischemic cardiomyopathy (ICM) undergoing VT ablation, CT-derived wall thickness channels (WTCs) may coincide with VT isthmuses. It is unknown if WTCs coincide with lines of block during mapping in sinus or paced rhythm. Furthermore, WTCs have yet to be characterized in patients with VT from non-ischemic cardiomyopathy (NICM).

PO-637-08 A COMPARISON BETWEEN DECELERATION ZONES ON ISOCHRONAL LATE ACTIVATION MAPPING AND SUBSTRATE FOR VENTRICULAR TACHYCARDIA USING CT LATE IODINATED CONTRAST ENHANCEMENT AND WALL THINNING

Isochronal late activation mapping (ILAM) is an important tool for identification of targets for ablation without requiring induction of ventricular tachycardia. Computed tomography is also a promising a non-invasive method of identification of scar. Late iodinated contrast enhancement and wall thinning with acquisition of sub-1mm slice thickness are used, which are surrogates for ablation targets. The relationship of deceleration zones observed on ILAM with substrate observed on CT imaging is unknown. To assess the correlation between deceleration zones seen on ILAM with CT substrate. Consecutive patients who underwent VT ablation during a 2-year period using the NAVX (St. Jude Medical, Minneapolis, MN) electroanatomic mapping system and underwent CT imaging (InHeart, Bordeaux, France) were retrospectively reviewed. Patients with incomplete maps, low density maps, or incomplete imaging were excluded (n=15). After CT image integration into the EA map, the presence of DZs was assessed and the presence of underlying substrate on imaging defined. All maps and images following integration were evaluated by 3 independent reviewers who were blinded to ablation lesion sets and clinical outcomes. The DZ was identified and demarcated and then the superimposed substrate on imaging was evaluated. There were 20 patients in the final analysis. The cohort was 80% male with mean age of 68 years with a left ventricular ejection fraction of 34%. Ischemic heart disease was present in 55% of subjects. In 17 of the 20 patients (85%) wall thinning of 1-3mm superimposed on the DZ sites was observed. Dense scar was present in only 7 patients (35%) at DZ sites. DZs observed on ILAM area are highly associated with areas of wall thinning from 1-3 mm on CT. Dense scar was less frequently noted with DZs. These findings may serve as a basis for imaging guided VT ablation in future studies.

Accuracy of standard bipolar amplitude voltage thresholds to identify late potential channels in ventricular tachycardia ablation

BackgroundVentricular tachycardia (VT) is caused by the presence of a slow conduction channel (CC) of border zone (BZ) tissue inside the scar-core tissue. Electroanatomic mapping can depict this tissue by voltage mapping. Areas of slow conduction can be detected as late potentials (LPs) and their abolition is the most accepted ablation endpoint. In the current guidelines, bipolar voltage thresholds for BZ and core scar are 1.5 and 0.5 mV respectively. The performance of these values is controversial. The aim of the study is to analyze the diagnostic yield of current amplitude thresholds in voltage map to define VT substrate in terms of CCs of LPs. Predictors of usefulness of current thresholds will be analyzed.MethodsAll patients with structural heart disease who underwent VT ablation in Hospital Clinic in 2016–2017 were included. Maps with delineation of CCs based on LPs were created with contact force sensor catheter. Thresholds were adjusted for every patient based on CCs. Diagnostic yield and predictors of performance of conventional thresholds were analyzed.ResultsDuring study period, 57 consecutive patients were included (age: 60.4 ± 8.5; 50.2% ischemic cardiomyopathy, LVEF 39.8 ± 13.5%). Cutoff voltages that better identified the scar and BZ according to the LP channels were 0.32 (0.02–2 mV) and 1.84 (0.3–6 mV) respectively. Current voltage thresholds identified correctly core and BZ in 87.7% and 42.1% of the patients respectively. Accuracy was worse in non-ischemic cardiomyopathy (NICM) especially for BZ (28.6% vs 55.2%, p = 0.042).ConclusionsAccuracy of standard voltage thresholds for scar and BZ is poor in terms of LPs detection. Diagnostic yield is worse in NICM patients specially for border zone.

Safety/Efficacy of DOAC Versus Aspirin for Reduction of Risk of Cerebrovascular Events Following VT Ablation.

The STROKE-VT (Safety and Efficacy of Direct Oral Anticoagulant Versus Aspirin for Reduction of Risk of Cerebrovascular Events in Patients Undergoing Ventricular Tachycardia Ablation) study is a multicenter, randomized controlled trial that examined the differences in cerebrovascular events between direct oral anticoagulant (DOAC) and aspirin (ASA) use postprocedurally in patients who underwent left ventricular arrhythmia (LVA) ablation (ventricular tachycardia [VT] or premature ventricular contraction [PVC]) using radiofrequency ablation (RFA). There exists limited data regarding antiplatelet or anticoagulation strategy following LVA ablation. A total of 246 patients scheduled for LVA-RFA were randomized 1:1 postprocedurally to receive DOACs or ASA. The study's primary endpoint was the incidence of stroke or transient ischemic attack (TIA) or asymptomatic cerebrovascular events (ACEs) detected by magnetic resonance imaging at 24 hours and 30days of follow-up. The secondary endpoints included procedure-related complications (composite of any vascular complication, pericardial complication, heart block, and thromboembolic event, excluding stroke or TIA) and in-hospital mortality. There were no differences between groups regarding baseline and ablation characteristics (except the percentage of patients who underwent VT ablation, rate of amiodarone use, and total RFA time). Postprocedure cerebrovascular events (stroke and TIA) were lower in the DOAC arm versus the ASA arm (0% vs 6.5%; P< 0.001 and 4.9% vs. 18%; P< 0.001, respectively). Patients in the ASA group had more MRI-detected ACEs compared with the DOAC group both at 24-hour (23% vs 12%; P=0.03) and 30-day (18% vs 6.5%; P=0.006) follow-up. Acute procedure-related complications and in-hospital mortality were similar between the 2 groups. DOAC use following endocardial and/or epicardial ablation for LVA-RFA was associated with reduced risk of TIA or stroke and asymptomatic MRI-detected cerebrovascular events.