Mapping Of Ventricular Tachycardia Research Articles

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.

Termination without global capture: electrocardiographic and anatomical characteristics using 3D-electroanatomical mapping system in reentrant ventricular tachycardia

Abstract Background Termination without global capture (TWGC) is the phenomenon which a pacing stimulus applied during ventricular tachycardia (VT) terminates the tachycardia without generating a QRS complex, and is considered as an indicator for the critical component of the circuit. The details of the electrocardiographic and anatomical characteristics of the site using a 3D-electroanatomical mapping system (3D-EAM) remain unknown. Purpose This study aimed to retrospectively analyze the cases that showed TWGC during VT mapping and ablation, and to investigate the electrocardiographic characteristics and relationship with the substrate identified by 3D-EAM. Methods Of 632 cases of VT associated with structural heart disease from July, 2019 to July, 2023 at a university hospital and a university medical center, cases with TWGC were analyzed. Results TWGC was observed in 10 patients (median age 61 years, 9 males, 5 ischemic cardiomyopathy, median LVEF 31%) at least once (12 times) in 11 locations. Local capture was observed in 6. The QRS morphology generated by continued pacing after TWGC matched the clinical VT in only 5 VTs (42%). Five showed decremental conduction of stimulus to QRS interval following the TWGC. In 11 locations, 4 corresponded to scar area (<0.1 mV) in the voltage map, 6 to border zone (0.1-1.5 mV), and 1 had no information on 3D-EAM. Of 12 times of TWGC, 3 were at the entrance, 1 at the central isthmus, and 1 at the exit. Acute elimination of clinical VT was successful in 7 of 10. Conclusions More than half of the sites with TWGC were located at the border zone in 3D-EAM. TWGC also occurred in the central or exit area, and local capture was observed frequently.Termination without global capture

Epicardial catheter ablation of ventricular tachycardia in patients of acm - from a university hospital report in switzerland

Abstract Background Arrhythmogenic left ventricular cardiomyopathy (ALVC) as a subtype of arrhythmogenic cardiomyopathy (ACM) is increasingly being recognized. Cardiac magnetic resonance (CMR) has emerged as the primary imaging modality for the diagnosis of ACM. In patients with right-dominant ACM (ARVC) and recurrent sustained ventricular tachycardia (VT), endocardial +/-epicardial ablation yields good clinical outcomes in the long-term. However, studies on VT ablation in ACM with LV involvement are scarce. Purpose We sought to investigate clinical outcomes of VT ablation in ACM patients with LV involvement. Methods The study included patients from the Zurich ACM Registry who met 2020 "Padua Criteria" for ACM and underwent VT ablation between January 2018 and July 2023. Epicardial ablation was performed in patients with recurrent sustained VT despite endocardial ablation, those lacking and endocardial substrate or if the ECG of the VT / substrate on CMR was suggestive of an epicardial origin. Catheter ablation was guided by activation/entrainment mapping for mappable VT, and pace mapping/voltage mapping during sinus rhythm for unmappable VT. Consecutive follow-up of all patients was performed according to our protocol. Results Twenty-one ACM patients underwent n=24 VT ablation procedures. Of those 20 patients, 6 patients (30%) had LV involvement on CMR. Eight (33%) patients underwent epicardial +/- endocardial ablation. Among patients receiving epicardial ablation, 3 patients (38%) had LV involvement. These three underwent a single ablation procedure, which was epicardial only. Total follow-up was 30 months (range 4-43). Three-month sustained VT/VF recurrence rates were 12% in the ACM group with LV involvement vs 25% in ACM without LV involvement. All patients with sustained VT/VF recurrence underwent repeat ablation via an epicardial approach within 3 months and were free of sustained VT/VF thereafter during a median follow-up of 12 months. One-year recurrence rate did not differ between ACM patients with LV involvement vs. without LV involvement (7.7% vs 8.3%, P＝0.117). Seven out of eight epicardial ablations achieved freedom from VT/VF after one-year follow-up. One ARVC patient with previous endocardial ablation had recurrent VT one month after epicardial ablation, which was free of VT after Flecainide combined with beta-blocker. No significant differences were found in the use of beta-blockers and antiarrhythmic drugs between both groups (ACM with LV involvement vs. without LV involvement) at baseline and during one-year follow-up. Conclusions Single or adjuvant epicardial substrate ablation of VT in arrhythmogenic cardiomyopathy is promising in terms of postprocedural VT free survival, especially in patients with left ventricular involvement demonstrated by CMR.Figure 1Figure 2

Manifestation of conduction block zones by substrate mapping evaluated under multidirectional pacing during ventricular tachycardia ablation

Abstract Introduction Catheter ablation (CA) has proven to be effective therapy for ventricular tachycardia (VT) in patients with structural heart disease. However, activation mapping during VT is often limited in case of non-inducible, non-sustained or hemodynamically tolerable. It has been reported that a substrate-based approach for identifying conduction block and slow-conducting sites during sinus rhythm and ventricular pacing is promising strategies for CA. However, detailed analysis on the effectiveness of substrate mapping with multidirectional pacing to identify critical isthmus in unmappable VT have been lacking. Purpose The purpose of the present study was to evaluate the effectiveness of substrate mapping with multidirectional pacing in VT ablation. Methods From April 2022 to July 2023, 7 consecutive patients (4 men, age 62±9years) who underwent CA of VTs at our institute were enrolled. Isochronal late activation mapping (ILAM) was performed during sinus rhythm, right ventricular (RV) and left ventricular (LV) pacing. Cardiovascular magnetic resonance were performed in 3 of 7 cases to assess the distribution of myocardial late gadolinium enhancement. For catheter ablation, 2Fr electrode catheter was inserted into the anterior interventricular vein (AIV) at the distal site of the coronary sinus. LV pacing was performed using an electrode catheter placed in the AIV. ILAM were constructed by annotating the last deflection of each electrogram. Results In the 7 patients, 5 had ischemic cardiomyopathy and 2 had non-ischemic cardiomyopathy (Figure 1). During sinus rhythm, a deceleration zone (DZ) was identified in only 1 of 7 cases, consistent with linear conduction block. RV pacing demonstrated DZ in 3 of 7 cases. LV pacing revealed DZ in 6 of 7 cases, all of which had conduction blocks. U-shaped conduction blocks, which was not detectable in activation mapping during sinus rhythm, was newly identified in 29% of RV pacing, 71% of LV pacing. Combined RV and LV pacing unmasked the U-shaped conduction block in 86% of the cases. Only in case 7, activation mapping of VT with a cycle length of 470ms could be performed, and VT isthmus activation was observed in the area surrounded by the U-shaped conduction block (Figure 2). In other cases, the clinical VTs were unmappable because of the hemodynamic instability with tachycardia cycle length of approximately 300 milliseconds. Eventually, VTs became non-inducible in 3 of 5 cases in which induction was performed after the CA. During the follow-up period of 7±5 months, 6 of 7 cases remained free from any VT episodes. One patient showed small amount of pericardial effusion after CA. However, there were no life-threatening complications in any patients. Conclusion Substrate mapping using several different wavefront vectors in unstable VTs unveiled conduction block zones that might be potential ablation target sites for VT.Figure 1Figure 2

Neural network for automatic ICD-EGMs matching in pace-mapping and ablation of ventricular arrhythmias

Abstract Background Mapping of the ventricular arrhythmias (VA) is often not possible due to the non-inducibility of the electrophysiological study (EPS). Since twelve-lead electrocardiograms (ECG) of the clinical ventricular tachycardia (VT) are also often not available, therefore stored implantable cardioverter-defibrillator (ICD) electrograms (EGMs) of the clinical VT are often the only documentation. The pace mapping matching to the stored ICD-EGM template of the clinical VT can help to identify the VT exit site. Automatic objective computing of similarity scores between EGMs is impossible because ICD programmer devices do not have any interface allowing the export of digital EGMs. Therefore, images can only be accessed for similarity by subjective eyeballing. The MatcherNet Siamese neural network takes a pair of EGM images and predicts their similarity. Purpose This study aimed to assess the feasibility of the automatic ICD-EGMs matching by MatcherNet neural network for pace mapping of VT/premature ventricular contraction (PVC) exit site. Methods Consecutive patients undergoing VT ablation or ablation of ventricular fibrillation, triggered by PVC were included in the study, if the clinical VT/PVC was not inducible during EPS but ICD-EGMs of clinical VT/PVC were stored in the device. Electro-anatomical mapping was performed to reveal substrates (low-voltage areas, abnormal potentials, DEEP-potentials, conduction crowding). Subsequently, the low-output pacing from various locations tagged on the 3D map of LV was performed, and the paced ICD-EGM images were stored from the ICD programmer device for offline analysis and calculation of the similarity. RF ablation was conducted based on the substrate map findings, including the area of the most remarkable similarity between paced ICD-EGMs and clinical ICD-EGM templates assessed by eyeballing. The ICD-EGMs similarity scores (Manhattan similarity and Pearson correlation) were predicted by MatcherNet for each pacing site offline and transferred to the 3D map for the assessment of similarity distribution (Figure 1). Results We included 7 patients with VA episodes registered and stored by their ICD. The clinical characteristics are presented in Table1. In all patients, we were able to find the sites of highest ICD-EGM similarity to the clinical template with gradual decrementing of the similarity score at the increasingly distant pacing areas. The site of the highest similarity was collocated with VT substrate and ablation areas in all patients. Abrupt change of the similarity score at the adjacent pacing sites was detected in the 2 cases, indicating the possible protected VT isthmus. After ablation procedure only one patient with DCM experienced VA recurrence. Conclusion This technology opens new possibilities for the utilization of ICD-EGMs during the pace mapping of ventricular tachycardia, especially in the cases of non-inducibility during electrophysiological study.Figure 1Table 1

Substrate characterization and outcomes of ventricular tachycardia ablation in amyloid cardiomyopathy: a worldwide study

Abstract Background the electrophysiological substrate underpinning ventricular tachycardia (VT) in cardiac amyloidosis (CA) remains elusive, and outcomes of catheter ablation in this peculiar population are currently unknown. Purpose we sought to describe the electrophysiological substrate and clinical outcomes of VT ablation in a cohort of patients with CA. Methods we included 19 consecutive patients (mean age, 69±10 years; male sex, 89%) with CA (ATTR, n=13; AL, n=6) undergoing catheter ablation for VT/ventricular fibrillation (VF) between 2013 and 2023 in a retrospective, observational, international study, involving 7 referral European and North American electrophysiology units. The primary efficacy outcome was recurrent VT/VF during follow-up, while the primary safety outcome included major procedure-related adverse events. Results the indication for ablation was drug-refractory VT in 16 patients (84%), and PVC-initiated polymorphic VT/VF in 3 (16%). Catheter ablation was performed using endocardial (n=14, 74%) or endo-epicardial approaches (n=5, 26%). Complete endocardial electroanatomical voltage maps of the left and right ventricles were obtained in 14 (74%) and 6 (32%) patients, respectively. Each patient had evidence of low-voltage areas, most commonly involving the interventricular septum (n=12); late potentials were recorded in 13 patients (68%). A median of 1 (1-2) VTs were inducible per patient; in 10 subjects (43% of mappable VTs), activation mapping was consistent with septal VT origin. Complete procedural success was obtained in 13 patients (68%), at the expense of 4 (21%) major procedure-related adverse events. After a median follow-up of 36 (18-54) months, sustained VT/VF recurrence was observed in 9 patients (47%); survival free from VT/VF recurrence was 74% (95%CI, 56-96%) at 12 months, and 53% (95%CI, 34-94%) at 36-month follow-up; the majority of patients remained on antiarrhythmic drugs (Figure). Low-voltage QRS (HR,21.96; p=0.022) and complete procedural success (HR,0.08; p=0.029) were associated with recurrent VT/VF at multivariable analysis (Figure). Conclusions catheter ablation of VT/VF is associated with favorable acute and mid-term arrhythmia control, yet with substantial risk of procedure-related complications and long-term recurrences. Septal substrate and frailty challenge successful management of patients with CA and VT/VF.Multimodality evaluation of LV substrateMain Study Outcomes

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.

Optimal cardiac rhythm during substrate mapping in scar-related ventricular tachycardia: Significance of wavefront direction on identifying critical sites

BackgroundA rotational activation pattern (RAP) around the localized line of a conduction block often correlates with sites specific to the critical zones of ventricular tachycardia (VT). The wavefront direction during substrate mapping affects manifestation of the RAP and line of block. ObjectiveThe purpose of this study was to investigate the most optimal cardiac rhythm for identifying RAP and line of block in substrate mapping. MethodsWe retrospectively evaluated 71 maps (median 3205 points/map) in 46 patients (65 ± 15 years; 33% with ischemic cardiomyopathy) who underwent high-density substrate mapping and ablation of scar-related VT. Appearance of a RAP during sinus, right ventricular (RV)-paced, left ventricular (LV)-paced, and biventricular-paced rhythms was investigated. ResultsRAP was identified in 24 of 71 maps (34%) in the region where wavefronts from a single direction reached but not in the region where wavefronts from multiple directions centripetally collided. The probability of identifying the RAP depended on scar location; that is, anteroseptal and inferoseptal, inferior and apical, and basal lateral RAPs were likely to be identified during sinus/atrial, RV-paced, and LV-paced rhythms, respectively. In 13 patients, the RAP was not evident in the baseline map but became apparent during remapping in the other rhythm, in which the wavefront reached the site earlier within the entire activation time. ConclusionThe optimal rhythm for substrate mapping depends on the spatial distribution of the area of interest. A paced rhythm with pacing sites near the scar may facilitate the identification of critical VT zones.

Pulsed Field Mapping of Ventricular Tachycardia: Verifying the Ablation Target at a Critical Location

Pulsed Field Mapping of Ventricular Tachycardia: Verifying the Ablation Target at a Critical Location

Successful open chest intraoperative epicardial ventricular tachycardia mapping and ablation during the HeartMate-3 left ventricular assist device implantation in Taiwan

Successful open chest intraoperative epicardial ventricular tachycardia mapping and ablation during the HeartMate-3 left ventricular assist device implantation in Taiwan

Catheter ablation for ventricular tachycardia after myocardial infarction: meta-analysis of randomised controlled trials

Abstract Background The prognostic impact of ventricular tachycardia (VT) catheter ablation is an important outstanding research question. Purpose We undertook a reconstructed individual patient data meta-analysis of randomised controlled trials comparing ablation to medical therapy in patients developing VT after myocardial infarction (MI). Methods We systematically identified all trials comparing catheter ablation to medical therapy in patients with VT and prior MI. The pre-specified primary endpoint was all-cause mortality assessed using reconstructed individual patient data obtained by digitisation of published Kaplan-Meier curves and subsequent construction of Cox proportional hazards regression models. Pre-specified secondary endpoints included trial-level assessment by random effects meta-analysis of all-cause mortality, VT recurrence, defibrillator shocks and all-cause hospitalisations. Meta-regression was performed to evaluate the effect of VT mapping in addition to substrate modification. Sensitivity analyses were performed depending on the proportion of patients with prior MI included. (PROSPERO ID CRD42023390799) Results Eight trials, recruiting a total of 874 patients, were included. 430 patients were randomised to catheter ablation and 444 to medical therapy. Catheter ablation reduced all-cause mortality compared to medical therapy when synthesising reconstructed individual patient data (hazard ratio 0.57, 95% confidence interval (CI) 0.38 to 0.85, p=0.007), but not in trial-level analysis (relative risk 0.91, 95%CI 0.67 to 1.23, p=0.53, I2=0%). Catheter ablation significantly reduced VT recurrence, defibrillator shocks and hospitalisations compared to medical therapy. Sensitivity analyses were consistent with the primary analyses. Conclusion In patients with post-infarct ventricular tachycardia, catheter ablation reduces mortality.

Abstract 18575: Impact of Mechanical Circulatory Support on In-Hospital Mortality in Ventricular Tachycardia Ablation: A United States Nationwide Analysis

Background: Mechanical circulatory support (MCS) devices have emerged as a valuable tool in ventricular tachycardia (VT) ablation procedures, offering potential benefits such as improved hemodynamic stability, preserved organ perfusion, and optimized coronary perfusion during prolonged VT induction and mapping. However, the impact of different MCS modalities on in-hospital mortality following VT ablation remains unclear. Objective: This study aimed to investigate the impact of various MCS modalities on in-hospital mortality in those undergoing VT ablation during hospitalization. Method: We analyzed data from the National Inpatient Sample to identify patients who underwent VT ablation and received transient mechanical cardiac support between 2019 and 2020. The primary endpoint was in-hospital mortality, stratified by different MCS modalities. Additionally, we explored independent predictors of in-hospital mortality. Result: A total of 850 patients underwent VT ablation and required MCS from January 2019 to December 2020. Among these patients, extracorporeal membrane oxygenation (ECMO), percutaneous left ventricular assist device (PLVAD), intra-aortic balloon pump (IABP), and a combination of more than one MCS modality were utilized in 5.8%, 64.7%, 18.8%, and 10.5% of cases, respectively. The in-hospital mortality rates for these groups were 40%, 16%, 22%, and 61%, respectively (p<0.01). Notably, the use of multiple MCS modalities, female sex, other races, and self-payment were independent predictors of mortality, with adjusted odds ratios (aOR) of 21.9 (p=0.008; 95% confidence interval [CI]: 2.2-217.1), 9.27 (p=0.045; 95% CI: 1.1-82.1), 27 (p=0.038; 95% CI: 1.1-29.4), and 27.6 (p=0.041; 95% CI: 1.2-660.8), respectively. Conclusion: Our study highlights that the use of multiple MCS modalities, female sex, other races, and self-payment are independent predictors of in-hospital mortality, highlighting the need for careful consideration and selection of MCS for VT ablation patients.

Efficient Patient-Specific Simulations of Ventricular Tachycardia Based on Computed Tomography-Defined Wall Thickness Heterogeneity

BackgroundElectrophysiological mapping of ventricular tachycardia (VT) is tedious and poorly reproducible. Substrate analysis on imaging cannot explicitly display VT circuits. ObjectivesThis study sought to introduce a computed tomography–based model personalization approach, allowing for the simulation of postinfarction VT in a clinically compatible time frame. MethodsIn 10 patients (age 65 ± 11 years, 9 male) referred for post-VT ablation, computed tomography–derived wall thickness maps were registered to 25 electroanatomical maps (sinus rhythm, paced, and VT). The relationship between wall thickness and electrophysiological characteristics (activation-recovery interval) was analyzed. Wall thickness was then employed to parameterize a fast and tractable organ-scale wave propagation model. Pacing protocols were simulated from multiple sites to test VT induction in silico. In silico VTs were compared to VT circuits mapped clinically. ResultsClinically, 6 different VTs could be induced with detailed maps in 9 patients. The proposed model allowed for fast simulation (median: 6 min/pacing site). Simulations of steady pacing (600 milliseconds) from 100 different sites/patient never triggered any arrhythmia. Applying S1-S2 or S1-S2-S3 induction schemes allowed for the induction of in silico VTs in the 9 of 10 patients who were clinically inducible. The patient who was not inducible clinically was also noninducible in silico. A total of 42 different VTs were simulated (4.2 ± 2 per patient). Six in silico VTs matched a VT circuit mapped clinically. ConclusionsThe proposed framework allows for personalized simulations in a matter of hours. In 6 of 9 patients, simulations show re-entrant patterns matching intracardiac recordings.

Long-term success of a multi-electrode substrate mapping and ablation strategy versus a classic single tip mapping and ablation strategy for ventricular tachycardia ablation in patients with ischemic cardiomyopathy.

Over the past years, mapping and ablation techniques for the treatment of ventricular tachycardia (VT) have evolved rapidly. High Density (HD) substrate mapping is now routine and pre-procedural imaging is increasingly used. The additional value of these techniques for long-term VT-free survival is not clear. We compared baseline and procedural characteristics, procedural success, safety and outcome of mapping and ablation of ventricular tachycardia in patients with ischemic heart disease between two groups. (1) Low Density (LD) group: VT mapping and ablation with a 4mm single tip catheter (2) HD group: HD substrate mapping with the Pentaray (Biosense Webster, USA) or HD Grid (Abbott, USA) catheter and ablation with a 4mm single tip catheter. VT ablation was performed in 133 patients (71 patients in LD group and 62 patients in HD group). The median follow-up was 5.0 years in LD group and 2.0 years in HD group. One-, two-, and five-year VT recurrence rates were 47%, 56%, and 65% in the LD group versus 39%, 50%, and 55% in the HD group (log-rank test for VT recurrence p=.70). One-, two-, and five-year ICD shock recurrence rates were 14%, 18%, and 24% in the LD group versus 8%, 15%, and 19% in the HD group (log-rank test for ICD-shock p=.79). All-cause mortality, cardiac (non-arrhythmic), and arrhythmic death, were similar in both groups. Severe procedural complications (tamponade, stroke, or procedural death) occurred in four patients (5%, 1 vascular, 3 tamponade) in the LD group versus two patients (3%, both tamponade) in the HD group (NS). In univariate and multivariable analysis, only a higher LVEF was significantly associated with VT-free survival. HD mapping was not significantly associated with VT-free survival. Anterior infarct location and age were significantly associated with ICD recurrent shock in both univariate and multivariable analyses. In patients with ischemic cardiomyopathy, a HD substrate mapping, and ablation strategy did not lead to higher VT-free survival and shock-free survival compared to a single tip mapping and ablation strategy. In this study, only LVF is an independent predictor for VT recurrence. Anterior infarct location and age predict recurrent ICD shocks.

Sex differences in catheter ablation for ventricular tachycardia in structural heart disease: a single center 10-years experience

Abstract Funding Acknowledgements Type of funding sources: None. Background Women are underrepresented in studies concerning ventricular tachycardia (VT) catheter ablation (CA). Different etiologies and type of structural heart diseases (SHD) are well established in women; nonetheless conflicting results about efficacy and safety of CA in women have been reported. Purpose To evaluate acute and long-term outcome of VT CA in SHD in women compared to men in a high-volume tertiary Center. Methods All consecutive procedures were included from January 2010 to December 2021. Clinical characteristics, VT etiologies and procedure data of female patients were compared to male population. Catheter ablation was performed according to standard protocol in our center. In mappable VTs, the reentry circuit was characterized, and ablation aimed at VT interruption during radiofrequency (RF); otherwise, a substrate modification approach aiming at late potentials abolition or ablation at sites of slow conduction during sinus rhythm was performed. Following ablation, prevention of any VT inducibility and substrate modification was considered ablation endpoint. Acute results, complications, and VT recurrences during follow up were analyzed comparing the two groups. Results Among 1608 overall VT CA procedures, 141 procedures were performed in 117 women. Female were younger, with less comorbidities, less ischemic VT etiology and higher left ventricular ejection fraction (LVEF) as compared to men (Table 1). They were also less likely ICD carriers. No significant differences were found with regards to: epicardial approach (39.7% vs 35.3%, p=0.68); VT inducibility at baseline (57.4% vs 67.6%, p=0.14), VT termination during RF (87.6% vs 77.6%, p=0.51), and prevention of any VT inducibility at the programmed electrical stimulation (PES) after ablation (79.5% vs 78.1%, p=0.7). Major complications occurred in 4.9% of females as compared to 4.3% of male patients. At median follow-up of 25 months, VT recurrences occurred in 24.7% of female population and 27.5% of male group (p=0.42). Cumulative VT-free survival was comparable in both groups (Figure 2). Conclusions Women with SHD have favorable acute and long-term outcome of VT ablation, despite a high prevalence of non-ischemic etiologies. VT recurrence rate and procedure safety is comparable to male patients, suggesting that catheter ablation can be offered as an effective treatment to women with refractory ventricular arrhythmias.

Periprocedural acute hemodynamic decompensation associated with substrate-based ablation of ventricular tachycardia in patients with structural heart disease - rare and nonpredictable event

Abstract Funding Acknowledgements Type of funding sources: None. Background Radiofrequency (RF) catheter ablation is an established treatment method in patients with structural heart disease (SHD) and recurrent ventricular tachycardia (VT). Due to underlying SHD, concomitant heart failure and a high burden of comorbidities, these patients are at considerable risk of periprocedural complications including acute hemodynamic decompensation (AHD) with a reported rate of up to 11%. The PAINESD score [sum of 5, 3, 6, 6, 3, 5, and 3 points for chronic obstructive pulmonary disease (COPD), age >60 years, ischemic cardiomyopathy (ICM), NYHA Class >2, LV ejection fraction (LVEF) <25%, electrical storm (ES), and diabetes mellitus (DM), respectively] was proposed to predict the risk of AHD, and identify the patients who may benefit from pre-emptive use of percutaneous left ventricular assist device (pVAD). Purpose The single-centre, retrospective study investigated the incidence of AHD in large-volume, tertiary referral EP centre and the predictive power of the PAINESD score. Methods We included patients who had their first ablation for SHD-related VT between August 2006 and December 2020. The procedure was performed under conscious sedation except for patients who were on mechanical ventilation because of hemodynamical or electrical instability before the ablation. Substrate mapping/ablation was performed primarily during spontaneous rhythm or right-ventricular pacing. Induced VTs were terminated by overdrive pacing or cardioverted. Activation and entrainment mapping were used rarely – only in well-tolerated VTs. The goal of ablation was to abolish all inducible VTs. A purposely established institutional registry for complications of invasive procedures was used to collect all periprocedural complications that were subsequently adjudicated using the source medical records. AHD triggered by ablation procedure was defined as intraprocedural or early post-procedural (<12 h) development of acute pulmonary oedema or refractory hypotension, requiring urgent intervention including (but not limited to) inotropic agents and/or artificial ventilation and/or pVAD implant. Results The study cohort consisted of 1143 patients (age: 63±13 years, males: 87%, ICM: 67%, ES: 25%, NYHA Class: 2.1±1.0, LVEF: 34±13%, DM: 32%, COPD: 12%). Their PAINESD score was 11.4±6.6 (median: 12, interquartile range: 6–17). The ablation procedure (total duration 187±78 min, RF time: 23±15 min) was complicated by AHD in 13/1143 = 1.1% patients and these adverse events were not predicted by PAINESD score (Figure). Conclusions We observed a substantially lower rate (1.1%) of AHD than previously reported (up to 11%). These events did not accumulate in patients with upper-tertile PAINESD score in whom the highest AHD risk was reported (up to 24%). This observation may be explained by careful substrate-based ablation under conscious sedation that prevents prolonged low-output state related to repeated VT induction and mapping in general anaesthesia.

PO-05-068 MAJOR VASCULAR COMPLICATIONS IN A LARGE COHORT OF PATIENTS UNDERGOING CATHETER ABLATION FOR VPB/VT IN A HIGH-VOLUME, TERTIARY EP CENTER

Catheter ablation is an established treatment method both in patients with idiopathic premature ventricular complexes (PVC) or ventricular tachycardia (VT) and in structural heart disease (SHD) VT. Major vascular complications (MVCs) are the most frequent in these populations. A retrospective study investigating the incidence of MVCs in large-volume, specialized VT center and analyzing their predictors. We included PVC/VT patients who had their first ablation procedure between August 2006 - December 2020. The procedures were performed under conscious sedation except for patients who were on mechanical ventilation because of hemodynamical or electrical instabilit. Activation mapping supported by an electroanatomic mapping system was used in idiopathic cases. In SHD, substrate mapping using an electroanatomic mapping system and pacemapping was employed as a prerequisite for complete substrate modification during spontaneous rhythm or pacing. Activation and entrainment mapping for well-tolerated VTs were rarely used. The goal of ablation was to abolish all inducible VTs. A specific institutional tracking system for complications of invasive procedures was used to collect all periprocedural complications that were subsequently adjudicated. MVCs were defined as those that result in permanent injury or death, require intervention or treatment, prolong hospitalization (>48 hrs) or require new hospitalization. Idiopathic PVC/VT ablation was performed in 656 pts (males: 50%, age: 51 ± 17 years, re-ablations: 15%). SHD VT was ablated in 1637 pts (males: 88%, age: 63 ± 13 years, re-ablations: 30%, ischemic cardiomyopathy: 65%, left ventricular ejection fraction: 34 ± 13%, electrical storm: 24%). In idiopathic PVC/VT, MVCs were observed in 2.4 % (4.0% in males vs. 0.9% in females, P <0.01). In SHD, the rate of MVCs reached 3.5 % (2.8% in males vs. 9.4% in females, P <0.00001). Based on the multivariable regression model, the composite risk score to predict MVCs was proposed that was calculated as a sum of risk points for age (0, 1, 2, and 3 points for <50, 50–59, 60–69, and ≥70 years, respectively), female gender (2 points), and serum creatinine >1.3mg/dL (2 points), range 0–7 (Figure). While in an idiopathic setting, MVCs were more frequent in males, which may reflect a higher proportion of more complex LV ablations and arterial access, there was a significant female predominance in MVCs in SHD. The composite risk score predicts the risk of MVCs independently of VT cause.

PO-05-065 HIGH DENSITY PACE-MAPPING TO IDENTIFY FUNCTIONAL ARRHYTHMOGENIC SUBSTRATE IN SCAR-MEDIATED VENTRICULAR TACHYCARDIA

The location of conduction abnormality including activation slowing and wavefront discontinuity, which often corresponds to the critical zones of reentrant circuit in scar-mediated ventricular tachycardia (VT), is affected by the wavefront direction during substrate mapping. We hypothesized that an abrupt change in paced-QRS morphologies may occur at the region with conduction abnormality. This study assessed the conduction velocity in substrate mapping during at least two rhythms at the region where an abrupt change in paced-QRS morphologies was obtained. In a retrospective review of 57 patients who underwent functional substrate mapping for scar-mediated VT, 21 patients underwent it during multiple rhythms, that is intrinsic rhythm and paced rhythm with high-density pace-mapping in the area of interest. In 10 of these patients, those critical sites, as determined by direct termination during ablation (4 VTs, 33%) or pace-mapping findings (8 VTs, 67%) were identified in a total of 12 VTs. Conduction velocities during an intrinsic rhythm or paced rhythm at the isthmus area were assessed based on the difference of local activation time between two sites along the site where pace-mapping scores changed abruptly. Pace-mapping scores, which were obtained at two adjacent sites along the presumed isthmus, showed 92% [interquartile range [IQR] 89-96%] at the exit side and 48% [IQR 41-56%] at the adjacent entrance side. Ten patients (71±9 years, 9 (90%) male, 6 (60%) nonischemic) underwent high-density substrate mapping during multiple rhythms, that is intrinsic rhythm including sinus rhythm (n=7) or right ventricular pacing (n=5) and paced rhythm including right (n=5) or left ventricular pacing (n=7). Conduction velocity during intrinsic rhythm at the location of abrupt pacemap change was 0.37m/sec [IQR 0.19-0.43 m/sec], which was no slower than 0.25 m/sec, defined as activation slowing in previous studies. However, conduction velocity at abrupt pacemap change site that was faster in one of the multiple rhythms, was significantly slowed down when changing to the other rhythm (0.41 m/sec [IQR 0.25-1.05 m/sec] vs. 0.09 m/sec [IQR0.07-0.22 m/sec], P<0.01) (Fig.1). The abrupt change in paced-QRS morphology in a novel high-density pace-mapping strategy, which is shown independent of wavefront direction during substrate mapping, can identify the high-yield regions with conduction abnormality being critical for reentry.

PO-05-039 PERIPROCEDURAL ACUTE HEMODYNAMIC DECOMPENSATION ASSOCIATED WITH SUBSTRATE-BASED ABLATION OF VENTRICULAR TACHYCARDIA IN PATIENTS WITH STRUCTURAL HEART DISEASE – RARE AND NONPREDICTABLE EVENT

Patients with structural heart disease (SHD) and recurrent ventricular tachycardia (VT) are at considerable risk of periprocedural complications of radiofrequency (RF) catheter ablation including acute hemodynamic decompensation (AHD). The PAINESD score [sum of 5, 3, 6, 6, 3, 5, and 3 points for chronic obstructive pulmonary disease (COPD), age >60 years, ischemic cardiomyopathy (ICM), NYHA Class >2, LV ejection fraction (LVEF) <25%, electrical storm (ES), and diabetes mellitus (DM), respectively] was proposed to predict the risk of AHD, and identify the patients who may benefit from pre-emptive use of percutaneous left ventricular assist device (pVAD). The single-center, retrospective study investigated the incidence of AHD in large-volume, tertiary referral EP center and the predictive power of the PAINESD score. We included patients who had their first ablation for SHD-related VT between August 2006 and December 2020. The procedure was performed under conscious sedation except for patients who were on mechanical ventilation because of hemodynamical or electrical instability before the ablation. Substrate mapping/ablation was performed primarily during spontaneous rhythm or right-ventricular pacing. Activation and entrainment mapping were used rarely, only in well-tolerated VTs. The goal of ablation was to abolish all inducible VTs. AHD triggered by ablation procedure was defined as intra- or early post-procedural (<12 h) development of acute pulmonary oedema or refractory hypotension, requiring urgent intervention like inotropic agents and/or artificial ventilation and/or pVAD implant. The study cohort consisted of 1143 patients (age: 63±13 years, males: 87%, ICM: 67%, ES: 25%, NYHA Class: 2.1±1.0, LVEF: 34±13%, DM: 32%, COPD: 12%). Their PAINESD score was 11.4 ± 6.6 (median: 12, interquartile range: 6–17). The ablation procedure (total duration 187±78 min, RF time: 23±15 min) was complicated by AHD in 13/1143 = 1.1% patients and these adverse events were not predicted by PAINESD score (Figure). We observed a substantially lower rate (1.1%) of AHD than previously reported (up to 11%). These events did not accumulate in patients with upper-tercile PAINESD score in whom the highest AHD risk was reported (up to 24%). This observation may be explained by careful substrate-based ablation under conscious sedation that prevents prolonged low-output state related to repeated VT induction and mapping in general anesthesia.

AB-452673-3 OUTCOMES OF FUNCTIONAL SUBSTRATE MAPPING OF VENTRICULAR TACHYCARDIA (FUNC-VT) - AN INTERNATIONAL MATCHED PROSPECTIVE REGISTRY

Dynamic substrate changes play a key role in facilitating conduction delay and re-entry in ventricular tachycardia (VT) circuits. Extrastimuli pacing can unmask functional channels demonstrated by dynamic delay, which may play a role in the VT circuit. We have previously developed sense protocol mapping, using short coupled single extrastimuli to delineate areas of maladaptive conduction delay, which play an essential part in VT development. This multicentre prospective propensity-matched registry of functional VT substrate mapping (Func-VT registry) aims to compare procedural and follow-up outcomes with conventional mapping and ablation. Procedure times, mortality, and probability of ATP/ICD shocks were compared to the matched institutional cohort. We conducted an international prospective registry of 44 patients with ischemic heart disease undergoing functional mapping of VT through single extra stimuli to invoke decremental signal delay (Sense Protocol). Areas of functional signal delay were targeted for ablation in conjunction with conventional pacemapping or entrainment mapping where appropriate. This data was compared against a matched institutional cohort of patients undergoing conventional substrate guided ablation through entrainment, pacemapping or substrate only guided ablation. The patients were propensity-matched to age, gender and left ventricular ejection fraction. There were 44 patients (mean age of 70 ±10.64 years, 95% males, mean ejection fraction (EF) of 33%) in the Func-VT registry matched to 49 patients in the institutional cohort (mean age of 72 ±9.42years, 90% males, mean EF of 29%). The median procedure time was 178min in the registry patients compared with 185min in the institutional cohort (p=<0.005). Post ablation, there was a mean ATP reduction of 13.74 ±4.53 (p=0.002) and a mean shock reduction of 4.078 ±5.74 (p=0.01) in the Func-VT registry as compared to the institutional cohort. The 12-month all-cause mortality rate was 4.5% in the registry vs 20.4% in the institutional data (OR 1.46, p=0.04). This prospective study shows that targeting functional signals using the Sense protocol in addition to conventional mapping methods improved outcomes in terms of device therapy and reduced procedure time in VT ablation when compared to previous institutional methods.