Local Abnormal Ventricular Activities Research Articles

Significance of Coherent Mapping in unveiling slow conduction zones of ventricular tachycardia substrate in ischemic cardiomyopathy

Abstract Introduction Ventricular tachycardia (VT) presents a formidable challenge, particularly in cases with extensive myocardial scar tissue, complicating critical ablation site identification. Prolonged interventions not only extend procedural durations but also heighten the risk of complications. This study aimed to assess the efficacy of coherent mapping techniques in precisely locating regions of slow conduction within scar tissue and explored potential correlations with electrophysiological markers in scar-related VT. Methods Seventeen patients (mean age: 61.6 ± 9.2 years, mean EF: 28 ± 9%) with ischemic cardiomyopathy (ICM) and frequent implantable cardioverter-defibrillator (ICD) shocks underwent high-density (>2000 points) left ventricular (LV) substrate mapping (15 endo, 2 epicardial) during sinus or right ventricular (RV) pacing and ablation. Coherent mapping tool was utilized for the identification of slow conduction, demonstrated by vector thickening. Bipolar low voltage areas (LVAs) below 0.5 mV were defined as dense scar, and bipolar voltage between 0.5 and 1.5 mV was defined as the border zone (Figure, panel A). Late potentials (LPs) and local abnormal ventricular activities (LAVA) were manually identified and tagged. Isochronal late activation mapping (ILAM) was also performed to elucidate the functional properties of the substrate (Figure, Panel B). Results LPs and LAVA were identified in all cases, with a mean number of LPs being 10.0 ± 7.1. Of these, 14/17 cases had LPs located in dense scar, while 4/17 cases had LPs in the border zone. The mean area of LAVA was 9.9 ± 7.7 mm², located in dense scar in 6/17 cases and in the border zone in 15/17 cases. Average deceleration zones (DZ, >3 isochrones in 1 cm radius) identified by ILAM was 2 ± 1. Coherent mapping consistently identified slow conduction zones adjacent to LVA in all cases, with these coherent map-based slow conduction zones (CM-SCZ) located in dense scar in 3/17 cases and in the border zone in 14/17 cases. The distance of CM-SCZ to LPs was 12.6 ± 13.9 mm (in 4 cases, LPs were recorded on the spot), and the distance to LAVAs was 18.8 ± 13.7 mm (in 2 cases, LAVAs were recorded on the spot). CM-SCZ was colocalized with DZ in 14/17 of the patients. Ablation lesions covered CM-SCZ in 10/17 cases. Over a mean follow-up duration of 11 ± 6.5 months, 4 patients experienced VT recurrence, with 3 having no ablation lesions covering CM-SCZ, and 2 patients died due to pump failure. Conclusion This study underscores the significance of coherent mapping in refining the understanding of VT substrate in ICM. Identifying and ablating CM-SCZ during substrate-based mapping may provide a potential additional benefit for VT ablation. Nevertheless, larger studies are needed to clarify the prognostic significance and validate the clinical benefits of this approach.Figure 1

A novel automated peak frequency annotation algorithm for identifying deceleration zones and ventricular tachycardia ablation sites

BackgroundCurrent annotation of local fractionated signals during ventricular electroanatomic mapping (EAM) requires manual input subject to variability and error. ObjectivesThe purpose of this study was to evaluate a novel peak frequency (PF) annotation software for its ability to automatically detect late potentials (LPs) and local abnormal ventricular activity (LAVA), determine an optimal range for display, and assess its impact on isochronal late activation mapping (ILAM). MethodsEAM data from 25 patients who underwent ventricular tachycardia (VT) ablation were retrospectively analyzed. Samplings of electrogram PFs from areas of normal bipolar voltage, areas of low voltage, and areas of low voltage with fractioned signals were performed. An optimal range of frequency display was identified from these patients and applied to a validation cohort of 10 prospective patients to assess high PF within scar as a predictor of VT ablation target sites, in particular deceleration zones (DZs) identified by ILAM, LP, and LAVA. ResultsVoltage and PF ranges of normal endocardial tissue varied widely. Using 220 Hz as a frequency cutoff value in areas of low bipolar voltage, areas of high fractionation were identified with sensitivity of 91% and specificity of 85% There was no significant reduction in targeted DZ surface areas, and colocalization with DZs was observed in all cases. Applied to the prospective cohort, PF predicted fractionated areas and DZ in 9 of 10 patients. ConclusionA PF annotation algorithm with a cutoff of 220 Hz accurately identifies areas of fractioned signals and accurately predicts DZs during ILAM.

Impact of filter configurations on bipolar EGMs: An optimal filter setting for identifying VT substrates.

The impact of filtering on bipolar electrograms (EGMs) has not been systematically examined. We tried to clarify the optimal filter configuration for ventricular tachycardia(VT)ablation. Fifteen patients with VT were included. Eight different filter configurations were prospectively created for the distal bipoles of the ablation catheter: 1.0-250, 10-250, 100-250, 30-50, 30-100, 30-250, 30-500,and 30-1000 Hz. Pre-ablation stable EGMs with good contact (contact force > 10 g) were analyzed. Baseline fluctuation, baseline noise, bipolar peak-to-peak voltage, and presence of local abnormal ventricular activity (LAVA) were compared between different filter configurations. In total, 2276 EGMs with multiple bipolar configurations in 246 sites in scar and border areas were analyzed. Baseline fluctuation was only observed in the high-pass filter of (HPF) ≤ 10 Hz (p < .001). Noise level was lowest at 30-50 Hz (0.018 [0.012-0.029] mV), increased as the low-pass filter (LPF) extended, and was highest at 30-1000 Hz (0.047 [0.041-0.061] mV) (p < .001). Conversely, the HPF did not affect the noise level at ≤30 Hz. As the HPF extended to 100 Hz, bipolar voltages significantly decreased (p < .001), but were not affected when the LPF was extended to ≥100 Hz. LAVAs were most frequently detected at 30-250 Hz (207/246; 84.2%) and 30-500 Hz (208/246; 84.6%), followed by 30-1000 Hz (205/246;83.3%), but frequently missed at LPF ≤ 100 Hz or HPF ≤ 10 Hz (p < .001). A 50-Hz notch-filter reduced the bipolar voltage by 43.9% and LAVA-detection by 34.5% (p < .0001). Bipolar EGMs are strongly affected by filter settings in scar/border areas. In all, 30-250or 30-500 Hz may be the best configuration, minimizing the baseline fluctuation, baseline noise, and detecting LAVAs. Not applying the 50-Hz notch filter may be beneficial to avoid missing VTsubstrate.

Ablation of left ventricle summit PVCs using guidewire and 2F octapolar microcatheter mapping

Abstract Funding Acknowledgements Type of funding sources: None. Background Ventricular arrhythmias originating in the left ventricular summit region are especially difficult to map and ablate. The development of microcatheters allows access to the septal coronary venous system, which facilitates its mapping. Purpose To describe the strategy for mapping and ablation of ventricular LV-Summit extrasystoles in the first 6 cases at our center, performed using a 2F octapolar microcatheter, as well as the results obtained. Methods 6 cases of left ventricular summit PVCs were recruited between January 2019 and October 2022. TTE and/or MRI were performed as well as initial Holter, evidencing a high density of PVCs. The studies were carried out with intracardiac echo and anatomical reconstruction with a navigator. The coronary sinus was cannulated with a 6F guide catheter for venography. Mapping of the septal coronary venous system was performed with a 4F vertebral catheter and angioplasty guidewire, connecting the guidewire to the polygraph where good precocity (up to -30 ms) was obtained with a QS pattern in the monopolar lead during PVCs. An octapolar catheter was advanced, obtaining maximum precocity and appreciating fragmented late potentials and local abnormal ventricular activities (LAVA) during sinus rhythm with greater precocity during extrasystole and achieving a topostimulation of 95% concordance with PVCs. Radiofrequency applications were made with an irrigated contact catheter in the areas facing the octapolar catheter until acute suppression of PVC was achieved and its absence was verified after infusion of isoprenaline. Results The mean age of the sample was 60 years, 3 of them women, with a mean LVEF of 51% and a daily average of PVCs of 17.28%. Three of the patients had previously studied cardiomyopathies. After ablation, antiarrhythmics were stopped in 80% of cases and beta-blockers in 40%. The percentage of PVCs was significantly reduced (mean after the procedure 4.4%, p = 0.04) with a single recurrence at follow-up. No complications were recorded. Conclusions The microcatheter-guided ablation of the septal coronary venous system is a safe and effective procedure for the removal of left ventricular summit PVCs.

Omnipolar mapping in ventricular tachycardia: will it be a game changer?

Abstract Funding Acknowledgements Type of funding sources: None. Background Ventricular tachycardias(VT) are life-theatening cardiac arrhythmias. Catheter ablation, the standard approach to VT is relying heavily on maps depicting intracardiac signals. The current mapping approach was based on bipolar electrograms, which are massively influenced by the direction of the underlying tissue activation. The omnipolar (OT) electrogram method was recently proposed to generate orientation-independent electrograms and has shown improved results in recent publications (1-2). We describe the first cohort of patients ablated for VT with the help of an OT-enabled catheter. Purpose To evaluate acute and mid-term follow-up of patients ablated for VT using an OT enabled mapping system. Methods Eighteen patients (age 65 ± 19; 2 females, 32% nonischemic, median ejection fraction 40), underwent catheter ablation for scar-related VT. 50% (9) n patients had previous ablation, 4 of which underwent epicardial access. High-density omnipolar maps were obtained with an HD-grid catheter after which ablation was performed with an irrigated-tip catheter. In all patients the ablation was primarily substrate-based with the support of CT scan scar visualization. In 18 patients local abnormal ventricular activities (LAVA) ablation was performed (3), while one patient showed no LAVA. In 7 patients VT mapping was possible due to stable blood pressure during the tachycardia. The median radiofrequency application duration was 36 min. While all patients except one were inducible at the beginning of the procedure, only 3 patients were inducible at the end with a protocol using up to 3 extrastimuli. Follow-up was available in 13 patients (7.1 ± 2.5 months) with 66% freedom from VT recurrence (60% in redo cases and 71% in first procedures). Conclusion OT is a reliable method to visualize signals and perform a substrate-based ablation in with good acute and mid-term outcomes. Future studies will evaluate the impact on long term outcomes.

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.

161 ABLATION OF EPICARDIAL VENTRICULAR TACHYCARDIA ORIGINATING IN THE AREA OF PERICARDIAL ADHESIONS INDUCED BY STEREOTACTIC RADIOABLATION IN A PATIENT WITH ISCHEMIC CARDIOMYOPATHY

Abstract This is the case of a 64-year-old male patient with prior inferior wall myocardial infarction, wearing a cardiac resynchronization therapy defibrillator and suffering from recurrent ventricular tachycardia (VT). The patient had undergone a transitory successful endocardial radiofrequency catheter ablation (RFCA) in 2013 and a stereotactic ablative body radiotherapy (SABR) in 2021, targeting the VT originating in the inferior wall myocardial scar. The patient was referred to our institution due to recurrent highly symptomatic slow-VT. A coronary angiography ruled out coronary artery disease (CAD) progression and a RFCA was rescheduled. Given the suspected epicardial origin of VT based on a 12-lead ECG, the decision was made to perform a combined epi-endocardial ablation. SABR-induced pericardial adhesions prevented posterior pericardial access, thus requiring an anterior access approach (Figure 1, Panel A, yellow star). Following epicardial and endocardial electroanatomic mapping (EAM), VT ablation relied on a substrate-based approach. Local abnormal ventricular activities (LAVAs), detected both in the accessible epicardial inferior wall of the left ventricle and at the opposite endocardial site, were eliminated by radiofrequency (RF) current. Upon completion of endocardial ablation, ventricular pacing induced hemodynamically unstable VT, exiting from the epicardial region corresponding to the SABR-induced pericardial adhesions. Mechanical adhesiolysis, using the elbow of the open-irrigated ablation catheter, was performed to disrupt SABR-induced pericardial adhesions in the inferior wall. The epicardial EAM performed with the open-irrigated catheter recorded LAVAs in the infero-posterior wall of the left ventricle, corresponding to the SABR-disrupted pericardial adhesions. A RF current was delivered, targeting LAVAs at this site (Figure 1, Panel B: the central green dot corresponds to the area of disrupted pericardial adhesions). At the end of the procedure, no sustained VT was induced by programmed ventricular stimulation. Conclusion SABR constitutes a novel and promising non-invasive radioablative treatment of VT, potentially associated with cardiac toxicity. To our knowledge, this is the first reported case of combined epicardial and endocardial RFCA of recurrent VT after SABR. Based on the first RFCA report and exclusion of CAD progression, we hypothesized that SABR might have favoured progression of the inferior low voltage area. With this case report, we would like to demonstrate that even if pericardial adhesions could be a consequence of SABR, gentle catheter-driven manoeuvres can be enough to disrupt the adhesions and to achieve full EAM. Further research is mandatory to shed light on SABR's long-term arrhythmogenic role.

Impact of different activation wavefronts on ischemic myocardial scar electrophysiological properties during high-density ventricular tachycardia mapping and ablation.

Scar-related ventricular tachycardia (VT) usually results from an underlying reentrant circuit facilitated by anatomical and functional barriers. The later are sensitive to the direction of ventricular activation wavefronts. We aim to evaluate the impact of different ventricular activation wavefronts on the functional electrophysiological properties of myocardial tissue. Patients with ischemic heart disease referred for VT ablation underwent high-density mapping using Carto®3 (Biosense Webster). Maps were generated during sinus rhythm, right and left ventricular pacing, and analyzed using a new late potential map software, which allows to assess local conduction velocitiesand facilitates the delineation of intra-scar conduction corridors (ISCC); and for all stable VTs. In 16 patients, 31 high-resolution substrate maps from different ventricular activation wavefronts and 7 VT activation maps were obtained. Local abnormal ventricular activities (LAVAs) were found in VT isthmus, but also in noncritical areas. The VT isthmus was localized in areas of LAVAs overlapping surface between the different activation wavefronts. The deceleration zone location differed depending on activation wavefronts. Sixty-six percent of ISCCs were similarly identified in all activating wavefronts, but the one acting as VT isthmus was simultaneously identified in all activation wavefronts in all cases. Functional based substrate mapping may improve the specificity to localize the most arrhythmogenic regions within the scar, making the use of different activation wavefronts unnecessary in most cases.

Influence of respiration and tissue contact on ventricular substrate identification during high density mapping: Results from an ovine infarct model.

Multielectrode mapping (MEM) and automated point collection are important enhancements to substrate mapping in ventricular tachycardia ablation. The effects of tissue contact and respiration on electrogram voltage with differing depolarization wavefronts with MEM catheters are unclear. Bipolar and unipolar voltages were collected from control (n = 5) and infarcted (n = 7) animals with a multispline MEM catheter. Electro-anatomic maps were created in sinus rhythm, and right and left ventricular pacing. Analysis was performed across three collections: standard settings (SS), respiratory-phase gating (RG), and electrode-tissue proximity (TP). Comparison was made to scar detected by cardiac MRI (cMRI). Compared to SS and RG acquisition, median bipolar and unipolar voltages were higher using TP, regardless of the depolarization wavefront. In infarct animals, bipolar voltages were 30.7%-50.5% higher for bipolar and 8.7%-13.8% higher on unipolar voltages with TP, compared to SS. The effect of RG on bipolar and unipolar voltages was minimal. Percentage of local abnormal ventricular activities was not impacted by acquisition settings or wavefront direction in infarct animals. Compared with cMRI defined scar, all three acquisition settings overestimated scar area using standard voltage-based cutoffs. RG improved the low voltage area concordance with MRI by 1.6%-5.1% whereas TP improved by 5.9%-8.4%. High density voltage mapping with a MEM catheter is influenced by point collection settings. Tissue contact filters reduced low voltage areas and improved agreement with cMRI fibrosis in infarcted ovine hearts. These findings have critical implications for optimizing filter settings for high density substrate mapping in the left ventricle.

Outcome of ventricular tachycardia catheter ablation in ischemic heart disease patients using a high-density mapping substrate-based approach: A prospective cohort study

Introduction and objectiveRadiofrequency catheter ablation (RCA) for ventricular tachycardia (VT) in patients with ischemic heart disease (IHD) is associated with a reduced risk of VT storm and implantable cardioverter defibrillator (ICD) shocks. We aim to report the outcome after a single RCA procedure for VT in patients with IHD using a high-density substrate-based approach. MethodsWe conducted a prospective, observational, single-center and single-arm study involving patients with IHD, referred for RCA procedure for VT using high-density mapping catheters. Substrate mapping was performed in all patients. Procedural endpoints were VT non-inducibility and local abnormal ventricular activities (LAVAs) elimination. The primary end point was survival free from appropriate ICD shocks and secondary end points included VT storm and all-cause mortality. ResultsSixty-four consecutive patients were included (68±9 years, 95% male, mean ejection fraction 33±11%, 39% VT storms, and 69% appropriate ICD shocks). LAVAs were identified in all patients and VT inducibility was found in 83%. LAVA elimination and non-inducibility were achieved in 93.8% and 60%, respectively. After a mean follow-up of 25±18 months, 90% and 85% of patients are free from appropriate ICD shocks at one and two years, respectively. The proportion of patients experiencing VT storm decreased from 39% to 1.6%. Overall survival was 89% and 84% at one and two years, respectively. ConclusionsRCA of VT in IHD using a high-density mapping substrate-based approach resulted in a steady freedom of ICD shocks and VT storm.

Abstract 13947: Catheter-Induced Ectopy During Ventricular Electroanatomical Mapping: Simply Annoying or Potentially Useful?

Background: During ventricular catheter mapping to guide catheter ablation of scar-related ventricular tachycardia (VT), creating an electroanatomical map can be frustrated by catheter-induced ventricular ectopy. However, we observed anecdotally that catheter-induced ventricular ectopy may unmask local abnormal ventricular activities (LAVA). The aim of this study was to compare LAVA characteristics between catheter-induced ventricular ectopy and intrinsic ventricular conduction in post-infarction patients undergoing electroanatomic mapping. Methods: We performed a retrospective review of electroanatomical maps from 136 consecutive post-infarction VT patients who had undergone mapping using a contact force-sensing catheter (Thermocool STSF &amp; CARTO, Biosense Webster Inc). Patients who had any diagnostic catheters inside the ventricular were excluded. From 8 patients, 1154 discrete points were screened during sinus rhythm or right atrial pacing, and 443 points were identified to have ectopic and intrinsic beats - confirmed to be colocalized using show-catheter functionality. Results: Among 443 points, LAVA were identified in 151 points - either during catheter-induced ectopy or intrinsic rhythm. The interval from onset of QRS to ventricular electrogram (EGM) were measured: ectopy revealed negative values compared to intrinsic rhythm (-43.5 (-65.5, 0) vs 18.5 (0, 35.0), P&lt;0.001). Catheter-induced ectopy had significantly longer EGM duration (206.0ms (161.0, 285.0) vs 140.0 (123.8, 168.3), P&lt;0.001) and smaller EGM amplitude (0.59mV (0.34, 0.82) vs 0.66 (0.36, 1.06), P=0.003) compared to intrinsic rhythm. For 77 of 151 (51.0%) points, LAVA potentials were unmasked only during catheter-induced ectopy. Conclusions: During mapping of infarcted ventricles, catheter-induced ectopy offers potential insights into the underlying tissue, warranting further investigation as a guide to VT ablation.

Impact of substrate-based ablation for ventricular tachycardia in patients with frequent appropriate implantable cardioverter-defibrillator therapy and dilated cardiomyopathy: Long-term experience with high-density mapping

IntroductionRecurrent ventricular tachycardia (VT) episodes have a negative impact on the clinical outcome of implantable cardioverter-defibrillator (ICD) patients. Modification of the arrhythmogenic substrate has been used as a promising approach for treating recurrent VTs. However, there are limited data on long-term follow-up. AimTo analyze long-term results of VT substrate-based ablation using high-density mapping in patients with severe left ventricular (LV) dysfunction and recurrent appropriate ICD therapy. MethodsWe analyzed 20 patients (15 men, 55% with non-ischemic cardiomyopathy, age 58±15 years, LV ejection fraction 32±5%) and repeated appropriate shocks or arrhythmic storm (>2 shocks/24 h) despite antiarrhythmic drug therapy and optimal heart failure medication. All patients underwent ventricular programmed stimulation (600 ms/S3) to document VT. A sinus rhythm (SR) voltage map was created with a three-dimensional electroanatomic mapping system (CARTO, Biosense Webster, CA) using a PentaRay® high-density mapping catheter (Biosense Webster, CA) to delineate areas of scarred myocardium (ventricular bipolar voltage ≤0.5 mV – dense scar; 0.5-1.5 mV – border zone; ≥1.5 mV – healthy tissue) and to provide high-resolution electrophysiological mapping. Substrate modification included elimination of local abnormal ventricular activities (LAVAs) during SR (fractionated, split, low-amplitude/long-lasting, late potentials, pre-systolic), and linear ablation to obtain scar homogenization and dechanneling. Pace-mapping techniques were used when capture was possible. The LV approach was retrograde in nine cases, transseptal in five and epi-endocardial in four. In two patients ablation was performed inside the right ventricle. ResultsLAVAs and scar areas were modified in all patients. Mean procedure duration was 149 min (105-220 min), with radiofrequency ranging from 18 to 70 min (mean 33 min) and mean fluoroscopy time of 15 min. Non-inducibility was achieved in 75% of cases (in four patients with hemodynamic deterioration and an LV assist device, VT inducibility was not performed). There were two cases of pericardial tamponade, drained successfully. During a follow-up of 50±24 months, 65% had no VT recurrences. Among the seven patients with recurrences, three underwent redo ablation and four, with fewer VT episodes, received appropriate ICD therapy. There were five hospital readmissions due to heart failure decompensation, one patient died in the first week after unsuccessful ablation of a VT storm and three died (stroke and pneumonia) >1 year after ablation. ConclusionCatheter ablation based on substrate modification is feasible and safe in patients with frequent VTs and severe LV dysfunction. This approach may be of clinical relevance, with potential long-term benefits in reducing VT burden.

Combined Endo-Epicardial Approach and Scar Dechanneling Ablation in Arrhythmogenic Right Ventricular Cardiomyopathy

A 47-year-old male diagnosed with Arrhythomogenic Right Ventricular Cardiomyopathy (ARVC) was referred for ablation due to recurrent ventricular tachycardia. Using the CARTO® 3 V6 system, both endocardial and epicardial voltage maps were acquired revealing an extensive epicardial scar with abundant local abnormal ventricular activities (LAVA) in distribution compatible with conducting channels. Epicardial scar dechanneling ablation allowed abolition of all LAVA’s. This case highlights the advantage of a combined endo-epicardial approach as a first-line therapy for ARVC, as well as of scar dechanneling ablation, which allowed elimination of all LAVA’s with a lesser extensive ablation.

B-PO01-065 LOCAL ABNORMAL VENTRICULAR ACTIVITY REVEALS CONDUCTION PROPERTY DIFFERENT TO SYSTOLIC ACTIVATION DIRECTION USING OMNIPOLAR METHODOLOGY: LAVA FLOW

Sites of local abnormal ventricular activity (LAVA) potentials are thought to be attractive targets for ventricular tachycardia (VT) ablation. Though they are thought isolated to conduction tracts, due to their discrete nature at LAVA sites, activation in these isolated tracts is not commonly determined. Omnipolar methodology (OT) takes advantage of the electric field of a wave on the myocardial surface allowing for determination of activation direction, independent of adjacent time annotation. Detection of Conduction Direction at LAVA sites using omnipolar methodology. Diseased isolated human hearts (IHH) were mapped using a high-density array of 112 electrodes arranged in a 14 by 8 grid during pacing. LAVA EGMs with distinct primary and secondary activations were expertly identified from each IHH. If there are two discernable activations separated by approximately 25 ms, a marker is placed between activations. Activation directions for primary and secondary activations were calculated using OT. Any OT vector that changes its angle by more than ±15° was considered to be significant. A total of 141 fractionated bipolar EGMs were included in the analysis. Among the OT cliques that were identified at LAVA sites for all 4 IHHs, we observed that an average of 87% ± 10% of the OT vectors changed their angle by more than 15° when comparing the activation direction between their primary and secondary activations. Discrete directional analysis at LAVA sites separate to systolic activation wave is possible using Omnipolar methodology and allows for conduction direction in LAVA tracts.

Accuracy of automatic abnormal potential annotation for substrate identification in scar-related ventricular tachycardia.

Ultrahigh-density mapping for ventricular tachycardia (VT) is increasingly used. However, manual annotation of local abnormal ventricular activities (LAVAs) is challenging in this setting. Therefore, we assessed the accuracy of the automatic annotation of LAVAs with the Lumipoint algorithm of the Rhythmia system (Boston Scientific). One hundred consecutive patients undergoing catheter ablation of scar-related VT were studied. Areas with LAVAs and ablation sites were manually annotated during the procedure and compared with automatically annotated areas using the Lumipoint features for detecting late potentials (LP), fragmented potentials (FP), and double potentials (DP). The accuracy of each automatic annotation feature was assessed by re-evaluating local potentials within automatically annotated areas. Automatically annotated areas matched with manually annotated areas in 64 cases (64%), identified an area with LAVAs missed during manual annotation in 15 cases (15%), and did not highlight areas identified with manual annotation in 18 cases (18%). Automatic FP annotation accurately detected LAVAs regardless of the cardiac rhythm or scar location; automatic LP annotation accurately detected LAVAs in sinus rhythm, but was affected by the scar location during ventricular pacing; automatic DP annotation was not affected by the mapping rhythm, but its accuracy was suboptimal when the scar was located on the right ventricle or epicardium. The Lumipoint algorithm was as/more accurate than manual annotation in 79% of patients. FP annotation detected LAVAs most accurately regardless of mapping rhythm and scar location. The accuracy of LP and DP annotations varied depending on mapping rhythm or scar location.

Long-Term outcome of ventricular tachycardia catheter ablation in ischemic heart disease patients using a high-density mapping substrate-based approach: a prospective cohort study

Abstract Funding Acknowledgements Type of funding sources: None. Introduction and objective Radiofrequency catheter ablation (RCA) for ventricular tachycardia (VT) in patients with ischemic heart disease (IHD) is associated with a reduced risk of VT storm and implantable cardioverter defibrillator (ICD) shocks. We aim to report the long-term outcome after a single RCA procedure for VT in patients with IHD using a high-density substrate-based approach. Methods We conducted a prospective, observational, single-centre and single-arm study involving patients with IHD, referred for RCA procedure for VT using high-density mapping catheters. Substrate mapping was performed in all patients. Procedural endpoints were VT noninducibility and local abnormal ventricular activities (LAVAs) elimination. The primary end point was survival free from appropriate ICD shocks and secondary end points included VT storm and all-cause mortality. Results Sixty-four consecutive patients were included (68 ± 9 years, 95% male, mean ejection fraction 33 ± 11% , 39% VT storms, and 69% appropriate ICD shocks). LAVAs were identified in all patients and VT inducibility was found in 83%. LAVAs elimination and noninducibility were achieved in 93.8% and 60%, respectively. After a mean follow-up of 25 ± 18 months, 90% and 85% of patients are free from appropriate ICD shocks at 1 and 2 years, respectively. The proportion of patients experiencing VT storm decreased from 39% to 1.6%. Overall survival was 89% and 84% at 1 and 2 years, respectively. Conclusions RCA of VT in IHD using a high-density mapping substrate-based approach resulted in a long-term steady freedom of ICD shocks and VT storm. Abstract Figure. Appropriate shock &amp; all cause mortality

Catheter Ablation of Ventricular Tachycardia Guided by Substrate Electrical Inexcitability.

Catheter Ablation of Ventricular Tachycardia Guided by Substrate Electrical Inexcitability.

Predictors of ventricular ablation’s success: Viability, innervation, or mismatch?

AimsSympathetic dys-innervation may play an important role in the development of post-ischemic ventricular arrhythmias (VA). Aim of this study was to prove that perfusion/innervation mismatch (PIM) evaluated by SPECT can identify areas of local abnormal ventricular activities (LAVA) on electroanatomic mapping (EAM). MethodsSixteen patients referred to post-ischemic VA catheter ablation underwent pre-procedural and 1-month post-ablation 123I-MIBG/99mTc-tetrofosmin rest SPECT myocardial imaging. PIM was defined according to the segmental distributions of 99mTc-tetrofosmin and 123I-MIBG. A 17-segment LV analysis was used for either SPECT or LV EAM voltage map. All patients were followed up clinically for at least 1 year. ResultsBefore ablation, the mean voltage in the PIM segments was higher than in the scarred ones but lower than in the normal regions. The presence of PIM in a specific LV zone was an independent predictor of LAVA. After ablation, PIM value was significantly reduced, mainly due to an increase in perfusion summed rest score, in particular in patients that were responders to ablation. ConclusionsPIM may associate with VA substrate expressed by LAVA and might provide a novel guide for substrate ablation. A significant reduction of PIM could predict a positive clinical response to ablation.

The challenge of optimising ablation lesions in catheter ablation of ventricular tachycardia.

Radiofrequency catheter ablation has become an established treatment for ventricular tachycardia. The exponential increase in procedures has provided further insights into mechanisms causing arrhythmias and identification of ablation targets with the development of new mapping strategies. Since the definition of criteria to identify myocardial dense scar, borderzone and normal myocardium, and the description of isolated late potentials, local abnormal ventricular activity and decrementing evoked potential mapping, substrate‐guided ablation has progressively become the method of choice to guide procedures. Accordingly, a wide range of ablation strategies have been developed from scar homogenization to scar dechanneling or core isolation using increasingly complex and precise tools such as multipolar or omnipolar mapping catheters. Despite these advances long‐term success rates for VT ablation have remained static and lower in nonischemic than ischemic heart disease because of the more patchy distribution of myocardial scar. Ablation aims to deliver an irreversible loss of cellular excitability by myocardial heating to a temperatures exceeding 50°C. Many indicators of ablation efficacy have been developed such as contact force, impedance drop, force‐time integral and ablation index, mostly validated in atrial fibrillation ablation. In ventricular procedures there is limited data and ablation lesion parameters have been scarcely investigated. Since VT arrhythmia recurrence can be related to inadequate RF lesion formation, it seems reasonable to establish robust markers of ablation efficacy.