Scar-related Ventricular Tachycardia Research Articles

Identification of reentry vulnerable targets during substrate mapping for ablation in scar related VT: the "visual" reentry vulnerability index

Abstract Introduction Conduction abnormalities including zones of deceleration (DZ) & late activation are functionally important targets for ablation in scar-related ventricular tachycardias (VT). Repolarisation heterogeneities are equally important but are not routinely assessed. Visualisation of a combination of both conduction & repolarisation metrics whilst in sinus in the form of a re-entry vulnerability index (RVI) may enable more precise identification of critical ablation targets. Rationale: To test accuracy of a novel functional substrate mapping strategy combining conduction & repolarisation metrics to "visually" estimate reentry vulnerability sites (RVIv) during scar related VT ablation without the need for offline processing required for "computational" RVI. Methods VT cases using a multipolar grid-catheter for contact mapping were reviewed. DZ &areas of late activation were tagged on omnipolar LAT substrate maps. The corresponding unipolar repolarisation maps depicting local repolarisation time (LRT) based on the Wyatt method (WOI over T-Wave annotating to +dV/dt, UEGM-Filter 0.05-100Hz) were then displayed side-by-side with the LAT map. Timing reference was set to onset of surface QRS. Colour scale of LRT maps was set to start at or ahead of the timing of latest LAT. "Visual RVI" zones were identified if the tagged zone of late activation was overlapping and/or directly adjacent to an area of "early" repolarisation (defined as before or within 100ms of latest LAT point) based on colour. In visually identified RVI areas, temporal (timing difference in ms) & spatial relationship (distance in mm) of EGMs with earliest RT (RTe) to EGM with latest AT (ATL) separated by max. 20mm were measured & RVI calculated (RTe subtracted by ATL). Number of RVIv zones per map, RVI metrics & distance from closest RVI to VT Exit site (defined per activation±entrainment or pace mapping) were assessed. The lower/negative the numeric RVI, the higher the vulnerability for reentry. Results 20 patients with scar-related reentry VT were included (90% male, 63.8±11.6 years, LVEF 36±16%, 60% ischemic/40% non-ischemic). LAT & LRT map point counts were 4835±2625 and 3596±2805. In 17 (85%) patients at least 1 RVIv zone was identified, with on avg. 3.3±1.7 RVIv zones/patient. Manual RVIs were calculated to 10.4±78.9ms ( "most vulnerable" RVI was -227ms) with on avg. 9.5±5.3mm distance between RTe & ATL. All maps with no RVIv zone on the mapped surface were of non-ischemic etiology. The shortest distance of RVIs to functionally critical sites during VT was 8.9±7.4mm (range 0-33mm). Conclusion Visual reentry vulnerability estimation based on a combination of established conduction and novel repolarisation maps is feasible & may help to identify functionally critical zones during substrate mapping. Future efforts should include dedicated automated repolarisation mapping tools to facilitate integration of repolarisation dynamics in functional VT substrate mapping workflows.Figure 1Example Visual RVI Mapping

The evaluation of the efficacy of automated peak frequency annotation algorithm for the identification of critical isthmus of ventricular tachycardia and deceleration zones

Abstract Background Substrate modification techniques have widely been adopted due to hemodynamic instability and non-inducibility of clinical ventricular tachycardia (VT). Accurate annotation of local near field EGMs is paramount to better evaluate the ventricular substrate. Furthermore, annotation of late potentials (LP) necessitates substantial manual input and isochronal late activation mapping (ILAM) involves constant sensitivity adjustments, potentially affecting the accuracy of local ventricular signal representation. Objective This study aims to assess the utility of novel automated peak frequency (PF), which aims to determine near field local activity in low voltage regions in the prediction of the CI of scar related reentrant VTs. Furthermore, the effectiveness of automated PF annotation of near field EGMs to identify deceleration zone (DZ) during ILAM was also evaluated. Methods A total of 18 patients with scar-related VT were analyzed. In all patients, VT isthmuses were identified based on activation maps and acute termination achieved during radiofrequency ablation. Automated PF annotation using Ensite X system (Abbott) was retrospectively performed in all cases specifically in areas of low voltage with fractioned signals. The accuracy of applying the PF value and automated ILAM map for detecting VT isthmus was also assessed. Results Among the study group, 12 (66.7%) had ischemic cardiomyopathy, while 6 (33.3%) had nonischemic cardiomyopathy [3 (16.7%) with arrhythmogenic right ventricular cardiomyopathy, 2 (11.1%) with idiopathic dilated cardiomyopathy, and 1 (5.6%) with hypertrophic cardiomyopathy]. All identified isthmuses were located in areas exhibiting bipolar voltage below 0.5 mV and a PF of 250 Hz with fractionated EGMs Automated NF DZ annotation predicted the VT isthmus in 16/18 (88.9%) of the cases similar to the conventional ILAM with manual adjustment (88.9%). Conclusion Using high-density electroanatomical mapping with near field algorithm, a PF cutoff of 250 Hz accurately identified the low voltage regions to predict the CI of VT. In addition, automated annotation of EGMs during ILAM similarly identified the DZs compared with conventional last deflection algorithm with manual adjustments, which were colocalized with CI of VTs.

Rhythm matters: sinus and pace rhythm map significantly differ in endo/epicardial 3D electroanatomic mapping

Abstract Introduction Left ventricular substrate assessment utilizing ultra-high density multipolar catheters is frequently used to guide ablation procedures in patients with scar related ventricular tachycardia. However, 3D electroanatomic mapping is often performed during either sinus or paced rhythm. The effect of the modality (sinus vs. paced) used during mapping on substrate assessment remains elusive. Methods and Results We compared biventricular endo- and epicardial 3D high-density voltage and activation maps in sinus- and right ventricular-paced rhythm in domestic pigs. Data was acquired using a 20-polar mapping catheter with a cardiac tissue proximity filter based on catheter location and impedance measurements. Ventricular pacing (120 bmp) was performed with a permanent pacemaker electrode in right ventricular septal position, and high-density maps were acquired from the endo- and epicardium in sinus and paced rhythm (criterion for low voltage: <0.5 mV). Electroanatomical voltage and activation high-density (>6500 points per heart) mapping were performed with sufficient coverage in the right and left ventricles and the epicardium. The size of the low voltage area varied significantly between sinus and right ventricular-paced rhythm, particularly in epicardial mapping. In SR, the total low voltage was 7.2 ± 5.8%, while 11.1 ± 0.03% in paced rhythm. SR and paced maps revealed e.g. low voltage areas in the basal to apical anterior wall corresponding to the LAD regions, however, this was especially pronounced in sinus maps (e.g. pig 1: 64.2 cm²) compared to the paced rhythm map (e.g. pig 1: 32.8 cm²). Conclusion The extent of low voltage regions differed significantly in RV/LV, endo- and epicardially. Sinus maps showed the most accurate electrical representation of local voltage and corresponded correctly to local anatomical landmarks like e.g. the LAD with its surrounding epicardial fat tissue.3D biventricular epicardial voltage map

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

Non-invasive assessment of the ventricular tachycardia isthmus during sinus rhythm

Abstract Background The ablation of ventricular tachycardias (VT) presents significant challenges due to the complex and time-consuming approaches involved in identifying arrhythmogenic regions. Combining non-invasive electrocardiographic imaging (ECGI) with endocardial mapping could potentially enhance the efficacy of interventions. Objective To evaluate the capability of ECGI in guiding operators towards areas of VT isthmuses during sinus rhythm. Methods Patients with scar-related VT, confirmed by late gadolinium enhancement cardiac magnetic resonance, were prospectively enrolled. We compared the areas of slowed conduction identified by ECGI with the VT sustaining regions identified endocardially. Simultaneous Electroanatomical Mapping (EAM) and ECGI mapping were performed during VT ablation procedures. In patients in whom a hemodynamically stable VT was maintained, the reentry circuit was mapped endocardially, and the ablation target was identified. The left ventricle was segmented into 9 regions, categorized as either VT-isthmus or non-VT isthmus based on EAM findings. Prior to ablation, local activation times (LAT) and conduction velocity (CV) ECGI sinus maps were computed. Slow conduction was quantified non-invasively by computing different ECGI metrics per region, including the mean and the standard deviation (SD) of LAT and CV, the regional Total Activation Time (rTAT) – time span between the earliest and latest activated nodes–, and the Slow Conduction Velocity (SCV) – the percentage of nodes where velocity falls below 60 cm/s -. Results The study included 20 consecutive patients with ischemic cardiomyopathy who were referred for VT ablation. A total of 21 regions linked to the VT isthmus were identified endocardially in 17 patients (age: 66.1±8.8 years, 94.1% male, left ventricular ejection fraction: 26.4±7.3%). Figure 1 illustrates the correlation between the VT circuit and the ECGI sinus map in two patients with extensive left ventricular fibrosis. ECGI metrics related to VT isthmuses exhibited a higher standard deviation in both LAT (18.1±2.0 vs 9.8±1.2 ms; p=0.001), and CV (50.4±4.7 vs 37.1±2.8 cm/s; p=0.011), and a greater percentage of nodes with slowed conduction (13.7±2.7 vs 7.4±1.6 %; p=0.029), compared to non-VT isthmus regions, Figure 2. Multivariate logistic regression analysis revealed that SD-LAT was the strongest predictor of VT isthmus localization. Conclusion ECGI has demonstrated the capability to pinpoint slowed conduction areas responsible for VT in sinus rhythm, showing promise in planning and guiding VT ablation strategies. This advancement paves the way for further research into using this non-invasive tool to improve risk stratification methods for ventricular arrhythmias.

Left and right ventricular function measured by strain analysis predicts one-year mortality in ventricular tachycardia ablation patients with structural heart disease

Abstract Introduction Radiofrequency catheter ablation has become increasingly important in the management of scar-related ventricular tachycardia (VT). Wide range of clinical and procedural predictors of VT recurrence and mortality are described by previous studies. However, currently known echocardiographic predictors are mainly limited to conventional echo parameters. Speckle tracking echocardiography (STE) is a novel and promising method to evaluate systolic and diastolic function. STE derived parameters, such as global longitudinal strain (GLS), are proven predictors of mortality and arrhythmic events in heart diseases. Aims The aim of the present study was to assess whether STE derived parameters could be considered predictors of VT recurrence and mortality after catheter ablation of ventricular tachycardia in patients with structural heart disease. Methods We measured pre-ablation strain and strain rate parameters with speckle tracking. Left ventricular four-chamber longitudinal strain (LV4CLS), early diastolic strain rate (e’-sr), right ventricular free wall longitudinal strain (RVFWLS) and right ventricular four-chamber longitudinal strain (RV4CLS) were assessed in 73 cases. Patients were followed up for one year. Endpoints were VT recurrence, which was defined as either ICD recording of a sustained VT episode requiring therapy or an episode of sustained VT recorded on 12-lead ECG or CIED, and all-cause mortality. Results Univariate analysis using the Cox proportional hazard model revealed that only lower LVEF (HR: 0.52 [0.31-0.88], p=0.02) was associated with higher VT recurrence in the first year among the echocardiographic parameters. High LVEDD (HR: 3.9 [1.31-11.65], p=0.02), low TAPSE (HR: 0.52 [0.28-0.98], p=0.04), low LV4CLS (HR: 0.4 [0.19-0.83], p=0.01) and low RV4CLS (HR: 0.31 [0.13-0.72], p<0.01) were the predictors of 1-year mortality. Conclusion Strain parameters, especially right ventricular four-chamber longitudinal strain may supplement conventional echocardiographic parameters in the prediction of one-year mortality after catheter ablation in patients with structural heart disease. Further prospective clinical studies are necessary to verify the significance of strain parameters.

Clinical validation of a novel digital twin framework for ventricular functional substrate simulation in post-infarction patients

Abstract Background Catheter ablation is a cornerstone treatment for scar related post-infarction ventricular arrhythmias. Functional substrate driven ablation strategies guided by local activation time (LAT) mapping have been proven as efficient and effective approaches, especially when dealing with large scar areas. In-silico electrophysiological modeling is emerging as a potential tool for procedural planning and guidance. Purpose To clinically validate the feasibility, diagnostic performance, and accuracy of a novel late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) based digital twin framework for simulated LAT map generation in post-infarction patients and their integration with CARTO3 EAM suite. Methods Five ischemic subjects who underwent CMR-aided scar-related ventricular tachycardia ablation at our referral center were retrospectively enrolled. Their CMR derived 3D pixel-signal-intensity (PSI) maps generated with ADAS3D were processed with novel in-house software to obtain patient-specific ventricular geometry, tissue characterization, and to generate a model of Purkinje system and myocyte fiber orientation. According to local normalized pixel intensity (NPI) values, myocardial regions were marked as healthy, scar, or border-zone. Electrophysiological properties of border-zone (BZ) were modulated according to local NPI. Continuous and 8-steps isochronal endo-epicardial LAT maps were generated and imported in CARTO3 system, aligned with electroanatomical mapping (EAM), and compared at an ASE 17-segments level, in terms of sensitivity, specificity, predictive values, and accuracy to actual high-density LAT maps obtained with a multipolar catheter. Deceleration Zones (DZ) were defined as previously described (>3 isochrones within 1 cm radius). Results A total of 85 ASE segments (34 epicardial) were analyzed. 24 EAM segments (28%) held DZs, 40 (47%) segments harbored bipolar scar or BZ. Thirty-seven (44%) CMR segments held scar core/BZ. Thirty (35%) digital model segments harbored DZs. Generated LAT maps were successfully imported and aligned with CARTO3 EAM suite for validation. In terms of DZ localization prediction, our LAT model showed 83% sensitivity (95% CI 63%-95%), 90% specificity (95% CI 80%-96%), 77% positive predictive value (PPV) (95% CI 56%-91%), 93% negative predictive value (NPV) (95% CI 83%-98%), 88% accuracy (95% CI 79%-94%). Conclusion Our newly developed framework for LGE-CMR derived functional substrate simulation in post-infarction patients holds high sensitivity, specificity, predictive values, and accuracy for DZ localization. Further validation, with a larger sample size, is required for evaluating potential implications in clinical practice.

Improving functional substrate delineation for ablation of ventricular tachycardia using high-density electroanatomic mapping and double ventricular extra stimuli protocol

Abstract Background A partial delineation of targets for ventricular tachycardia (VT) ablation may contribute to a suboptimal success rate. Abnormal electrograms (EGMs) with low-voltage near-field components might be concealed within high-amplitude far-field signals. Our hypothesis posited that acquiring functional mapping after double ventricular extrastimuli (S3 protocol) could reveal relevant areas of functional substrate overlooked during sinus or S1 mapping. Purpose To assess the benefit and feasibility of functional substrate mapping using a full ventricle S3 protocol and to evaluate its colocalization with conducting channels (CCs) identified in late gadolinium enhancement cardiac magnetic resonance (LGE-CMR). Methods (Figure 1) - An S3 mapping protocol with a drive train of S1 followed by S2 (effective refractory period (ERP) +30ms) and S3 (ERP+50ms) from the RV apex was conducted in 40 consecutive patients undergoing scar-related VT ablation. Deceleration zones (DZs) and areas of late potentials (LPs) were identified for all maps (S1, S2, and S3). Pre-procedural non-invasive substrate assessment was performed with LGE-CMR and post-processing using a commercially available system with automated CC identification. Results The S3 protocol was completed in 34 of the 40 procedures (85.0%). Repeated induction of ventricular arrhythmias prevented the full S3 protocol in 5 patients (15.0%). Functional substrate identified during S3 activation mapping was significantly more extensive than that identified using S2 and S1, including a higher number of DZs (2.94, 2.47, and 1.82, respectively; p<0.01) and a wider area of LPs (44.1cm2, 38.2cm2, and 29.4cm2, respectively; p<0.001). The percentage of CCs unmasked by DZs and LPs using S3 maps was significantly higher than the ones using S2 and S1 maps(78%, 65%, and 48%; p<0.001, and 88%, 81%, and 68%; p<0.01, repectively). After VT ablation based on an S3 protocol, 77.9% of patients have been VT free during a median follow-up of 13.6 months. Conclusions (Graphical abstract -Figure 2) - This novel substrate-based protocol for assessing functional substrate is feasible in most patients, enables better identification of ablation targets, and has the potential to improve patient prognosis post-ablation.Methods - The S3 protocolConclusion - Graphical abstract

Targeting Wavefront Discontinuity Linesfor Scar-Related Ventricular Tachycardia Ablation: A Novel Functional Substrate Ablation Approach.

The boundaries of critical isthmuses for re-entrant ventricular tachycardia (VT) are formed by wave-front discontinuities (fixed lines of block, slow propagation, and rotational propagation) seen during baseline rhythm. It is unknown whether wavefront discontinuities can be automatically identified and targeted for ablation using electroanatomic mapping systems. The purpose of this study was to assess the electrophysiologic characteristics of automatically projected wavefront discontinuity lines (WADLs) and outcomes of an ablation strategy targeting WADLs in a mixed cohort of VT patients. Late activation substrate maps were analyzed from 1 or more baseline rhythm wavefronts. WADLs were identified using the Carto Extended Early Meets Late module. Number, total length, and distance to critical VT sites were measured. VT recurrence and VT-free survival were followed. In total, 49 patients underwent 52 ablations with 71 unique substrate maps analyzed (18.8% epicardial; 62.0% right ventricular paced, 28.2% sinus rhythm, 9.9% left ventricular paced). A total of 28 VT critical sites were identified in 24 patients. WADLs were present in 49 of 71 (69.0%) maps. WADLs were present regardless of cardiomyopathy etiology, mapping wavefront, or surface. At a WADL threshold of 30%, 73.9% of critical VT sites were in close proximity (≤15mm) to a WADL. VT-free survival was 62% at 1 year, with a competing risk model estimating a 1-year risk of VT recurrence of 23%. WADLs can be automatically projected in a majority of patients in a mixed cohort of cardiomyopathy etiology, mapped wavefronts, and myocardial surfaces mapped. Targeting WADLs results in low rate of VT recurrence at 1 year.

Substrate Mapping for Ventricular Tachycardia Ablation Through High-Density Whole-Chamber Double Extra Stimuli: The S3 Protocol

BackgroundA partial delineation of targets for ablation of ventricular tachycardia (VT) during a stable rhythm is likely responsible for a suboptimal success rate. The abnormal low-voltage near-field functional components may be hidden within the high-amplitude far-field signal. ObjectivesThe aim of this study was to evaluate the benefit and feasibility of functional substrate mapping using a full-ventricle S3 protocol and to assess its colocalization with arrhythmogenic conducting channels (CCs) on late gadolinium enhancement cardiac magnetic resonance. MethodsAn S3 mapping protocol with a drive train of S1 followed by S2 (effective refractory period + 30 ms) and S3 (effective refractory period + 50 ms) from the right ventricular apex was performed in 40 consecutive patients undergoing scar-related VT ablation. Deceleration zones (DZs) and areas of late potentials (LPs) were identified for all maps. A preprocedural noninvasive substrate assessment was done using late gadolinium enhancement cardiac magnetic resonance and postprocessing with automated CC identification. ResultsThe S3 protocol was completed in 34 of the 40 procedures (85.0%). The S3 protocol enhanced the identification of VT isthmus on the basis of DZ (89% vs 62%; P < 0.01) and LP (93% vs 78%; P = 0.04) assessment. The percentage of CCs unmasked by DZs and LPs using S3 maps was significantly higher than the ones using S2 and S1 maps (78%, 65%, and 48% [P < 0.001] and 88%, 81%, and 68% [P < 0.01], respectively). The functional substrate identified during S3 activation mapping was significantly more extensive than the one identified using S2 and S1, including a greater number of DZs (2.94, 2.47, and 1.82, respectively; P < 0.001) and a wider area of LPs (44.1, 38.2, and 29.4 cm2, respectively; P < 0.001). After VT ablation, 77.9% of patients have been VT free during a median follow-up period of 13.6 months. ConclusionsThe S3 protocol was feasible in 85% of patients, allows a better identification of targets for ablation, and might improve VT ablation results.

Personalized voltage maps guided by cardiac magnetic resonance in the era of high-density mapping

BackgroundVoltage mapping could identify the conducting channels potentially responsible for ventricular tachycardia (VT). Standard thresholds (0.5–1.5 mV) were established using bipolar catheters. No thresholds have been analyzed with high-density mapping catheters. In addition, channels identified by cardiac magnetic resonance (CMR) has been proven to be related with VT. ObjectiveThe purpose of this study was to analyze the diagnostic yield of a personalized voltage map using CMR to guide the adjustment of voltage thresholds. MethodsAll consecutive patients with scar-related VT undergoing ablation after CMR (from October 2018 to December 2020) were included. First, personalized CMR-guided voltage thresholds were defined systematically according to the distribution of the scar and channels. Second, to validate these new thresholds, a comparison with standard thresholds (0.5–1.5 mV) was performed. Tissue characteristics of areas identified as deceleration zones (DZs) were recorded for each pair of thresholds. In addition, the relation of VT circuits with voltage channels was analyzed for both maps. ResultsThirty-two patients were included [mean age 66.6 ± 11.2 years; 25 (78.1%) ischemic cardiomyopathy]. Overall, 52 DZs were observed: 44.2% were identified as border zone tissue with standard cutoffs vs 75.0% using personalized voltage thresholds (P = .003). Of the 31 VT isthmuses detected, only 35.5% correlated with a voltage channel with standard thresholds vs 74.2% using adjusted thresholds (P = .005). Adjusted cutoff bipolar voltages that better matched CMR images were 0.51 ± 0.32 and 1.79 ± 0.71 mV with high interindividual variability (from 0.14–1.68 to 0.7–3.21 mV). ConclusionPersonalized voltage CMR-guided personalized voltage maps enable a better identification of the substrate with a higher correlation with both DZs and VT isthmuses than do conventional voltage maps using fixed thresholds.

Intramural needle ablation or repeated standard ablation in patients referred for repeat ablation of scar-related ventricular tachycardia.

When ventricular tachycardia (VT) recurs after standard RF ablation (sRFA) some patients benefit from repeat sRFA, whereas others warrant advanced methods such as intramural needle ablation (INA). Our objectives are to assess the utility of repeat sRFA and to clarify the benefit of INA when repeat sRFA fails in patients with VT due to structural heart disease. In consecutive patients who were prospectively enrolled in a study for INA for recurrent sustained monomorphic VT despite sRFA, repeat sRFA was considered first. INA was performed during the same procedure if repeat sRFA failed or no targets for sRFA were identified. Of 85 patients enrolled, acute success with repeat sRFA was achieved in 30 patients (35%), and during the 6-month follow-up, 87% (20/23) were free of VT hospitalization, 78% were free of any VT, and 7 were lost to follow-up. INA was performed in 55 patients (65%) after sRFA failed, or no endocardial targets were found abolished or modified inducible VT in 35/55 patients (64%). During follow-up, 72% (39/54) were free of VT hospitalization, 41% were free of any VT, and 1 was lost to follow-up. Overall, 59 out of 77 (77%) patients were free of hospitalization and 52% were free of any VT. Septal-origin VTs were more likely to need INA, whereas RV and papillary muscle VTs were less likely to require INA. Repeat sRFA was beneficial in 23% (18/77) of patients with recurrent sustained VT who were referred for INA. The availability of INA increased favorable outcomes to 52%.

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.

Surpoint algorithm for improved guidance of ablation for ventricular tachycardia (SURFIRE-VT): A pilot study.

The utility of ablation index (AI) to guide ventricular tachycardia (VT) ablation in patients with structural heart disease is unknown. The aim of this study was to assess procedural characteristics and clinical outcomes achieved using AI-guided strategy (target value 550) or conventional non-AI-guided parameters in patients undergoing scar-related VT ablation. Consecutive patients (n = 103) undergoing initial VT ablation at a single center from 2017 to 2022 were evaluated. Patient groups were 1:1 propensity-matched for baseline characteristics. Single lesion characteristics for all 4707 lesions in the matched cohort (n = 74) were analyzed. The impact of ablation characteristics was assessed by linear regression and clinical outcomes were evaluated by Cox proportional hazard model. After propensity-matching, baseline characteristics were well-balanced between AI(n = 37) and non-AI(n = 37) groups. Lesion sets were similar (scar homogenization [41% vs. 27%;p = .34], scar dechanneling [19% vs. 8%;p = .18], core isolation [5% vs.11%;p = .4],linear and elimination late potentials/local abnormal ventricular activities[35% vs. 44%;p = .48], epicardial mapping/ablation [11% vs.14%;p = .73]). AI-guided strategy had 21% lower procedure duration (-47.27 min, 95% confidence interval[CI][-81.613, -12.928];p = .008), 49% lower radiofrequency time per lesion (-13.707 s, 95%CI[-17.86, -9.555];p < .001), 21% lower volume of fluid administered (1664 cc[1127, 2209] vs. 2126 cc [1750, 2593];p = .005). Total radiofrequency duration (-339 s [-24%], 95%CI[-776, 62];p = .09) and steam pops (-155.6%, 95%CI[19.8%,-330.9%];p = .08) were nonsignificantly lower in the AI group. Acute procedural success (95% vs.89%;p = .7) and VT recurrence (0.97, 95% CI[0.42-2.2];p = .93) were similar for both groups. Lesion analysis (n = 4707) demonstrated a plateau in the magnitude of impedance drops once reaching an AI of 550-600. In this pilot study, an AI-guided ablation strategy for scar-related VT resulted in shorter procedure time and average radiofrequency time per lesion with similar acute procedural and intermediate-term clinical outcomes to a non-AI-guided approach utilizing traditional ablation parameters.

Transcoronary mapping with an over-the-wire multielectrode catheter in scar-related ventricular tachycardia patients.

The usefulness of coronary venous system mapping has been reported for assessing intramural and epicardial substrates in patients with scar-related ventricular tachycardia (VT). However, there has been little data on mapping from coronary arteries. We investigated the safety and utility of mapping from coronary arteries with a novel over-the-wire multielectrode catheter in scar-related VT patients. Ten consecutive scar-related VT patients with non-ischaemic cardiomyopathy who underwent mapping from a coronary artery were analysed. Six patients underwent simultaneous coronary venous mapping. High-density maps were created by combining the left ventricular endocardium and coronary vessels. Substrate maps were created during the baseline rhythm with 2438 points (IQR 2136-3490 points), including 329 (IQR 59-508 points) in coronary arteries. Abnormal bipolar electrograms were successfully recorded within coronary arteries close to the endocardial substrate in seven patients. During VT, isthmus components were recorded within the coronary vessels in three patients with no discernible isthmus components on endocardial mapping. The ablation terminated the VT from an endocardial site opposite the earliest site in the coronary arteries in five patients. The transcoronary mapping with an over-the-wire multielectrode catheter can safely record abnormal bipolar electrograms within coronary arteries. Additional mapping data from the coronary vessels have the potential to assess three-dimensional ventricular substrates and circuit structures in scar-related VT patients.

Lipomatous metaplasia is the best CT predictor for conducting channel localization in scar-related ventricular tachycardia ablation

Abstract Introduction Recent evidence has shown that intramyocardial lipomatous metaplasia (LM) can be directly identified with cardiac computer tomography (CT) and plays a significant role in ventricular arrhythmogenesis and facilitation in structural heart disease. Purpose We sought to explore the diagnostic performance of three different CT features (LM, CT channels, wall thinning) identified at ADAS3D post-processing as electroanatomical substrate predictors and their potential role in planning and aiding ventricular tachycardia (VT) scar dechanneling procedures. Methods All patients undergoing VT ablation at our institution were enrolled. CT images were post-processed with ADAS3D software to assess LM and left ventricle wall thickness. Images were then retrospectively imported into CARTO3 software and concordance between CT and electroanatomical features (conducting channels, channel entrances, bipolar scar, voltage channels, ablation VISITAGs) was assessed at a cardiac segment level. Results From July 2016 to December 2022 131 patients underwent VT ablation at our institution. 88 patients did not undergo preprocedural CT examination, 15 patients had a low-quality CT scan and, at ADAS3D analysis 9 patients did not have significant LM. 19 patients (14 ischemic and 5 non-ischemic, 323 cardiac segments) were then included for analysis. 90 segments (27,86%) showed LM, 93 segments (28,79%) showed thickness &amp;lt; 5 mm and 12 segments (3,72%) held CT channels. In terms of conducting channel prediction, in ischemic patients, LM showed 70% sensitivity, 89% specificity, 73% PPV and 88% NPV when compared to CT channels (10% sensitivity, 98% specificity, 70% PPV, 72% NPV) or wall thinning (61% sensitivity, 82% specificity, 58% PPV and 84% NPV). In non-ischemic patients LM showed with 69% sensitivity, 81% specificity, 39% PPV and 94% NPV when compared to CT channels (15% sensitivity, 100% specificity, 100% PPV, 87% NPV) or wall thinning (46% sensitivity, 82% specificity, 32% PPV and 89% NPV). Overall, at multivariate analysis only LM (OR 12,46 95% C.I. 6,59-23,58) and wall thinning (OR 4,73 95% C.I. 2,45-9,14) were independent predictors for conducting channel. Conclusion Lipomatous metaplasia is the best CT predictor for conducting channel presence both in ischemic and non-ischemic patients with scar related ventricular tachycardia and a potentially useful tool for procedure planning and guidance.CT predictors for EAM substrate findingsMultivariate forest plots

Optimal pixel signal intensity threshold for the assessment of endocardial left-ventricular scar by 3D dark blood MRI compared to bipolar voltage electro-anatomical mapping

Abstract Background Late gadolinium enhancement (LGE) MRI is considered the standard for noninvasive assessment of 3D scar architecture. Intraprocedural integration of 3D scar models improve the outcome of catheter ablation for ventricular tachycardia (VT). A pixel signal intensity (PSI) cut-off of 40 to 60% has been widely used for conventional bright-blood LGE MRI. Novel 3D MRI acquisitions with dark-blood (DB) nulling with higher spatial resolution and superior detection of (subendocardial) scar patterns are increasingly available, but the optimal pixel signal intensity (PSI) value remains unknown. Purpose To compare the accuracy of the 3D DB MRI-derived endocardial scar reconstructions at three different PSI cut-offs with endocardial electro-anatomical contact mapping in patients with scar-related VT. Methods Preprocedural 3D DB LGE MRIs were retrospectively compared to high-density endocardial left-ventricular (LV) bipolar voltage mapping (cut-off 0.5-1.5mV) obtained during endocardial mapping at sinus rhythm using the ADAS3D software. The LV scar models were aligned using the mitral valve, left ventricular apex and aorta cusps. Points with a Euclidean node-to-node distance of ≥10 mm were excluded. Variable upper PSI thresholds were set at 50%, 60% and 70%; the lower threshold at two-thirds of the upper limit. The 10% LV layer from the 3D MRI was used. The pairs of points were checked for agreement for scar or healthy (%). The Pearson correlation was used to analyze the agreement between core scar, border zone and healthy tissue area (in %) at three thresholds. Results Ten patients (90% male, mean age 65±11 year, 8 ischemic/2 nonischemic, LV ejection fraction 41±6%) were analyzed. A mean of 2024 (range 385-6810) pairs were analyzed per patient at three PSI thresholds. A correct correlation for scar or healthy was present in 67%, 69% and 69% for the upper PSI thresholds of 50%, 60% and 70% respectively. The optimal match was obtained for an upper PSI cutoff value of 70%, for healthy (r2=0.57; P=0.01), border zone (r2=0.73; P=0.01), 50% for core (r2=0.09; P=0.39). Using a 60% PSI cutoff the scar core % increased significantly compared to the 70% cutoff (12.8 ±13.8 versus 4.9±7.3, P=0.001). Conclusion The optimal depiction of the boundary between healthy and border zone scar by 3D DB MRI is best depicted at an upper PSI threshold of 70%.

A comparison of general anesthesia versus monitored anesthesia care during catheter ablation for ventricular tachycardia

Abstract Background Catheter ablation of ventricular tachycardia (VT) may be performed under general anesthesia (GA) or monitored anesthesia care (MAC). There is a paucity of data studying these two sedation strategies with respect to intraprocedural characteristics, and outcomes of VT ablation. Purpose The purpose of this study was to assess the effects of anesthesia techniques on VT inducibility and outcomes. Methods A single-center, retrospective study of patients undergoing catheter ablation for scar-related VT, from 2016-2022, was conducted. Data collected included demographics, comorbidities, medications, relevant laboratory abnormalities, electrocardiograms, echocardiograms, detailed procedural characteristics, and outcomes. Results One hundred sixty-eight patients who underwent a total of 200 VT ablation procedures were included. The patients undergoing GA had a greater burden of comorbidities including congestive heart failure (77.2% vs. 60.9%), hypertension (66.9% vs. 60.0%), atrial arrhythmias (50.7% vs. 43.8%), diabetes mellitus (21.3% vs. 9.4%), chronic kidney disease (44.1% vs. 31.3%), prior stroke (11.8% vs. 10.9%), myocardial infarction (31.6% vs. 29.7%), pre-existing implantable cardioverter-defibrillator (86.8% vs. 71.9%) and had a higher median number of antiarrhythmic drugs at baseline (2 vs. 1) [Figure 1]. There was a greater percentage of patients with non-ischemic cardiomyopathy (58.1% vs. 51.6%) in the GA cohort. The mean left ventricular ejection fraction was not different among the two groups (39.3 ± 13.9 vs. 42.5 ± 15.3). The GA group had more hemodynamic instability at baseline (p &amp;lt; 0.01), and during VT induction (p &amp;lt; 0.01). There was no significant difference in the number of VT induced, or tachycardia cycle length, in each group. Despite higher radiofrequency energy delivery time in the GA group as compared to the MAC group, the GA group had higher VT inducibility post-procedure and were more likely to be discharged on antiarrhythmic drugs. Even though the recurrence of VT was higher in the GA group compared to the MAC group (41.9% vs. 31.3%), the VT-free survival curves were not significantly different by Kaplan-Meier analysis (p=0.19) [Figure 2]. In a multivariate regression analysis, the sedation strategy was not an independent predictor of VT recurrence (p=NS). However, baseline hemodynamic instability was an independent predictor of VT recurrence after accounting for all intraprocedural characteristics (p=0.008). Conclusion Patients undergoing VT ablation under GA have more comorbidities and tend to be on more antiarrhythmic drugs. The GA group had more hemodynamic instability during the procedure and had greater overall VT recurrence, however, not significant in a time-based analysis. The greater overall recurrence in the GA group could be because they represent a sicker population, or the hemodynamics during the procedure preclude adequate ablation of the VT circuit elements.Figure 1Figure 2

Outcomes of catheter ablation for ventricular tachycardia in the geriatric population

Abstract Background Catheter ablation has emerged as the first-line therapy for management of ventricular tachycardia (VT) over the last decade. There is a reluctance for older patients to be referred for catheter ablation with concerns for complications and poor outcomes. Purpose The purpose of the study was to assess the safety and outcomes of catheter ablation for VT in patients more than 74 years of age in comparison to younger patients. Methods A single-center retrospective study of 200 procedures in 168 patients undergoing catheter ablation for scar-related VT was conducted. Data collected included demographics, comorbidities, medications, relevant laboratory abnormalities, electrocardiograms, Holter, device electrograms, structural data including echocardiograms and cardiac magnetic resonance imaging, detailed procedural characteristics, and outcomes. Results The mean age in the older cohort was 77.7 ± 3.7 years compared to 57.6 ± 13.1 years in the younger group (p &amp;lt; 0.01) [Figure 1]. The geriatric patients had more males (93.6% vs. 75.8%) and had greater proportion of comorbidities including congestive heart failure (89.4% vs. 66.7%), hypertension (91.5% &amp; 56.9%), atrial arrhythmias (66.0% vs. 43.1%), chronic kidney disease (68.1% vs. 31.4%), prior myocardial infarction (53.2% vs. 24.2%), and stroke (21.3% vs. 8.5%). The older patients were on more antiarrhythmic drugs at baseline. During the procedure, the number of cases with VT induction and hemodynamic stability was similar in older and younger groups. In cases where VT was induced, the older patients had a greater number of VTs induced (2.7 ± 3.0 vs. 1.9 ± 1.8), with slower cycle lengths (454.9 ± 122.6 vs. 379.3 ± 108.1 milliseconds). There was no difference noted in the procedural complications between the two groups. Older patients were more likely to be discharged on antiarrhythmic medications (87.2% vs. 71.2%) and had higher long-term mortality (29.8% vs. 7.8%). The older group was less likely to have a repeat ablation procedure (8.5% vs 24.2%). There was no difference in long-term VT-free survival rates among the two groups [Figure 2]. Conclusion Patients more than 74 years of age undergoing catheter ablation for structural VT have a greater comorbidity burden but demonstrate similar procedural complications and VT-free survival rates, when compared to the younger cohort.Figure 1Figure 2

Differences in the outcomes of catheter ablation for ventricular tachycardia by sex

Abstract Background Catheter ablation of ventricular tachycardia (VT) has emerged as the mainstay of management for these sick patients. There is a lack of long-term data studying the characteristics and outcomes of VT ablation in females and the comparison with males. Purpose The purpose of the study was to assess the impact of sex on outcomes of catheter ablation for ventricular tachycardia. Methods A single-center retrospective study of 200 procedures in 168 patients undergoing catheter ablation for scar-related VT under GA or MAC sedation was conducted. Data collected included demographics, comorbidities, medications, relevant laboratory abnormalities, electrocardiograms, structural data including echocardiograms and cardiac magnetic resonance imaging, detailed procedural characteristics, and outcomes. Results Females undergoing VT ablation were younger (49.4 ± 15.6 vs. 65.5 ± 12.2 years) [Figure 1]. Females had a lower burden of comorbidities, including congestive heart failure (30.0 % vs. 82.5%), hypertension (27.5% vs. 74.4%), atrial arrhythmias (20.0% vs. 55.6%), chronic kidney disease (25.0% vs. 43.8%), prior myocardial infarction (15.0% &amp; 35.0%), and coronary artery bypass graft surgery (0.0% &amp; 23.8%). Females were on fewer antiarrhythmic drugs at baseline. During the procedure, males had a greater likelihood of undergoing general anesthesia (72.5% vs. 50.0%) and associated hemodynamic instability at baseline (30.0% vs. 12.5%). It was more likely for VT to be induced in males, and females required more induction medications. There was no difference in complication rates between males and females. A greater proportion of males were discharged and maintained on antiarrhythmic drugs after the procedure. There was no significant difference in VT recurrence or long-term mortality. Using Kaplan-Meier analysis, no difference was seen in long-term VT-free survival by sex (p=0.20) [Figure 2]. In a multivariate regression model, female sex had no bearing on the VT-free survival. Conclusion Females undergoing catheter ablation for VT are younger and have fewer comorbidities. They tend to be on fewer antiarrhythmic drugs at baseline, and after ablation. Interestingly, despite a healthier baseline profile, females do not experience less VT recurrence or mortality compared to males. Further study would be needed to investigate this association.Figure 1Figure 2