Scar-related Ventricular Tachycardia Ablation Research Articles

Rate-Dependent Pacemap Matching in Scar-Related Ventricular Tachycardia: Impact of “TR Fusion” Phenomenon

BackgroundThe impact of varying rates of pacemapping (PM) rates on QRS morphology and PM score matching in patients with scar-related ventricular tachycardia (VT) has not been systematically assessed. ObjectivesIn this study, the authors sought to assess the variability in PM score matching at different pacing rates. MethodsDuring substrate mapping for VT ablation, PM was performed at cycle lengths (CLs) of 600 ms, 500 ms, 400 ms, 300 ms, and VT CL. PM scores were compared for the entire QRS, the first half (H1) of QRS, and the second half (H2) of QRS to examine the influence of the preceding T-wave superimposed into the onset of paced QRS complex (TR fusion). ResultsA total of 269 PMs in 40 patients undergoing scar-related VT ablation were systematically analyzed. The PM score improved at rates closer to VT with a median difference of 6% (Q1-Q3: 4%-10%; range: 0%-33%) between the lowest and the highest PM scores at a given site. Greater slurring of the QRS onset was observed at faster-paced CL, corresponding to a superimposition of the preceding T-wave into QRS onset, with significant differences in H1 but not H2 of the QRS complex. At faster PM rates, 32% of overall sites developed pseudo delta wave and 69% of endocardial pacing sites fulfilled epicardial criteria. ConclusionsThe rate of pacemapping can significantly alter morphologic score matching, with the most optimal match observed closest to VT CL. The onset of QRS complex morphology is influenced by superimposition of the preceding T-wave at faster rates, resulting in an underrecognized TR fusion phenomenon that may confound epicardial electrocardiographic criteria predicated upon the initial QRS slope and vector.

Spatial analysis and characteristics of persistent late potentials after ablation of scar-related VT substrate: Implications for late potential elimination as a procedural endpoint with high-resolution mapping

BackgroundLate potential (LP) elimination has been proposed as a surrogate endpoint for scar-related ventricular tachycardia (VT) ablation procedures. The characteristics, distribution, and predictors of persistent late potentials (pLPs) after ablation have not been studied. ObjectiveThe purpose of this study was to characterize the spatial distribution and features of pLP after catheter ablation of VT substrate with high-resolution mapping. MethodsCases of scar-related VT ablation with adequate pre- and postablation electroanatomic maps (EAMs) acquired exclusively using a high-density grid catheter were reviewed from 2021 to 2023. ResultsA total of 62 EAMs (pre- and postablation) from 31 cases using a high-density grid catheter were reviewed. pLPs were observed in 19 cases (61%) after ablation. New LP, spatially distinct from preablation LP, at the periphery of the ablation area comprised the majority of pLPs (16/19 [84%]). Isolated pLPs were more prevalent than fractionated pLPs, with a median amplitude of 0.26 mV (0.09–0.59 mV). The presence of pLP was associated with a significantly lower left ventricular ejection fraction (LVEF) and septal ablation but not low voltage, LP, or ablation area compared to absence of pLP (22.8% ± 7.8% vs 31.5% ± 8.0%, P = .008 for LVEF; 83% vs 44%, P = .033 for septal ablation). ConclusionFormation of spatially distinct new LP after targeted VT ablation is common, especially in patients with lower LVEF and septal substrate independent of ablation burden. This finding highlights the limitations of complete LP elimination as an endpoint to VT ablation procedures.

Acute post-procedural inducibility is a poor predictor of clinical outcomes in high-risk patients (PAINESD > 17) undergoing scar-related ventricular tachycardia ablation.

Ventricular tachycardia (VT) non-inducibility in response to programmed ventricular stimulation (PVS) is a widely used procedural endpoint for VT ablation despite inconclusive evidence with respect to clinical outcomes in high-risk patients. The aim is to determine the utility of acute post-ablation VT inducibility as a predictor of VT recurrence, mortality, or mortality equivalent in high-risk patients. We conducted a retrospective analysis of high-risk patients (defined as PAINESD > 17) who underwent scar-related VT ablation at our institution between July 2010 and July 2022. Patients' response to PVS (post-procedure) was categorized into three groups: Group A, no clinical VT or VT with cycle length > 240 ms inducible; Group B, only non-clinical VT with cycle length > 240 ms induced; and Group C, all other outcomes (including cases where no PVS was performed). The combined primary endpoint included death, durable left ventricular assist device placement, and cardiac transplant (Cox analysis). Ventricular tachycardia recurrence was considered a secondary endpoint (competing risk analysis). Of the 1677 VT ablation cases, 123 cases met the inclusion criteria for analysis. During a 19-month median follow-up time (interquartile range 4-43 months), 82 (66.7%) patients experienced the composite primary endpoint. There was no difference between Groups A and C with respect to the primary [hazard ratio (HR) = 1.21 (0.94-1.57), P = 0.145] or secondary [HR = 1.18 (0.91-1.54), P = 0.210] outcomes. These findings persisted after multivariate adjustments. The size of Group B (n = 13) did not permit meaningful statistical analysis. The results of post-ablation PVS do not significantly correlate with long-term outcomes in high-risk (PAINESD > 17) VT ablation patients.

Periprocedural acute haemodynamic decompensation during substrate-based ablation of scar-related ventricular tachycardia: a rare and unpredictable event.

Patients with structural heart disease (SHD) undergoing catheter ablation (CA) for ventricular tachycardia (VT) are at considerable risk of periprocedural complications, including acute haemodynamic decompensation (AHD). The PAINESD score was proposed to predict the risk of AHD. The goal of this study was to validate the PAINESD score using the retrospective analysis of data from a large-volume heart centre. Patients who had their first radiofrequency CA for SHD-related VT between August 2006 and December 2020 were included in the study. Procedures were mainly performed under conscious sedation. Substrate mapping/ablation was performed primarily during spontaneous rhythm or right ventricular pacing. 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. Acute haemodynamic decompensation triggered by CA procedure was defined as intraprocedural or early post-procedural (<12 h) development of acute pulmonary oedema or refractory hypotension requiring urgent intervention. The study cohort consisted of 1124 patients (age, 63 ± 13 years; males, 87%; ischaemic cardiomyopathy, 67%; electrical storm, 25%; New York Heart Association Class, 2.0 ± 1.0; left ventricular ejection fraction, 34 ± 12%; diabetes mellitus, 31%; chronic obstructive pulmonary disease, 12%). Their PAINESD score was 11.4 ± 6.6 (median, 12; interquartile range, 6-17). Acute haemodynamic decompensation complicated the CA procedure in 13/1124 = 1.2% patients and was not predicted by PAINESD score with AHD rates of 0.3, 1.8, and 1.1% in subgroups by previously published PAINESD terciles (<9, 9-14, and >14). However, the PAINESD score strongly predicted mortality during the follow-up. Primarily substrate-based CA of SHD-related VT performed under conscious sedation is associated with a substantially lower rate of AHD than previously reported. The PAINESD score did not predict these events. The application of the PAINESD score to the selection of patients for pre-emptive mechanical circulatory support should be reconsidered.

Targeting Wavefront Discontinuity Lines for Scar-Related Ventricular Tachycardia Ablation: A Novel Functional Substrate Ablation Approach

BackgroundThe boundaries of critical isthmuses for re-entrant ventricular tachycardia (VT) are formed by wavefront 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. ObjectivesThe 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. MethodsLate 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. ResultsIn 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 (≤15 mm) 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%. ConclusionsWADLs 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.

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&amp;lt;0.01) and a wider area of LPs (44.1cm2, 38.2cm2, and 29.4cm2, respectively; p&amp;lt;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&amp;lt;0.001, and 88%, 81%, and 68%; p&amp;lt;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

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 (&amp;gt;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.

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.

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.

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

Systematic use of half normal saline during ablation of ventricular tachycardia in structural heart disease.

Efficiency and safety of ablation using half normal saline (HNS) has been shown in refractory ventricular tachycardia (VT), but no evaluation in unselected larger populations has been made. To evaluate the efficiency and safety of systematic HNS ablation in VT ablation. All successive VT ablations in patients with structural heart disease from 2018 to 2021 used HNS in our center and were retrospectively included. One hundred seventy-seven successive VT ablation procedures using HNS have been performed in 148 patients (91% males, mean 64±12 years, ischemic cardiomyopathy 64%, left ventricular ejection fraction 38±13%). A mean of 19±7.5 min of RF was delivered, with a mean power of 44±7W. Relevant complications happened in 9% (strokes 2%, tamponades 3%, atrioventricular block during septal ablations 5%). Over a mean follow-up of 15±9 months, VT recurred in 46%. Final recurrence rate after one or several procedures was 36% (18 months follow-up). Number of VT episodes decreased from 14±35 before to 2.5±10 after ablation (p<.0001) and number of ICD shocks decreased from 4.8±6.8 to 1.5±0.8 (p=.027). Systematic use of HNS during VT ablations in patients with structural heart disease leads to long-term recurrences rates and complications in the range of what is reported using normal saline. Although controlled studies are needed for demonstrating the superiority of such attitude, the use of HNS in every scar-related VT ablation seems safe for standard cases and may be furthermore useful in case of refractory arrhythmias due to difficult-to-ablate substrates.

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

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

Post-Ablation cardiac Magnetic resonance to assess Ventricular Tachycardia recurrence (PAM-VT study).

Conducting channels (CCs) detected by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) are related to ventricular tachycardia (VT). The aim of this work was to study the ability of post-ablation LGE-CMR to evaluate ablation lesions. This is a prospective study of consecutive patients referred for a scar-related VT ablation. LGE-CMR was performed 6-12 months prior to ablation and 3-6 months after ablation. Scar characteristics of pre- and post-ablation LGE-CMR were compared. During the study period (March 2019-April 2021), 61 consecutive patients underwent scar-related VT ablation after LGE-CMR. Overall, 12 patients were excluded (4 had poor-quality LGE-CMR, 2 died before post-ablation LGE-CMR, and 6 underwent post-ablation LGE-CMR 12 months after ablation). Finally, 49 patients (age: 65.5 ± 9.8 years, 97.9% male, left ventricular ejection fraction: 34.8 ± 10.4%, 87.7% ischaemic cardiomyopathy) were included. Post-ablation LGE-CMR showed a decrease in the number (3.34 ± 1.03 vs. 1.6 ± 0.2; P < 0.0001) and mass (8.45 ± 1.3 vs. 3.5 ± 0.6 g; P < 0.001) of CCs. Arrhythmogenic CCs disappeared in 74.4% of patients. Dark core was detected in 75.5% of patients, and its presence was not related to CC reduction (52.2 ± 7.4% vs. 40.8 ± 10.6%, P = 0.57). VT recurrence after one year follow-up was 16.3%. The presence of two or more channels in the post-ablation LGE-CMR was a predictor of VT recurrence (31.82% vs. 0%, P = 0.0038) with a sensibility of 100% and specificity of 61% (area under the curve 0.82). In the same line, a reduction of CCs < 55% had sensibility of 100% and specificity of 61% (area under the curve 0.83) to predict VT recurrence. Post-ablation LGE-CMR is feasible, and a reduction in the number of CCs is related with lower risk of VT recurrence. The dark core was not present in all patients. A decrease in VT substrate was also observed in patients without a dark core area in the post-ablation LGE-CMR.

Vasovagal Responses to Human Monomorphic Ventricular Tachycardia: Hemodynamic Implications From Sinus Rate Analysis

BackgroundFactors determining hemodynamic stability during human ventricular tachycardia (VT) are incompletely understood. ObjectivesThe purposes of this study were to characterize sinus rate (SR) responses during monomorphic VT in association with hemodynamic stability and to prospectively assess the effects of vagolytic therapy on VT tolerance. MethodsThis is a retrospective analysis of patients undergoing scar-related VT ablation. Vasovagal responses were evaluated by analyzing sinus cycle length before VT induction and during VT. SR responses were classified into 3 groups: increasing (≥5 beats/min, sympathetic), decreasing (≥5 beats/min, vagal), and unchanged, with the latter 2 categorized as inappropriate SR. In a prospective cohort (n = 30) that exhibited a failure to increase SR, atropine was administered to improve hemodynamic tolerance to VT. ResultsIn 150 patients, 261 VT episodes were analyzed (29% untolerated, 71% tolerated) with median VT duration 1.6 minutes. A total of 52% of VT episodes were associated with a sympathetic response, 31% had unchanged SR, and 17% of VTs exhibited a vagal response. A significantly higher prevalence of inappropriate SR responses was observed during untolerated VT (sustained VT requiring cardioversion within 150 seconds) compared with tolerated VT (84% vs 34%; P < 0.001). Untolerated VT was significantly different between groups: 9% (sympathetic), 82% (vagal), and 32% (unchanged) (P < 0.001). Atropine administration improved hemodynamic tolerance to VT in 70%. ConclusionsNearly one-half of VT episodes are associated with failure to augment SR, indicative of an under-recognized pathophysiological vasovagal response to VT. Inappropriate SR responses were more predictive of hemodynamic instability than VT rate and ejection fraction. Vagolytic therapy may be a novel method to augment blood pressure during VT.

Procedural Adaptations to Avoid Haemodynamic Instability During Catheter Ablation of Scar-related Ventricular Tachycardia.

Classically, catheter ablation for scar-related ventricular tachycardia (VT) relied upon activation and entrainment mapping of induced VT. Advances in post-MI therapies have led to VTs that are faster and haemodynamically less stable, because of more heterogeneous myocardial fibrosis patterns. The PAINESD score is one means of identifying patients at highest risk for haemodynamic decompensation during attempted VT induction, who may, therefore, benefit from alternative ablation strategies. One strategy is to use temporary mechanical circulatory support, although this warrants formal assessment of cost-effectiveness. A second strategy is to minimise or avoid VT induction altogether by employing a family of 'substrate'-based approaches aimed at identifying VT isthmuses during sinus or paced rhythm. Substrate mapping techniques are diverse, and focus on the timing, morphology and amplitude of local ventricular electrograms - sometimes aided by advanced non-invasive cardiac imaging modalities. In this review, the evolution of VT ablation over time is discussed, with an emphasis on procedural adaptations to the challenge of haemodynamic instability.

Prevalence and risk factors of cardiac thrombus prior to ventricular tachycardia catheter ablation in structural heart disease.

Assess prevalence, risk factors, and management of patients with intra-cardiac thrombus referred for scar-related ventricular tachycardia (VT) ablation. Consecutive VT ablation referrals between January 2015 and December 2019 were reviewed (n = 618). Patients referred for de novo, scar-related VT ablation who underwent pre-procedure cardiac computed tomography (cCT) were included. We included 401 patients [61 ± 14 years; 364 male; left ventricular ejection fraction (LVEF) 40 ± 13%]; 45 patients (11%) had cardiac thrombi on cCT at 49 sites [29 LV; eight left atrial appendage (LAA); eight right ventricle (RV); four right atrial appendage]. Nine patients had pulmonary emboli. Overall predictors of cardiac thrombus included LV aneurysm [odds ratio (OR): 6.6, 95%, confidence interval (CI): 3.1-14.3], LVEF < 40% (OR: 3.3, CI: 1.5-7.3), altered RV ejection fraction (OR: 2.3, CI: 1.1-4.6), and electrical storm (OR: 2.9, CI: 1.4-6.1). Thrombus location-specific analysis identified LV aneurysm (OR: 10.9, CI: 4.3-27.7) and LVEF < 40% (OR: 9.6, CI: 2.6-35.8) as predictors of LV thrombus and arrhythmogenic right ventricular cardiomyopathy (OR: 10.6, CI: 1.2-98.4) as a predictor for RV thrombus. Left atrial appendage thrombi exclusively occurred in patients with atrial fibrillation. Ventricular tachycardia ablation was finally performed in 363 including 7 (16%) patients with thrombus but refractory electrical storm. These seven patients had tailored ablation with no embolic complications. Only one (0.3%) ablation-related embolic event occurred in the entire cohort. Cardiac thrombus can be identified in 11% of patients referred for scar-related VT ablation. These findings underscore the importance of systematic thrombus screening to minimize embolic risk.

Temporal and spatial pacemap parameters for identification of cardiac surfaces with critical sites for ventricular tachycardia.

Multisurface pacemapping may help identify the surface of interest in scar-related ventricular tachycardia (VT). This study aimed to investigate the performance of pacemap parameters for detecting critical sites through multisurface mapping. In 26 patients who underwent scar-related VT ablation, pacemap parameters including a matching score, the difference between the longest and shortest stimulus-QRS intervals (Δs-QRS), and the distance between the good pacemap sites were measured. The parameters were compared between surfaces with and without critical sites and ablation outcomes. A total of 941 pacemapat 56 surfaces targeting 35 VTs were analyzed. A greater Δs-QRS (40 vs. 8 ms, p < .001) and longer distance between two good pacemap sites (24 vs. 13 mm, p < .001) were observed on the surfaces with critical sites. A similar trend was seen in multisurface pacemapping for the same VTs (52 vs. 18 ms in Δs-QRS, p = .021; 37 vs. 12 mm in distance, p = .019), although the best pacemap scores were comparable (94 vs. 87, p = .295). The Δs-QRS > 20 ms and the distance >19 mm showed high positive likelihood ratios (19.8 and 6.1, respectively) for discriminating the surface harboring the critical site. Ablation of VTs fulfilling these parameters was successful on the surfaces, but without the required multisurface ablation. Temporal (Δs-QRS) and spatial (distance) parameters for good pacemap match sites were excellent markers for detecting the surface harboring critical sites in scar-related VT. A multisurface pacemapping can successfully identify the surface of interest.

Novel "late potential map" algorithm: Abnormal potentials and scar channels detection for ventricular tachycardia ablation.

Automated systems for substrate mapping in the context of ventricular tachycardia (VT) ablation may annotate far-field rather than near-field signals, rendering the resulting maps hard to interpret. Additionally, quantitative assessment of local conduction velocity (LCV) remains an unmet need in clinical practice. We evaluate whether a new late potential map (LPM) algorithm can provide an automatic and reliable annotation and localized bipolar voltage measurement of ventricular electrograms (EGMs) and if LCV analysis allows recognizing intrascar conduction corridors acting as VT isthmuses. In 16 patients referred for scar-related VT ablation, 8 VT activation maps and 29 high-resolution substrate maps from different activation wavefronts were obtained. In offline analysis, the LPM algorithm was compared to manually annotated substrate maps. Locations of the VT isthmuses were compared with the corresponding substrate maps in regard to LCV. The LPM algorithm had an overall/local abnormal ventricular activity (LAVA) annotation accuracy of 94.5%/81.1%, which compares to 83.7%/23.9% for the previous wavefront algorithm. The resultant maps presented a spatial concordance of 88.1% in delineating regions displaying LAVA. LAVA median localized bipolar voltage was 0.22 mV, but voltage amplitude assessment had modest accuracy in distinguishing LAVA from other abnormal EGMs (area under the curve: 0.676; p < .001). LCV analysis in high-density substrate maps identified a median of two intrascar conduction corridors per patient (interquartile range: 2-3), including the one acting as VT isthmus in all cases. The new LPM algorithm and LCV analysis may enhance substrate characterization in scar-related VT.