Clinical Ventricular Tachycardia Research Articles

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

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

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

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

Modification of deceleration zones and late potentials after ventricular tachycardias substrate ablation

Abstract Introduction Characterization of ventricular substrate is crucial during ventricular tachycardias (VT) ablation. Isochronal Late Activation Mapping (ILAM) is a recently introduced visualization tool that permit to identify areas of slow conduction (deceleration zones, DZs), these seems to well correlate with VT isthmuses. However, there are limited data about changes in this substrate after catheter ablations. Purpose To evaluate changes that occur to DZs and late potentials (LPs) after repeated ablative lesion sets. Methods High density voltage map and ILAM of the left ventricles (LV) during paced rhythm were performed in all cases. LV activation map was divided into 8 isochrones and DZ was defined as the presence of 3 isochrones within 1 cm-radius. LPs were defined as EGMs with late and fragmented components after the QRS. PES was performed at the beginning and at the end of the procedure. Each RF lesion set were applied with force-sensing irrigation catheter (target LSI 6-6.5) to abolish all the DZs and LPs discovered at baseline. After the first lesion set a re-map was performed looking for persistent DZs or LPs in the same LV segment (residual) or the appearance in a new ones (shift) in a 17-segment LV model; additional RF lesions and maps were performed only if DZs or LPs were still present in the last map. Results Of 28 VT cases considered, 9 patients with detailed LV maps and subsequent remaps were analyzed. Median age was 66 yo, 8 males, 7/9 with ischemic heart disease. In 7/9 patients clinical VTs were also induced and mapped. At baseline ILAM maps identified 24 DZs; after the first lesion set, 9 DZs were still appreciable at the same localization and 9 shifts to another LV segment (e.g. fig1). In 100% of patients at least one DZ was still appreciable at the first remap, while in 78% of patients a shift of the previous one was noted. At remap after a second lesion set 9 DZs were still present (3 residual, 6 shifts) in 33% of pts. Finally after a third lesion set only 2 DZs were still present in the same segment and then abolished. Furthermore, at baseline LPs were present in 28 LV segments, and after the first lesion set LPs were still present in 15 segments (9 residual, 6 new LPs). At first remap 78% of patients still showed LPs. After a second lesion set LPs were still visible in 6 segments (3 residual, 3 shift) in 22% of patients. In the third remap only in 2 segments could still be appreciated (1 residual, 1 shift) and finally were all abolished (summary in fig2). In 5/7 patients the clinical VT isthmus were identified in a DZ at baseline. At median FU of 6 months 7/9 patients has no VT recurrences, while there was one non-cardiovascular death. Conclusions Frequently DZs and LPs persistence is observed after first sets of lesions and additional RF deliveries are required for complete abolition. Remapping often demonstrates that both DZs and LPs move to other adjacent LV segments, likely where they were previously masked.Fig1Fig2

Ablation of hemodynamically unstable ventricular tachycardia guided by ultra-high density pacemapping and PASO correlation map, a multi-center clinical trial

Abstract Background Due to hemodynamic instability during ventricular tachycardia (VT), obtaining a complete electroanatomic map is often difficult if not impossible. Pace-mapping has progressed but still lacks precision and may not reveal sufficient details for complete ablation of the potential critical isthmus. Purpose We hypothesized that a novel strategy of combining ultra-high density (HD) pace-mapping using the PASO algorithm and Carto system to match the induced/clinical VT may aid in the reconstruction of the VT critical isthmus and effective VT ablation leading to reduce the risks of VT recurrence. Methods This was a prospective, multi-center trial conducted between January 2021 and July 2023. We enrolled 30 patients with ischemic heart disease and scar mediated recurrent VT clinically indicated for ablation. Following induction of clinical VT, we performed ultra-HD pace-mapping (5-10 mm distance between pacing points) of the identified ventricular substrate. Using PASO Module, a pacing correlation map (PCM) was constructed based on the percentage match to the induced VT. Using the PCM and the measured stimulation to electrogram intervals, the potential VT critical isthmus was reconstructed. Radiofrequency ablation was carried out to completely transect the delineated isthmus. Post ablation, repeat HD mapping and ablation was performed, until the PASO % correlation dropped from >93% to <70%, indicating at least uni-directional (orthodromic to the perceived VT circuit) conduction block through the ablation line. Follow-up data, including ICD interrogations were collected via chart review. Outcomes were compared to 60 propensity-score matched patients with an ICD who were enrolled in the Ranolazine in High-Risk Patients with Implanted Cardioverter-Defibrillators (RAID) trial who did not undergo VT ablation and served as the control group. The primary endpoint was the first occurrence of any VT at 1-year of follow-up. Results Patients enrolled had a mean age of 69 ± 9 years and 13% were women. Propensity matched patients from the RAID trial had similar baseline clinical characteristics to patients who underwent VT ablation (Table). At 1 year follow up, there was a significantly lower cumulative probability of VT/VF recurrent events in the patients who underwent PCM guided ablation as compared with the control group (17% vs 69%, respectively; log-rank p<0.001 Figure). There were no serious procedure related complications with all patients remaining free of adverse events or death at 30 days. Conclusion Our findings suggest that ablation for unstable or unmappable VT is enhanced by ultra-high density pace-mapping to reconstruct the potential VT circuit and is associated with a significantly lower rate of recurrent VT as compared with patients managed with aggressive and escalating medical therapy.Cumulative probability of ICD therapyBaseline clinical characteristics

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.

CONTINUOUS LEFT STELLATE GANGLION BLOCK DURING VT ABLATION TO SLOW VT AND IMPROVE ABLATION OUTCOME

Abstract Introduction Perioperative management of advanced patients with indication to ventricular tachycardia (VT) ablation is complex. A PAINESD score ≥ 15 was proposed to identify those who might benefit from pre–emptive mechanical cardiopulmonary support (MCS). We present a case successfully managed with continuous percutaneous left stellate ganglion block (C–PLSGB). Case A 71–year–old diabetic man with severe post–ischemic cardiomyopathy (LVEF 24%, NYHA Class III) and chronic pulmonary disease was admitted for electrical storm with multiple ICD shocks due to poorly tolerated monomorphic VT (MMVT) at 176 bpm resistant to anti–tachycardia pacing (ATP), despite ongoing chronic oral therapy with amiodarone and carvedilol. Poorly tolerated and ATP–resistant MMVTs at 170–180 bpm recurred despite intravenous (iv) amiodarone and lidocaine (20 mcg/kg/min) and oral propranolol. Ultrasound guided C–PLSGB was therefore started; lidocaine was chosen for the continuous infusion due to the short half–life, at the initial dose of 10 mg/h; 6 hours later, his poorly tolerated MMVT recurred at 167 bpm. Therefore, at first we increased iv lidocaine to 30 mcg/kg/min, without benefit, then we increased C–PLSGB at 37.5 mg/h and decreased iv lidocaine to 20 mcg/kg/min due to neurological symptoms. With this regimen, the patient stayed VT free for 2 hours, then the clinical VT recurred at 130 bpm, with good hemodynamic tolerability and ATP–response. C–PLSGB infusion was than increased to 75 mg/h, with no more VT. Endocardial VT ablation was planned. Despite a very high PAINESD score (31) we decided to avoid pre–emptive MCS. We stopped lidocaine (both iv and as C–PLSGB) 2 hours before ablation. As soon as the patient came in the EP room (before instrumentation), the clinical MMVT recurred at 133 bpm. C–PLSGB was then resumed (initially at 100 mg/h for 30 minutes, then at 37.5 mg/h). The MMVT then spontaneously recurred at 133 bpm: it was mapped and ablated in the medio–apical anterior wall, with acute VT interruption. A second VT morphology then appeared, that was mapped and ablated at a more basal site, despite a partial epicardial component of the circuit was identified. C–PLSGB was then stopped and no more VT occurred nor were induced 1 hour later. At 8 months the patient is still alive with no more VT. Conclusion C–PLSGB with individually tailored infusion rates could be used during VT ablation as a mean to reduce VT cycle length and allow for mapping without MCS.

Exploring the Full Potential of Radiofrequency Technology: A Practical Guide to Advanced Radiofrequency Ablation for Complex Ventricular Arrhythmias.

Percutaneous radiofrequency (RF) catheter ablation is an established strategy to prevent ventricular tachycardia (VT) recurrence and ICD shocks. Yet delivery of durable lesion sets by means of traditional unipolar radiofrequency ablation remains challenging, and left ventricular transmurality is rarely achieved. Failure to ablate and eliminate functionally relevant areas is particularly common in deep intramyocardial substrates, e.g. septal VT and cardiomyopathies. Here, we aim to give a practical-orientated overview of advanced and emerging RF ablation technologies to target these complex VT substrates. We summarize recent evidence in support of these technologies and share experiences from a tertiary VT centre to highlight important "hands-on" considerations for operators new to advanced RF ablation strategies. A number of innovative and modified radiofrequency ablation approaches have been proposed to increase energy delivery to the myocardium and maximize RF lesion dimensions and depth. These include measures of impedance modulation, combinations of simultaneous unipolar ablations or true bipolar ablation, intramyocardial RF delivery via wires or extendable RF needles and investigational linear or spherical catheter designs. Recent new clinical evidence for the efficacy and safety of these investigational technologies and strategies merits a re-evaluation of their role and clinic application for percutaneous VT ablations. Complexity of substrates targeted with percutaneous VT ablation is increasing and requires detailed preprocedural imaging to characterize the substrate to inform the procedural approach and selection of ablation technology. Depending on local experience, options for additional and/or complementary interventional treatments should be considered upfront in challenging substrates to improve the success rates of index procedures. Advanced RF technologies available for clinical VT ablations include impedance modulation via hypotonic irrigation or additional dispersive patches and simultaneous unipolar as well as true bipolar ablation. Promising investigational RF technologies involve an extendable needle RF catheter, intramyocardial RF delivery over intentionally perforated wires as well as a variety of innovative ablation catheter designs including multipolar linear, spherical and partially insulated ablation catheters.

Therapeutic potential of conduction system pacing as a method for improving cardiac output during ventricular tachycardia.

Ventricular tachycardia (VT) reduces cardiac output through high heart rates, loss of atrioventricular synchrony, and loss of ventricular synchrony. We studied the contribution of each mechanism and explored the potential therapeutic utility of His bundle pacing to improve cardiac output during VT. Study 1 aimed to improve the understanding of mechanisms of harm during VT (using pacing simulated VT). In 23 patients with left ventricular impairment, we recorded continuous ECG and beat-by-beat blood pressure measurements. We assessed the hemodynamic impact of heart rate and restoration of atrial and biventricular synchrony. Study 2 investigated novel pacing interventions during clinical VT by evaluating the hemodynamic effects of His bundle pacing at 5bpm above the VT rate in 10 patients. In Study 1, at progressively higher rates of simulated VT, systolic blood pressure declined: at rates of 125, 160, and 190bpm, -22.2%, -42.0%, and -58.7%, respectively (ANOVA p < 0.0001). Restoring atrial synchrony alone had only a modest beneficial effect on systolic blood pressure (+ 3.6% at 160bpm, p = 0.2117), restoring biventricular synchrony alone had a greater effect (+ 9.1% at 160bpm, p = 0.242), and simultaneously restoring both significantly increased systolic blood pressure (+ 31.6% at 160bpm, p = 0.0003). In Study 2, the mean rate of clinical VT was 143 ± 21bpm. His bundle pacing increased systolic blood pressure by + 14.2% (p = 0.0023). In 6 of 10 patients, VT terminated with His bundle pacing. Restoring atrial and biventricular synchrony improved hemodynamic function in simulated and clinical VT. Conduction system pacing could improve VT tolerability and treatment.

Catheter ablation of ventricular tachycardia in patients with arrhythmogenic right ventricular cardiomyopathy and biventricular involvement.

Catheter ablation of ventricular tachycardia (VT) improves VT-free survival in 'classic' arrhythmogenic right ventricular cardiomyopathy (ARVC). This study aims to investigate electrophysiological features and ablation outcomes in patients with ARVC and biventricular (BiV) involvement. We assembled a retrospective cohort of definite ARVC cases with sustained VTs. Patients were divided into the BiV (BiV involvement) group and the right ventricular (RV) (isolated RV involvement) group based on the left ventricular systolic function detected by cardiac magnetic resonance. All patients underwent electrophysiological mapping and VT ablation. Acute complete success was non-inducibility of any sustained VT, and the primary endpoint was VT recurrence. Ninety-eight patients (36 ± 14 years; 87% male) were enrolled, including 50 in the BiV group and 48 in the RV group. Biventricular involvement was associated with faster clinical VTs, a higher VT inducibility, and more extensive arrhythmogenic substrates (all P < 0.05). Left-sided VTs were observed in 20% of the BiV group cases and correlated with significantly reduced left ventricular systolic function. Catheter ablation achieved similar acute efficacy between these two groups, whereas the presence of left-sided VTs increased acute ablation failure (40 vs. 5%, P = 0.012). Over 51 ± 34 months [median, 48 (22-83) months] of follow-up, cumulative VT-free survival was 52% in the BiV group and 58% in the RV group (P = 0.353). A multivariate analysis showed that younger age, lower RV ejection fraction (RVEF), and non-acute complete ablation success were associated with VT recurrence in the BiV group. Biventricular involvement implied a worse arrhythmic phenotype and increased the risk of left-sided VTs, while catheter ablation maintained its efficacy for VT control in this population. Younger age, lower RVEF, and non-acute complete success predicted VT recurrence after ablation.

Epicardial ventricular tachycardia ablation: safety and efficacy of access and ablation using low-iodine content.

Epicardial ablation has become an integral part of the treatment of ventricular tachycardias (VT). This study reports the safety of epicardial access as well as the efficacy of epicardial ablation of structural heart disease in a tertiary single-center experience. Between January 2016 and February 2022, consecutive patients undergoing an epicardial access for VT ablation were included. Different puncture techniques and occurrence of epicardial access-related complications as well as the safety of ablation using non-ionic 5% dextrose in water (D5W) compared to standard 0.9% normal saline (NS) irrigation were analyzed. VT recurrence rates during a mean follow-up of 37 ± 23months were reported. In total, 197 patients undergoing a total of 239 procedures were included (59.8 ± 15.3years, 86% males). A total of 154 patients (78%) had non-ischemic cardiomyopathies with a mean LVEF of 37 ± 14. Anterior-oriented epicardial access was aimed for in all cases and was successful in 217 (91%) of all procedures, whereas access was achieved in 19 procedures (8%) only using an inferior oriented access and in three procedures (1%) using surgical access due to severe adhesions or anatomical requirements. Overall epicardial puncture-related complications occurred in 18 (8%) of all procedures with minor pericardial bleeding in nine, pericardial tamponade in one, pneumothorax in five, pneumopericardium in one, and abdominal puncture in two cases. Presence of adhesions could be identified as the only independent predictor of epicardial access-related complications. D5W was used in 79 cases and regular 0.9% saline in 117 procedures. No differences were seen regarding acute ablation success or complications. During follow-up, 47% of all patients were free from any VTs (56% D5W vs. 40% NS; log-rank p = 0.747) and 92% of clinical VTs (98% D5W vs. 91% NS; log-rank p = 0.139). In this large single-centre experience, epicardial access and ablation were safe and feasible. Although long-term clinical VT recurrence rates were low, overall VT recurrences as well as mortality were high advocating for a highly experienced, interdisciplinary approach including intense management of underlying cardiac disease/heart failure. Routine usage of D5W was safe and associated with comparable short- or long-term clinical or overall VT freedom.

Clinical and Laboratory Predictors of Long-Term Outcomes after Catheter Ablation for a Ventricular Electrical Storm.

Ventricular electrical storm (VES) is characterized by the occurrence of multiple episodes of sustained ventricular arrhythmias (VA) over a short period of time. Radiofrequency ablation (RFA) has been reported as an effective treatment in patients with ventricular tachycardia (VT). The aim of the present study was to indicate the short-term and long-term predictors of recurrent VA after RFA was performed due to VES. A retrospective, single-centre study included patients, who had undergone RFA due to VT between 2012 and 2021. In terms of the short-term (at the end of RFA) effectiveness of RFA, the following scenarios were distinguished: complete success: inability to induce any VT; partial success: absence of clinical VT; failure: inducible clinical VT. In terms of the long-term (12 months) effectiveness of RFA, the following scenarios were distinguished: effective ablation: no recurrence of any VT; partially successful ablation: VT recurrence; ineffective ablation: VES recurrence. The study included 62 patients. Complete short-term RFA success was obtained in 77.4% of patients. The estimated cumulative VT-free survival and VES-free survival were, respectively, 28% and 33% at the 12-month follow-up. Ischemic cardiomyopathy and complete short-term RFA success were predictors of long-term RFA efficacy. Neutrophil to lymphocyte ratio (NLR) and GFR <60 mL/min/1.73 m2 were associated with VES recurrence. NLR ≥2.95 predicted VT and/or VES recurrence with a sensitivity of 66.7% and specificity of 72.2%. Ischemic cardiomyopathy and short-term complete success of RFA were predictors of no VES recurrence during the 12-month follow-up, while NLR and GFR <60 ml/min/1.73 m2 were associated with VES relapse.

Impact of repeat ablation of ventricular tachycardia in patients with structural heart disease.

Recurrences of ventricular tachycardia (VT) after initial catheter ablation is a significant clinical problem. In this study, we report the efficacy and risks of repeat VT ablation in patients with structural heart disease (SHD) in a tertiary single centre over a 7-year period. Two hundred ten consecutive patients referred for repeat VT ablation after previous ablation in our institution were included in the analysis (53% ischaemic cardiomyopathy, 91% males, median age 65 years, mean left ventricular ejection fraction 35%). After performing repeat ablation, the clinical VTs were acutely eliminated in 82% of the patients, but 46% of the cohort presented with VT recurrence during the 25-month follow-up. Repeat ablation led to a 73% reduction of shock burden in the first year and 61% reduction until the end of follow-up. Similarly, VT burden was reduced 55% in the first year and 36% until the end of the study. Fifty-two patients (25%) reached the combined endpoint of ventricular assist device implantation, heart transplantation, or death. Advanced New York Heart Association functional class, anteroseptal substrate, and periprocedural complication after repeat ablation were associated with worse prognosis independently of the type of cardiomyopathy. While complete freedom from VT after repeat ablation in SHD was difficult to achieve, ablation led to a significant reduction in VT and shock burden. Besides advanced heart failure characteristics, anteroseptal substrate and periprocedural complications predicted a worse outcome.

Machine-Learning-Based Prediction of 1-Year Arrhythmia Recurrence after Ventricular Tachycardia Ablation in Patients with Structural Heart Disease.

Ventricular tachycardia (VT) recurrence after catheter ablation remains a concern, emphasizing the need for precise risk assessment. We aimed to use machine learning (ML) to predict 1-month and 1-year VT recurrence following VT ablation. For 337 patients undergoing VT ablation, we collected 31 parameters including medical history, echocardiography, and procedural data. 17 relevant features were included in the ML-based feature selection, which yielded six and five optimal features for 1-month and 1-year recurrence, respectively. We trained several supervised machine learning models using 10-fold cross-validation for each endpoint. We observed 1-month VT recurrence was observed in 60 (18%) cases and accurately predicted using our model with an area under the receiver operating curve (AUC) of 0.73. Input features used were hemodynamic instability, incessant VT, ICD shock, left ventricular ejection fraction, TAPSE, and non-inducibility of the clinical VT at the end of the procedure. A separate model was trained for 1-year VT recurrence (observed in 117 (35%) cases) with a mean AUC of 0.71. Selected features were hemodynamic instability, the number of inducible VT morphologies, left ventricular systolic diameter, mitral regurgitation, and ICD shock. For both endpoints, a random forest model displayed the highest performance. Our ML models effectively predict VT recurrence post-ablation, aiding in identifying high-risk patients and tailoring follow-up strategies.

Abstract 16093: Hemodynamic Implications of Transseptal Access for Ventricular Tachycardia Ablation in Patients With Left Ventricular Assist Devices

Introduction: Ventricular tachycardia (VT) is common in patients with left ventricular assist devices (LVAD), and catheter ablation can be an effective treatment strategy. Although transseptal approach for LV mapping and ablation is often preferred, iatrogenic atrial septal defect (ASD) after transseptal access may theoretically result in clinically significant right-to-left shunting. The short- and long-term implications of transseptal puncture, including hemodynamic changes in LVAD patients, remain uncertain. Methods and Results: From 2013-2023, 15 LVAD patients (age 68.5±12 years; 2 women) underwent 18 VT ablation procedures with single transseptal access for LV ablation without ASD closure afterwards. Clinical VT was eliminated in 83%. No patients had prior PFO/ASD; Mean RVSP was 45mmHg, 6 (40%) had pulmonary hypertension, and 8 (53.3%) had moderate or severe RV dysfunction. All patients had previously failed at least 1 antiarrhythmic drug (amiodarone 100%; sotalol 33%; mexiletine 94%). Procedural complications occurred in 3 procedures (all related to vascular access, none directly related to transseptal access; 1 patient with interrupted IVC requiring transhepatic access had bleeding due to transection of intercostal artery requiring arterial embolization). Post-procedure echocardiograms (n=14; mean time to echo 90±116 days) showed no intra-cardiac shunting or persistent ASD. Right heart catheterization (pre: n=12; post: n=8, at mean follow-up 187±243 days) showed similar pre- and post-ablation RA pressures (11.6 vs 14.9 mmHg, p =0.24) and wedge pressures (14.9 vs 20.4 mmHg, p =0.8) with absence of significant shunting based on pre- and post-ablation arterial (95.2% vs 97.7%, p =0.06) and PA oxygen saturations (56.5% vs 51.3%, p =0.29). No episodes of clinically significant hypoxia occurred after ablation. Conclusion: Transseptal access for VT ablation can be safely performed in LVAD patients and is unlikely to result in clinically or hemodynamically significant residual shunting over long-term follow-up. Therefore, empiric ASD closure after transseptal access in all LVAD patients is likely unnecessary.

Sinus rhythm QRS morphology reflects right ventricular activation and anatomical ventricular tachycardia isthmus conduction in repaired tetralogy of Fallot

Patients with repaired tetralogy of Fallot (TOF) are at risk for ventricular tachycardia (VT) related to well-described anatomical isthmuses. The purpose of this study was to explore QRS morphology as an indicator of anatomical isthmus conduction. Patients with repaired TOF and complete right bundle branch block referred for transcatheter pulmonary valve replacement (PVR) or presenting with sustained VT underwent comprehensive 3-dimensional mapping in sinus rhythm. Electrocardiographic characteristics were compared to right ventricular (RV) activation and anatomical isthmus conduction properties. Twenty-two patients (19 pre-pulmonary valve replacement and 3 clinical VT) underwent comprehensive 3-dimensional mapping (median 39 years; interquartile range [IQR] 27-48 years; 55% male). Septal RV activation (median 40 ms; IQR 34-46 ms) corresponded to the nadir in lead V1 and free wall activation (median 71 ms; IQR 64-81 ms) to the upstroke of the R' wave. Patients with isthmus block between the pulmonary annulus and the ventricular septal defect and between the ventricular septal defect and the tricuspid annulus (when present), were more likely to demonstrate lower amplitude R' waves in lead V1 (5.8 mV vs 9.4 mV; P = .005), QRS fragmentation in lead V1 (15 [94%] vs 2 [13%]; P < .001), and terminal S waves in lead aVF (15 [94%] vs 6 [40%]; P < .001) than those with intact conduction. During catheter ablation, identical QRS changes developed with isthmus block. For patients with repaired TOF, the status of septal isthmus conduction was associated with sinus rhythm QRS morphology. Low-amplitude, fragmented R' waves in lead V1 and terminal S waves in the inferior leads were related to septal isthmus conduction abnormalities, providing a mechanistic link between RV activation and common electrocardiographic findings.

Utility of Substrate Mapping Using Extrasystole to Localise Comprehensive Ventricular Tachycardia Circuits: Results From Intra-operative Mapping Studies.

Substrate mapping-based identification of all ventricular tachycardia (VT) circuits (diastolic activation), including partial and complete diastolic circuits in clinical and nonclinical VT, could be beneficial in guiding VT ablation to prevent VT recurrence. The utility of extrasystole induced late potentials has not been compared with late potentials in sinus rhythm (SR) and right ventricular pacing (RVp). Intraoperative simultaneous panoramic endocardial mapping of 21 VTs in 16 ischemic heart disease patients was performed with the use of a 112-bipole endocardial balloon. The decrement of near-field electrogram later than surface QRS during extrasystole (eLP) was studied. Patients had a mean age of 52 ± 9 years and were predominantly (75%) male. The mean sensitivity of eLP (0.75 [95% confidence interval [CI] 0.72-0.78]) to detect VT circuits was better than SR (0.33 [0.30-0.36]; P < 0.001) and RVp (0.36 [0.33-0.39]; P < 0.001) without significant differences in specificity, eLP (0.77 [0.74-0.81], SR (0.82 [0.80-0.84]; P= 0.23), and RVp (0.81 [0.78-0.83]; P= 0.11). Both negative (NPV) and positivie (PPV) predictive values were significantly better for eLP mapping. The mean NPV was 0.77 (95% CI 0.74-0.81), 0.57 (0.55-0.59), and 0.58 (0.55-0.61) for eLP, SR, and RVp, respectively (P < 0.0001). PPV was 0.75 (95% CI 0.72-0.78), 0.63 (0.59-0.67), and 0.63 (0.59-0.67) for eLP, SR, and RVp, respectively (P < 0.001). Overall diagnostic performance (area under the receiver operating characteristic curve) was significantly better for eLP (0.85 [95% CI 0.80-0.90] compared with SR (0.63 [0.56-0.72]; P < 0.001) or RVp (0.61 [0.52-0.74]; P < 0.001). Evoked late potential mapping is a better tool to detect comprehensive diastolic circuits activated during VT, compared with eLP mapping in sinus rhythm or RV pacing.

High-power radiofrequency ablation for ventricular tachycardia in patients with structural heart disease: one-year follow-up data from the multicenter prospective registry

Background: The outcomes of ventricular tachycardia (VT) ablation in patients with structural heart disease (SHD) are not ideal. High-power radiofrequency ablation (RFA) may have a long-term beneficial effect in this patient cohort.Objective: To evaluate the safety, early and long-term efficacy of high-power RFA for VT and concomitant SHD in a multicenter prospective registry.Methods: Our study included a total of 63 patients (66,7% of them were men; median age was 61.0 [51.0-66.5] years) with ischemic heart disease and drug-resistant VT who were scheduled for RFA (50 W). Non-fluoroscopic 3D mapping systems were used for bipolar and activation mapping with standard settings. The safety end point included perioperative complications, such as death, hemopericardium, stroke, myocardial infarction, electrical storm, and vascular complications. The efficacy end points included VT non-inducibility at the end of ablation and freedom from VT at 12 months of the follow-up. The secondary end points were changes in implantable cardioverter-defibrillator (ICD) therapy, sonographic findings, and number of hospital admissions.Results: All patients underwent VT ablation under general sedation. One clinical VT was induced in 96.8% of the patients before ablation. After ablation no clinical VTs were induced (P &lt; .0001 vs baseline). No perioperative complications were observed. Freedom from VT without antiarrhythmic drugs was 82.6% at 12 months of the follow-up. The number of ICD therapies significantly decreased at 12 months of the follow-up compared with baseline (3.2% vs 31.7%, respectively; P = .0001). The left ventricular ejection fraction increased from 48.7% ± 14.7% at baseline to 50.3% ± 11.9% at 12 months of the follow-up (P = .038). There was a statistically significant decrease in hospital admission rate before and after ablation (from 2 [range: 0-12] to 0 [range: 0-3], P &lt; .0001).Conclusion: High-power RFA for VT in patients with ischemia demonstrated its safety and high perioperative and long-term efficacy, which were linked to clinical improvement. Further randomized studies will help introduce this VT ablation approach into routine clinical practice. Received 5 September 2022. Revised 16 February 2023. Accepted 31 May 2023. Funding: The study did not have sponsorship. Conflict of interest: The authors declare no conflict of interest. Contribution of the authorsConception and study design: S.V. Korolev, A.Sh. Revishvili, A.B. Romanov Data collection and analysis: S.V. Korolev, E.A. Artyukhina, V.V. Shabanov, O.V. Sapelnikov, A.V. Tsyganov, A.Sh. Revishvili, A.B. RomanovStatistical analysis: S.V. Korolev Drafting the article: S.V. Korolev Critical revision of the article: A.B. Romanov, A.Sh. Revishvili Final approval of the version to be published: S.V. Korolev, E.A. Artyukhina, V.V. Shabanov, O.V. Sapelnikov, A.V. Tsyganov, A.Sh. Revishvili, A.B. Romanov

Optimisation of decrementing evoked potential mapping for functional substrate identification in ischaemic ventricular tachycardia ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background Decrement evoked potential (DeEP) mapping has been shown to identify the functional substrate critical to the Ventricular Tachycardia (VT) circuit with a higher specificity than late potential mapping.[1] However, there is limited data on methodological optimisation of this technique which could identify more relevant regions of conduction delay and functional block that occurs during clinical VT by activating the substrate at coupling intervals closer to the VT cycle length (CL). Purpose The goal of this study was to investigate a range of short coupled extra-stimuli and decrement thresholds to improve DeEP mapping target identification in patients with ischaemic cardiomyopathy. Methods Thirteen patients (70±12 years) underwent VT ablation. Mapping was performed with the Advisor HD Grid multipolar catheter. Maps were generated using omnipolar electrograms (EGMs). DeEP mapping was performed using 3 different extra-stimuli (S2) sequentially in each case: (1) 400 ms (DeEP-400); (2) VT cycle length (VTCL); (3) ventricular effective refractory period (VERP) + 20 ms. For each of the DeEP-400, DeEP-VTCL and DeEP-VERP maps, the definition of a DeEP was altered from the standard 10 ms decrement to multiple thresholds of 10 ms to 50 ms in 10 ms increments (figure 1). DeEP maps were compared to the VT exit site identified with VT activation maps. All patients underwent DeEP-400 focused ablation. Results All patients had 1 clinical VT (VTCL = 353 ± 48 ms; VERP + 20 ms = 300 ± 20 ms). Mean left ventricular ejection fraction was 30 ± 12 %. Sensitivity and specificity analyses (figure 2) show the optimal threshold for defining a DeEP is with an EGM prolongation of ≥ 20 ms for the DeEP-400 (sens. 77%, spec. 79%, ROC AUC 0.84), DeEP-VTCL (sens. 77%, spec. 79%, ROC AUC 0.83) and DeEP-VERP (sens. 69%, spec. 74%, ROC AUC 0.76) maps. Proportional to total mapped area, the DeEP-400 map area was significantly smaller than DeEP-VERP map area (19.0 ± 7.6 % vs 26.4 ± 14.3%; p=0.02). Delivering the S2 at the conventional VERP + 20 ms using a 10 ms decrement definition yielded a sensitivity of 84.6% and a specificity of 62.0% with a target ablation area of 33.9 cm2. With the optimised protocol of delivering the S2 at 400 ms using a 20 ms decrement definition, the sensitivity remains high at 76.9% with an improved specificity of 79.0%, thus reducing the ablation target area by 50% to 16.8 cm2. 92% patients were free of any VT after DeEP-400 guided ablation at 6-month median follow-up. Conclusion In this prospective, mechanistic study utilising omnipolar technology to explore a range of S2 extra-stimuli and decrement thresholds, DeEPs were optimally defined by a conduction delay of ≥ 20 ms with an S2 extra-stimulus coupling interval of 400 ms or VTCL to more accurately localise the VT exit site. This optimised DeEP mapping protocol further refines identification of the critical myocardial sites involved in the initiation and maintenance of VT.

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

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

The effect of scar imaging quality on in-silico pace-mapping of post-infarction ventricular tachycardia

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): Wellcome Trust and British Heart Foundation. Background In-silico pacing mapping is a technique which involves using an anatomically-personalised image-based computational model to generate a ‘virtual’ clinical pace map for enhanced pre-procedural ablation planning of post-infarction ventricular tachycardia (VT). Utilising, as it does, a direct clinical ECG (or implanted device) recording of the clinical VT in order to construct the map, it has a number of advantages over other computational methods which attempt to simulate patient-specific VTs to identify ablation targets. However, accurate model construction relies on adequate scar imaging data, which may not be available with current clinical cardiac MR (CMR) sequences. Purpose To investigate the impact of scar imaging quality on the ability of in-silico pace-mapping to determine the VT origin. Methods VTs were simulated in three post-infarction porcine heart models reconstructed from high resolution (1mm isotropic) contrast-enhanced CMR data. Visual analysis of the VT circuits was performed to identify the VT site of origin (exit site) in each case (as the gold standard). The ECG of each simulated VT was computed and used as input for the construction of the in-silico virtual pace-mapping approach. Prior to pace map construction, the scar anatomy was modified to represent three different levels of imaging resolution: high resolution scar mapping (default); low resolution scar (representing standing clinical CMR sequences), obtained by performing dilation and erosion in the scar to close all inner pathways; and, finally, no scar (cardiac anatomy only, representing CT-based reconstructions). In-silico pace-mapping was performed by pacing the heart in N = 1000 sites from randomly chosen locations, on both surfaces and intramurally, within close proximity (&amp;lt;5mm) from the infarct. ECG signals computed following each paced activation wavefront were compared to the VT ECG through correlation analysis to construct the virtual pace map. The distance d between the VT exit site and the pacing location with the strongest correlation was also computed. Results As can be seen in Figure 1, correlation between VT and paced ECGs was found to be strongest at pacing locations near the VT exit site in all models. Correlation coefficients were similar in value and distribution in models with high- (min: -0.49±0.27 and max: 0.92±0.05) and low-resolution scars (min: -0.46±0.29 and max: 0.93±0.05). While the correlation map in the absence of scar had smaller values when compared to the other two models (min: -0.50±0.24 and max: 0.71±0.09), the VT exit was still located near the pacing location with the strongest correlation: d = 9.47±2.83 (high-res), d = 6.63±6.35mm (low-res) and d = 18.60±7.10mm (no scar). Conclusion In-silico pace-mapping successfully detected the VT exit sites regardless the resolution of the scar. This finding suggest that the level of infarct anatomical detail has a minor effect on simulated paced activation to localize VT ablation.