Utility of Prolonged Duration Endocardial Ablation for Ventricular Arrhythmias Originating From the Left Ventricular Summit

Radiofrequency-aided venous ethanol vs optimized radiofrequency for primary and repeat ablation of left ventricular summit arrhythmias: A propensity score-matched comparison

BACKGROUND

Radiofrequency (RF) ablation of left ventricular summit arrhythmias (LVSAs) is challenging and may fail due to the anatomical inaccessibility of the substrate. Coronary venous ethanol ablation (CVEA) has been suggested as an alternative ablation strategy for drug- and RF-refractory LVSA.

OBJECTIVE

This study compared venous ethanol with or without adjunctive RF (CVEA ± RF) vs optimized RF (ORF) for primary or repeat ablation of LVSA.

METHODS

After propensity score matching, 41 of 43 patients treated with CVEA ± RF were compared to 41 of 93 patients who underwent ORF ablation.

RESULTS

Patient characteristics were similar for both groups (77% male, median age 65 [56-71] years, median 2 [1-2] previous ablation procedures). The mean pace-match was 97.1 ± 1.7% for venous vs 94.7 ± 3% for conventional mapping (P < .0001). The earliest presystolic signal was -41 ± 11 ms for venous vs -28 ± 10 ms conventional mapping (P < .0001). Acute procedural success was 95% vs 83% for CVEA ± RF and ORF respectively (P = .077). Ventricular premature beat burden decreased by 58% after ORF and by 91% following CVEA ± RF (P = .041). In patients with ventricular tachycardia, ventricular tachycardia burden decreased by 96% after CVEA ± RF (P < .0001), while a 70% reduction was not significant for ORF. After a median follow-up of 24 (12-58) months, 20% of CVEA ± RF patients recurred as compared to 54% following ORF (P = .002). Following ORF ablation, 1 patient developed pericarditis, 1 patient tamponade, and 1 patient atrioventricular block. In the CVEA ± RF group, one patient suffered a vascular access complication. No patients died.

CONCLUSION

When venous mapping supports intramural origin, RF-aided venous ethanol ablation is an effective strategy for the treatment of LVSA also when compared to ORF ablation.

3D mapping quest: How far can we see with recent advances in 3D mapping?

Recent advances in three-dimensional (3D) ultra-high-density mapping systems have uncovered previously unknown mechanisms underlying various arrhythmias. This clinical review, titled "3D Mapping Quest," focuses on the recently uncovered mechanisms of four types of arrhythmias. (1) To elucidate the precise mechanisms underlying atrial fibrillation (AF), ultra-high-density mapping with adequate spatial and temporal resolution is essential. Various mapping systems have been employed to investigate the chaotic activation during AF. The question remains: Is the AF driver characterized by focal activation or rotational activation? A novel mapping strategy is expected to provide the answer. (2) In atrioventricular nodal reentrant tachycardia (AVNRTs), 3D mapping revealed that the pivot point of activation at the lower end of a functional block line extending vertically downward from the His-bundle area, or a fractionated potential observed during AVNRT, can be targeted for slow pathway ablation. Either approach may prevent unnecessary radiofrequency applications while maintaining the success rate. (3) In premature ventricular contractions originating from the left ventricular summit, 3D mapping has enabled precise identification of the optimal endocardial ablation sites. By performing long-duration ablation at these optimal endocardial sites, the ablation outcomes have improved. (4) In scar-related reentrant ventricular tachycardia (VT), substrate mapping focusing on wavefront discontinuity has allowed for the identification of specific ablation targets within the broad scar. High-density VT activation mapping has revealed the complexity of the circuit structure, such as the 3D VT circuit. The VT circuit delineation on the cardiac surface is conceptualized as a cross-section of a hyperboloid model. Thus, it is anticipated that integrating histological and electrophysiological insights with advanced ultra-high-density mapping technologies will further facilitate a comprehensive understanding of the mechanisms.

Contemporary Trends in Pulsed Field Ablation for Cardiac Arrhythmias

Pulsed field ablation (PFA) is a catheter-based procedure that utilizes short high voltage and short-duration electrical field pulses to induce tissue injury. The last decade has yielded significant scientific progress and quickened interest in PFA as an energy modality leading to the emergence of the clinical use of PFA technologies for the treatment of atrial fibrillation. It is generally agreed that more research is needed to improve our biophysical understanding of PFA for clinical cardiac applications as well as its potential as a potential alternative energy source to thermal ablation modalities for the treatment of other arrhythmias. In this review, we discuss the available preclinical and clinical evidence for PFA for atrial fibrillation, developments for ventricular arrhythmia (VA) ablation, and future perspectives.

Anatomical vs. electrophysiological approach for ablation of premature ventricular contractions originating from the left ventricular summit (ISESHIMA-SUMMIT Study)

AIMS

Catheter ablation (CA) of idiopathic ventricular arrhythmias (VAs) from the epicardial left ventricular summit is challenging. The endocardial approach targets two sites: the endocardial closest site (ECS) to the epicardial earliest activation site (epi-EAS) and the endocardial earliest activation site (endo-EAS). We aimed to differentiate between cases where CA at the ECS was effective and where CA at the endo-EAS yielded success.

METHODS AND RESULTS

Fifty-eight patients (47 men; age 60 ± 13 years) were analysed with VAs in which the EAS was observed in the coronary venous system (CVS). Overall, VAs were successfully eliminated in 42 (72%) patients: 8 in the CVS, 8 where the ECS matched with the endo-EAS, 11 at the ECS, and 15 at the endo-EAS. A successful ECS ablation was associated with a shorter epi-EAS-ECS distance (10.2 ± 4.7 vs. 18.8 ± 5.3 mm; P < 0.001) and shorter epi-EAS-left main coronary trunk (LMT) ostial distance (20.3 ± 7.6 vs. 30.3 ± 8.4 mm; P = 0.005), with optimal cut-off values of ≤12.6 and ≤24.0 mm, respectively. A successful endo-EAS ablation was associated with an earlier electrogram at the endo-EAS [23 (8, 36) vs. 15 (0, 19) ms preceding the QRS; P < 0.001] and shorter epi-EAS-endo-EAS interval [6 (1, 8) vs. 22 (12, 25) ms; P < 0.001], with optimal cut-off values of ≥18 and ≤9 ms, respectively.

CONCLUSION

Shorter anatomical distances between the epi-EAS and ECS, and between the epi-EAS and LMT ostium, predict a successful ECS ablation. The prematurity of the endo-EAS electrogram and a shorter interval between the epi-EAS and endo-EAS predicted a successful endo-EAS ablation.

Anatomical approach to suppression of para-Hisian ventricular arrhythmias with changes in QRS morphology after ablation at the earliest activation site

BACKGROUND

The anatomical approach for the management of para-Hisian ventricular arrhythmias (VAs) with QRS morphological changes after catheter ablation (CA) has not been well investigated.

OBJECTIVE

We aimed to evaluate the electrocardiographic and electrophysiological findings and ablation outcomes of para-Hisian VAs with QRS morphological changes after CA.

METHODS

Of the 30 patients who underwent CA for para-Hisian VAs at 4 institutions, 10 (33%) had QRS morphological changes after ablation. All 10 patients underwent an anatomical approach, targeting the site anatomically opposite to the site where the QRS morphology had been changed by ablation. We investigated the safety and efficacy of the anatomical approach.

RESULTS

Of the 10 patients evaluated, the approach was switched from the right ventricular septum to the left ventricular septum/aortic root in 7 (70%) (RL group) whereas 3 (30%) underwent left-to-right switches (LR group). After CA, the precordial transition zone tended to be earlier in the RL group and later in the LR group. In the RL group, successful VA suppression was achieved, despite suboptimal pace map concordance from the left side or a relatively delayed earliest activation time. Of the 10 patients who underwent an anatomical approach, 8 (80%) had procedural success, and ablation was discontinued in 1 (10%) because of the risk of atrioventricular block.

CONCLUSION

The anatomical approach showed promising results regarding safety and efficacy. Therefore, it should be considered when QRS morphological changes are observed during or after CA of para-Hisian VAs.

Left Ventricular Summit Arrhythmias: State-of-the-Art Review of Anatomy, Mapping, and Ablation Strategies

The left ventricular summit (LVS) is the most common site of epicardial arrhythmias. Ablation of LVS arrhythmias continue to pose a challenge to the electrophysiologist because of its complex and intimate anatomical location. In this review, we undertake a detailed examination of the intricate anatomy of the LVS alongside a comprehensive synthesis of mapping and ablation strategies used to treat LVS arrhythmias.

Bipolar Ablation From the Anterior Interventricular Vein to the Left Ventricle

Ventricular tachycardia from the left ventricular summit can be challenging for catheter ablation due to difficult accessibility and proximity to coronary arteries. This paper presents a case of premature ventricular contraction-induced ventricular tachycardia from the left ventricular summit that was ablated using bipolar radiofrequency ablation from the anterior interventricular vein and adjacent left ventricular endocardium.

Technological advances in ventricular tachycardia catheter ablation: the relentless quest for novel solutions to old problems

BACKGROUND

Several novel technologies allowing catheter ablation (CA) with a favorable safety/efficacy profile have been recently developed, but not yet extensively clinically tested in the setting of ventricular tachycardia CA.

METHODS

In this technical report, we overview technical aspects and preclinical/clinical information concerning the application of three novel CA technologies in the ventricular milieu: a pulsed field ablation (PFA) generator (CENTAURI™, Galaxy Medical) to be used with linear, contact force-sensing radiofrequency ablation catheters; a contact force-sensing radiofrequency ablation catheter equipped with six thermocouples and three microelectrodes (QDOT Micro™, Biosense-Webster), allowing high-resolution mapping and temperature-controlled CA; and a flexible and mesh-shaped irrigation tip, contact force-sensing radiofrequency ablation catheter (Tactiflex, Abbott). We also report three challenging VT cases in which CA was performed using these technologies.

RESULTS

The CENTAURI system was used with the Tacticath™ (Abbott) ablation catheter to perform ventricular PFA in a patient with advanced heart failure, electrical storm, and a deep intramural septal substrate. Microelectrode mapping using QDOT Micro™ helped to refine substrate assessment in a VT patient with congenitally corrected transposition of the great arteries, and allowed the identification of the critical components of the VT circuit, which were successfully ablated. Tactiflex™ was used in two challenging CA cases (one endocardial and one epicardial), allowing acute and mid-term control of VT episodes without adverse events.

CONCLUSION

The ideation and development of novel technologies initially intended to treat atrial arrhythmias and successfully implemented in the ventricular milieu is contributing to the progressive improvement in the clinical benefits derived from VT CA, making this procedure key for successful management of increasingly complex patients.

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

INTRODUCTION

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Bipolar ablation involving coronary venous system for refractory left ventricular summit arrhythmias

Background

Catheter ablation of premature ventricular complexes (PVCs) and ventricular tachycardia (VT) from the left ventricular summit (LVS) may require advanced ablation techniques. Bipolar ablation from the coronary veins and adjacent endocardial structures can be effective for refractory LVS arrhythmias.

Objective

The aim of this study was to investigate the outcomes of bipolar ablation performed between the coronary venous system and adjacent endocardial left ventricular outflow tract (LVOT) or right ventricular outflow tract (RVOT).

Methods

This multicenter study included consecutive patients with LVS PVC/VT who underwent bipolar ablation between the anterior interventricular vein (AIV) or great cardiac vein (GCV) and the endocardial LVOT/RVOT after failed unipolar ablation. Ablation was started with powers of 10-20 W and uptitrated to achieve an impedance drop of at least 10%. Angiography was performed in all cases to confirm a safe distance (>5 mm) of the catheter from the major coronary arteries.

Results

Between 2013 and 2023, bipolar radiofrequency ablation between the AIV/GCV and the adjacent LVOT/RVOT was attempted in 20 patients (4 female; age 57 ± 16 years). Unipolar ablation from sites of early activation (AIV/GCV, LVOT, aortic cusps, RVOT) failed to effectively suppress the PVC/VT in all subjects. Bipolar ablation was delivered with a maximum power of 30 ± 8 W and total duration of 238 ± 217 s and led to acute PVC/VT elimination in all patients. No procedural-related complications occurred. Over a follow-up period of 30 ± 24 months, the freedom from arrhythmia recurrence was 85% (1 recurrence in the VT group and 2 in the PVC group). PVC burden was reduced from 22% ± 10% to 4% ± 8% (P <.001).

Conclusion

In cases of LVS PVC/VT refractory to unipolar ablation, bipolar ablation between the coronary venous system and adjacent endocardial LVOT/RVOT is safe and effective if careful titration of power and intraprocedural angiography are performed to ensure a safe distance from the coronary arteries.

Left ventricular summit premature ventricular contractions treated by venous ethanol infusion: Scar assessment by magnetic resonance imaging

Left ventricular (LV) summit premature ventricular contractions (PVCs) are often unresponsive to radiofrequency (RF) ablation. Retrograde venous ethanol infusion (RVEI) can be a valuable alternative in this scenario. A 43-year-old woman without structural heart disease presented with LV summit PVCs unresponsive to RF ablation because of their deep-seated origin. Unipolar pace mapping performed through a wire inserted into a branch of the distal great cardiac vein (GCV) demonstrated 12/12 concordance with the clinical PVCs thus indicating close proximity to PVCs' origin. RVEI abolished the PVCs without complications. Subsequently, magnetic resonance imaging (MRI) evidenced an intramural myocardial scar produced by ethanol ablation. In conclusion, RVEI effectively and safely treated PVC arising from a deep site in the LVS. The scar provoked by chemical damage was well characterized by MRI imaging.

Fluoroless Catheter Ablation of Left Ventricular Summit Arrhythmias: A Step-by-Step Approach

Prolonged use of fluoroscopy during catheter ablation (CA) of arrhythmias is associated with a significant exposure to ionizing radiation and risk of orthopedic injuries given the need for heavy protective equipment. CA of ventricular arrhythmias (VAs) arising from the left ventricular (LV) summit is challenging, requiring a vast knowledge of the intricate cardiac anatomy of this area and careful imaging delineation of the different anatomical structures, which is frequently performed using fluoroscopic guidance. Certain techniques, including pericardial mapping and ablation, use of intracoronary wires, and mapping and ablation inside the coronary venous system have been proposed, further prolonging fluoroscopy time. Fluoroless CA procedures are feasible with currently available technology and appear to have similar safety and efficacy outcomes compared with conventional techniques. To successfully perform fluoroless CA of LV summit arrhythmias, it is important to be fully acquainted with intracardiac echocardiography (ICE) imaging and electroanatomic mapping (EAM). We will describe our approach to perform fluoroless CA in LV summit VAs.