Substrate-guided Ventricular Tachycardia Ablation Research Articles

P1125 Safety and efficacy of ventricular tachycardia ablation during sinus rhythm in patients with structural heart disease

Abstract Funding Acknowledgements Project “PI-0057-2017”, funded by Junta de Andalucía and co-funded by European Union (ERDF/ESF, “Invesing in your future”) Background The best strategy for scar related ventricular tachycardia (VT) ablation is not yet established. Recently, the use of ventricular assist devices is being proposed to allow ablation during unstable VT. Purpose Analyze the results of a multicenter registry of substrate-guided VT ablation performed primarily during stable rhythm. Methods This prospective multicenter registry included 433 VT ablation procedures performed in 372 consecutive patients with structural heart disease undergoing VT ablation. Substrate ablation (scar dechanneling technique) during sinus rhythm without initial VT induction was the standard protocol. Any episode of sustained VT or appropriate ICD therapy was considered VT recurrence. Results Myocardial infarction was the arrhythmogenic substrate in 64% of patients. 90.5% of patients were male, mean age 64 ± 13 years. Mean LVEF was 38 ± 13%.No ventricular assist device was used in any case. After substrate ablation no VT was inducible in 69% of cases. End-procedure non-inducibility was achieved in 73.1% of cases. Complication rate was 6.7 %. 30-days mortality was 1.9% (7 patients), including one procedure related death. At one year after first procedure 17 patients died (4.5%). Age, chronic obstructive pulmonary disease and renal failure were independent predictors of mortality. One-year freedom from VT recurrence was 84%. Conclusion Substrate-guided VT ablation during stable rhythm as main approach for scar-related VT treatment is associated to low complication and recurrence rates in this prospective multicenter study.

Does Ventricular Tachycardia Ablation Targeting Local Abnormal Ventricular Activity Elimination Reduce Ventricular Fibrillation Incidence?

Various strategies for ablation of ventricular tachycardia (VT) have been described, but their impact on ventricular fibrillation (VF) is largely unknown. The aim of our study was to assess the effect of substrate-based VT ablation targeting local abnormal ventricular activity (LAVA) on recurrent VF events in patients with structural heart disease. A retrospective 2-center study was performed on patients with structural heart disease and both VT and VF, with incident VT ablation procedures targeting LAVAs. Generalized estimating equations with a Poisson loglinear model were used to assess the impact of catheter ablation on VF episodes. The change in VF events before and after catheter ablation was compared with matched controls without ablation. From a total of 686 patients with an incident VT ablation procedure targeting LAVAs, 21 patients (age, 57±14 years; left ventricular ejection fraction, 30±10%) had both VT and VF and met inclusion criteria. A total of 80 VF events were recorded in the implantable cardioverter-defibrillator logs the 6 months preceding ablation. Complete and partial LAVA elimination was achieved in 11 (52%) and 10 (48%) patients, respectively. Catheter ablation was associated with a highly significant reduction in VF recurrences (P<0.0001), which were limited to 3 (14%) patients at 6 months. The total number of VF events thereby decreased from 80 to 3, from a median of 1.0 (range, 1-29) to 0.0 (range, 0-1) in the 6 months before and after ablation, respectively. The reduction in VF events was significantly greater in patients with catheter ablation compared with 21 matched controls during 6-month periods following and preceding a baseline assessment (Poisson β-coefficient, 1.39; P=0.0003). Substrate-guided VT ablation targeting LAVAs may be associated with a significant reduction in recurrent VF, suggesting that VT and VF share overlapping arrhythmogenic substrates in patients with structural heart disease.

Substrate-Guided Ablation of Ischemic Ventricular Tachycardia: Is it Really Necessary to Induce Ventricular Tachycardia to be Successful?

Traditionally, catheter ablation of ventricular tachycardia (VT) consists of mapping the circuit during VT, and using pacing maneuvers to localize critical isthmus of the circuit. However, substrate-guided ablation of VT is a relatively new technique and involves identifying potentially arrhythmogenic regions of myocardium in sinus rhythm and avoids the need for mapping during VT. In this short editorial article, we aimed to discuss substrate mapping of VT.

Substrate-guided ablation of haemodynamically tolerated and untolerated ventricular tachycardia in patients with structural heart disease: effect of cardiomyopathy type and acute success on long-term outcome.

The purpose of this study was to evaluate the outcomes of purely substrate-guided ventricular tachycardia (VT) ablation in patients with non-ischaemic dilated cardiomyopathy (NIDCM) and ischaemic cardiomyopathy (ICM) and the impact of acute procedural success on long-term outcome. One hundred and forty-two patients (65 ± 12 years old, 72% male) with ICM (n = 87) and with NIDCM (n = 55) underwent substrate-guided VT ablation. The ablation approach involved eliminating all LP regions and ablating all scar border zone regions with 10 or more out of 12 pace-matching. All patients were followed with regular implantable defibrillator interrogations for mean 641 ± 301 days. Complete acute success (no inducible VT) was achieved in 60 patients with ICM (69%) and in 29 patients with NIDCM (53%) (P = 0.03). Partial success (elimination of clinical VT only) was obtained in nine patients with ICM (10%) and in four patients with NIDCM (7%) (P = 0.14). Procedural failure (clinical VT still inducible) occurred in 18 patients within the ICM group (21%) and in 22 patients of the NIDCM (40%) (P = 0.04). Overall, 51 patients presented with recurrence of ventricular arrhythmias: 23 in the group with ICM (26%) and 28 in the group with NIDCM (51%) (P = 0.03). Long-term success was related to acute procedural outcome. Substrate-guided ablation is an effective approach in the treatment of VT with long-term outcome directly related to acute procedural success. Success rates are significantly lower in patients with NIDCM compared with those with ICM.

Use of a novel fragmentation map to identify the substrate for ventricular tachycardia in postinfarction cardiomyopathy.

Substrate ablation is commonly performed in patients with postinfarction cardiomyopathy and ventricular tachycardia (VT). Recognition of fragmented and late potentials during sinus rhythm is a tedious process subject to operator fatigue. The purpose of this study was to assess the value of automated analysis to quantify electrogram fragmentation and to determine the relationship of fragmented regions to the VT isthmus. Detailed left ventricular (LV) mapping was performed in 2 groups: (1) 14 patients with previous myocardial infarction and tolerated VT and (2) 14 controls with structurally normal hearts. In patients with VT, mid-isthmus sites were identified using entrainment mapping. Sinus rhythm endocardial LV electrograms underwent time- and frequency-domain analysis and were displayed as fragmentation or frequency maps. The region of fractionated electrograms and their relation to the VT isthmus sites were determined. Cutoffs for abnormal electrogram fragmentation were ventricular fractionation index ≥ 7 and fast Fourier transform ratio ≥ 14%, respectively. In the time domain, LV surface area with fractionated electrograms was significantly smaller than the total scar surface area (27.3% ± 7.1% vs 42.1% ± 12.3%, P <.001), yet contained 100% of VT isthmus sites. In the frequency domain, areas of abnormal fractionation occupied 9.7% ± 6.9% of total LV surface area and included only 60% of the VT isthmus sites. Automated electrogram fractionation analysis represents an objective tool to rapidly quantify electrogram fragmentation and guide substrate-based ablation of VT. Empiric ablation of these regions may be a new strategy for substrate-guided VT ablation.

Lines, circles, channels, and clouds: looking for the best design for substrate-guided ablation of ventricular tachycardia

This editorial refers to ‘Electrical isolation of substrate after myocardial infarction: a novel ablation strategy for unmappable ventricular tachycardias—feasibility and clinical outcome’ by R. R. Tilz et al ., on page 1041 . Radiofrequency (RF) catheter ablation of ventricular tachycardia (VT) has become an important part of the therapeutic armamentarium for treating ventricular arrhythmias in patients with structural heart disease.1 Catheter ablation has proven to control arrhythmic storm and reduce shocks in implantable cardioverter-defibrillator (ICD) recipients with ventricular arrhythmia episodes.2 Novel VT catheter ablation techniques have been developed to overcome the limitations of conventional mapping and ablation. These new techniques aim to characterize and eliminate the arrhythmogenic substrate during stable rhythms. In addition, the advent of three-dimensional non-fluoroscopic systems that allow a detailed electroanatomic reconstruction of the ventricles has facilitated the development of substrate-guided ablation. However, despite improvements in the ablation technology, the rate of recurrence after ablation remains high.3 Based on the surgical experience, Marchlinski et al .4 proposed targeting scar border zone tissue areas with bipolar voltage from 0.5 to 1.5 mV. The best ablation design was considered the creation of ‘linear ablation lines’ transecting the dense scar (<0.5 mV) until reaching the normal myocardium or valve continuity. Pacemapping was used to reduce RF application.4,5 Different markers of VT isthmus have been identified during sinus or paced rhythms and have been proposed as …

Sinus rhythm detection of conducting channels and ventricular tachycardia isthmus in arrhythmogenic right ventricular cardiomyopathy

The identification of conducting channels (CCs) based on its relative high voltage or the presence of electrograms with delayed components has been proposed for substrate-guided scar-related ventricular tachycardia (VT) ablation. The relationship of these channels with the VT isthmuses remains unclear. To assess the link between CCs identified during sinus rhythm (SR) and VT isthmuses in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). Twenty-two consecutive patients with ARVC undergoing substrate-guided VT ablation (scar dechanneling technique) were analyzed. High-density endocardial and epicardial electroanatomic maps were obtained during SR. Standard bipolar cutoff values (0.5-1.5 and <0.5 mV) were used to define border zone and dense scar. The CCs were identified by voltage threshold adjustment (voltage channels) or by tagging the electrograms with delayed components that are sequentially activated (late potential channels). A total of 87 CCs were identified; 65 (74.7%) of them on the epicardial surface. Twenty-four (27.6%) CCs were voltage channels, and compared with late potential CCs, these had a higher bipolar voltage (0.96 [0.48-1.29] mV vs 0.39 [0.26-0.50] mV; P < .001] and required more radiofrequency applications (5 [4-7] vs 3 [2-5]; P = .048]. Eighteen (90%) of 20 identified VT isthmuses were located on the epicardium. Only 8 (40%) VT isthmuses were related to a voltage CC. The remaining 12 (60%) VT isthmuses were linked to a late potential CC. Late potential CCs more frequently act as the VT substrate in ARVC and therefore should also be considered to guide SR substrate-guided ablation.

Clinical Application of PET/CT Fusion Imaging for Three‐Dimensional Myocardial Scar and Left Ventricular Anatomy during Ventricular Tachycardia Ablation

Integration of 3D PET with Voltage Map for VT Ablation. Background: Image integration has the potential to display three-dimensional (3D) scar anatomy and facilitate substrate characterization for ventricular tachycardia (VT) ablation. However, the current generation of clinical mapping systems cannot display 3D left ventricle (LV) anatomy with embedded 3D scar reconstructions or allow display of border zone and high-resolution anatomic scar features. Objective: This study reports the first clinical experience with a mapping system allowing an integrated display of 3D LV anatomy with detailed 2D/3D scar and border zone reconstruction. Methods: Ten patients scheduled for VT ablation underwent contrast-enhanced computed tomography (CT) and Rubidium-82 perfusion/F-18 Fluorodeoxyglucose metabolic Positron Emission Tomography (PET) imaging to reconstruct 3D LV and scar anatomy. LV and scar models were co-registered using a 3D mapping system and analyzed with a 17-segment model. Metabolic thresholding was used to reconstruct the 3D border zone. Real-time display of CT images was performed during ablation. Results: Co-registration (error 4.3 +/- 0.7 mm) allowed simultaneous visualization of 3D LV anatomy and embedded scar and guided additional voltage mapping. Segments containing homogenous or partial scar correlated in 94.4% and 85.7% between voltage maps and 3D PET scar reconstructions, respectively. Voltage-defined scar and normal myocardium had relative FDG uptakes of 40 +/- 13% and 89 +/- 30% (P < 0.05). The 3D border zone correlated best with a 46% metabolic threshold. Real-time display of registered high-resolution CT images allowed the simultaneous characterization of scar-related anatomic changes. Conclusion: Integration of PET/CT reconstruction allows simultaneous 3D display of myocardial scar and border zone embedded into the LV anatomy as well as the display of detailed scar anatomy. Multimodality imaging may enable a new image-guided approach to substrate-guided VT ablation.