Combined Endocardial-Epicardial Versus Endocardial Catheter Ablation Alone for Ventricular Tachycardia in Structural Heart Disease

Pre- and post-procedural cardiac imaging (computed tomography and magnetic resonance imaging) in electrophysiology: a clinical consensus statement of the European Heart Rhythm Association and European Association of Cardiovascular Imaging of the European Society of Cardiology

Imaging using cardiac computed tomography (CT) or magnetic resonance (MR) imaging has become an important option for anatomic and substrate delineation in complex atrial fibrillation (AF) and ventricular tachycardia (VT) ablation procedures. Computed tomography more common than MR has been used to detect procedure-associated complications such as oesophageal, cerebral, and vascular injury. This clinical consensus statement summarizes the current knowledge of CT and MR to facilitate electrophysiological procedures, the current value of real-time integration of imaging-derived anatomy, and substrate information during the procedure and the current role of CT and MR in diagnosing relevant procedure-related complications. Practical advice on potential advantages of one imaging modality over the other is discussed for patients with implanted cardiac rhythm devices as well as for planning, intraprocedural integration, and post-interventional management in AF and VT ablation patients. Establishing a team of electrophysiologists and cardiac imaging specialists working on specific details of imaging for complex ablation procedures is key. Cardiac magnetic resonance (CMR) can safely be performed in most patients with implanted active cardiac devices. Standard procedures for pre- and post-scanning management of the device and potential CMR-associated device malfunctions need to be in place. In VT patients, imaging-specifically MR-may help to determine scar location and mural distribution in patients with ischaemic and non-ischaemic cardiomyopathy beyond evaluating the underlying structural heart disease. Future directions in imaging may include the ability to register multiple imaging modalities and novel high-resolution modalities, but also refinements of imaging-guided ablation strategies are expected.

Radiation therapy for ventricular arrhythmias

Ventricular arrhythmias (VA) can be life-threatening arrhythmias that result in significant morbidity and mortality. Catheter ablation (CA) is an invasive treatment modality that can be effective in the treatment of VA where medications fail. Recurrence occurs commonly following CA due to an inability to deliver lesions of adequate depth to cauterise the electrical circuits that drive VA or reach areas of scar responsible for VA. Stereotactic body radiotherapy is a non-invasive treatment modality that allows volumetric delivery of energy to treat circuits that cannot be reached by CA. It overcomes the weaknesses of CA and has been successfully utilised in small clinical trials to treat refractory VA. This article summarises the current evidence for this novel treatment modality and the steps that will be required to bring it to the forefront of VA treatment.

Impact of preventive substrate catheter ablation on implantable cardioverter-defibrillator interventions in patients with ischaemic cardiomyopathy and infarct-related coronary chronic total occlusion

AIMS

Primary prevention patients with ischaemic cardiomyopathy and chronic total occlusion of an infarct-related coronary artery (CTO) are at a particularly high risk of implantable cardioverter-defibrillator (ICD) therapy occurrence. The trial was designed to evaluate the efficacy of preventive CTO-related substrate ablation strategy in ischaemic cardiomyopathy patients undergoing primary prevention ICD implantation.

METHODS AND RESULTS

The PREVENTIVE VT study was a prospective, multicentre, randomized trial including ischaemic patients with ejection fraction ≤40%, no documented ventricular arrhythmias (VAs), and evidence of scar related to the coronary CTO. Patients were randomly assigned 1:1 to a preventive substrate ablation before ICD implantation or standard therapy with ICD implantation only. The primary outcome was a composite of appropriate ICD therapy or unplanned hospitalization for VAs. Secondary outcomes included the primary outcome's components, the incidence of appropriate ICD therapies, cardiac hospitalization, electrical storm, and cardiovascular (CV) mortality. Sixty patients were included in the study. During the mean follow-up of 44.7 ± 20.7 months, the primary outcome occurred in 5 (16.7%) patients undergoing preventive substrate ablation and in 13 (43.3%) patients receiving only ICD [hazard ratio (HR): 0.33; 95% confidence interval (CI): 0.12-0.94; P = 0.037]. Patients in the preventive ablation group also had fewer appropriate ICD therapies (P = 0.039) and the electrical storms (Log-rank: P = 0.01). While preventive ablation also reduced cardiac hospitalizations (P = 0.006), it had no significant impact on CV mortality (P = 0.151).

CONCLUSION

Preventive ablation of the coronary CTO-related substrate in patients undergoing primary ICD implantation is associated with the reduced risk of appropriate ICD therapy or unplanned hospitalization due to VAs.

Epicardial ablation of ventricular tachycardia in ischemic cardiomyopathy: A review and local experience

Myocardial scar in ischemic cardiomyopathy is predominantly endocardial, however, between 5% and 15% of these patients have an arrhythmogenic epicardial substrate. Percutaneous epicardial ablation should be considered in patients with ICM and VT especially if they failed an endocardial ablation. Simultaneous epicardial and endocardial ablation of VT in ICM may reduce short- and medium-term VT recurrence compared with an endocardial only approach. Cardiac imaging could be used to help guide patient selection for a combined epi-endo approach. Complications related to epicardial access can happen in up to 7% of patients. Epicardial ablation in these patients should be referred to experienced tertiary centers. We review the literature and share interesting cases.

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

AIMS

The usefulness of coronary venous system mapping has been reported for assessing intramural and epicardial substrates in patients with scar-related ventricular tachycardia (VT). However, there has been little data on mapping from coronary arteries. We investigated the safety and utility of mapping from coronary arteries with a novel over-the-wire multielectrode catheter in scar-related VT patients.

METHODS AND RESULTS

Ten consecutive scar-related VT patients with non-ischaemic cardiomyopathy who underwent mapping from a coronary artery were analysed. Six patients underwent simultaneous coronary venous mapping. High-density maps were created by combining the left ventricular endocardium and coronary vessels. Substrate maps were created during the baseline rhythm with 2438 points (IQR 2136-3490 points), including 329 (IQR 59-508 points) in coronary arteries. Abnormal bipolar electrograms were successfully recorded within coronary arteries close to the endocardial substrate in seven patients. During VT, isthmus components were recorded within the coronary vessels in three patients with no discernible isthmus components on endocardial mapping. The ablation terminated the VT from an endocardial site opposite the earliest site in the coronary arteries in five patients.

CONCLUSION

The transcoronary mapping with an over-the-wire multielectrode catheter can safely record abnormal bipolar electrograms within coronary arteries. Additional mapping data from the coronary vessels have the potential to assess three-dimensional ventricular substrates and circuit structures in scar-related VT patients.

Innovations in ventricular tachycardia ablation

Catheter ablation of ventricular arrhythmias (VAs) has evolved significantly over the past decade and is currently a well-established therapeutic option. Technological advances and improved understanding of VA mechanisms have led to tremendous innovations in VA ablation. The purpose of this review article is to provide an overview of current innovations in VA ablation. Mapping techniques, such as ultra-high density mapping, isochronal late activation mapping, and ripple mapping, have provided improved arrhythmogenic substrate delineation and potential procedural success while limiting duration of ablation procedure and potential hemodynamic compromise. Besides, more advanced mapping and ablation techniques such as epicardial and intramyocardial ablation approaches have allowed operators to more precisely target arrhythmogenic substrate. Moreover, advances in alternate energy sources, such as electroporation, as well as stereotactic radiation therapy have been proposed to be effective and safe. New catheters, such as the lattice and the saline-enhanced radiofrequency catheters, have been designed to provide deeper and more durable tissue ablation lesions compared to conventional catheters. Contact force optimization and baseline impedance modulation are important tools to optimize VT radiofrequency ablation and improve procedural success. Furthermore, advances in cardiac imaging, specifically cardiac MRI, have great potential in identifying arrhythmogenic substrate and evaluating ablation success. Overall, VA ablation has undergone significant advances over the past years. Innovations in VA mapping techniques, alternate energy source, new catheters, and utilization of cardiac imaging have great potential to improve overall procedural safety, hemodynamic stability, and procedural success.

Prevention of Sudden Death and Management of Ventricular Arrhythmias in Arrhythmogenic Cardiomyopathy

Arrhythmogenic cardiomyopathy is an umbrella term for a group of inherited diseases of the cardiac muscle characterized by progressive fibro-fatty replacement of the myocardium. As suggested by the name, the disease confers electrical instability to the heart and increases the risk of the development of life-threatening arrhythmias, representing one of the leading causes of sudden cardiac death (SCD), especially in young athletes. In this review, the authors review the current knowledge of the disease, highlighting the state-of-the-art approaches to the prevention of the occurrence of SCD.

Twenty-five years of catheter ablation of ventricular tachycardia: a look back and a look forward

This article will discuss the past, present, and future of ventricular tachycardia ablation and the continuing contribution of the Europace journal as the platform for publication of milestone research papers in this field of ventricular tachycardia ablation.

Novel Epicardial Access Technique Facilitated by Carbon Dioxide Insufflation of the Pericardium for Ablation of Ventricular Arrhythmias: Lessons From the Early Experience From a Single Centre in Australia

INTRODUCTION

Epicardial access for mapping and ablation of the epicardial substrate may be required in catheter ablation of ventricular tachycardias (VT). However, high complication rates are associated with the standard epicardial access approach. Recently, a novel method of intentional coronary vein (CV) exit with pericardial CO₂ insufflation to facilitate epicardial access has been described. This study describes our initial experience with this technique.

METHODS

Patients undergoing epicardial VT ablation between 1 February 2021 to 31 May 2022 at the Royal Prince Alfred Hospital, Sydney, NSW, were included in this study. Via femoral venous access, a branch of the coronary sinus was sub-selected and intentional CV exit was performed with a high tip load coronary angioplasty wire. A microcatheter was then advanced over the wire into the pericardial space, followed by pericardial CO₂ insufflation, facilitating subxiphoid pericardial puncture.

RESULTS

Five (5) patients underwent epicardial access for VT mapping and ablation. All patients had successful intentional CV exit and CO₂ facilitated epicardial access. The mean time to successful epicardial access was 37.2±17.5 minutes. With increasing operator experience, there was improvement in epicardial access times, with the fifth case requiring only 13 minutes. There was one case of inadvertent right ventricular puncture (without haemodynamic or ventilatory compromise) due to inappropriate CO₂ insufflation into the right ventricle. Epicardial access was successful on the second attempt.

CONCLUSION

This is the first case series of epicardial access facilitated by CO₂ insufflation in Australia. This technique enabled successful epicardial access in all patients in our early experience, with no adverse outcomes from epicardial access. With increasing operator experience, this technique may allow for more widespread adoption of up-front epicardial access for the treatment of VT.

Outcomes of a combined vs non-combined endo-epicardial ventricular tachycardia ablation strategy

BACKGROUND

Direct comparisons of combined (C-ABL) and non-combined (NC-ABL) endo-epicardial ventricular tachycardia (VT) ablation outcomes are scarce. We aimed to investigate the long-term clinical efficacy and safety of these 2 strategies in ischemic heart disease (IHD) and non-ischemic cardiomyopathy (NICM) populations.

METHODS

Multicentric observational registry included 316 consecutive patients who underwent catheter ablation for drug-resistant VT between January 2008 and July 2019. Primary and secondary efficacy endpoints were defined as VT-free survival and all-cause death after ablation. Safety outcomes were defined by 30-day mortality and procedure-related complications.

RESULTS

Most of the patients were male (85%), with IHD (67%) and mean age of 63 ± 13 years. During a mean follow-up of 3 ± 2 years, 117 (37%) patients had VT recurrence and 73 (23%) died. Multivariate survival analysis identified electrical storm (ES) at presentation, IHD, left ventricular ejection fraction (LVEF), New York Heart Association (NYHA) functional class III / IV, and C-ABL as independent predictors of VT recurrence. In 135 patients undergoing repeated procedures, only C-ABL and ES were independent predictors of relapse. The identified independent predictors of mortality were C-ABL, ES, LVEF, age, and NYHA class III / IV. C-ABL survival benefit was only seen in patients with a previous ablation (P for interaction = 0.04). Mortality at 30 days was similar between NC-ABL and C-ABL (4% vs. 2%, respectively, P = 0.777), as was complication rate (10.3% vs. 15.1%, respectively, P = 0.336).

CONCLUSION

A combined or sequential endo-epicardial VT ablation strategy was associated with lower VT recurrence and lower all-cause death in IHD and NICM patients undergoing repeated procedures. Both approaches seemed equally safe.

Best Practices for the Catheter Ablation of Ventricular Arrhythmias

Techniques for catheter ablation have evolved to effectively treat a range of ventricular arrhythmias. Pre-operative electrocardiographic and cardiac imaging data are very useful in understanding the arrhythmogenic substrate and can guide mapping and ablation. In this review, we focus on best practices for catheter ablation, with emphasis on tailoring ablation strategies, based on the presence or absence of structural heart disease, underlying clinical status, and hemodynamic stability of the ventricular arrhythmia. We discuss steps to make ablation safe and prevent complications, and techniques to improve the efficacy of ablation, including optimal use of electroanatomical mapping algorithms, energy delivery, intracardiac echocardiography, and selective use of mechanical circulatory support.

Improving Outcomes in Ventricular Tachycardia Ablation Using Imaging to Identify Arrhythmic Substrates

Ventricular tachycardia (VT) ablation is limited by modest acute and long-term success rates, in part due to the challenges in accurately identifying the arrhythmogenic substrate. The combination of multimodality imaging along with information from electroanatomic mapping allows for a more comprehensive assessment of the arrhythmogenic substrate which facilitates VT ablation, and the use of preprocedural imaging has been shown to improve long-term ablation outcomes. Beyond regional recognition of the arrhythmogenic substrate, advanced imaging techniques can be used to create tailored ablation strategies preprocedurally. This review will focus on how imaging can be used to guide ablation planning and execution with a focus on clinical applications aimed at improving the outcome of VT ablation procedures.

Substrate Ablation by Multivein, Multiballoon Coronary Venous Ethanol for Refractory Ventricular Tachycardia in Structural Heart Disease

BACKGROUND

Ablation of ventricular tachycardia (VT) in the setting of structural heart disease often requires extensive substrate elimination that is not always achievable by endocardial radiofrequency ablation. Epicardial ablation is not always feasible. Case reports suggest that venous ethanol ablation (VEA) through a multiballoon, multivein approach can lead to effective substrate ablation, but large data sets are lacking.

METHODS

VEA was performed in 44 consecutive patients with ablation-refractory VT (ischemic, n=21; sarcoid, n=3; Chagas, n=2; idiopathic, n=18). Targeted veins were selected by mapping coronary veins on the epicardial aspect of endocardial scar (identified by bipolar voltage <1.5 mV), using venography and signal recording with a 2F octapolar catheter or by guidewire unipolar signals. Epicardial mapping was performed in 15 patients. Vein segments in the epicardial aspect of VT substrates were treated with double-balloon VEA by blocking flow with 1 balloon while injecting ethanol through the lumen of the second balloon, forcing (and restricting) ethanol between balloons. Multiple balloon deployments and multiple veins were used as needed. In 22 patients, late gadolinium enhancement cardiac magnetic resonance imaged the VEA scar and its evolution.

RESULTS

Median ethanol delivered was 8.75 (interquartile range, 4.5-13) mL. Injected veins included interventricular vein (6), diagonal (5), septal (12), lateral (16), posterolateral (7), and middle cardiac vein (8), covering the entire range of left ventricular locations. Multiple veins were targeted in 14 patients. Ablated areas were visualized intraprocedurally as increased echogenicity on intracardiac echocardiography and incorporated into 3-dimensional maps. After VEA, vein and epicardial ablation maps showed elimination of abnormal electrograms of the VT substrate. Intracardiac echocardiography demonstrated increased intramural echogenicity at the targeted region of the 3-dimensional maps. At 1 year of follow-up, median of 314 (interquartile range, 198-453) days of follow-up, VT recurrence occurred in 7 patients, for a success of 84.1%.

CONCLUSIONS

Multiballoon, multivein intramural ablation by VEA can provide effective substrate ablation in patients with ablation-refractory VT in the setting of structural heart disease over a broad range of left ventricular locations.

Temporal and Spatial Pacemap Parameters for Identification of Cardiac Surfaces with Critical Sites for Ventricular Tachycardia

INTRODUCTION

Multi-surface pacemapping may help identify the surface of interest in scar-related ventricular tachycardia. This study aimed to investigate the performance of pacemap parameters for detecting critical sites through multi-surface mapping.

METHODS AND RESULTS

In 26 patients who underwent scar-related ventricular tachycardia 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 pacemaps at 56 surfaces targeting 35 ventricular tachycardias were analyzed. A greater Δs-QRS (40 vs. 8 ms, P<0.001) and longer distance between two good pacemap sites (24 vs. 13 mm, P<0.001) were observed on the surfaces with critical sites. A similar trend was seen in multi-surface pacemapping for the same ventricular tachycardias (52 vs 18 ms in Δs-QRS, P=0.021; 37 vs. 12 mm in distance, P=0.019), although the best pacemap scores were comparable (94 vs. 87, P=0.295). 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 ventricular tachycardias fulfilling these parameters was successful on the surfaces, but without the required multi-surface ablation.

CONCLUSION

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 ventricular tachycardia. A multi-surface pacemapping can successfully identify the surface of interest. This article is protected by copyright. All rights reserved.

First-Line Catheter Ablation of Monomorphic Ventricular Tachycardia in Cardiomyopathy Concurrent with Defibrillator Implantation: The PAUSE-SCD Randomized Trial

Background: Catheter ablation as first-line therapy for ventricular tachycardia (VT) at the time of implantable cardioverter defibrillator (ICD) implantation has not been adopted into clinical guidelines. Also, there is an unmet clinical need to prospectively examine the role of VT ablation in patients with non-ischemic cardiomyopathy (NICM), an increasingly prevalent population referred for advanced therapies globally. Methods: We conducted an international, multi-center, randomized controlled trial enrolling 180 patients with cardiomyopathy and monomorphic VT with an indication for implantable cardioverter defibrillator (ICD) implantation to assess the role of early, first-line ablation therapy. A total of 121 patients were randomized (1:1) to ablation + an ICD versus conventional medical therapy + an ICD. Patients who refused ICD (n=47) were followed in a prospective registry after stand-alone ablation treatment. The primary outcome was a composite endpoint of VT recurrence, cardiovascular hospitalization, or death. Results: Randomized patients had a mean age of 55 years old (IQR 46-64) and left ventricular ejection fraction of 40 % (IQR 30-49 %); 81 % were male. The underlying heart disease was ischemic cardiomyopathy (ICM) in 35 %, NICM in 30 %, and arrhythmogenic cardiomyopathy (ARVC) in 35 %. Ablation was performed a median of 2 days prior to ICD implantation (IQR 5 days prior to 14 days after). At 31-months, the primary outcome occurred in 49.3 %of the ablation group and 65.5 % in the control group (HR 0.58, 95 % CI, 0.35-0.96; P=0.04). The observed difference was driven by a reduction in VT recurrence in the ablation arm (HR 0.51 [95 %CI, 0.29-0.90 ]; P=0.02). A statistically significant reduction in both ICD shocks (10.0 vs 24.6 %; p=0.03) and anti-tachycardia pacing (16.2 % vs 32.8 %; p=0.04) was observed in patients who underwent ablation compared with control. No differences in cardiovascular hospitalization (32.0 % vs. 33.7 %; HR 0.82 [95 % CI, 0.43-1.56 ]; P=0.55) or mortality (8.9% vs 8.8 %, HR 1.40 [95 %CI, 0.38-5.22 ]; P=0.62]) were observed. Ablation-related complications occurred in 8.3 % of patients. Conclusions: Among patients with cardiomyopathy of varied etiologies, early catheter ablation performed at the time of ICD implantation significantly reduced the composite primary outcome of VT recurrence, cardiovascular hospitalization, or death. These findings were driven by a reduction in ICD therapies.

Meta-Analysis of Catheter Ablation Outcomes in Patients With Cardiac Sarcoidosis Refractory Ventricular Tachycardia

Cardiac sarcoidosis (CS) frequently leads to ventricular tachycardia (VT), which is often refractory to antiarrhythmic and/or immunosuppressive medications and requires catheter ablation. We conducted a systematic review and meta-analysis to evaluate the role of catheter ablation in patients with refractory VT undergoing catheter ablation. We searched PubMed, Embase, and Scopus databases from their inception to December 31, 2021 with search terms "cardiac sarcoidosis" AND "electrophysiological studies OR ablation." Fifteen studies were ultimately included for evaluation. Patient demographics, VT mapping, and acute and long-term procedural outcomes were extracted. A total of 15 studies were included in our meta-analysis, with a total of 401 patients, of whom 66% were male, with ages ranging from 39 to 64 years. A total of 95% of patients were on antiarrhythmics and 79% of patients were on immunosuppressants. Left ventricular ejection fraction ranged from 35% to 49% and procedure duration ranged from 269 to 462 minutes. Ablation was reported using both irrigated and nonirrigated catheter tips. A total of 25% of patients (84/339) underwent repeat ablation. Acute procedural success was achieved in 57% (161/285). Procedure complications occurred in 5.7% (17/297) procedures. VT recurrence after first ablation was 55% (confidence interval 48% to 63%, 213/401); VT recurrence after multiple ablations was 37% (81/220). The composite end point of death, heart transplant, and left ventricular assist device implantation was 21% (confidence interval 14% to 30%, 55/297). In conclusion, catheter ablation is a useful modality in patients with CS with refractory VT. However, patients with CS presenting with refractory VT after undergoing VT ablation carry a poor prognosis.

A novel ECG finding in patients with epicardial infarct-associated ventricular tachycardia: a case series

OBJECTIVES

This study analyzes the incidence, characteristics, and ECG morphology of ventricular tachycardia (VT) in post-infarction patients undergoing epicardial VT ablation.

BACKGROUND

Ablation of recurrent VTs in patients with ischemic cardiomyopathy is typically performed endocardially. In rare cases, epicardial access is required to achieve non-inducibility.

METHODS AND RESULTS

The study evaluated the baseline characteristics, procedural data, and ECG morphology of clinical VT in patients undergoing epicardial VT ablation. From the initial 491 patients with coronary heart disease (CHD) and recurrent VTs undergoing ablation at the Heart Center of Leipzig, Germany, between 2012 and 2020, only 39 patients required an additional epicardial access. In 17 patients, the VTs were associated with infarction scar, while the remaining patients had concomitant CHD without infarction-associated scar and were excluded from the analysis. A propensity match study was performed at a 1:2 ratio for these 17 patients, with 34 patients of the initial cohort as a control group to evaluate the differences in baseline characteristics, procedural data, and ECG morphology of the VTs. The specific VT morphology of negative concordance and superior axis in patients with inferior scar as well as the history of VT ablation were independent predictors of the need for epicardial access.

CONCLUSIONS

In addition to previous endocardial ablation, VT ECG morphology with negative concordance and superior axis in post-infarction patients with inferior scar predicted the need for epicardial VT ablation.

Ring-like late gadolinium enhancement for predicting ventricular tachyarrhythmias in non-ischaemic dilated cardiomyopathy

AIMS

Myocardial fibrosis is associated with clinical ventricular tachyarrhythmia (VTA) events in patients with non-ischaemic dilated cardiomyopathy (DCM). Subepicardial or mid-wall ring-like late gadolinium enhancement (LGE) has received increasing attention in recent years. The aim of this study was to investigate the relationship between ring-like LGE and VTAs in DCM.

METHODS AND RESULTS

Patients diagnosed with non-ischaemic DCM who underwent cardiac magnetic resonance with LGE imaging at baseline were investigated. The composite outcome was the occurrence of VTAs defined as sustained ventricular tachycardia, ventricular fibrillation/flutter, aborted sudden cardiac death (SCD), SCD, and appropriate implantable cardioverter-defibrillator intervention. The final cohort comprised 157 patients, including 36 (22.9%) in no LGE group, 48 (30.6%) in focal LGE group, 40 (25.5%) in multi-focal LGE group, and 33 (21%) in ring-like LGE group. Ring-like LGE group patients were younger compared to focal and multi-focal LGE group (P < 0.001) with higher left ventricular ejection fraction (33.0% vs. 24.4% vs. 22.1%, P < 0.001). After a median of 13 ± 7 months follow-up, compared to patients with no LGE, the hazard ratios (HRs) with 95% confidence intervals (CIs) for VTAs were 2.90 (0.56-15.06), 5.55 (1.21-25.44), and 11.75 (2.66-51.92) for patients with focal LGE, multi-focal LGE, and ring-like LGE, respectively. After multivariable adjustment, ring-like LGE group remained associated with increased risk of VTAs (adjusted HR 10.00, 95% CI 1.54-64.98; P = 0.016) independent of the global LGE burden.

CONCLUSION

The ring-like pattern of LGE is independently associated with an increased risk of VTAs in patients with non-ischaemic DCM.

Epicardial origin of cardiac arrhythmias: clinical evidences and pathophysiology

Recent developments in imaging, mapping, and ablation techniques have shown that the epicardial region of the heart is a key player in the occurrence of ventricular arrhythmic events in several cardiac diseases, such as Brugada syndrome, arrhythmogenic cardiomyopathy, or dilated cardiomyopathy. At the atrial level as well, the epicardial region has emerged as an important determinant of the substrate of atrial fibrillation, pointing to common underlying pathophysiological mechanisms. Alteration in the gradient of repolarization between myocardial layers favouring the occurrence of re-entry circuits has largely been described. The fibro-fatty infiltration of the subepicardium is another shared substrate between ventricular and atrial arrhythmias. Recent data have emphasized the role of the epicardial reactivation in the formation of this arrhythmogenic substrate. There are new evidences supporting this structural remodelling process to be regulated by the recruitment of epicardial progenitor cells that can differentiate into adipocytes or fibroblasts under various stimuli. In addition, immune-inflammatory processes can also contribute to fibrosis of the subepicardial layer. A better understanding of such ‘electrical fragility’ of the epicardial area will open perspectives for novel biomarkers and therapeutic strategies. In this review article, a pathophysiological scheme of epicardial-driven arrhythmias will be proposed.

First Asian population study of stereotactic body radiation therapy for ventricular arrhythmias

We report the first Asian series on stereotactic body radiation (SBRT) for refractory ventricular arrhythmia (VA) in Taiwanese patients. Three-dimensional electroanatomic maps, delayed-enhancement magnetic resonance imaging (DE-MRI), and dual-energy computed tomography (CT) were used to identify scar substrates. The main target volume was treated with a single radiation dose of 25 Gy and the margin volume received 20 Gy using simultaneous integrated boost delivered by the Varian TrueBeam system. Efficacy was assessed according to VA events recorded by an implantable cardioverter-defibrillator (ICD) or a 24-h Holter recorder. Pre- and post-radiation therapy imaging studies were performed. From February 2019 to December 2019, seven patients (six men, one woman; mean age, 55 years) were enrolled and treated. One patient died of hepatic failure. In the remaining six patients, at a median follow-up of 14.5 months, the VA burden and ICD shocks significantly decreased (only one patient with one ICD shock after treatment). Increased intensity on DE-MRI might be associated with a lower risk for VA recurrence, whereas dual-energy CT had lower detection sensitivity. No acute or minimal late adverse events occurred. In patients with refractory VA, SBRT is associated with a marked reduction in VA burden and ICD shocks, and DE-MRI might be useful for monitoring treatment effects.

Epicardial-Endocardial Reentry in Ischemic Cardiomyopathy

In ischemic cardiomyopathy, endocardial reentry has traditionally been the mechanistic paradigm for understanding ventricular tachycardia (VT). However, recognition is growing that epicardial myocardium is a critical component for VT substrate, even in patients with ischemic cardiomyopathy. In this report, we present a novel case of a three-dimensional VT reentry involving epicardial components and an endocardial exit.

The role of imaging in catheter ablation of ventricular arrhythmias

Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) and multidetector cardiac computed tomography (MDCT) have emerged as novel, fascinating imaging tools for arrhythmogenic substrate identification and characterization. The role of these techniques for aiding and guiding the catheter ablation of ventricular tachycardia, either as a complement or a surrogate of the electroanatomic map, has been rising in recent years. Integrating pixel signal intensity maps or wall thickness maps delivered from LGE-CMR or MDCT, respectively, into the navigation system has become a cornerstone for VT ablation procedures in a few centers of excellence around the world. The pre-procedure scar characterization offers some advantages, helping decide for the best procedure planning and approach; complete substrate identification and characterization, helping to focus electroanatomical mapping in regions of interest and also has a positive impact in procedure efficiency and outcomes. In the present article, we perform a review of the most practical aspects for using LGE-CMR or MDCT when a VT ablation procedure is planned, from the image acquisition to the integration into the navigation system, analyzing the current role of the LGE-CMR and MDCT for arrhythmogenic substrate characterization as well as for guiding VT ablation.

Meta-analysis comparing outcomes of catheter ablation for ventricular arrhythmia in ischemic versus nonischemic cardiomyopathy

Background

Catheter ablation is an effective treatment for ventricular arrhythmia (VA) in ischemic cardiomyopathy (ICM). However, results in non‐ICM (NICM) patients are not satisfactory, and studies comparing differences between NICM and ICM are limited. We conducted a meta‐analysis of procedural characteristics and long‐term outcomes of catheter ablation for VA, comparing results between ICM and NICM.

Methods

Studies in the PubMed, EMBASE, and Cochrane databases were systematically reviewed. Four studies reporting comparison of catheter ablation of VA between ICM and NICM were examined. The Newcastle‐Ottawa Scale was used to appraise study quality. A random‐effects model with inverse variance method was used for comparisons.

Results

Epicardial approach was significantly more undertaken for the NICM group than in the ICM group (odds ratio [OR]: 0.13; 95% confidence interval [CI]: 0.09‐0.18; P < .00001). Mean ablation time (P = .54), fluoroscopy time (P = .55), and procedural time (P = .18) did not differ significantly between the ICM and NICM groups. Procedural failure rates (OR: 0.46; 95% CI: 0.24‐0.89; P = .02) and VA recurrence rates (risk ratio [RR]: 0.68; 95% CI: 0.46‐1.01; P = .06) were significantly higher in the NICM group than in the ICM group. However, all‐cause mortality (RR: 1.37; 95% CI: 0.75‐2.49; P = .31) did not differ significantly between groups.

Conclusions

Procedural failure and VA recurrence rates were significantly higher in the NICM group, despite significantly more frequent epicardial access. These highlight the limitations of catheter ablation for VA in NICM, given our current knowledge.

First-line ablation of ventricular tachycardia in ischemic cardiomyopathy: stratification of outcomes by left ventricular function

PURPOSE

First-line catheter ablation of ventricular tachycardia/ventricular fibrillation (VT/VF) in patients with ischemic cardiomyopathy (ICM) has been associated with improved outcomes; however, most benefit seems to be in patients with moderately depressed left ventricular ejection fraction (LVEF). Herein, outcomes were stratified based on LVEF.

METHODS

A meta-analysis of randomized controlled trials (RCTs) evaluating first-line ablation versus medical therapy in patients with VT and ICM was performed. Risk estimates and 95% confidence intervals (CI) were measured.

RESULTS

Four RCTs with a total of 505 patients (mean age 66 ± 9 years, 89% male, 80% with previous revascularization) were included. Mean LVEF was 35 ± 8%. At a mean follow-up of 24 ± 9 months, a significant benefit in survival-free from appropriate implantable cardioverter-defibrillator (ICD) therapies was observed in all patients undergoing first-line catheter ablation compared with medical management (RR 0.70, 95% CI 0.56-0.86). In patients with moderately depressed LVEF (> 30-50%), first-line VT ablation was associated with a statistically significant reduction in the composite endpoint of survival free from VT/VF and appropriate ICD therapies (HR 0.52, 95% CI 0.36-0.76), whereas there was no difference in patients with severely depressed LVEF (≤30%) (HR 0.56, 95% CI 0.24-1.32). Funnel plots did not show asymmetry suggesting lack of bias.

CONCLUSIONS

Patients with ICM and VT undergoing first-line ablation have a significantly lower rate of appropriate ICD therapies without a mortality difference compared with patients receiving an initial approach based on medical therapy. The beneficial effect of a first-line ablation approach was only observed in patients with moderately depressed LVEF (> 30-50%).

Epicardial Ablation Complications

The percutaneous epicardial approach has become an adjunctive tool for electrophysiologists to treat disparate cardiac arrhythmias, including accessory pathways, atrial tachycardia, and particularly ventricular tachycardia. This novel technique prompted a strong impulse to perform epicardial access as an alternative strategy for pacing and defibrillation, left atrial appendage exclusion, heart failure with preserved ejection fraction, and genetically engineered tissue delivery. However, because of the incremental risk of major complications compared with stand-alone endocardial ablation, it is still practiced in a limited number of highly experienced centers across the world.

Epicardial Ablation of Ventricular Tachycardia in Ischemic Cardiomyopathy

Catheter ablation can effectively reduce the frequency of ventricular tachycardia in ischemic cardiomyopathy by ablating sites of reentry within complex regions of myocardial scar. In cases of near transmural infarction, this arrhythmia substrate may be nearer the epicardium than the endocardium, and epicardial ablation may be necessary. An epicardial substrate location can potentially be predicted by imaging that suggests transmural infarction. Percutaneous epicardial ablation improves outcomes in selected patients, but is higher risk and avoided in patients with prior coronary artery bypass grafting.

Endo-epicardial ablation vs endocardial ablation for the management of ventricular tachycardia in arrhythmogenic right ventricular cardiomyopathy: A systematic review and meta-analysis

BACKGROUND

The pathologic process of ARVC (arrhythmogenic right ventricular cardiomyopathy) typically originates in the epicardium or subepicardial layers with progression toward endocardium. However, in the most recent ARVC international task force consensus statement, epicardial ventricular tachycardia (VT) ablation is recommended as a Class I indication only in patients with at least one failed endocardial VT ablation attempt.

OBJECTIVE

The aim of this meta-analysis is to assess the outcomes of ARVC patients undergoing combined endo-epicardial VT ablation, as compared to endocardial ablation alone.

METHODS

A systematic review of PubMed, Embase, and Cochrane was performed for studies reporting clinical outcomes of endo-epicardial VT ablation vs endocardial-only VT ablation in patients with ARVC. Fixed-Effect model was used if I₂ < 25 and the Random-Effects Model was used if I₂ ≥ 25%.

RESULTS

Nine studies consisting of 452 patients were included (mean age 42.3 ± 5.7 years; 70% male). After a mean follow-up of 48.1 ± 21.5 months, endo-epicardial ablation was associated with 42% relative risk reduction in VA recurrence as opposed to endocardial ablation alone (risk ratio [RR], 0.58; 95% confidence interval [CI], 0.45-0.75; P < .0001). No significant differences were noted between endo-epicardial and endocardial VT ablation groups in terms of all-cause mortality (RR, 1.19; 95% CI, 0.03-47.08; P = .93) and acute procedural complications (RR, 5.39; 95% CI, 0.60-48.74; P = .13).

CONCLUSIONS

Our findings suggest that in patients with ARVC, endo-epicardial VT ablation is associated with a significant reduction in VA recurrence as opposed to endocardial ablation alone, without a significant difference in all-cause mortality or acute procedural complications.

Application of noninvasive signal-averaged electrocardiogram analysis in predicting the requirement of epicardial ablation in patients with arrhythmogenic right ventricular cardiomyopathy

BACKGROUND

Signal-averaged electrocardiogram (SAECG) provides not only diagnostic information but also the prognostic implication of ablation in arrhythmogenic right ventricular cardiomyopathy (ARVC).

OBJECTIVE

This study aimed to validate the role of SAECG in identifying arrhythmogenic substrates requiring an epicardial approach in ARVC.

METHODS

Ninety-one patients with a definite diagnosis of ARVC who underwent successful ablation for drug-refractory ventricular arrhythmia were enrolled and classified into 2 groups: group 1 who underwent successful ablation at the endocardium only and group 2 who underwent successful ablation requiring an additional epicardial approach. The baseline characteristics of patients and SAECG parameters were obtained for analysis.

RESULTS

Male predominance, worse right ventricular (RV) function, higher incidence of syncope, and depolarization abnormality were observed in group 2. Moreover, the number of abnormal SAECG criteria was higher in group 2 than in group 1. After a multivariate analysis, the independent predictors of the requirement of epicardial ablation included the number of abnormal SAECG criteria (odds ratio 2.8, 95% confidence interval 1.4-5.4; P = .003) and presence of syncope (odds ratio 11.7; 95% confidence interval 2.7-50.4; P = .001). In addition, ≥2 abnormal SAECG criteria were associated with larger RV endocardial unipolar low-voltage zone (P < .001), larger RV endocardial/epicardial bipolar low-voltage zone/scar (P < .05), and longer RV endocardial/epicardial total activation time (P < .001 and P = .004, respectively).

CONCLUSION

The number of abnormal SAECG criteria was correlated with the extent of diseased epicardial substrates and could be a potential surrogate marker for predicting the requirement of epicardial ablation in patients with ARVC.

Hybrid Ventricular Tachycardia Ablation after Failed Percutaneous Endocardial and Epicardial Ablation

INTRODUCTION

Recurrent ventricular tachycardia (VT) after percutaneous ablation is associated with a high morbidity and mortality. We assessed the feasibility of open chest extracorporeal circulation (ECC)-supported 3D multielectrode mapping and targeted VT substrate ablation in patients with previously failed percutaneous endocardial and epicardial VT ablations.

METHODS

In patients with previously failed percutaneous endocardial and epicardial VT ablations and a high risk of hemodynamic collapse during the procedure, open chest ECC-supported mapping and ablation were performed in a hybrid EP lab setting. Electro-anatomic maps (3D) were acquired during sinus rhythm and VT using a multielectrode mapping catheter (HD grid; Abbott or Pentaray, Biosense Webster). Irrigated radiofrequency ablations of all inducible VT were performed with a contact force ablation catheter.

RESULTS

Hybrid VT ablation was performed in 5 patients with structural heart disease (i.e., 3 with previous old myocardial infarction and 2 with nonischemic cardiomy-opathy) and recurrent VT. Acute procedural success was achieved in all patients. Four patients were successfully weaned off the ECC. In 1 patient with a severely reduced LVEF (16%), damage to the venous graft occurred after sternotomy and that patient died after 1 month. Four patients (80%) remained VT free after a median follow-up of 6 (IQR 4-10) months.

CONCLUSION

In high-risk patients with previously failed percutaneous endocardial and epicardial VT ablations, open chest ECC-supported multielectrode epicardial mapping revealed a VT substrate in all of the patients, and targeted epicardial ablation abolished VT substrate in these patients.

Mapping and Ablation of Ventricular Arrhythmias in Cardiomyopathies

Mapping and ablation of ventricular arrhythmias in patients with nonischemic cardiomyopathies remain a major challenge. The electroanatomic abnormalities are frequently inaccessible to conventional endocardial ablations. Diagnostic diligence with a thorough understanding of the potential mechanisms/substrate, coupled with detailed electroanatomic mapping, is essential. Careful procedural planning, advanced imaging, and unipolar recordings help to formulate ablation strategy, facilitate work flow, and improve outcomes. Inaccessibility of arrhythmogenic substrate and disease progression are important causes of ablation failure. Early intervention may help to improve outcome and minimize complications. Several novel adjunctive ablation techniques are capable of serving as alternative options in refractory cases.

Substrate Mapping in Ventricular Arrhythmias

Ventricular tachycardia is typically hemodynamically unstable. Strategies to target the arrhythmogenic substrate during sinus rhythm are essential for therapeutic ablation. Electroanatomic mapping is the cornerstone of substrate-based strategies; ablation can be directed within a delineated scar region defined by low voltage. Bipolar voltage mapping has inherent limitations. Specific electrogram characteristics may improve the specificity of localizing the most arrhythmogenic regions within the substrate. Deceleration zones during sinus rhythm are niduses for reentry and can be identified by isochronal late activation mapping, which is a functional analysis of substrate propagation with local annotation to electrogram offset.

Role of catheter ablation in patients with ischemic ventricular tachycardia: From basic to clinical practice

Catheter ablation provides a therapeutic option for decreasing episodes of ventricular tachycardia in patients with coronary artery disease. Clinical studies show improvement with catheter ablation in reducing arrhythmia recurrence and therapy from implantable defibrillators, but not in decreasing mortality. Ablation can be an important tool for patients with electrical storm. Overall, complication rates of catheter ablation are acceptable, but recurrence rates are still significant. Advances in mapping and ablation technologies could be expected to improve the success rates and reduce the mortality.