Adjunctive Interventional Techniques When Percutaneous Catheter Ablation for Drug Refractory Ventricular Arrhythmias Fail: A Contemporary Review

Perioperative and long-term outcomes of bilateral cardiac sympathetic denervation via video-assisted thoracoscopic surgery in patients with refractory ventricular arrhythmias

BACKGROUND

Bilateral cardiac sympathetic denervation (CSD) performed via video-assisted thoracoscopic (VAT) surgery shows potential in managing ventricular tachycardia (VT), thereby reducing arrhythmic burden. In this setting, the scarcity of studies addressing both perioperative and long-term outcomes creates a substantial gap in the optimal management of patients with multiple comorbidities and limited treatment options. This observational study aimed to assess the medical comorbidities, as well as the short- and long-term outcomes of patients who underwent CSD for VT refractory to catheter ablation and medical therapy at a referral tertiary teaching hospital.

MATERIALS

We retrospectively analyzed data of all patients with VT who underwent bilateral CSD-VAT surgery at a single center. Unadjusted Kaplan-Meier survival curves were generated to analyze the survival rates at 1-year and 2-years following the procedure.

RESULTS

Ten consecutive patients were unrolled between August 2014 and March 2024. Bilateral CSD-VAT surgery was successfully performed in all patients. Pre-operative ejection fraction was 33 % (26-41). Two patients (22 %) suffered cardiogenic shock and 1 vasoplegia. Half (50 %) of the patients necessitated inotrope/vasopressor support and 1 an intra-aortic balloon pump. Median hospital stay was 12 (9-19) days. Three (33 %) patients required postoperative ICU admission. All patients were alive upon hospital discharge. Neither major surgical complications nor complications typically associated with VAT-CSD (e.g., Horner's syndrome) were observed. The 1-year survival was 80 % while the survival at 24 months was 60 %.

CONCLUSIONS

CSD-VAT is a feasible rescue treatment in patients with refractory VT and is associated with limited intra- and postoperative complications alongside an acceptable long-term survival rate.

Whole-Heart Histological and CMR Validation of Electroanatomic Mapping by Multielectrode Catheters in an Ovine Model

BACKGROUND

Accurate electroanatomic mapping is critical for identifying scar and the long-term success of ventricular tachycardia ablation.

OBJECTIVES

This study sought to determine the accuracy of multielectrode mapping (MEM) catheters to identify scar on cardiac magnetic resonance (CMR) and histopathology.

METHODS

In an ovine model of myocardial infarction, we examined the effect of electrode size, spacing, and mapping rhythm on scar identification compared to CMR and histopathology using 5 multielectrode mapping catheters. We co-registered electroanatomic mapping, CMR, and histopathology for comparison. Catheter-specific voltage thresholds were identified based on underlying amounts of normal myocardium on transmural histology biopsies.

RESULTS

Ten animals were included: 6 with anteroseptal myocardial infarction and 4 control animals. A total of 419,597 points were manually reviewed across the catheters, with 315,487 points used in the analysis. There were minimal differences in bipolar and unipolar voltages, scar areas, and abnormal electrograms between catheters and between rhythms. Catheter-specific bipolar and unipolar voltage thresholds for normal myocardium were High-Density Grid >2.78 mV and >6.19 mV, DuoDecapolar >2.22 mV and >6.05 mV, PentaRay >1.66 mV and >5.35 mV, Decanav >1.36 mV and >4.75 mV, Orion >1.21 mV and >6.05 mV, respectively. Catheter-specific bipolar thresholds improved the accuracy for detecting endo-mid myocardial scar on CMR by 1.8%-15.6% and catheter-specific unipolar thresholds improved the accuracy in the mid-epicardial layers by 25.3%-81.1%.

CONCLUSIONS

Minimal differences were observed in scar detection and electrogram markers between commercially available multielectrode mapping catheters and differing wave fronts. Compared to traditional voltage criteria for bipolar and unipolar scar, catheter-specific thresholds markedly improved accuracy for delineating scar on CMR.

An optimized approach for increasing lesion size in temperature-controled setting using a catheter with a surface thermocouple and efficient irrigation

Background

We explore an optimized approach for increasing lesion size using a novel ablation catheter with a surface thermocouple and efficient irrigation in a temperature-control setting.

Methods

We conducted radiofrequency applications at various power levels (35 W, 40 W, and 45 W), contact forces (CFs, 10 g/20 g), and durations (60 s/120 s/180 s) in perpendicular/parallel catheter orientations, with normal saline irrigation (NS-irrigation) and Half NS-irrigation (HNS-irrigation) in an ex-vivo model (Step 1). In addition, we performed applications (35 W/40 W/45 W for 60 s/120 s/180 s in NS-irrigation and 35 W/40 W for 60 s/120 s/180 s in HNS-irrigation) in four swine (Step 2), evaluating lesion characteristics and the occurrence of steam pops.

Results

In Step 1, out of 288 lesions, we observed 47 (16.3%) steam pops, with 13 in NS-irrigation and 34 in HNS-irrigation (p = .001). Although steam pops were mostly observed with the most aggressive setting (45 W/180 s, 54%) with NS-irrigation, they happened in less aggressive settings with HNS irrigation. Lesion size significantly increased with longer-duration ablation but not with HNS-irrigation. The optimal %impedance-drop cutoff to predict steam pops was 20% with a negative-predictive-value (NPV) = 95.1% including NS- and HNS-irrigation groups, and 22% with an NPV = 96.1% in NS-irrigation group. In Step 2, similar to the ex-vivo model, lesion size significantly increased with longer-duration ablation but not with HNS-irrigation. Steam pops were absent with NS-irrigation (0/35) even with the largest %impedance-drop reaching 31% at 45 W/180 s. All steam pops were observed with HNS-irrigation (6/21, 29%). The optimal %impedance-drop cutoff predicting steam pops was 24% with an NPV = 96.3% including both NS- and HNS-irrigation groups.

Conclusions

Rather than using HNS-irrigation, very long-duration of radiofrequency applications up to 45 W/180 s may be recommended to safely and effectively increase lesion dimensions using this catheter with NS-irrigation.

Mapping and Ablation of Ventricular Tachycardia in Inherited Left Ventricular Cardiomyopathies

Advances in the field of human genetics have led to an accumulating understanding of the genetic basis of distinct nonischemic cardiomyopathies associated with ventricular tachycardias (VTs) and sudden cardiac death. To date, there is an increasing proportion of patients with inherited cardiomyopathies requiring catheter ablation for VTs. This review provides an overview of disease-causing gene mutations frequently encountered and relevant for clinical electrophysiologists. Available data on VT ablation in patients with an inherited etiology and a phenotype of a nondilated left ventricular cardiomyopathy, dilated cardiomyopathy, or hypertrophic cardiomyopathy are summarized. VTs amenable to catheter ablation are related to nonischemic fibrosis. Recent insights into genotype-phenotype relations of subtype and location of fibrosis have important implications for treatment planning. Current strategies to delineate nonischemic fibrosis and related arrhythmogenic substrates using multimodal imaging, image integration, and electroanatomical mapping are provided. The ablation approach depends on substrate location and extension. Related procedural aspects including patient-tailored (enhanced) ablation strategies and outcomes are outlined. Challenging substrates for VT and the underlying inherited etiologies with a high risk for rapid progressive heart failure contribute to poor outcomes after catheter ablation. Electroanatomical data obtained during ablation may allow the identification of patients at particular risk who need to be considered for early work-up for left ventricular assist device implantation or heart transplantation.

Venous Ethanol Ablation Approaches for Radiofrequency-Refractory Cardiac Arrhythmias

PURPOSE OF REVIEW

In this review, we summarize the procedural approach and outcomes of venous ethanol infusion in the treatment of ventricular arrhythmias with intramural site of origin.

RECENT FINDINGS

Coronary venous ethanol infusion has emerged as a novel, safe, and effective adjunctive strategy to radiofrequency ablation of drug refractory ventricular arrhythmias with an intramural origin. Radiofrequency catheter ablation is the first-line treatment for drug refractory ventricular arrythmias. Its success is highly dependent on the ability to reach targeted myocardium. Radiofrequency failures are common in patients with ventricular arrhythmias arising from deep intramural substrates, and those whose origin is in close proximity to vital structures such as coronary arteries or the phrenic nerve. Coronary venous ethanol infusion has emerged as a novel technique that circumvents these limitations.

Recurrent arrhythmic storms and unsuccessful catheter ablation in chronic ischemic heart disease

The prototypical substrate for reentrant ventricular tachycardia (VT) is post-myocardial infarction (MI) scar. Catheter ablation is an important therapeutic option for recurrent VT but sometimes it is not effective despite the technical advances. Here we describe the case of a 60-year-old man who suffered a MI in 1998 and presented with recurrent arrhythmic storms during his long-term follow-up. Twenty years later, he underwent two catheter ablations with bipolar electroanatomic voltage mapping (EVM) demonstrating only an area of low voltages in the lateral left ventricular free wall. Both procedures were unsuccessful and the patient eventually underwent cardiac transplantation in 2019. Pathology examination revealed circumferential subendocardial scar with hypertrabeculation, so that the reentry substrate was unreachable by ablation with the use of standard techniques. The comparison of EVM findings with the morphologic ones in patients with chronic ischemic heart disease can help to better understand the feasibility and effectiveness of VT substrate ablation.

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.

Post-ablation augmentation of skin sympathetic nerve activity predicts a poor outcome of idiopathic ventricular arrhythmias

BACKGROUND

The neuromodulation effect after ventricular arrhythmia (VA) ablation is unclear. The study aimed to investigate skin sympathetic nerve activity (SKNA) changes in patients receiving catheter ablations for idiopathic VA.

METHODS

Of 43 patients with drug-refractory symptomatic VA receiving ablation, SKNA was continuously recorded for 10 min during resting from electrocardiogram lead I configuration and bipolar electrodes on the right arm 1 day before and 1 day after ablation.

RESULTS

Twenty-two patients with acute procedure success and no recurrence during follow-ups were classified as sustained success group (group 1). Other 21 patients were classified as failed ablation group (group 2). Baseline SKNA showed no significant difference between the two groups. Post-ablation SKNA in group 2 was significantly higher than in group 1. In patients with ablation involved right ventricular outflow tract (RVOT), the post-ablation SKNA was also significantly higher in group 2. In contrast, there was no difference in post-ablation SKNA between groups in patients receiving non-RVOT ablation.

CONCLUSION

The neuromodulation response after RVOT ablation may correspond to the sympathetic nerve distribution at RVOT. Augmentation of sympathetic activity after VA ablation indicates an unsuccessful VA suppression, especially in patients receiving ablation of RVOT VA.

Acute and Long-Term Scar Characterization of Venous Ethanol Ablation in the Left Ventricular Summit

BACKGROUND

Venous ethanol ablation (VEA) can be effective for ventricular arrhythmias from the left ventricular summit (LVS); however, there are concerns about excessive ablation by VEA.

OBJECTIVES

The purpose of this study was to delineate and quantify the location, extent, and evolution of ablated tissue after VEA as an intramural ablation technique in the LVS.

METHODS

VEA was performed in 59 patients with LVS ventricular arrhythmias. Targeted intramural veins were selected by electrograms from a 2F octapolar catheter or by guide-wire unipolar signals. Median ethanol delivered was 4 mL (IQR: 4-7 mL). Ablated areas were estimated intraprocedurally as increased echogenicity on intracardiac echocardiography (ICE) and incorporated into 3-dimensional maps. In 44 patients, late gadolinium enhancement cardiac magnetic resonance (CMR) imaged VEA scar and its evolution.

RESULTS

ICE-demonstrated increased intramural echogenicity (median volume of 2 mL; IQR: 1.7-4.3) at the targeted region of the 3-dimensional maps. Post-ethanol CMR showed intramural scar of 2.5 mL (IQR: 2.1-3.5 mL). Early (within 48 hours after VEA) CMR showed microvascular obstruction (MVO) in 30 of 31 patients. Follow-up CMR after a median of 51 (IQR: 41-170) days showed evolution of MVO to scar. ICE echogenicity and CMR scar volumes correlated with each other and with ethanol volume. Ventricular function and interventricular septum remained intact.

CONCLUSIONS

VEA leads to intramural ablation that can be tracked intraprocedurally by ICE and creates regions of MVO that are chronically replaced by myocardial scar. VEA scar volume does not compromise septal integrity or ventricular function.

Global research trends in catheter ablation and surgical treatment of atrial fibrillation: A bibliometric analysis and science mapping

Introduction

To evaluate the global research results of the catheter ablation and surgical treatment of atrial fibrillation in the past 40 years by bibliometrics, and to explore the hotspots and prospects for future development.

Methods

Relevant literatures were selected from the Web of Science Core Collection. VOSviewer 1.6.17, SciMAT 1.1.04, and CiteSpace 5.8.R1 were used to analyze the data objectively, deeply and comprehensively.

Results

As of July 14, 2021, 11,437 studies for the catheter ablation and surgical treatment of atrial fibrillation have been identified from 1980 to 2021. The Journal of Cardiovascular Electrophysiology and Circulation respectively ranked first in terms of the number of publications and the number of co-citations. A total of 6,631 institutions from 90 countries participated in the study, with USA leading the way with 3,789 documents. Cryoablation, atrial fibrosis, substrate modification, minimally invasive and access surgery will still be the research focus and frontier in the next few years.

Conclusions

The publication information for the catheter ablation and surgical treatment of atrial fibrillation were reviewed, including country, institution, author, journal publications, and so on. Developed countries had the advantage in this research areas, and cooperation with low-income countries should be improved. The former research hotspots in the field of catheter ablation and surgical treatment of atrial fibrillation were analyzed, and the future research direction was predicted.

Advanced management of ventricular arrhythmias in chronic Chagas cardiomyopathy

Chagas cardiomyopathy is a parasitic infection caused by Trypanosoma cruzi. Structural and functional abnormalities are the result of direct myocardial damage by the parasite, immunological reactions, dysautonomia, and microvascular alterations. Chronic Chagas cardiomyopathy (CCC) is the most serious and important manifestation of the disease, affecting up to 30% of patients in the chronic phase. It results in heart failure, arrhythmias, thromboembolism, and sudden cardiac death. As in other cardiomyopathies, scar-related reentry frequently results in ventricular tachycardia (VT). The scars typically are located in the inferior and lateral aspects of the left ventricle close to the mitral annulus extending from endocardium to epicardium. The scars may be more prominent in the epicardium than in the endocardium, so epicardial mapping and ablation frequently are required. Identification of late potentials during sinus rhythm and mid-diastolic potentials during hemodynamically tolerated VT are the main targets for ablation. High-density mapping during sinus rhythm can identify late isochronal regions that are then targeted for ablation. Preablation cardiac magnetic resonance imaging with late enhancement can identify potentials areas of arrhythmogenesis. Therapeutic alternatives for VT management include antiarrhythmic drugs and modulation of the cardiac autonomic nervous system.

Efficacy and tolerability of quinidine as salvage therapy for monomorphic ventricular tachycardia in patients with structural heart disease

INTRODUCTION

Quinidine is an effective therapy for a subset of polymorphic ventricular tachycardia and ventricular fibrillation (VF) syndromes; however, the efficacy of quinidine in scar-related monomorphic ventricular tachycardia (MMVT) is unclear.

METHODS AND RESULTS

Between 2009 and 2020 a single VT referral center, a total of 23 patients with MMVT and structural heart disease (age 66.7 ± 10.9, 20 males, 15 with ischemic cardiomyopathy, mean LVEF 22.2 ± 12.3%, 9 with left ventricular assist device [LVAD]) were treated with quinidine (14 quinidine gluconate; 996 ± 321 mg, 8 quinidine sulfate; 1062 ± 588 mg). Quinidine was used in combination with other antiarrhythmics (AAD) in 19 (13 also on amiodarone). All patients previously failed >1 AAD (amiodarone 100%, mexiletine 73%, sotalol 32%, other 32%) and eight had prior ablations (median of 1.5). Quinidine was initiated in the setting of VT storm despite AADs (6), inability to tolerate other AADs (4), or recurrent VT(12). Ventricular arrhythmias recurred despite quinidine in 13 (59%) patients at a median of 26 (4-240) days after quinidine initiation. In patients with recurrent MMVT, VT cycle length increased from 359 to 434 ms (p = .02). Six (27.3%) patients remained on quinidine at 1 year with recurrence of ventricular arrhythmias in all. The following adverse effects were seen: gastrointestinal side effects (6), QT prolongation (2), rash (1), thrombocytopenia (1), neurologic side effects (1). One patient discontinued due to cost.

CONCLUSION

Quinidine therapy has limited tolerability and long-term efficacy when used in the management of amiodarone-refractory scar-related MMVT.

Anesthetic management in bilateral video-assisted thoracoscopic sympathectomy for refractory ventricular arrhythmias: A case report

Cardiac Sympathetic Denervation (CSD) has been shown to reduce shocks and subsequent pain of implantable cardiac defibrillator (ICD) in patients with heart diseases and recurrent Ventricular Tachycardia (VT) who did not respond properly to oral therapy and ablation. A 68-year-old man who presented an idiopathic dilated cardiomyopathy with impaired ejection fraction was treated for VT. A bilateral cardiac sympathetic denervation was performed under general anesthesia. Patient was extubated in the operating room and transferred to ICU where he presented hypotension. He was discharged after five days and remained symptom-free without any incident of VT during hospital stay. Currently no definite anesthetic management is available to treat such patients. This report discusses an approach that made heart rate control and safe patient discharge possible.

Open surgical ablation of ventricular tachycardia: Utility and feasibility of contemporary mapping and ablation tools

Background

Ventricular tachycardia (VT) catheter ablation success may be limited when transcutaneous epicardial access is contraindicated. Surgical ablation (SurgAbl) is an option, but ablation guidance is limited without simultaneously acquired electrophysiological data.

Objective

We describe our SurgAbl experience utilizing contemporary electroanatomic mapping (EAM) among patients with refractory VT storm.

Methods

Consecutive patients with recurrent VT despite antiarrhythmic drugs (AADs) and prior ablation, for whom percutaneous epicardial access was contraindicated, underwent open SurgAbl using intraoperative EAM guidance.

Results

Eight patients were included, among whom mean age was 63 ± 5 years, all were male, mean left ventricular ejection fraction was 39% ± 12%, and 2 (25%) had ischemic cardiomyopathy. Reasons for surgical epicardial access included dense adhesions owing to prior cardiac surgery, hemopericardium, or pericarditis (n = 6); or planned left ventricular assist device (LVAD) implantation at time of SurgAbl (n = 2). Cryoablation guided by real-time EAM was performed in all. Goals of clinical VT noninducibility or core isolation were achieved in 100%. VT burden was significantly reduced, from median 15 to 0 events in the month pre- and post-SurgAbl (P = .01). One patient underwent orthotopic heart transplantation for recurrent VT storm 2 weeks post-SurgAbl. Over mean follow-up of 3.4 ± 1.7 years, VT storm–free survival was achieved in 6 (75%); all continued AADs, although at lower dose.

Conclusion

Surgical mapping and ablation of refractory VT with use of contemporary EAM is feasible and effective, particularly among patients with contraindication to percutaneous epicardial access or with another indication for cardiac surgery.

Alcohol Ablation for Ventricular Tachycardia

Catheter-based radiofrequency (RF) ablation is an effective, well-established therapy for ventricular tachycardia (VT). However, a large number of patients still have recurrences, particularly those with substrates arising from intramural locations that are inaccessible through endo- or epicardial catheter approaches. Several unconventional ablation techniques have been proposed to treat RF-refractory VT, including transarterial coronary ethanol ablation and retrograde coronary venous ethanol ablation. We review the evidence regarding the mechanisms, procedural aspects, and alcohol ablation outcomes for ventricular arrhythmias.

Long-term clinical outcomes of cardiac sympathetic denervation in patients with refractory ventricular arrhythmias

BACKGROUND

Cardiac sympathetic denervation (CSD) is a useful therapeutic option in patients with structural heart disease (SHD) and ventricular tachycardia (VT) who are otherwise refractory to standard antiarrhythmic drug (AAD) therapy or catheter ablation (CA). In this study, we sought to retrospectively analyze the long-term outcomes of CSD in patients with refractory VT and/or VT storm with a majority of the patients being taken up for CSD ahead of CA.

METHODS

We included consecutive patients with SHD who underwent CBD from 2010 to 2019 owing to refractory VT. A complete response to CSD was defined as a greater than 75% reduction in the frequency of ICD shocks for VT.

RESULTS

A total of 65 patients (50 male, 15 female) were included. The underlying VT substrate was ischemic heart disease (IHD) in 30 (46.2%) patients while the remaining 35 (53.8%) patients had other nonischemic causes. The mean duration of follow-up was 27 ± 24 months. A complete response to CSD was achieved in 47 (72.3%) patients. There was a significant decline in the number of implantable cardioverter-defibrillator (ICD) or external defibrillator shocks post-CSD (24 ± 37 vs. 2 ± 4, p < .01). Freedom from a combined endpoint of ICD shock or death at 2 years was 51.5%. An advanced New York Heart Association class (III and IV) was the only parameter found to be associated with this combined endpoint.

CONCLUSION

The current retrospective analysis re-emphasizes the role of surgical CSD and explores its role ahead of CA in the treatment of patients with refractory VT or VT storm.

Renal Denervation for the Management of Refractory Ventricular Arrhythmias: A Systematic Review

OBJECTIVES

The authors performed a systematic review and meta-analysis to determine the efficacy of renal denervation (RDN) in patients with refractory ventricular arrhythmias (VA) or electrical storm (ES).

BACKGROUND

Although catheter ablation is efficacious for the treatment of structural heart disease ventricular tachycardia (VT), there are proportion of patients who have refractory VT despite multiple procedures. In this setting, novel adjunctive therapies such as renal denervation have been performed.

METHODS

A systematic review of published data was performed. Studies that evaluated patients undergoing RDN for VA or ES were included. Outcome measures of VA, sudden cardiac death, ES, or device therapy were required. Case reports, editorials, and conference presentations were excluded. Random effects meta-analysis was conducted to explore change or final mean values in the study outcomes.

RESULTS

A total of 328 articles were identified by the literature search. Seven studies met the eligibility criteria and were included in the systematic review, with a total of 121 pooled patients. The weighted mean age was 63.8 ± 13.1 years, ejection fraction 30.5 ± 10.3%, 76% were men, 99% were on a beta blocker, 79% were on amiodarone, 46% had previously undergone catheter ablation, and 8.3% had previously undergone cardiac sympathetic denervation. Meta-analysis demonstrated a significant effect of RDN in reducing implantable cardiac defibrillator therapies, with a standardized mean difference (SMD) of -3.11 (p < 0.001). RDN also reduced the number of VA episodes (SMD -2.13; p < 0.001), antitachycardia pacing episodes (SMD -2.82; p = 0.002), and shocks (SMD -2.82; p = 0.002).

CONCLUSIONS

RDN is an effective treatment for refractory VAs and ES, although randomized data are lacking.

Ablation of Incessant Premature Ventricular Complex Through Retrograde Transvenous Ethanol Infusion

Ethanol infusion has been used for the treatment of ventricular arrhythmia. We describe a case of ethanol infusion through the coronary sinus venous network to treat refractory epicardial premature ventricular complexes. The premature ventricular complexes were initially successfully suppressed but recurred after resolution of the myocardial edema. (Level of Difficulty: Intermediate.).

Arrhythmogenic Cardiomyopathy: Molecular Insights for Improved Therapeutic Design

Arrhythmogenic cardiomyopathy (ACM) is an inherited disorder characterized by structural and electrical cardiac abnormalities, including myocardial fibro-fatty replacement. Its pathological ventricular substrate predisposes subjects to an increased risk of sudden cardiac death (SCD). ACM is a notorious cause of SCD in young athletes, and exercise has been documented to accelerate its progression. Although the genetic culprits are not exclusively limited to the intercalated disc, the majority of ACM-linked variants reside within desmosomal genes and are transmitted via Mendelian inheritance patterns; however, penetrance is highly variable. Its natural history features an initial “concealed phase” that results in patients being vulnerable to malignant arrhythmias prior to the onset of structural changes. Lack of effective therapies that target its pathophysiology renders management of patients challenging due to its progressive nature, and has highlighted a critical need to improve our understanding of its underlying mechanistic basis. In vitro and in vivo studies have begun to unravel the molecular consequences associated with disease causing variants, including altered Wnt/β-catenin signaling. Characterization of ACM mouse models has facilitated the evaluation of new therapeutic approaches. Improved molecular insight into the condition promises to usher in novel forms of therapy that will lead to improved care at the clinical bedside.

Renal Denervation in Asia: Consensus Statement of the Asia Renal Denervation Consortium

The Asia Renal Denervation Consortium consensus conference of Asian physicians actively performing renal denervation (RDN) was recently convened to share up-to-date information and regional perspectives, with the goal of consensus on RDN in Asia. First- and second-generation trials of RDN have demonstrated the efficacy and safety of this treatment modality for lowering blood pressure in patients with resistant hypertension. Considering the ethnic differences of the hypertension profile and demographics of cardiovascular disease demonstrated in the SYMPLICITY HTN (Renal Denervation in Patients With Uncontrolled Hypertension)-Japan study and Global SYMPLICITY registry data from Korea and Taiwan, RDN might be an effective hypertension management strategy in Asia. Patient preference for device-based therapy should be considered as part of a shared patient-physician decision process. A practical population for RDN treatment could consist of Asian patients with uncontrolled essential hypertension, including resistant hypertension. Opportunities to refine the procedure, expand the therapy to other sympathetically mediated diseases, and explore the specific effects on nocturnal and morning hypertension offer a promising future for RDN. Based on available evidence, RDN should not be considered a therapy of last resort but as an initial therapy option that may be applied alone or as a complementary therapy to antihypertensive medication.

Ventricular Tachycardia Ablation in Non-ischemic Cardiomyopathy

Non-ischemic cardiomyopathies are a heterogeneous group of diseases of the myocardium that have a distinct proclivity to ventricular arrhythmias. Of these, ventricular tachycardias pose significant management challenges with the risk of sudden cardiac death and morbidity from multiple causes. Catheter ablation of ventricular tachycardias is becoming an increasingly utilised intervention that has been found to have significant benefits with improving symptoms, reducing anti-arrhythmic drug burden and debilitating device therapies, thereby improving quality of life. Nonetheless, the approach to the ablation of ventricular tachycardias in non-ischemic cardiomyopathies is governed heavily by the disease process, with several distinct differences from ischemic cardiomyopathy including a preponderance to epicardial and deep intramural substrate. This contemporary review aims to present the various disease processes within non-ischemic cardiomyopathies, catheter ablation techniques which have been developed to target ventricular tachycardia and more novel adjunctive therapeutic measures.

Ventricular Tachycardia Ablation in Nonischemic Cardiomyopathy

Catheter ablation is being increasingly performed as adjunctive treatment to prevent recurrent implantable cardioverter-defibrillator therapies in patients with nonischemic cardiomyopathy and ventricular tachycardia (VT). In the context of VT ablation, nonischemic cardiomyopathy usually refers to dilated cardiomyopathy (DCM) as one morphological phenotype. Over the past decades, progress has been made to better characterize distinct subtypes and to differentiate between causes of DCM, which has important practical and prognostic implications. The goal of this review is to summarize available data on VT ablation in patients with DCM and, more specifically, review procedural and outcome data in specific etiologies and substrate location. It will focus on our current understanding of nonischemic scars, as well as the value of multimodal imaging, image integration, and electroanatomic mapping for substrate identification, procedural planning, and ablation. In addition, recent findings from whole human heart histology of patients with DCM and VT and their potential implications for imaging and mapping will be discussed.

Minimally invasive transtracheal cardiac plexus block for sympathetic neuromodulation

BACKGROUND

Bilateral thoracoscopic stellectomy has antiarrhythmic effects, but the procedure is invasive with associated morbidity. Sympathetic nerves from both stellate ganglia form the deep cardiac plexus (CP) in the aortopulmonary window, anterior to the trachea.

OBJECTIVE

The purpose of this study was to demonstrate a novel and minimally invasive transtracheal approach to block the CP in porcine models.

METHODS

In 12 Yorkshire pigs, right (RSG) and left (LSG) stellate ganglia were electrically stimulated and sympathetic baseline response recorded (hemodynamic parameters and T-wave pattern). Aortopulmonary window was accessed transtracheally with endobronchial ultrasound guidance, and local stimulation of CP confirmed the location. Injection of 1% lidocaine (n = 10) or saline solution (n = 2) was performed, and RSG and LSG responses were re-evaluated and compared with baseline.

RESULTS

Transtracheal lidocaine injection into the CP successfully blocked bilateral sympathetic induced changes (%) in T-wave amplitude (282.8% ± 152.2% vs 20.1% ± 16.5%; P <.001 [LSG]; 338.9% ± 189.8% vs 28% ± 18.3%; P <.001 [RSG]), Tp-Te interval (87.9% ± 37.2% vs 6.9% ± 6.7%; P <.001 [LSG]; 32.6% ± 27.4% vs 6.9% ± 4.7%; P <.035 [RSG]), and left ventricular dP/dT_max (148.3% ± 108.5% vs 16.5% ± 13.4%; P <.001 [LSG]; 243.1% ± 105.2% vs 19.0% ± 12.4%; P <.001 [RSG]). RSG-induced elevations of systemic, left ventricular, and pulmonary arterial pressures were blocked by lidocaine injection into CP (P <.005 for all comparisons). Stellate ganglia response was not affected in sham studies. No complications were observed during the procedures.

CONCLUSION

Minimally invasive transtracheal injection of lidocaine into the CP blocked the sympathetic response of either RSG and LSG. Transtracheal assessment of CP may allow for minimally invasive and selective ablation of cardiac innervation, extending the cardiac sympathectomy denervation benefits to those not suitable for surgery.

Repeat ablation of refractory ventricular arrhythmias in patients with nonischemic cardiomyopathy: Impact of midmyocardial substrate and role of adjunctive ablation techniques

INTRODUCTION

Multiple ablations are often necessary to manage ventricular arrhythmias (VAs) in nonischemic cardiomyopathy (NICM) patients. We assessed characteristics and outcomes and role of adjunctive, nonstandard ablation in repeat VA ablation (RAbl) in NICM.

METHODS AND RESULTS

Consecutive NICM patients undergoing RAbl were analyzed, with characteristics of the last VA ablations compared between those undergoing 1 versus multiple-repeat ablations (1-RAbl vs. >1RAbl), and between those with or without midmyocardial substrate (MMS). VA-free survival was compared. Eighty-eight patients underwent 124 RAbl, 26 with > 1RAbl, and 26 with MMS. 1-RAbl and > 1-RAbl groups were similar in age (57 ± 16 vs. 57 ± 17 years; P = 0.92), males (76% vs. 69%; P = 0.60), LVEF (40 ± 17% vs. 40 ± 18%; P = 0.96), and amiodarone use (31% vs. 46%, P = 0.22). One-year VA freedom between 1-RAbl vs. > 1RAbl was similar (82% vs. 80%; P = 0.81); adjunctive ablation was utilized more in >1RAbl (31% vs. 11%, P = 0.02), and complication rates were higher (27% vs. 7%, P = 0.01), most due to septal substrate and anticipated heart block. >1-RAbl patients had more MMS (62% vs. 16%, P < 0.01). Although MMS was associated with worse VA-free survival after 1-RAbl (43% vs. 69%, P = 0.01), when >1RAbl was performed, more often with nonstandard ablation, VA-free survival was comparable to non-MMS patients (85% vs. 81%; P = 0.69). More RAbls were required in MMS versus non-MMS patients (2.00 ± 0.98 vs. 1.16 ± 0.37; P < 0.001).

CONCLUSION

For NICM patients with recurrent, refractory VAs despite previous ablation, effective arrhythmia control can safely be achieved with subsequent ablation, although >1 repeat procedure with adjunctive ablation is often required, especially with MMS.

Cardiac Imaging in Patients With Ventricular Tachycardia

Ventricular tachycardia (VT) is a major cause of sudden cardiac death. The majority of malignant VTs occur in patients with structural heart disease. Multimodality imaging techniques play an integral role in determining the underlying etiology and prognostic significance of VT. In recent years, advances in imaging technology have enabled characterization of the structural arrhythmogenic substrate in patients with VT with increasing precision. In parallel with these advances, the role of cardiac imaging has expanded from a largely diagnostic tool to an adjunctive tool to guide interventional approaches for treatment of VT. Invasive and noninvasive imaging techniques, often used in combination, have made it possible to integrate structural and electrophysiological information during VT ablation procedures. An important area of current development is the use of noninvasive imaging techniques based on body surface electrocardiographic mapping to elucidate the mechanisms of VT. In the future, these techniques may provide a priori information on mechanisms of VT in patients undergoing interventional procedures. This review provides an overview of the role of cardiac imaging in patients with VT.

Ventricular Arrhythmias

Ventricular tachycardia (VT) is the most common form of wide complex tachycardia and is associated with a high mortality rate. Electrocardiographic analysis remains paramount in diagnosis and helps to direct therapy. Antiarrhythmic agents, although effective in reducing arrhythmia burden, have never demonstrated a mortality benefit. The implantable cardioverter-defibrillator aids not only in the acute termination of ventricular arrhythmia, but provides a wealth of information for the long-term management of patients with VT. Contemporary treatment options such as catheter ablation are increasingly used and effective, but often remain imperfect, with recurrent VT being not uncommon.

Cardiac sympathectomy for the management of ventricular arrhythmias refractory to catheter ablation

BACKGROUND

Catheter ablation is now a mainstay of therapy for ventricular arrhythmias (VAs). However, there are scenarios where either physiological or anatomical factors make ablation less likely to be successful.

OBJECTIVE

The purpose of this study was to demonstrate that cardiac sympathetic denervation (CSD) may be an alternate therapy for patients with difficult-to-ablate VAs.

METHODS

We identified all patients referred for CSD at a single center for indications other than long QT syndrome and catecholaminergic polymorphic ventricular tachycardia who had failed catheter ablation. Medical records were reviewed for medical history, procedural details, and follow-up.

RESULTS

Seven cases of CSD were identified in patients who had failed prior catheter ablation or had disease not amenable to ablation. All patients had VAs refractory to antiarrhythmic drugs, with a median arrhythmia burden of 1 episode of sustained VA per month. There were no acute complications of sympathectomy. One of 7 patients (14%) underwent heart transplant. No patient had sustained VA after sympathectomy at a median follow-up of 7 months.

CONCLUSION

Because of anatomical and physiological constraints, many VAs remain refractory to catheter ablation and remain a significant challenge for the electrophysiologist. While CSD has been described as a therapy for long QT syndrome and catecholaminergic polymorphic ventricular tachycardia, data regarding its use in other cardiac conditions are sparse. This series illustrates that CSD may be a viable treatment option for patients with a variety of etiologies of VAs.

Cardiac Sympathetic Denervation for Refractory Ventricular Arrhythmias

BACKGROUND

Cardiac sympathetic denervation (CSD) has been shown to reduce the burden of implantable cardioverter-defibrillator (ICD) shocks in small series of patients with structural heart disease (SHD) and recurrent ventricular tachyarrhythmias (VT).

OBJECTIVES

This study assessed the value of CSD and the characteristics associated with outcomes in this population.

METHODS

Patients with SHD who underwent CSD for refractory VT or VT storm at 5 international centers were analyzed by the International Cardiac Sympathetic Denervation Collaborative Group. Kaplan-Meier analysis was used to estimate freedom from ICD shock, heart transplantation, and death. Cox proportional hazards models were used to analyze variables associated with ICD shock recurrence and mortality after CSD.

RESULTS

Between 2009 and 2016, 121 patients (age 55 ± 13 years, 26% female, mean ejection fraction of 30 ± 13%) underwent left or bilateral CSD. One-year freedom from sustained VT/ICD shock and ICD shock, transplant, and death were 58% and 50%, respectively. CSD reduced the burden of ICD shocks from a mean of 18 ± 30 (median 10) in the year before study entry to 2.0 ± 4.3 (median 0) at a median follow-up of 1.1 years (p < 0.01). On multivariable analysis, pre-procedure New York Heart Association functional class III and IV heart failure and longer VT cycle lengths were associated with recurrent ICD shocks, whereas advanced New York Heart Association functional class, longer VT cycle lengths, and a left-sided-only procedure predicted the combined endpoint of sustained VT/ICD shock recurrence, death, and transplantation. Of the 120 patients taking antiarrhythmic medications before CSD, 39 (32%) no longer required them at follow-up.

CONCLUSIONS

CSD decreased sustained VT and ICD shock recurrence in patients with refractory VT. Characteristics independently associated with recurrence and mortality were advanced heart failure, VT cycle length, and a left-sided-only procedure.