Catheter ablation of right atrial ganglionated plexi to treat cardioinhibitory neurocardiogenic syncope: a long-term follow-up prospective study

Cardioneuroablation for vasovagal syncope: insights on patients' selection, centre settings, procedural workflow and endpoints-results from an European Heart Rhythm Association survey

AIMS

Cardioneuroablation (CNA) is a catheter-based intervention for recurrent vasovagal syncope (VVS) that consists in the modulation of the parasympathetic cardiac autonomic nervous system. This survey aims to provide a comprehensive overview of current CNA utilization in Europe.

METHODS AND RESULTS

A total of 202 participants from 40 different countries replied to the survey. Half of the respondents have performed a CNA during the last 12 months, reflecting that it is considered a treatment option of a subset of patients. Seventy-one per cent of respondents adopt an approach targeting ganglionated plexuses (GPs) systematically in both the right atrium (RA) and left atrium (LA). The second most common strategy (16%) involves LA GP ablation only after no response following RA ablation. The procedural endpoint is frequently an increase in heart rate. Ganglionated plexus localization predominantly relies on an anatomical approach (90%) and electrogram analysis (59%). Less utilized methods include pre-procedural imaging (20%), high-frequency stimulation (17%), and spectral analysis (10%). Post-CNA, anticoagulation or antiplatelet therapy is prescribed, with only 11% of the respondents discharging patients without such medication. Cardioneuroablation is perceived as effective (80% of respondents) and safe (71% estimated <1% rate of procedure-related complications). Half view CNA emerging as a first-line therapy in the near future.

CONCLUSION

This survey offers a snapshot of the current implementation of CNA in Europe. The results show high expectations for the future of CNA, but important heterogeneity exists regarding indications, procedural workflow, and endpoints of CNA. Ongoing efforts are essential to standardize procedural protocols and peri-procedural patient management.

Cardioneuroablation for Cardioinhibitory Vasovagal Syncope: Rationale, Approaches, and Its Role in Long-Term Management

Purpose of Review

Cardioneuroablation (CNA) has emerged as a potential alternative to pacemaker therapy in well-selected cases with vasovagal syncope (VVS). In recent years, the number of CNA procedures performed by electrophysiologists has considerably risen. However, some important questions, including proper patient selection and long-term results, remain unanswered. The present article aims to critically review and interpret latest scientific evidence for clinical indications and how to approach long-term management.

Recent Findings

CNA is a new approach that has been supported mainly by retrospective or observational data for its use in syncope. Overall, in mixed population studies treated with CNA, 83.3 to 100% have been reported to be free of syncope over follow-up periods of 6 to 52.1 months. For studies including patients who underwent CNA with pure VVS, 73.2 to 100% have been reported to be syncope-free over follow-up periods of 4 to 45.1 months. One large meta-analysis showed 91.9% freedom from syncope after CAN. To date, only one randomized controlled trial with small case number has been performed of CNA compared to non-pharmacological treatment in VVS. In this study of 48 patients with an average of 10 ± 9 spontaneous syncopal episodes prior to study enrollment and 3 ± 2 episodes in the year prior to CNA. After CNA, 92% were free of syncope compared with 46% treated with optimal non-pharmacological treatment to prevent new syncope episodes (P = 0.0004). To date, most studies have included younger patients (< 60 years of age). There are only limited data in patients older than 60, and some studies suggest less of an effect in relatively older patients.

Summary

Cardioneuroablation can be performed to decrease syncope recurrence in adult patients aged < 60 years, with severe or recurrent cardioinhibitory syncope without prodromal symptoms, after proven failure of conventional therapies. Due to a paucity of data supporting efficacy in older individuals or for vasodepressor components, CNA in adult patients aged > 60 years or in the presence of a dominant vasodepressor should be considered investigational in severely symptomatic patients after proven failure of pharmacological and non-pharmacological therapies.

Cryoballoon cardioneuroablation: New electrophysiological insights

Background

Cardioneuroablation (CNA) targeting ganglionated plexi has shown promise in treating vasovagal syncope. Only radiofrequency ablation has been used to achieve this goal thus far.

Objective

The purpose of this study was to investigate the utility of cryoballoon ablation (CBA) of the pulmonary veins (PVs) as a potential simplified approach to CNA.

Methods

We report our observations of autonomic modulation in a series of 17 patients undergoing CBA for atrial fibrillation and our early experience using CBA of the PVs in 3 patients with malignant vagal syncope. In 17 patients undergoing CBA of AF, sinus cycle length was recorded intraprocedurally after ablation of individual PVs.

Results

The most pronounced shortening of the sinus cycle length was observed after isolation of the right upper PV, which was ablated last. Reduced sinus node recovery time and atrioventricular (AV) nodal effective refractory period were observed after CBA. Resting heart rate was elevated by 6-7 bpm after CBA and persisted during 12-month follow-up. CBA of the PVs was performed in 3 patients with recurrent vagal syncope mediated by sinus arrest (n = 2) and AV block (n = 1). In all patients, isolation of the right upper PV resulted in marked shortening of sinus cycle length. During follow-up of 178 ± 43 days (134-219 days), CNA resulted in abolition of pauses, bradycardia-related symptoms, and syncope in all patients.

Conclusion

CBA of the PVs (particularly the right upper PV) may be a predictable anatomic CNA approach in patients with refractory vagal syncope due to sinus arrest and/or AV block and may warrant systematic investigation as a tool to perform CNA.

Cardioneuroablation as a strategy to prevent pacemaker implantation in young patients with vasovagal syncope

Background

Cardioneuroablation (CNA) is an ablation technique that targets epicardial ganglionic plexi to reduce syncope burden and avoid pacemaker implantation in patients with cardioinhibitory vasovagal syncope (VVS). This study aims to demonstrate feasibility and safety of CNA in high-risk refractory VVS patients using continuous monitoring with an implantable loop recorder (ILR).

Methods

Data was collected prospectively for patients undergoing CNA. Patients were required to have recurrent syncope with documented asystole, refractory to conservative measures. Ganglionic plexi (GPs) were identified by fragmented signals and high frequency stimulation (HFS). Ablation was performed until loss of positive response to HFS, Wenckebach cycle shortening was achieved, or an increase in sinus rate of > 20 bpm. Follow-up was performed through remote and clinic follow-up of their ILRs.

Results

Between December 2020 and July 2023 six patients (mean age 29 ± 3, 67 % female)underwent CNA. The baseline heart rate and Wenckebach cycle length was 63.2 ± 15 bpm and 582 ms before and 91 ± 5 bpm and 358 ms after ablation respectively. During a median follow-up of 13.4 months, 3/5 patients had no further syncopal episodes, 1 had a recurrence, underwent repeat CNA with no further episodes at 1 year, and 1 had 5 syncopal events, which was a dramatic reduction from nearly daily episodes pre-CNA. There were no procedure related complications.

Conclusions

A dramatic reduction in documented pauses and syncope burden was noted post CNA. Appropriate patient selection with rigorous objective follow-up in an experienced center is necessary. Larger studies are required to confirm these findings.

Cardioneuroablation for reflex asystolic syncope: Mid-term safety, efficacy, and patient's acceptance

BACKGROUND

Cardioneuroablation (CNA) is a promising therapy for reflex asystolic syncope; however, convincing data on the mid-term safety and efficacy of this procedure are lacking.

OBJECTIVE

The purpose of this study was to assess the mid-term safety, efficacy, and patient acceptance of CNA.

METHODS

This prospective observational single-center study included 115 consecutive patients (mean age 39 ± 13 years; 58% female) treated between 2016 and 2022 who completed at least 1-year follow-up.

RESULTS

No significant procedure-related acute complications occurred. During median follow-up of 28 months (range 12-75), 95 (83%) remained free from syncope. Of the 20 patients (17%) with syncope recurrence, syncope burden decreased from a mean 17 (median 6.5) to 3.75 (median 2.5) episodes (P = .015). In 9 of 10 patients, pacing system removal was possible. Repeated CNA was needed in 3 patients (3%), whereas pacemaker implantation was performed in 5 (4%). The most frequent mid-term complication of CNA was sinus rhythm acceleration (from 60 ± 14 bpm to 90 ± 16 bpm; P <.0001), which was symptomatic in 31 patients (27%); 8 patients (7%) required chronic beta-blocker and/or ivabradine. Sinus node modification was necessary in 1 patient. Other complaints included dyspnea, chronic chest pain, and decreased exercise capacity, which were mild and reported by 16 patients (14%). Patient acceptance of CNA was very high: 96% stated that it was worth undergoing the procedure.

CONCLUSIONS

Mid-term efficacy of CNA exceeds 80%, and acute complications are absent. The most frequent mid-term chronic complication is inappropriate sinus tachycardia, which in 7% required chronic treatment. The procedure is well accepted by patients.

The Intrinsic Cardiac Nervous System: From Pathophysiology to Therapeutic Implications

The cardiac autonomic nervous system (CANS) plays a pivotal role in cardiac homeostasis as well as in cardiac pathology. The first level of cardiac autonomic control, the intrinsic cardiac nervous system (ICNS), is located within the epicardial fat pads and is physically organized in ganglionated plexi (GPs). The ICNS system does not only contain parasympathetic cardiac efferent neurons, as long believed, but also afferent neurons and local circuit neurons. Thanks to its high degree of connectivity, combined with neuronal plasticity and memory capacity, the ICNS allows for a beat-to-beat control of all cardiac functions and responses as well as integration with extracardiac and higher centers for longer-term cardiovascular reflexes. The present review provides a detailed overview of the current knowledge of the bidirectional connection between the ICNS and the most studied cardiac pathologies/conditions (myocardial infarction, heart failure, arrhythmias and heart transplant) and the potential therapeutic implications. Indeed, GP modulation with efferent activity inhibition, differently achieved, has been studied for atrial fibrillation and functional bradyarrhythmias, while GP modulation with efferent activity stimulation has been evaluated for myocardial infarction, heart failure and ventricular arrhythmias. Electrical therapy has the unique potential to allow for both kinds of ICNS modulation while preserving the anatomical integrity of the system.

Cardioneuroablation for the Treatment of Vasovagal Syncope: Current Status and Impact on Quality of Life

PURPOSE OF REVIEW

Vasovagal syncope (VVS) is a common entity causing transient loss of consciousness and affecting quality of life. Guideline-recommended therapy involves conservative measures and pacing in selected patients. Cardioneuroablation (CNA) targeting the ganglionated plexi in the heart has been shown to reduce excessive vagal excitation, which plays a major role in the pathophysiology of VVS and functional bradycardia.

RECENT FINDINGS

The introduction of CNA has fueled research into its value for the treatment of VVS. Multiple observational studies and one randomized trial have demonstrated the safety and efficacy of CNA and the positive impact on quality of life. This review describes the rationale and CNA procedural techniques and outcomes. Patient selection and future directions have also been described. Cardioneuroablation is a promising treatment for patients with recurrent VVS and functional bradycardia. Further large-scale randomized studies are needed to further verify the safety and efficacy of this approach.

Ganglionated Plexus Ablation Procedures to Treat Vasovagal Syncope

Vasovagal syncope (VVS) refers to a heterogeneous group of conditions whereby the cardiovascular reflexes normally controlling the circulation are interrupted irregularly in response to a trigger, resulting in vasodilation, bradycardia, or both. VVS affects one-third of the population at least once in their lifetime or by the age of 60, reduces the quality of life, and may cause disability affecting certain routines. It poses a considerable economic burden on society, and, despite its prevalence, there is currently no proven pharmacological treatment for preventing VVS. The novel procedure of ganglionated plexus (GP) ablation has emerged rapidly in the past two decades, and has been proven successful in treating syncope. Several parameters influence the success rate of GP ablation, including specific ablation sites, localization and surgical techniques, method of access, and the integration of other interventions. This review aims to provide an overview of the existing literature on the physiological aspects and clinical effectiveness of GP ablation in the treatment of VVS. Specifically, we explore the association between GPs and VVS and examine the impact of GP ablation procedures as reported in human clinical trials. Our objective is to shed light on the therapeutic significance of GP ablation in eliminating VVS and restoring normal sinus rhythm, particularly among young adults affected by this condition.

Cardioneuroablation for Treating Vasovagal Syncope: Current Status and Future Directions

Syncope is defined by transient and spontaneous loss of consciousness with rapid recovery. Vasovagal syncope (VVS) is the most common form of syncope and is strongly associated with hypervagotonia. There is, however, a lack of effective therapies for VVS. Cardioneuroablation (CNA) is an emerging and promising intervention for VVS with favourable outcomes. CNA has been shown to suppress excessive excitation of vagal activity through ablating the cardiac ganglionated plexi. CNA in the management of VVS requires more structured and comprehensive studies and several issues concerning patient selection, selection of ablation targets, ablation endpoints and the long-term effect of CNA are yet to be determined. This review describes its clinical applications and future directions based on current research data and the authors' own experiences.

Ganglionated plexi ablation in the right atrium for the treatment of cardioinhibitory syncope

Neurocardiogenic syncope, also called vasovagal syncope, represents one of the clinical manifestations of neurally mediated syncopal syndrome. Generally, the prognosis of the cardioinhibitory form of neurocardiogenic syncope is good, but quality of life is seriously compromised in patients who experience severe forms. Drug therapy has not achieved good clinical results and very heterogeneous data come from studies regarding permanent cardiac pacing. In this scenario, the ganglionated plexi ablation has been proposed as an effective and safe method in patients with cardioinhibitory neurocardiogenic syncope, especially in young patients in order to avoid or prolong, as much as possible, the timing of definitive cardiac pacing. Certainly, making this procedure less extensive and limiting the ablation in the right atrium (avoiding the potential complications of a left atrial approach) and at level of anatomical regions of the most important ganglionated plexy, considered 'gateway' of the sino-atrial and atrio-ventricular node function (through the recognition of specific endocardial potentials), could be very advantageous in this clinical scenario. Finally, randomized, multicentre, clinical trials on a large population are needed to better understand which is the best ablation treatment (right-only or bi-atrial) and provide evidence for syncope guidelines.

Cardioneuroablation for Reflex Syncope: Efficacy and Effects on Autonomic Cardiac Regulation-A Prospective Randomized Trial

BACKGROUND

Treatment of cardioinhibitory vasovagal syncope (VVS) is difficult. Recently, cardioneuroablation (CNA) has emerged as a new therapeutic option.

OBJECTIVES

This study sought to assess the effects of CNA on syncope recurrences in patients with VVS.

METHODS

This study was a prospective, open, randomized, controlled, investigator-initiated trial comparing CNA versus optimal nonpharmacologic therapy in patients with cardioinhibitory VVS. Patients were included if they had documented symptomatic cardioinhibitory or mixed VVS and positive atropine test. CNA was performed using radiofrequency ablation of the ganglionated plexi from the left and right atria. Follow-up lasted 2 years. Primary endpoint was time to first syncope recurrence. Secondary endpoints included changes in sinus rhythm and heart rate variability measured in Holter electrocardiography at baseline and 3, 12, and 24 months after CNA, as well as changes in quality of life at baseline and after completion of follow-up.

RESULTS

A total of 48 patients (17 male, mean age 38 ± 10 years, 24 in CNA group, 24 in control group) entered the study. The primary endpoint occurred in 2 patients (8%) from the CNA group versus 13 control patients (54%) (P = 0.0004). After CNA the mean sinus rhythm at 24-hour Holter electrocardiography was significantly faster and heart rate variability parameters significantly changed toward parasympathetic withdrawal compared with baseline values. Quality of life significantly improved in the CNA group (30 ± 10 points vs 10 ± 7 points; P = 0.0001), whereas it remained stable in control patients (31 ± 10 points vs 30 ± 10 points; P = 0.5501).

CONCLUSIONS

This is the first randomized study documenting efficacy of CNA in patients with cardioinhibitory VVS. Larger studies are needed to confirm these findings. (Cardioneuroablation for Reflex Syncope [ROMAN]; NCT03903744).

Cardioneuroablation for vasovagal syncope: A systematic review and meta-analysis

BACKGROUND

Cardioneuroablation (CNA) has emerged as promising therapy for patients with refractory vasovagal syncope (VVS).

OBJECTIVE

The purpose of this study was to provide a freedom from syncope estimate for CNA, including subgroup analysis by method and target of ablation.

METHODS

A systematic search was performed in MEDLINE and EMBASE according to the PRISMA guidelines until February 14, 2022. Observational studies and clinical trials reporting freedom from syncope were included. Meta-analysis was performed with a random-effects model.

RESULTS

A total of 465 patients were included across 14 studies (mean age 39.8 ± 4.0 year; 53.5% female). Different techniques were used to guide CNA: 50 patients (10.8%) by mapping fractionated electrograms, 73 (15.7%) with the spectral method, 210 (45.2%) with high-frequency stimulation, 73 (15.7%) with a purely anatomically guided method, and 59 (12.6%) with a combination. The target was biatrial in 168 patients (36.1%), left atrium only in 259 (55.7%), and right atrium only in 38 (8.2%). The freedom from syncope was 91.9% (95% confidence interval [CI] 88.1%-94.6%; I2 = 6.9%; P = .376). CNA limited to right atrial ablation was associated with a significant lower freedom from syncope (81.5%; 95% CI 51.9%-94.7%; P <.0001) vs left atrial ablation only (94.0%; 95% CI 88.6%--6.9%) and biatrial ablation (92.7%; 95% CI 86.8%-96.1%). Subgroup analysis according to the technique used to identify ganglionated plexi did not show any significant difference in freedom from syncope (P = .206).

CONCLUSION

This meta-analysis suggests a high freedom from syncope after CNA in VVS. Well-designed, double-blind, multicenter, sham-controlled randomized clinical trials are needed to provide evidence for future guidelines.

The future of cardioneuroablation in cardiovascular medicine

INTRODUCTION

Cardioneuroablation is increasingly being utilized to improve outcomes in patients with vagally mediated bradyarrhythmias. However, there are still controversial issues in the field including patient selection, safety and efficacy, and procedural end-points.

AREAS COVERED

In this review, the current role of cardioneuroablation is summarized, and controversial issues related to the modality are discussed.

EXPERT OPINION

According to small open-label cohort studies, overall freedom from syncope recurrence was higher than 90% after cardioneuroablation in patients with vasovagal syncope (VVS). Use of the electrogram-based strategy or high-frequency stimulation demonstrate similar success rate except in procedures limited to the right atrium. Based on a recently published randomized controlled trial and metanalysis, it may be possible now to make a strong recommendation for cardioneuroablation in patients <40 years of age, and those with the cardioinhibitory or mixed type of VVS who continue to experience frequent and/or burdensome syncope recurrences. Considering patients with VVS are prone to significant placebo/expectation effect, sham-controlled trials may help to quantify the placebo effect. In well-selected patients with functional atrioventricular block and sinus bradycardia, may result in encouraging medium-term outcomes. However, functional bradycardia is identified in a minority of patients presenting with high-grade atrioventricular block or sinus node dysfunction.

Cardioneuroablation for Treatment of Atrioventricular Block

[Figure: see text].

Intrinsic cardiac autonomic nervous system: What do clinical electrophysiologists need to know about the "heart brain"?

It is increasingly recognized that the autonomic nervous system (ANS) is a major contributor in many cardiac arrhythmias. Cardiac ANS can be divided into extrinsic and intrinsic parts according to the course of nerve fibers and localization of ganglia and neuron bodies. Although the role of the extrinsic part has historically gained more attention, the intrinsic cardiac ANS may affect cardiac function independently as well as influence the effects of the extrinsic nerves. Catheter-based modulation of the intrinsic cardiac ANS is emerging as a novel therapy for the management of patients with brady and tachyarrhythmias resulting from hyperactive vagal activation. However, the distribution of intrinsic cardiac nerve plexus in the human heart and the functional properties of intrinsic cardiac neural elements remain insufficiently understood. The present review aims to bring the clinical and anatomical elements of the immune effector cell-associated neurotoxicity together, by reviewing neuroanatomical terminologies and physiological functions, to guide the clinical electrophysiologist in the catheter lab and to serve as a reference for further research.

Atrial fibrillation and autonomic nervous system: A translational approach to guide therapeutic goals

The autonomic nervous system (ANS) is known to play an important role in the genesis and maintenance of atrial fibrillation (AF). Biomolecular and genetic mechanisms, anatomical knowledges with recent diagnostic techniques acquisitions, both invasive and non-invasive, have enabled greater therapeutic goals in patients affected by AF related to ANS imbalance. Catheter ablation of ganglionated plexi (GP) in the left and right atrium has been proposed in varied clinical conditions. Moreover interesting results arise from renal sympathetic denervation and vagal nerve stimulation. Despite all this, in the scenario of ANS modulation translational strategies we necessary must consider the treatment or correction of dynamic factors such as obesity, obstructive sleep apnea, lifestyle, food, and stress. Finally, new antiarrhythmic drugs, gene therapy and "ablatogenomic" could be represent exciting future therapeutic perspectives.

The benefit of cardioneuroablation to reduce syncope recurrence in vasovagal syncope patients: a case-control study

BACKGROUND

Adequate and effective therapy for resistant vasovagal syncope patients is lacking and the benefit of cardioneuroablation (CNA) in this cohort is still debated. The aim of this study is to assess the long-term effect of CNA versus conservative therapy (CT) in a retrospectively followed cohort.

METHODS

A total of 2874 patients underwent head-up tilt test (HUT) and 554 (19.2 %) were reported as positive, with VASIS type 2B response or > 3 s asystole in 130 patients. After exclusion of 29 patients under 18 years and over 65 years of age, 101 patients were included final analysis. Fifty-one patients (50.4%) underwent CNA and 50 (49.6%) patients received CT. After propensity score matching, 19 pairs of patients were successfully matched. The recurrence rate of syncope was compared between groups.

RESULTS

During a median follow-up of 22 months (IQR, 13-35), syncope was seen in 12 (11.8%) cases. In the 19 propensity-matched patients, recurrent syncope was observed in 8 patients in the CT group and in 2 patients in the CNA group, respectively. In mixed effect Cox regression analysis, CNA was associated with less syncope recurrence risk at follow-up (HR 0.23, 95% CI 0.03-0.99, p = 0.049). The 4-year Kaplan-Meier syncope free rate was 0.86 (95% CI, 0.63-1.00) for CNA group and 0.50 (95% CI, 0.30-0.82) for CT group in the matched cohort.

CONCLUSIONS

In highly selected patients with HUT-induced cardioinhibitory response, CNA is associated with a significant reduction in syncope recurrence during follow-up when compared to CT.

New insights in diagnostics and therapies in syncope: a novel approach to non-cardiac syncope

This article aims to give advice on how to identify and manage patients with syncope who are at risk of severe outcomes, that is, at risk of trauma, potentially life-threatening episodes or frequent recurrences reducing quality of life. The first step of syncope diagnostic assessment is to identify patients with cardiac syncope, and once established, these patients must receive the adequate mechanism-specific treatment. If cardiac syncope is unlikely, reflex (neurally mediated) syncope and orthostatic hypotension are the most frequent causes of transient loss of consciousness. For these presentations, efficacy of therapy is largely determined by the mechanism of syncope rather than its aetiology or clinical features. The identified mechanism of syncope should be carefully assessed and assigned either to hypotensive or bradycardic phenotype, which will determine the choice of therapy (counteracting hypotension or counteracting bradycardia). The results of recent trials indicate that 'mechanism-specific therapy' is highly effective in preventing recurrences. Established mechanism-specific treatment strategies include withdrawal of hypotensive drugs, applying fludrocortisone and midodrine for the hypotensive phenotype and cardiac pacing in the bradycardic phenotype.