The anatomical basis behind the neuromodulation effects associated with pulmonary vein isolation

Vagal response during radiofrequency catheter ablation initiated from right superior pulmonary vein: Incidence, risk factors, and clinical outcomes

BACKGROUND

The vagal response (VR) is unavoidable during pulmonary vein isolation (PVI) for atrial fibrillation (AF). In this study, we aimed to investigate the incidence, risk factors, and clinical outcomes of VR during PVI initiated from the right superior pulmonary vein (RSPV).

METHODS

Patients with AF were consecutively enrolled. PVI was initiated from the RSPV, followed by other PVs. The VR was defined as atrioventricular block (AVB), asystole, or a 50 % increase in the R-R interval.

RESULTS

We enrolled 702 patients with AF (paroxysmal = 380, persistent = 322). Seventy-seven (11.0 %) patients developed 81 VR episodes, which were more common in paroxysmal than persistent AF (74 [19.5 %] vs. 3 [0.9 %], P < 0.001). VR manifestations in paroxysmal AF included sinus arrest in 51 (63.0 %) patients, sinus bradycardia in 26 (32.1 %), and AVB in one (1.2 %) patient. For persistent AF, VR manifested as AVB. Most VR episodes were observed in the left superior ganglionated plexi (n = 67, 82.7 %). Body mass index (BMI) ≥28.0 kg/m2 (odds ratio [OR] = 2.261, P = 0.005) and left ventricular ejection fraction (LVEF) ≥60.0 % (OR = 2.622, P = 0.018) were independent risk factors. Among patients with paroxysmal AF, seven (9.5 %) with VR and 34 (11.1 %) without VR had AF recurrence during a follow-up of 15.5 ± 4.6 months (P = 0.582).

CONCLUSIONS

VR occurred more often in paroxysmal AF than in persistent AF during RSPV-initiated PVI, with specific manifestations. Increased BMI and LVEF were independent risk factors. Inadvertent VR does not predict better clinical outcome.

Cardioneural ablation-the first case series without the use of fluoroscopy

INTRODUCTION

Cardioneural ablation (CNA) and fluoroless ablation (FA) are emerging procedures and movements in contemporary in electrophysiology. Ablation of ganglionated plexus (GP) inputs in the atrium has been successfully targeted as a treatment for symptomatic bradyarrhythmias due to increased parasympathetic tone. As most of these patients are young, avoidance of ionizing radiation is of critical importance to limit potential long term deleterious effects. With widespread use of 3D electroanatomic mapping systems and advanced intracardiac echo (ICE) imaging, fluoroless ablation has become more widely adopted. However, fluoroless CNA has not been widely performed. The objective of this study is to demonstrate that CNA can be done safely and effectively without fluoroscopy.

METHODS

At a single-center, consecutive patients undergoing CNA with a fluoroless approach are described. GP mapping and ablation were performed in both atria. From the right atrium (RA), the right atrium-superior vena cava (RA-SVC GP), the posteromedial ganglionated plexus (PMLGP), which can be accessed from the right atrium-coronary sinus ostium, and the Vein of Marshall GP (VOM-GP) were evaluated. From the left atrium (LA), the superior left atrial ganglionated plexus (LSGP), the left inferior ganglionated plexus (LIGP), the right anterior ganglionated plexus (RAGP), and the right inferior ganglionated plexus (RIGP) were targeted.

RESULTS

Over the study period, beginning on January 31, 2021, 30 consecutive subjects (15 females/15 males) aged 42.9 ± 13.6 years underwent GP ablation. The average subject had 9.5 (± 9.2) episodes of syncope prior to ablation. The average CHADS2-VA2SC score was zero. The average LVEF was 64.8% (± 4.9). Two of the subjects had concomitant ablations, six failed prior medical therapy, and one had a prior pacemaker placed. All of the procedures were done without fluoroscopy. The average follow-up was 604 (± 366) days. There were 8 patients that did not improve symptomatically postfirst ablation. Four of the eight underwent repeat ablation and have subsequently improved. 26/30 patients symptomatically improved after the 1st or 2nd ablation. There were no complications noted.

CONCLUSION

In comparison to the traditional CNA with fluoroscopy, this proof of concept study reveals fluoroless GP ablation can be performed safely. In addition, the durability and success rate are comparable to other studies of CNA. Given the young age of the cohort and the longitudinal risks of ionizing radiation, fluoroless CNA is a feasible procedure for this patient population.

Cardioneuroablation: the known and the unknown

Cardioneuroablation (CNA) is a novel interventional procedure for the treatment of recurrent vasovagal syncope (VVS) and advanced atrioventricular block secondary to hyperactivation of vagal tone in young patients. By damaging the cardiac parasympathetic ganglia, CNA seems to be able to mitigate and/or abolish the excessive vagal activity and improve patients' outcome. This review is intended to give a detailed and comprehensive overview of the current evidences regarding (1) the clinical applications of CNA (2) the identification of ablation targets and procedural endpoints (3) the medium-long term effect of the procedure and its future perspectives. However, clinical data are still limited, and expert consensus or recommendations in the guidelines regarding this technique are still lacking.

Pulsed field ablation of the right superior pulmonary vein prevents vagal responses via anterior right ganglionated plexus modulation

BACKGROUND

Pulsed field ablation (PFA) is selective for the myocardium. However, vagal responses and reversible effects on ganglionated plexi (GP) are observed during pulmonary vein isolation (PVI). Anterior-right GP ablation has been proven to effectively prevent vagal responses during radiofrequency-based PVI.

OBJECTIVE

The purpose of this study was to test the hypothesis that PFA-induced transient anterior-right GP modulation when targeting the right superior pulmonary vein (RSPV) before any other pulmonary veins (PVs) may effectively prevent intraprocedural vagal responses.

METHODS

Eighty consecutive paroxysmal atrial fibrillation patients undergoing PVI with PFA were prospectively included. In the first 40 patients, PVI was performed first targeting the left superior pulmonary vein (LSPV-first group). In the last 40 patients, RSPV was targeted first, followed by left PVs and right inferior PV (RSPV-first group). Heart rate (HR) and extracardiac vagal stimulation (ECVS) were evaluated at baseline, during PVI, and postablation to assess GP modulation.

RESULTS

Vagal responses occurred in 31 patients (78%) in the LSPV-first group and 5 (13%) in the RSPV-first group (P <.001). Temporary pacing was needed in 14 patients (35%) in the LSPV-first group and 3 (8%) in the RSPV-first group (P = .003). RSPV isolation was associated with similar acute HR increase in the 2 groups (13 ± 11 bpm vs 15 ± 12 bpm; P = .3). No significant residual changes in HR or ECVS response were documented in both groups at the end of the procedure compared to baseline (all P >.05).

CONCLUSION

PVI with PFA frequently induced vagal responses when initiated from the LSPV. Nevertheless, an RSPV-first approach promoted transient HR increase and reduced vagal response occurrence.

Clinical impact of aging on outcomes of cardioneuroablation for reflex syncope or functional bradycardia: Results from the cardionEuroabLation: patiEnt selection, imaGe integrAtioN and outComEs-The ELEGANCE multicenter study

BACKGROUND

Cardioneuroablation (CNA) is a novel treatment for reflex syncope. The effect of aging on CNA efficacy is not fully understood.

OBJECTIVE

The purpose of this study was to assess the impact of aging on candidacy and efficacy of CNA for treating vasovagal syncope (VVS), carotid sinus syndrome (CSS), and functional bradyarrhythmia.

METHODS

The ELEGANCE (cardionEuroabLation: patiEnt selection, imaGe integrAtioN and outComEs) multicenter study assessed CNA in patients with reflex syncope or severe functional bradyarrhythmia. Patients underwent pre-CNA Holter electrocardiography (ECG), head-up tilt testing (HUT), and electrophysiological study. CNA candidacy and efficacy was assessed in 14 young (18-40 years), 26 middle-aged (41-60 years), and 20 older (>60 years) patients.

RESULTS

Sixty patients (37 men; mean age 51 ± 16 years) underwent CNA. The majority (80%) had VVS, 8% had CSS, and 12% had functional bradycardia/atrioventricular block. Pre-CNA Holter ECG, HUT, and electrophysiological findings did not differ across age groups. Acute CNA success was 93%, without differences between age groups (P = .42). Post-CNA HUT response was negative in 53%, vasodepressor in 38%, cardioinhibitory in 7%, and mixed in 2%, without differences across age groups (P = .59). At follow-up (8 months, interquartile range 4-15), 53 patients (88%) were free of symptoms. Kaplan-Meier curves did not show differences in event-free survival between age groups (P = .29). The negative predictive value of a negative HUT was 91.7%.

CONCLUSION

CNA is a viable treatment for reflex syncope and functional bradyarrhythmia in all ages, and is highly effective in mixed VVS. HUT is a key step in postablation clinical assessment.

Different time course effect of autonomic nervous modulation after cryoballoon and hotballoon catheter ablations for paroxysmal atrial fibrillation

BACKGROUND

Few studies have reported on the quantitative evaluation of autonomic nerve modification after balloon ablation. Therefore, this study aimed to evaluate the effects of cryoballoon and hotballoon ablations on the autonomic nervous system (ANS) and their relationship with prognosis.

METHODS

We included 234 patients who underwent cryoballoon ablation (n = 190) or hotballoon ablation (n = 44) for paroxysmal atrial fibrillation. Heart rate variability (HRV) analysis was performed on all patients using a 3-min electrocardiogram at baseline, 1, 3, 6, and 12 months after ablation. HRV parameters and prognoses were compared between the two balloon systems.

RESULTS

Ln low-frequency (LF), Ln high-frequency (HF), standard deviation of the R-R intervals (SDNN), and RR intervals significantly decreased after 1 month in both groups, but the changes were more pronounced in the cryoballoon group than in the hotballoon group. In contrast, HRV indices in the hotballoon ablation group decreased gradually and reached their lowest point 3-to-6 months after the procedure, which was later than in the cryoballoon ablation group. The recurrence rate did not differ between the two groups. HRV parameters changed similarly in the cryoballoon group, regardless of recurrence. However, patients with recurrence had significantly higher SDNN and Ln LF at 12 months than those without recurrence in the hotballoon group (41.2 ± 39.3 ms vs. 18.5 ± 12.6 ms, p = 0.006, and 2.2 ± 0.7 ms² vs. 1.5 ± 0.7 ms², p = 0.003, respectively).

CONCLUSIONS

The time course of HRV changes differed between cryoballoon and hotballoon ablations. Hence, the two balloon systems may have distinct effects on the ANS and its role in prognosis.

Intrinsic Cardiac Neuromodulation in the Management of Atrial Fibrillation- A Potential Missing Link?

Atrial fibrillation (AF) is the most common supraventricular arrhythmia that is linked with higher cardiovascular morbidity and mortality. Recent evidence has demonstrated that catheter-based pulmonary vein isolation (PVI) is not only a viable alternative but may be superior to antiarrhythmic drug therapy for long-term freedom from symptomatic AF episodes, a reduction in the arrhythmia burden, and healthcare resource utilization with a similar risk of adverse events. The intrinsic cardiac autonomic nervous system (ANS) has a significant influence on the structural and electrical milieu, and imbalances in the ANS may contribute to the arrhythmogenesis of AF in some individuals. There is now increasing scientific and clinical interest in various aspects of neuromodulation of intrinsic cardiac ANS, including mapping techniques, ablation methods, and patient selection. In the present review, we aimed to summarize and critically appraise the currently available evidence for the neuromodulation of intrinsic cardiac ANS in AF.

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 Vasovagal Syncope and Atrioventricular Block: A Step-by-Step Guide

Catheter based cardioneuroablation is increasingly being utilized to improve outcomes in patients with vasovagal syncope and atrioventricular block due to vagal hyperactivity. There is now increasing convergence amongst enthusiasts on its various aspects, including patient selection, technical steps, and procedural end-points. This pragmatic review aims to take the reader through a step-by-step approach to cardioneuroablation: we begin with a brief overview of the anatomy of intrinsic cardiac autonomic nervous system, before focusing on the indications, pre- and post-procedure management, necessary equipment, and its potential limitations. This article is protected by copyright. All rights reserved.

Vagal response during circumferential pulmonary vein isolation decreases the recurrence of atrial fibrillation in the short-term in patients with paroxysmal atrial fibrillation: A prospective, observational study

BACKGROUND

Vagal responses (VRs) are often seen in patients undergoing circumferential pulmonary vein isolation (CPVI). The possible mechanism of VR is that CPVI creates a coincidental modification of the cardiac ganglionated plexi (GP).

AIM

To investigate whether the presence of VR during CPVI impacts post-ablation recurrence in patients with paroxysmal atrial fibrillation (AF).

METHODS

A total of 112 consecutive patients with symptomatic paroxysmal AF who underwent CPVI for the first time from October 1, 2017 to April 30, 2019 were prospectively enrolled, of which two were lost the follow-up. Patients were divided into two groups based on whether VRs were experienced during CPVI. Electrophysiological parameters, including atrial effective refractory period (AERP) and mean heart rate (MHR), were measured before and post-ablation. The patients were then followed up for 12 months.

RESULTS

The 71 patients who had experienced VRs during CPVI were assigned to group B, and the remaing 39 patients who did not experience VR during CPVI were assigned to group A. The MHR (79.6 ± 8.3 vs 70.4 ± 7.8 b/min; p ≤ 0.001) was significantly higher; and the AERP (244 ± 22 vs 215 ± 27 ms; p ≤ 0.001) was prolonged in group B compared to respective pre-ablation values. There were no significant changes in the MHR (69.5 ± 7.9 vs 69.7 ± 8.7 b/min; p = 0.541) and AERP (224 ± 28 vs 225 ± 33 ms; p = 0.542) in group A. During the first four months of follow-up after ablation, the MHR gradually slowed down to pre-procedural levels in group B. The recurrence of AF (6/71 vs 7/39; p = 0.023) significantly decreased in group B relative to group A during the first 6 months after ablation, but there was no significant difference (14/71 vs 9/39; p = 0.598) at the end of the 12-month follow-up period.

CONCLUSION

Patients with paroxysmal AF who develop VRs during CPVI might have a decreased recurrence of AF and accelerated MHR in the short-term.

Procedural and short-term results of electroanatomic-mapping-guided ganglionated plexus ablation by first-time operators: A multicenter study

INTRODUCTION

Single-center observational studies have shown promising results with fragmented electrogram (FE)-guided ganglionated plexus (GP) ablation in patients with vagally mediated bradyarrhythmia (VMB). We aimed to compare the acute procedural characteristics during FE-guided GP ablation in patients with VMB performed by first-time operators and those of a single high-volume operator.

METHODS AND RESULTS

This international multicenter cohort study included data collected over 2 years from 16 cardiac hospitals. The primary operators were classified according to their prior GP ablation experience: a single high-volume operator who had performed > 50 GP ablation procedures (Group 1), and operators performing their first GP ablation cases (Group 2). Acute procedural characteristics and syncope recurrence were compared between groups. Forty-seven consecutive patients with VMB who underwent FE-guided GP ablation were enrolled, n = 31 in Group 1 and n = 16 in Group 2. The mean number of ablation points in each GP was comparable between groups. The ratio of positive vagal response during ablation on the left superior GP was higher in Group 1 (90.3% vs. 62.5%, p = .022). Ablation of the right superior GP increased heart rate acutely without any vagal response in 45 (95.7%) cases. The procedure time was longer in group 2 (83.4 ± 21 vs. 118.0 ± 21 min, respectively, p < .001). Over a mean follow-up duration of 8.0 ± 3 months (range 2-24 months), none of the patients suffered from syncope.

CONCLUSION

This multi-center pilot study shows for the first time the feasibility of FE-guided GP ablation across a large group of procedure-naïve operators.

Molecular Insights in Atrial Fibrillation Pathogenesis and Therapeutics: A Narrative Review

The prevalence of atrial fibrillation (AF) is bound to increase globally in the following years, affecting the quality of life of millions of people, increasing mortality and morbidity, and beleaguering health care systems. Increasingly effective therapeutic options against AF are the constantly evolving electroanatomic substrate mapping systems of the left atrium (LA) and ablation catheter technologies. Yet, a prerequisite for better long-term success rates is the understanding of AF pathogenesis and maintenance. LA electrical and anatomical remodeling remains in the epicenter of current research for novel diagnostic and treatment modalities. On a molecular level, electrical remodeling lies on impaired calcium handling, enhanced inwardly rectifying potassium currents, and gap junction perturbations. In addition, a wide array of profibrotic stimuli activates fibroblast to an increased extracellular matrix turnover via various intermediaries. Concomitant dysregulation of the autonomic nervous system and the humoral function of increased epicardial adipose tissue (EAT) are established mediators in the pathophysiology of AF. Local atrial lymphomononuclear cells infiltrate and increased inflammasome activity accelerate and perpetuate arrhythmia substrate. Finally, impaired intracellular protein metabolism, excessive oxidative stress, and mitochondrial dysfunction deplete atrial cardiomyocyte ATP and promote arrhythmogenesis. These overlapping cellular and molecular alterations hinder us from distinguishing the cause from the effect in AF pathogenesis. Yet, a plethora of therapeutic modalities target these molecular perturbations and hold promise in combating the AF burden. Namely, atrial selective ion channel inhibitors, AF gene therapy, anti-fibrotic agents, AF drug repurposing, immunomodulators, and indirect cardiac neuromodulation are discussed here.

Clinician needs and perceptions about cardioneuroablation for recurrent vasovagal syncope: An international clinician survey

BACKGROUND

Cardioneuroablation (CNA) targets the intrinsic cardiac autonomic nervous system ganglionated plexi located in the peri-atrial epicardial fat. There is increasing interest in CNA as a treatment of vasovagal syncope (VVS), despite no randomized clinical trial (RCT) data.

OBJECTIVE

The purpose of this study was to poll the opinion on CNA) for VVS.

METHODS

A REDCap (Research Electronic Data Capture) survey was administered to international physicians treating patients with VVS on their opinion about patient selection criteria, ablation approach, RCT design, and most appropriate end points for CNA procedures.

RESULTS

The survey was completed by 118 physicians; 86% were cardiac electrophysiologists. The majority of respondents (79%) would consider referring a patient with refractory VVS for CNA, and 27% have performed CNA for VVS themselves. Most felt patient selection should require a head-up tilt test with a cardioinhibitory response (67%) and suggest a minimum age of 18 years with a median of 3 (interquartile range 2-5) episodes in the past year. There were differences in patient selection between physicians who have performed CNA themselves and those who have not. The majority felt that the ablation strategy should include both atria (70%) with an anatomical approach in combination with autonomic stimulation (85%). Performing a sham procedure in the control arm was supported by 56% of respondents, providing equipoise in RCT design. The preferred primary outcome was freedom from syncope within 1 year of follow-up.

CONCLUSION

There is widespread support for well-designed RCTs to confirm the hypothesized clinical benefit of CNA, provide data to guide the risk-benefit equations during patient selection, and appropriately estimate the placebo effect.