The short-term impact of the catheter ablation on noninvasive autonomic nervous system parameters in patients with paroxysmal atrial fibrillation

Electrophysiology and 3D-imaging reveal properties of human intracardiac neurons and increased excitability with atrial fibrillation

Altered autonomic input to the heart plays a major role in atrial fibrillation (AF). Autonomic neurons termed ganglionated plexi (GP) are clustered on the heart surface to provide the last point of neural control of cardiac function. To date the properties of GP neurons in humans are unknown. Here we have addressed this knowledge gap in human GP neuron structure and physiology in patients with and without AF. Human right atrial GP neurons embedded in epicardial adipose tissue were excised during open heart surgery performed on both non-AF and AF patients and then characterised physiologically by whole cell patch clamp techniques. Structural analysis was also performed after fixation at both the single cell and at the entire GP levels via three-dimensional confocal imaging. Human GP neurons were found to exhibit unique properties and structural complexity with branched neurite outgrowth. Significant differences in excitability were revealed between AF and non-AF GP neurons as measured by lower current to induce action potential firing, a reduced occurrence of low action potential firing rates, decreased accommodation and increased synaptic density. Visualisation of entire GPs showed almost all neurons are cholinergic with a small proportion of noradrenergic and dual phenotype neurons. Phenotypic distribution differences occurred with AF including decreased cholinergic and dual phenotype neurons, and increased noradrenergic neurons. These data show both functional and structural differences occur between GP neurons from patients with and without AF, highlighting that cellular plasticity occurs in neural input to the heart that could alter autonomic influence on atrial function. KEY POINTS: The autonomic nervous system plays a critical role in regulating heart rhythm and the initiation of AF; however, the structural and functional properties of human autonomic neurons in the autonomic ganglionated plexi (GP) remain unknown. Here we perform the first whole cell patch clamp electrophysiological and large tissue confocal imaging analysis of these neurons from patients with and without AF. Our data show human GP neurons are functionally and structurally complex. Measurements of action potential kinetics show higher excitability in GP neurons from AF patients as measured by lower current to induce action potential firing, reduced low firing action potential rates, and decreased action potential accommodation. Confocal imaging shows increased synaptic density and noradrenergic phenotypes in patients with AF. Both functional and structural differences occur in GP neurons from patients with AF that could alter autonomic influence on atrial rhythm.

Long-Term Differences in Autonomic Alterations After Cryoballoon vs Radiofrequency Atrial Fibrillation Ablation

BACKGROUND

The long-term natural history of autonomic alterations following catheter ablation of drug-refractory paroxysmal atrial fibrillation is poorly defined.

OBJECTIVES

The authors sought to define the long-term impact of thermal catheter ablation on the cardiac autonomic system.

METHODS

The study included 346 patients with drug-refractory paroxysmal atrial fibrillation undergoing pulmonary vein isolation using thermal ablation energy (radiofrequency or cryoballoon ablation). All patients underwent insertion of a Reveal LINQ implantable cardiac monitor prior to ablation. The implantable cardiac monitor continuously recorded physical activity, heart rate variability (HRV) (measured as the standard deviation of the average normal-to-normal), daytime heart rate, and nighttime heart rate (NHR). Longitudinal autonomic data in the 2-month period prior to the date of ablation were compared with the 3 years following ablation.

RESULTS

Following ablation, there was a significant decrease in HRV (10-20 ms; P < 0.0001) and significant increases in daytime heart rate and NHR (10 beats/min [P < 0.0001] and 7 beats/min [P < 0.0001], respectively). Changes in autonomic parameters were greatest in the first 3 months following ablation but remained significantly different from baseline for 36 months following ablation. Greater changes in NHR and HRV were associated with improved freedom from recurrent arrhythmia. The type of thermal ablation energy had no influence on the heart rate and autonomic parameters.

CONCLUSIONS

Pulmonary vein isolation using thermal ablation energy results in significant sustained changes in the heart rate parameters related to autonomic function. These changes are independent of the ablation technology employed and are associated with procedural success. (Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double Short vs Standard Exposure Duration [CIRCA-DOSE]; NCT01913522).

Impact of Physical Activity in Patients With Atrial Fibrillation Undergoing Catheter Ablation: The Multicenter Randomized BE-ACTION Trial

BACKGROUND

Arrhythmia recurrence after pulmonary vein isolation (PVI) is common. We conducted a multicenter, randomized trial to determine the impact of increased physical activity on atrial fibrillation recurrence after PVI.

METHODS

From 2018 to 2020, we randomly assigned 200 patients with atrial fibrillation to the ACTION or NO-ACTION group in 4 different centers in the local country of Brandenburg, Germany. Patients were eligible if they were scheduled to undergo PVI, aged ≥50 to ≤77 years, body mass index ≥23 to ≤35 kg/m2, and accepted wearing an activity tracker allowing 24-hour activity monitoring via mobile app. Patients in the ACTION group were actively remote-controlled via transmitted activity data by a physiotherapist, and individual motivational interviewing call sessions were scheduled with each ACTION patient every 2 weeks. The primary end point was the composite of recurrence of any atrial arrhythmia >30 seconds, additional ablation procedure, cardioversion, and new onset of antiarrhythmic drugs earliest after 90 days after index PVI over 12 months.

RESULTS

Overall, the median age of patients was 66 (interquartile range, 61-71) years, 33.5% were women, and 52% had persistent atrial fibrillation. The number of steps per day increased in both groups of patients from baseline to 12 months (P<0.001). The absolute increase in steps per day did not differ between patients in the ACTION group with +3205 steps (597-4944) compared with those in the NO-ACTION group +2423 steps (17-4284), P=0.325. Unadjusted intention-to-treat analysis showed no difference in the primary composite end point in the ACTION group (27.3%) versus the NO-ACTION group (32.7%), P=0.405.

CONCLUSIONS

Physical activity improved in patients after PVI. The present randomized controlled trial shows that activity tracker and motivational calls to increase physical activity versus activity tracker alone did not reduce the occurrence of the primary composite end point of atrial fibrillation recurrence or the absolute increase in steps per day.

REGISTRATION

URL: https://www.cochranelibrary.com; Unique identifier: DRKS00012914.

Is Increased Resting Heart Rate after Radiofrequency Pulmonary Vein Isolation a Predictor of Favorable Long-Term Outcome of the Procedure?

Background: Increased resting heart rate (RHR) after pulmonary vein isolation (PVI) for treatment of atrial fibrillation (AF) is a common observation, possibly resulting from ganglionated plexus modification during ablation. Previous trials have suggested that an increase in RHR after ablation might be related to higher efficacy of the procedure. The aim of this study was to determine whether or not higher increase in RHR after radiofrequency (RF) PVI might predict better long-term outcome of the procedure in a real-life cohort of patients in whom index ablation for paroxysmal AF was performed. Material and methods: The health records of patients who underwent index point-by-point or drag lesion RF PVI for paroxysmal AF in our department between January 2014 and November 2018 were analyzed. Resting heart rate (RHR) was determined from 12-lead ECG recorded prior to the ablation and before discharge to evaluate changes in RHR after PVI. Only patients in sinus rhythm before the procedure and at discharge were included in the analysis. Telephone follow-up was collected for evaluation of arrhythmia recurrence status. Results: A total of 146 patients who underwent PVI for paroxysmal AF were included. Mean follow-up time was 3.5 years. RHR increased from 64 [58.5−70], prior to procedure, to 72 [64.25−80] bpm at discharge (p < 0.001). Higher increase in RHR was not protective from arrhythmia recurrence in long-term observation in both univariable HR = 1.001 (CI 0.99−1.017, p = 0.857) and multivariable analyses HR = 1.001 (CI 0.99−1.02, p = 0.84). Conclusions: RHR after PVI increased in comparison to baseline in our cohort. However, we did not observe higher increase in RHR to be associated with more favorable long-term effectiveness of the procedure.

Autonomic Alterations After Pulmonary Vein Isolation in the CIRCA-DOSE (Cryoballoon vs Irrigated Radiofrequency Catheter Ablation) Study

Background

The natural history of autonomic alterations following catheter ablation of drug‐refractory paroxysmal atrial fibrillation is poorly defined, largely because of the historical reliance on non‐invasive intermittent rhythm monitoring for outcome ascertainment.

Methods and Results

The study included 346 patients with drug‐refractory paroxysmal atrial fibrillation undergoing pulmonary vein isolation using contemporary advanced‐generation ablation technologies. All patients underwent insertion of a Reveal LINQ (Medtronic) implantable cardiac monitor before ablation. The implantable cardiac monitor continuously recorded physical activity, heart rate variability (measured as the SD of the average normal‐to‐normal), daytime heart rate, and nighttime heart rate. Longitudinal autonomic data in the 2‐month period leading up to the date of ablation were compared with the period from 91 to 365 days following ablation. Following ablation there was a significant decrease in SD of the average normal‐to‐normal (mean difference versus baseline of 19.3 ms; range, 12.9–25.7; P<0.0001), and significant increases in daytime and nighttime heart rates (mean difference versus baseline of 9.6 bpm; range, 7.4–11.8; P<0.0001, and 7.4 bpm; range, 5.4–9.3; P<0.0001, respectively). Patients free of arrhythmia recurrence had significantly faster daytime (11±11 versus 8±12 bpm, P=0.001) and nighttime heart rates (8±9 versus 6±8 bpm, P=0.049), but no difference in SD of the average normal‐to‐normal (P=0.09) compared with those with atrial fibrillation recurrence. Ablation technology and cryoablation duration did not influence these autonomic nervous system effects.

Conclusions

Pulmonary vein isolation results in significant sustained changes in the heart rate parameters related to autonomic function. These changes are correlated with procedural outcome and are independent of the ablation technology used.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT01913522.

Applying the CHA2DS2-VASc score to predict the risk of future acute coronary syndrome in patients receiving catheter ablation for atrial fibrillation

•

AF patients without catheter ablation have a higher risk of future ACS when compared to normal control group.

•

The presence of AF without catheter ablation is an independent risk factor for future acute coronary events.

•

Catheter ablation to AF could reduce future risk of acute coronary events over a very long-term follow-up.

•

The cut-off value of baseline CHA₂DS₂-VASc score ≥ 4 can strongly predict future acute coronary events in patients with AF.

Objective

It remains unknown whether catheter ablation for atrial fibrillation (AF) reduces future acute coronary syndrome (ACS) risk or whether the CHA₂DS₂-VASc score has a role in predicting this risk. We aimed to compare very long-term risk of ACS between patients who received catheter ablation to AF or antiarrhythmic medications and controls without AF.

Methods

Propensity scores were calculated for each patient and used to assemble a cohort of 787 patients undergoing AF ablation in 2003–2012. Patients were compared to an equal number of AF patients treated with antiarrhythmic medications and a control group without AF. Patients with previous coronary events were excluded. The primary endpoint was ACS occurrence.

Results

Baseline clinical characteristics were comparable. After a mean 9.1 ± 3.2-year follow-up, the ablation group had lower incidence of new onset ACS than the medication and non-AF control groups (annual incidence: 0.15%. 0.78%, and 0.35%; with 2.67, 4.16, and 10.44 cases/1000 person-years, respectively; P < 0.001). After adjusting for multiple confounders, the ablation group had lower future ACS risk than the medication (hazard ratio [HR]: 0.20, 95% confidence interval [CI]: 0.13–0.30) and control groups (HR: 0.30, 95% CI: 0.20–0.45). The CHA₂DS₂-VASc score was a strong predictor of ACS (HR: 1.61, 95% CI: 1.47–1.76; AUC: 85.9%, 95% CI: 78.5–93.2%). A baseline CHA₂DS₂-VASc score ≥ 4 predicted future ACS (positive predictive rate: 14.3%).

Conclusions

This study suggested that catheter ablation for AF may be beneficial to reduce future ACS risk in AF patients, and a high baseline CHA₂DS₂-VASc score can predict future acute coronary events.

Cryoballoon pulmonary vein isolation-mediated rise of sinus rate in patients with paroxysmal atrial fibrillation

Background

Modulation of the cardiac autonomic nervous system by pulmonary vein isolation (PVI) influences the sinoatrial nodal rate. Little is known about the causes, maintenance and prognostic value of this phenomenon. We set out to explore the effects of cryoballoon PVI (cryo-PVI) on sinus rate and its significance for clinical outcome.

Methods and results

We evaluated 110 patients with paroxysmal atrial fibrillation (AF), who underwent PVI using a second-generation 28 mm cryoballoon by pre-, peri- and postprocedural heart rate acquisition and analysis of clinical outcome. Ninety-one patients could be included in postinterventional follow-up, indicating that cryo-PVI resulted in a significant rise of sinus rate by 16.5% (+ 9.8 ± 0.9 beats/min, p < 0.001) 1 day post procedure compared to preprocedural acquisition. This effect was more pronounced in patients with initial sinus bradycardia (< 60 beats/min.) compared to patients with faster heart rate. Increase of rate was primarily driven by ablation of the right superior pulmonary vein and for a subset of patients, in whom this could be assessed, persisted ≥ 1 year after the procedure. AF recurrence was neither predicted by the magnitude of the initial rate, nor by the extent of rate change, but postprocedural sinus bradycardia was associated with higher recurrence of AF in the year post PVI.

Conclusions

Cryo-PVI causes a significant rise of sinus rate that is more pronounced in subjects with previous sinus bradycardia. Patient follow-up indicates persistence of this effect and suggests an increased risk of AF recurrence in patients with postprocedural bradycardia.

Graphic abstract

Electronic supplementary material

The online version of this article (10.1007/s00392-020-01659-0) contains supplementary material, which is available to authorized users.

Respiratory sinus arrhythmia is reduced after pulmonary vein isolation in patients with paroxysmal atrial fibrillation

INTRODUCTION

Respiratory sinus arrhythmia (RSA) describes heart rate (HR) changes in synchrony with respiration. It is relevant for exercise capacity and mechanistically linked with the cardiac autonomic nervous system. After pulmonary vein isolation (PVI), the current therapy of choice for patients with paroxysmal atrial fibrillation (AF), the cardiac vagal tone is often diminished. We hypothesized that RSA is modulated by PVI in patients with paroxysmal AF.

MATERIAL AND METHODS

Respiratory sinus arrhythmia, measured by using a deep breathing test and heart rate variability parameters, was studied in 10 patients (64 ±3 years) with paroxysmal AF presenting in stable sinus rhythm for their first catheter-based PVI. Additionally, heart rate dynamics before and after PVI were studied during sympathetic/parasympathetic coactivation by using a cold-face test. All tests were performed within 24 h before and 48 h after PVI.

RESULTS

After PVI RSA (E/I difference: 7.9 ±1.0 vs. 3.5 ±0.6 bpm, p = 0.006; E/I ratio: 1.14 ±0.02 vs. 1.05 ±0.01, p = 0.003), heart rate variability (SDNN: 31 ±3 vs. 14 ±3 ms, p = 0.006; RMSSD: 17 ±2 vs. 8 ±2 ms, p = 0.002) and the HR response to sympathetic/parasympathetic coactivation (10.2 ±0.7% vs. 5.7 ±1.1%, p = 0.014) were diminished. The PVI-related changes in RSA correlated with the heart rate change during sympathetic/parasympathetic coactivation before vs. after PVI (E/I difference: r = 0.849, p = 0.002; E/I ratio: r = 0.786, p = 0.007). One patient with vagal driven arrhythmia experienced AF recurrence during follow-up (mean: 6.5 ±0.6 months).

CONCLUSIONS

Respiratory sinus arrhythmia is reduced after PVI in patients with paroxysmal AF. Our findings suggest that this is related to a decrease in cardiac vagal tone. Whether and how this affects the clinical outcome including exercise capacity need to be determined.

Panic features strongly predict the subjective but not the objective benefit of pulmonary vein isolation

PURPOSE

Clinically observed discrepancies between electrocardiogram findings and subjective report of symptoms related to atrial fibrillation (AF) often remain unexplained. One could hypothesize that after a technically successful ablation, preoperative panic behavior might affect the report of AF-related symptoms. However, research on comorbid panic behavior in patients with AF is limited.

METHODS

In this observational prospective cohort study, we investigated psychological characteristics, in particular the prevalence of panic features, among 112 patients with AF and its possible influence on experienced outcome of subsequent ablation treatment.

RESULTS

Twelve percent of the AF patients (n = 12) were pre-operatively characterized by panic features. This group experienced higher levels of distress and more limitations in daily life compared to AF patients without panic features, but was not characterized by higher levels of neuroticism. However, AF-ablation resulted in a similar reduction of experienced limitations in daily functioning and levels of distress in both groups.

CONCLUSION

Patients with panic features experience more distress and more limitations in daily life from AF, but these complaints are reduced by AF ablation in a similar rate as in patients without panic features. Additional psychological therapy is suggested as a method to further reduce subjective AF disease burden in these patients.

Time-dependent cervical vagus nerve stimulation and frequency-dependent right atrial pacing mediates induction of atrial fibrillation

Objective:

This study aimed to investigate the effects of right cervical vagus trunk simulation (RVTS) and/or right atrial pacing (RAP) on the induction of atrial fibrillation (AF).

Methods:

Twenty-four healthy adult dogs were randomly divided into four groups: RAP groups comprising RAP₅₀₀ (RAP with 500 beats/min) and RAP₁₀₀₀ (RAP with 1000 beats/min) and RVTS groups comprising RVTS and RAP₅₀₀+RVTS. All dogs underwent 12-h intermittent RAP and/or RVTS once every 2 h. The AF induction rate, AF duration, atrial effective refractory period (ERP), and dispersion of ERP (dERP) were compared after every 2 h of RAP or/and RVTS.

Results:

All groups had successful AF induction. The RAP₁₀₀₀ group had the highest AF induction rate and the longest AF duration. The RAP₁₀₀₀ group also had a shortened ERP in comparison to the other groups as well as the maximum dERP. Compared to the RAP₅₀₀ group, RAP₅₀₀+RVTS had an increased capacity to induce AF as measured by the AF induction rates, AF duration, ERP, and dERP.

Conclusion:

Increased tension in the vagus nerve and the intrinsic cardiac autonomic nervous system plays an important role in AF induction through different potential mechanisms. Interventions involving the vagus nerve and/or intrinsic cardiac autonomic nervous system can be a future potential therapy for AF.

Synaptic Plasticity in Cardiac Innervation and Its Potential Role in Atrial Fibrillation

Synaptic plasticity is defined as the ability of synapses to change their strength of transmission. Plasticity of synaptic connections in the brain is a major focus of neuroscience research, as it is the primary mechanism underpinning learning and memory. Beyond the brain however, plasticity in peripheral neurons is less well understood, particularly in the neurons innervating the heart. The atria receive rich innervation from the autonomic branch of the peripheral nervous system. Sympathetic neurons are clustered in stellate and cervical ganglia alongside the spinal cord and extend fibers to the heart directly innervating the myocardium. These neurons are major drivers of hyperactive sympathetic activity observed in heart disease, ventricular arrhythmias, and sudden cardiac death. Both pre- and postsynaptic changes have been observed to occur at synapses formed by sympathetic ganglion neurons, suggesting that plasticity at sympathetic neuro-cardiac synapses is a major contributor to arrhythmias. Less is known about the plasticity in parasympathetic neurons located in clusters on the heart surface. These neuronal clusters, termed ganglionated plexi, or “little brains,” can independently modulate neural control of the heart and stimulation that enhances their excitability can induce arrhythmia such as atrial fibrillation. The ability of these neurons to alter parasympathetic activity suggests that plasticity may indeed occur at the synapses formed on and by ganglionated plexi neurons. Such changes may not only fine-tune autonomic innervation of the heart, but could also be a source of maladaptive plasticity during atrial fibrillation.