Coincidental ganglionated plexus modification during radiofrequency pulmonary vein isolation and post-ablation arrhythmia recurrence

Cardiac Sympathetic Activity and Rhythm Control Following Pulmonary Vein Isolation in Patients with Paroxysmal Atrial Fibrillation-A Prospective 123I-mIBG-SPECT/CT Imaging Study

BACKGROUND

Pulmonary vein isolation (PVI) and antiarrhythmic drug therapy are established treatment strategies to preserve sinus rhythm in atrial fibrillation (AF). However, the efficacy of both interventional and pharmaceutical therapy is still limited. Solid evidence suggests an important role of the cardiac sympathetic nervous system in AF. In this blinded, prospective observational study, we studied left ventricular cardiac sympathetic activity in patients treated with PVI and with antiarrhythmic drugs. Prospectively, Iodine-123-benzyl-guanidine single photon emission computer tomography (¹²³I-mIBG-SPECT) was performed in a total of 23 patients with paroxysmal AF, who underwent PVI (n = 20) or received antiarrhythmic drug therapy only (n = 3), respectively. ¹²³I-mIBG planar and SPECT/CT scans were performed before and 4 to 8 weeks after PVI (or initiation of drug therapy, respectively). For semiquantitative SPECT image analysis, attenuation-corrected early/late images were analyzed. Quantitative SPECT analysis was performed using the AHA 17-segment model of the left ventricle.

RESULTS

PVI with point-by-point radiofrequency ablation led to a significantly (p < 0.05) higher visual sympathetic innervation defect score when comparing pre-and post PVI. Newly emerging innervation deficits post PVI were localized predominantly in the inferior lateral wall. These findings were corroborated by semiquantitative SPECT analysis identifying inferolateral segments with a reduced tracer uptake in comparison to SPECT before PVI. Following PVI, patients with an AF relapse showed a different sympathetic innervation pattern compared to patients with sufficient rhythm control.

CONCLUSIONS

PVI results in novel defects of cardiac sympathetic innervation. Differences in cardiac sympathetic innervation remodelling following PVI suggest an important role of the cardiac autonomous nervous system in the maintenance of sinus rhythm following PVI.

Autonomic cardiogastric neural interaction after pulmonary vein isolation in patients with atrial fibrillation

PURPOSE

Clinical significance of reduced vagal activity following pulmonary vein isolation (PVI) for atrial fibrillation (AF) remains unclear. Periesophageal vagal nerve injury following PVI may be a powerful contributing factor of decreased vagal tone.

METHODS

Drug-refractory 51 AF patients (31 males, 64 ± 11 years), who underwent successful PVI, were enrolled. We performed esophagogastroduodenoscopy 2 days after PVI and assessed delayed gastric emptying (DGE). Additionally, the coefficient of variance of R-R interval (CVRR) as a surrogate for vagal tone was measured before PVI, as well as at 1 day and 3 months after PVI. The patients were divided into two groups, patients with DGE and patients without DGE, and changes in CVRR were compared.

RESULTS

After PVI, 12 out of 51 patients (23.5%) had DGE. The baseline CVRR did not differ between the patients with (n = 12) and those without (n = 39) DGE (median 3.13%, interquartile range 1.69-5.13 vs. median 3.76%, interquartile range 2.96-5.90, P = 0.297). However, CVRR at 1 day after PVI was significantly lower in the patients with DGE than in those without (median 1.49%, interquartile range 0.90-2.19 vs. median 2.59%, interquartile range 1.58-3.86, P = 0.035), and then CVRR at 3 months became similar between the two groups, suggesting that the two groups had different changes in vagal tone after PVI. The recurrence of AF was similar at 3-6 months after PVI between the two groups.

CONCLUSIONS

A significantly decreased CVRR immediately after PVI is a sign of DGE incidence, implying collateral damage to the esophagus.

Effects of Renal Denervation via Renal Artery Adventitial Cryoablation on Atrial Fibrillation and Cardiac Neural Remodeling

Introduction

Catheter-based renal denervation (RDN) could reduce cardiac sympathetic nerve activity (SNA) and inhibit atrial fibrillation (AF). However, the reliability is uncertain, because the renal sympathetic nerves are mainly distributed in the adventitial surface of the renal artery.

Objective

The aims of this study were to test the hypothesis that renal artery adventitial ablation (RAAA) definitely had the effects of RDN and to study the effects of RDN via renal artery adventitial cryoablation (RAAC) on AF and cardiac neural remodeling.

Methods

Twenty beagle canines were randomly assigned to two groups: the left RDN group (LRDN, n=10), which underwent left RDN via RAAC; the Sham group (n=10). After 2 months of postoperative recovery, AF vulnerability, AF duration, and histological examination were performed in both groups.

Results

Compared with the Sham group, left stellate ganglion (LSG) tissue fibrosis was increased in the LRDN group. LRDN significantly increased the percentage of TH-negative ganglionic cells and decreased the density of TH-positive nerves in the LSG (P < 0.001). Also, the densities of TH-positive nerves and GAP43 immunoreactivity within the left atrium (LA) were significantly decreased in the LRDN group (P < 0.05). After LA burst pacing, all 10 canines (100%) could be induced AF in the Sham group, but only 4 of 10 canines (40%) could be induced AF in the LRDN group (P=0.011). The percentage of LA burst stimulation with induced AF was 26.7% (8/30) in the LRDN group, which was significantly decreased compared with that of the Sham group (53.3%, 16/30) (P=0.035). In addition, AF duration was also significantly decreased in the LRDN group (13.3 ± 5.1 s) compared with that of the Sham group (20.3 ± 7.3 s, P=0.024).

Conclusions

RDN via RAAC could cause cardiac neural remodeling and effectively inhibit AF inducibility and shorten AF duration. It may be useful in selecting therapeutic approaches for AF patients.

Can We Predict Vagal Response to Cryoballoon Application Using Intracardiac Recordings?

The effects of cryoballoon (CB) ablation in non-pulmonary vein sites have not clearly elucidated. Herein we present a new definition method which helps to predict autonomic modification effect of CB application using atrial electrogram (EGM) characteristics and vagal responses (VRs). A 54-year-old man underwent pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation. Both atria were mapped with the aid of electroanatomical mapping system prior to ablation procedure. The atrial EGMs were divided into 3 groups according to duration, amplitude, and number of deflections. The sites demonstrating fractionated pattern on 2.5 centimeters outside of pulmonary vein ostia were tagged on the mapping to predict the relationship between VR and EGM characteristics during CB application. CB application in the PV demonstrating intensive fractionated EGMs caused a significant VR. We concluded that our case may be starting point to understand mechanism of PVI induced VR during CB application.