3D mapping of phrenic nerve course for radiofrequency pulmonary vein isolation

Acute Procedural Results of Pulsed Field Cryoablation for Persistent Atrial Fibrillation: Multicenter First-in-Human PARALELL Trial

INTRODUCTION

Pulsed Field Cryoablation (PFCA) is a dual-energy cardiac ablation modality consisting of short-duration ultra-low temperature cryoablation (ULTC) followed immediately by pulsed field ablation (PFA) delivered from the same catheter. It is hypothesized that PFCA may improve contact stability during PFA, while maintaining lesion depth and effectiveness of ULTC.

METHODS

PARALELL is a first-in-human multicenter study evaluating safety and effectiveness of a novel PFCA catheter and system in patients with persistent atrial fibrillation (PsAF) using the combination of pulmonary vein (PVI) and posterior wall (PWI) isolation.

RESULTS

Sixty-six patients were ablated at six sites. One groin hematoma and one intubation-related hospitalization were the only serious procedure- or device-related adverse events recorded in the study. Per protocol, acute effectiveness was evaluated in 46 patients, including 31 patients with post-hoc analysis of cryogenic energy per lesion. After an average of 21.1 ± 9.3 lesions per patient the rates of PVI and PWI were 95.7% (176/184) and 97.7% (42/43), respectively. The average cryogenic energy per patient was highly predictive of acute isolation success with ROC AUC = 0.944% and 100% rates of both PVI and PWI in 24 patients in the optimal energy cohort. Grade I microbubbles and faint muscle contractions were detected in 1.1% and 0.5% of ablations, respectively.

CONCLUSION

This initial multi-center experience suggests that PFCA can be efficiently performed for PVI and PWI using a single versatile catheter system, with high acute success and good early safety profile. The evaluation of the chronic 12-month effectiveness of PFCA is ongoing.

Impact of right pulmonary vein anatomical variations on the phrenic nerve trajectory and pulmonary vein isolation strategy: Preprocedural imaging and 3D mapping insights

BACKGROUND

Predicting phrenic nerve (PN) location based on right pulmonary vein (RPV) anatomy using preablation imaging may help avoid PN injury.

OBJECTIVE

The purpose of this study was to determine the relationship between RPV anatomical variations and PN trajectory.

METHODS

One hundred three consecutive patients who underwent preablation computed tomography or magnetic resonance imaging had RPV anatomy identified as typical with separate right superior PV (RSPV) and right inferior PV (RIPV) showing distal branching vs right middle PV (RMPV) or early branching of the RSPV. PN location was identified using high-output pacing (50 mA × 2 ms) over 3 contiguous RPV ostial and paraseptal antral zones: RSPV, RPV carina, and RIPV. The relationship between anatomical variations and the PN trajectory, with the need to adjust planned ablation lines to more distal antral position (greater than additional 10 mm from the ostium), was determined.

RESULTS

Early branching of the RSPV occurred in 24%, and an RMPV was present in 21% with anatomical variations more frequent in women (65% vs 38%; P=.01). PN capture extending to the RIPV antrum was significantly more common in patients with an RMPV (59.1%; prevalence ratio [PR] 10.3; 95% confidence interval [CI] 2.5-43.2) or early branching of the RSPV (64%; PR 10.9; 95% CI 2.7-44) compared to typical anatomy (3.6%). Antral ablation line adjustments to avoid PN injury were required in 28% of patients, more frequently in those with an RMPV (50%; PR 5.6; 95% CI 2-15.7) or early branching (56%; PR 5.2; 95% CI 1.3-15.3) compared to typical anatomy (7.1%).

CONCLUSION

RMPV or early branching of the RSPV increases the likelihood of PN capture in the RIPV proximal antrum by 10-fold and requires a more distal antral ablation line to avoid phrenic nerve injury.

Phrenic nerve injury after atrial fibrillation ablation: different recovery courses among cryoballoon, laser balloon, and radiofrequency ablation

BACKGROUND

Phrenic nerve injury (PNI) is one of the common complications in atrial fibrillation (AF) ablation, which often recovers spontaneously. However, the course of its recovery has not been examined fully, especially in regard to the different ablation methods. We sought to compare the recovery course of PNI in cryoballoon, laser balloon, and radiofrequency ablation.

METHODS

This multicenter retrospective study analyzed 355 patients who suffered from PNI during AF ablation. PNI occurred during cryoballoon ablation (CB group) and laser balloon ablation (LB group) for a pulmonary vein isolation in 288 and 20 patients, and radiofrequency ablation for a superior vena cava (SVC) isolation (RF-SVC group) in 47 patients, respectively RESULTS: There was a significant difference in the estimated probability of PNI recovery after the procedure between the methods (p = 0.01). PNI recovered significantly earlier in the CB group, especially within 24 h and 3 months post-procedure (the percentage of the recovery within 24 h and 3 months: 49.7% and 71.5% in the CB group, 15.0% and 22.2% in the LB group, and 23.4% and 41.9% in the RF-SVC group, respectively). Persistent PNI after 12 months was observed in only seven patients in the CB group, one in the LB group, and four in the RF-SVC group, respectively.

CONCLUSION

PNI rarely persists over 12 months after AF ablation; however, there is a difference in the timing of its recovery. PNI recovers quicker with cryoballoon ablation than with laser balloon ablation or radiofrequency ablation of the SVC.

Voltage-Guided and Non-Voltage-Guided Superior Vena Cava Isolation in Patients With Atrial Fibrillation

BACKGROUND

In addition to the pulmonary vein, the superior vena cava (SVC) is an important focus of atrial fibrillation (AF). However, SVC isolation may cause serious complications, and appropriate settings and techniques for SVC isolation are lacking.

METHODS

This study enrolled 86 consecutive patients with AF who underwent SVC isolation. Voltage mapping using a multi-electrode catheter and ablation were performed under the guidance of an electro-anatomical mapping system. The lines encircling the SVC were divided into eight anatomic segments on the SVC geometry, and each segment was subjected to voltage-guided (VG) ablation in decreasing order of voltage (starting from the segment with the highest voltage). Non-VG (NVG) ablation was performed anatomically from the anterior wall toward the septum with one-round cautery.

RESULTS

A total of 86 cases (66 males, mean age 69 [60, 74], mean CHA2DS2 VASc score 2 [1, 3], 58 paroxysmal AF) with AF were included for ablation. Electrical SVC isolation was successfully achieved in all patients. The length of the myocardial sleeves, as measured from the SVC-RA junction to the end of the local signal, was 37 [28, 45] mm. Major axis of the RA-SVC junction was 15 [13, 17] and minor axis of the RA-SVC junction was 11 [9, 13]. The number of ablation points with VG SVC isolation was fewer than that for NVG SVC isolation (8 [5, 11.5] vs. 11.5 [8.8, 13.3]; p = 0.001). The procedure time of VG SVC isolation was greater than that of NVG SVC isolation (259 s [154, 379] vs. 167 s [115, 222]; p = 0.012). There were no significant differences in the complication rates.

CONCLUSIONS

VG SVC isolation reduced the number of ablation points compared with NVG SVC isolation.

Value of high-output pace-mapping of the right phrenic nerve for enabling safe radiofrequency ablation of atrial fibrillation: insights from three-dimensional computed tomography segmentation

AIMS

Right phrenic nerve (RPN) injury is a disabling but uncommon complication of atrial fibrillation (AF) radiofrequency ablation. Pace-mapping is widely used to infer RPN's course, for limiting the risk of palsy by avoiding ablation at capture sites. However, information is lacking regarding the distance between the endocardial sites of capture and the actual anatomic RPN location. We aimed at determining the distance between endocardial sites of capture and anatomic CT location of the RPN, depending on the capture threshold.

METHODS AND RESULTS

In consecutive patients undergoing AF radiofrequency ablation, we defined the course of the RPN on the electroanatomical map with high-output pacing at up to 50 mA/2 ms, and assessed RPN capture threshold (RPN-t). The true anatomic course of the RPN was delineated and segmented using CT scan, then merged with the electroanatomical map. The distance between pacing sites and the RPN was assessed. In 45 patients, 1033 pacing sites were analysed. Distances from pacing sites to RPN ranged from 7.5 ± 3.0 mm (min 1) when RPN-t was ≤10 mA to 19.2 ± 6.5 mm (min 9.4) in cases of non-capture at 50 mA. A distance to the phrenic nerve > 10 mm was predicted by RPN-t with a ROC curve area of 0.846 [0.821-0.870] (P < 0.001), with Se = 80.8% and Sp = 77.5% if RPN-t > 20 mA, Se = 68.0% and Sp = 91.6% if RPN-t > 30 mA, and Se = 42.4% and Sp = 97.6% if non-capture at 50 mA.

CONCLUSION

These data emphasize the utility of high-output pace-mapping of the RPN. Non-capture at 50 mA/2 ms demonstrated very high specificity for predicting a distance to the RPN > 10 mm, ensuring safe radiofrequency delivery.

Detection of Epicardial Connection Through Intercaval Bundle Involving Right Pulmonary Veins After Ipsilateral Circumferential Ablation by Intra-Atrial Activation Sequence Pacing From the Right Pulmonary Vein

BACKGROUND

An epicardial connection (EC) through the intercaval bundle (EC-ICB) between the right pulmonary vein (RPV) and right atrium (RA) is one of the reasons for the need for carina ablation for PV isolation and may reduce the acute and chronic success of PV isolation. We evaluated the intra-atrial activation sequence during RPV pacing after failure of ipsilateral RPV isolation and sought to identify specific conduction patterns in the presence of EC-ICB.

METHODS AND RESULTS

This study included 223 consecutive patients who underwent initial catheter ablation of atrial fibrillation. If the RPV was not isolated using circumferential ablation or reconnected during the waiting period, an exit map was created during mid-RPV carina pacing. If the earliest site on the exit map was the RA, the patient was classified into the EC-ICB group. The exit map, intra-atrial activation sequence, and RPV-high RA time were evaluated. First-pass isolation of the RPV was not achieved in 36 patients (16.1%), and 22 patients (9.9%) showed reconnection. Twelve and 28 patients were classified into the EC-ICB and non-EC-ICB groups, respectively, after excluding those with multiple ablation lesion sets or incomplete mapping. The intra-atrial activation sequence showed different patterns between the 2 groups. The RPV-high RA time was significantly shorter in the EC-ICB than in the non-EC-ICB group (69.2±15.2 versus 148.6±51.2 ms; P<0.001), and RPV-high RA time<89.0 ms was highly predictive of the existence of an EC-ICB (sensitivity, 91.7%; specificity, 89.3%).

CONCLUSIONS

An EC-ICB can be effectively detected by intra-atrial sequencing during RPV pacing, and an RPV-high RA time of <89.0 ms was highly predictive.

A randomized controlled trial of the size-adjustable cryoballoon vs conventional cryoballoon for paroxysmal atrial fibrillation: The CONTRAST-CRYO II trial rationale and design

Background

Pulmonary vein isolation (PVI) with cryoballoon technology is a well-established therapy for treatment of atrial fibrillation (AF). Recently, a size-adjustable cryoballoon (POLARxTM FIT) that enables delivery in a standard 28-mm or an expanded 31-mm size was introduced.

Objective

The purpose of this study was to perform a randomized clinical trial to evaluate the safety and efficacy of this novel cryoballoon compared to the conventional cryoballoon.

Methods

The CONTRAST-CRYO II trial is a multicenter, prospective, open-label, randomized controlled trial in which 214 patients with paroxysmal AF will be randomized 1:1 to cryoballoon ablation with either a conventional cryoballoon (Arctic Front AdvanceTM Pro) or a size-adjustable cryoballoon (POLARx FIT). The study was approved by the Institutional Review Boards at all investigational sites and has been registered in the UMIN Clinical Trials Registry (UMIN000052500).

Results

The primary endpoint of this study will be the incidence of phrenic nerve injury. Secondary endpoints include procedural success, chronic success through 12 months, procedure-related adverse events, biophysiological parameters during applications for each pulmonary vein (PV), total procedural and fluoroscopy times, level of PVI and isolation area, and probability of non-PV foci initiating AF.

Conclusion

The CONTRAST-CRYO II trial is a multicenter, prospective, randomized controlled trial designed to assess the safety and efficacy of the POLARx FIT vs the Arctic Front Advance Pro. The findings from this trial will provide additional utility data on the efficacy of the size-adjustable cryoballoon for isolating PVs in patients with paroxysmal AF.

Can phrenic nerve injury be anticipated by larger cryoballoons?

Recently, a novel size-adjustable cryoballoon has been introduced in clinical practice, which can be inflated to two different diameters (28 and 31 mm). The 31 mm cryoballoon is specifically designed to achieve better contact with remodeled pulmonary veins (PVs) that have wider ostia while avoiding deep cannulation, thereby potentially reducing the risk of phrenic nerve injury (PNI) associated with deep balloon cannulation. However, we encountered two cases of PNI during cryoballoon ablation using the novel system among our initial 25 consecutive case series. Herein, we present two cases that exhibited PNI during freezing of the right superior PV with a size-adjustable balloon. While larger balloons are expected to create a larger area of isolation, the safety of this novel balloon system needs to be evaluated in a large-scale clinical study.

Effective superior vena cava isolation using a novel C-shaped approach

Introduction

Superior vena cava (SVC) isolation has been proposed as part of the ablation strategy for atrial fibrillation. However, circumferential isolation of the SVC can lead to late-onset complications, such as SVC stenosis.

Methods

We describe a detailed observation of the SVC conduction pattern and present a newly developed approach for SVC isolation that involves creating a C-shaped non-circumferential ablation line while sparing the lateral segment.

Results

Twelve consecutive patients were included in the study, all of whom achieved bidirectional block during the ablation procedure.

Discussion

This approach to SVC isolation is effective and has the potential to reduce ablation related complications; however, larger studies and long-term follow-up is warranted to confirm these findings.