Phrenic nerve paralysis during cryoballoon ablation for atrial fibrillation: A comparison between the first- and second-generation balloon

The Hot and the Cold: Radiofrequency Versus Cryoballoon Ablation for Atrial Fibrillation

Catheter ablation is superior to antiarrhythmic drugs in maintaining sinus rhythm for patients with atrial fibrillation (AF). Pulmonary vein (PV) isolation is the cornerstone of any AF ablation procedure. Conventionally, this is achieved by performing point by point lesions using radiofrequency (RF) energy. However, this is technically challenging, time consuming and is associated with a number of complications. Long-term durability of PV isolation is also a concern. To address these issues, 'one-shot' energy delivery systems and alternative energy sources have been developed. The cryoballoon system has emerged as the most commonly used alternative to point by point RF technology. In this paper, we compare the technology, biophysics and clinical data of cryoballoon to conventional RF ablation for AF. The safety and efficacy of cryoballoon compared to RF ablation is critically reviewed. We conclude by looking at future applications of this technology.

Femoral venous pressure waveform as indicator of phrenic nerve injury in the setting of second-generation cryoballoon ablation

AIMS

Femoral venous pressure waveform (VPW) analysis has been recently described as a novel method to assess phrenic nerve function during atrial fibrillation ablation procedures by means of the cryoballoon technique. In this study, we sought to evaluate the feasibility and effectiveness of this technique, with respect to the incidence of phrenic nerve injury (PNI), in comparison with the traditional abdominal palpation technique alone.

METHODS

Consecutive patients undergoing second-generation cryoballoon ablation (CB-A) from June 2014 to June 2015 were retrospectively analyzed. Diagnosis of PNI was made if any reduced motility or paralysis of the hemidiaphragm was detected on fluoroscopy.

RESULTS

During the study period, a total of 350 consecutive patients (man 67%, age 57.2 ± 12.9 years) were enrolled (200 using traditional phrenic nerve assessment and 150 using VPW monitoring). The incidence of PNI in the overall population was 8.0% (28/350); of these, eight were impending PNI (2.3%), 14 transient (4.0%), and six persistent (1.7%). Patients having undergone CB-A with traditional assessment experienced 18 phrenic nerve palsies (9.0%) vs two in 'VPW monitoring' group (1.3%; P = 0.002). Specifically, the former presented 12 transient (6.0%) and six persistent (3.0%) phrenic nerve palsies, and the latter exhibited two transient (1.3%; P = 0.03) and no persistent (0%; P = 0.04) phrenic nerve palsies.

CONCLUSION

In conclusion, this novel method assessing the VPW for predicting PNI is inexpensive, easily available, with reproducible measurements, and appears to be more effective than traditional assessment methods.

What have we learned of ablation procedures for atrial fibrillation?

Atrial fibrillation is a widespread disease of growing clinical, economic and social importance. Interventional therapy for atrial fibrillation offers encouraging results, with pulmonary vein isolation (PVI) as the established cornerstone. Yet, the challenge to create durable transmural lesions remains, leading to recurrence of atrial fibrillation in long-term follow-up even after multiple ablation procedures in 20% of patients with paroxysmal atrial fibrillation and approximately 50% with persistent atrial fibrillation. To overcome these limitations, innovative tools such as the cryoballoon and contact force catheters have been introduced and have demonstrated their potential for safe and effective PVI. Furthermore, advanced pharmacological and pacing manoeuvres enhance evaluation of conduction block in PVI.

Long-Term Evolution of Patients Treated for Paroxysmal Atrial Fibrillation with First and Second Generation Cryoballoon Catheter Ablation with a Prospective Protocol Guided by Complete Bidirectional Left Atrium-Pulmonary Veins Disconnection after Adenosine as Main Target end Point to achieved. Seven Years Follow-up of Patients with a rough estimation profile of Low ALARMEc Score. A Single Center Report

INTRODUCTION

Cryoballoon ablation (CB) has proven effective for treating patients with paroxysmal atrial fibrillation (PAF). We analyzed our seven year follow-up of patients, treated for PAF with first (CB1) and second generation (CB2), with demonstration of LA-PV disconnection with bidirectional block (BB) after adenosine (AD).

METHODS

Since November 2008 to May 2015, 128 patients, 97 male (58±7 years), without heart disease, highly symptomatic, refractory to antiarrhythmic drugs (AAD) were treated, and follow-up (1411 ±727 days). Left atrial size: 37±6 mm.

RESULTS

A total of 439 PV were successfully isolated (91.9%). Acute reconduction: 44 PV (9%): 16 after CB; 16 unmasked by AD; 12 extrapulmonary muscular connections (EMC). Main complication was phrenic nerve palsy (PNP): 9 (7 %). On follow-up, 114 patients (89%) remain asymptomatic in sinus rhythm (SR), free of medication. Fourteen patients (11%) had arrhythmia recurrence: 12 male (52±8 years). Early recurrences occurred in 9 male. Late recurrences presented 3 male at 24, 27 and 60 months, and 2 female at 7 and 40 months respectively. All recurrence patients were Redo, and remain in SR without medication during follow-up.

CONCLUSIONS

CB alone is very effective and safe for the definitive treatment of patients suffering PAF with 72.6% success rate, increasing up to 89.1% when this protocol is applied in a single procedure. After Redo, all population group (100%), remain in sinus rhythm, freedom of arrhythmia, without AAD, in this very long term follow-up. Checking for BB, AD protocol, and ruling out EMC allowed-us to identified 14.8% of patients with underlying substrate for potential arrhythmia recurrence. CB2 applications entail a highest risk of PNP. Patients with a rough estimated profile of low ALARMEc score (≤ 1) have an excellent long term outcome, being this series the largest follow-up described so far, for patients treated for PAF with CB.

Bonus-freeze: benefit or risk? Two-year outcome and procedural comparison of a "bonus-freeze" and "no bonus-freeze" protocol using the second-generation cryoballoon for pulmonary vein isolation

Background

Second-generation cryoballoon based pulmonary vein isolation has demonstrated encouraging acute and mid-term clinical outcome. Customarily, a bonus-freeze is applied after successful pulmonary vein isolation.

Objective

To compare the long-term clinical outcome and safety profile of a bonus-freeze and a no bonus-freeze protocol.

Methods

A total of 120 consecutive patients with paroxysmal [95/120 (79 %)] or persistent atrial fibrillation [25/120 (21 %)] underwent CB2-based PVI. Freeze-cycle duration was 240 s. In the first 60 patients a bonus-freeze was applied after successful PVI (group 1), while in the following 60 patients the bonus-freeze was omitted (group 2).

Results

Procedure and fluoroscopy times were significantly shorter in group 2 [113.8 ± 32 vs 138.2 ± 29 min (p = 0.03) and 19.2 ± 6 vs 24.3 ± 8 min (p = 0.02)]. No differences in procedural complications were found. During a mean follow-up of 849 ± 74 (group 1) and 848 ± 101 days (group 2, p = 0.13) 69 % of patients (group 1) and 67 % of patients (group 2) remained in stable sinus rhythm without any differences between the groups (p = 0.69).

Conclusions

Freedom from atrial fibrillation after second-generation cryoballoon based pulmonary vein isolation and a follow-up of >2 years is comparable when applying a bonus- and a no bonus-freeze protocol, while procedure and fluoroscopy times are significantly shorter when omitting the bonus-freeze. No differences in periprocedural complications were identified.

ECG-Guided Surveillance Technique in Cryoballoon Ablation for Paroxysmal and Persistent Atrial Fibrillation: A Strategy to Prevent From Phrenic Nerve Palsy

AIMS

Phrenic nerve palsy (PNP) is still a cause for concern in Cryoballoon ablation (CBA) procedures. New surveillance techniques, such as invasive registration of the compound motor action potential (CMAP), have been thought to prevent the occurrence of PNP. The present study investigates the impact of CMAP surveillance via an alternative and non-invasive ECG-conduction technique during CBA.

METHODS

PVI with CBA was performed in 166 patients suffering from AF. Diaphragmal contraction was monitored by abdominal hands-on observation in Observation Group I; Observation Group II was treated using additional ECG-conduction, as a means of modified CMAP surveillance method. During the ablation of the right superior and inferior pulmonary veins, the upper extremities lead I was newly adjusted between the inferior sternum and the right chest, thereby recording the maximum CMAP. The CMAP in the above-mentioned ECG leads was continuously observed in a semi-quantitative manner.

RESULTS

PNP was observed in 10 (6%) patients in total. In Observation Group I, 6 out of 61 (9.8%) demonstrated PNP. In Observation Group II a significant decrease of PNP could be demonstrated (p <0,001) and occurred in 4 out of 105 patients (3.8%). While three patients from Observation Group I left the EP lap with an ongoing PNP, none of the patients in Observation Group II had persistent PNP outside of the EP lab.

CONCLUSION

The present study demonstrates that additional ECG-conduction, used as modified CMAP surveillance, is an easy, effective and helpful additional safety measure to prevent PNP in CBA.

Long Term Follow-up of Pulmonary Vein Isolation Using Cryoballoon Ablation

BACKGROUND

Cryoballoon ablation is an established catheter-based approach to treating atrial fibrillation (AF). There is little data regarding the long-term efficacy of this approach.

METHODS

We enrolled 200 consecutive patients with symptomatic AF who had failed therapy with at least one anti-arrhythmic medication and followed them for five years. The primary efficacy endpoint was symptomatic recurrence of AF after a single cryoballoon ablation procedure.

RESULTS

Two hundred patients formed the study group. Median follow-up was 56 months. Following a single procedure, 46.7% of patients with paroxysmal AF remained free of symptomatic recurrence of AF compared to 35.6% of patients with persistent AF. When allowing for repeat ablations, at the end of the follow-up period 53.3% of patients in the paroxysmal group remained free of symptomatic AF compared to 47.5% in the persistent group. The rate of complications was low.

CONCLUSIONS

Cryoballoon ablation is an effective catheter-based approach for treating symptomatic AF with a low risk of complications.

Phrenic nerve injury during ablation with the second-generation cryoballoon: analysis of the temperature drop behaviour in a large cohort of patients

AIMS

The present study sought to analyse the relationship between the temperature drop during the cryoenergy application and the occurrence of phrenic nerve injury (PNI) in a large cohort of patients having undergone second-generation cryoballoon ablation (CB-A).

METHODS AND RESULTS

The first 550 consecutive patients having undergone CB-A for atrial fibrillation were enrolled. Attained temperatures at 20, 30, 40, and 60 s during cryoablation in the right-sided pulmonary veins (PVs) were collected. Diagnosis of PNI was made if reduced motility or paralysis of the hemidiaphragm was detected. The incidence of PNI in the study population was 7.3% (40/550); among them, only four (0.7%) did not resolve until discharge and one (0.2%) still persisted at 23 months. Patients with PNI exhibited significantly lower temperatures at 20, 30, and 40 s after the beginning of the cryoapplication in the right superior PV (RSPV) (P = 0.006, P = 0.003, and P = 0.003, respectively). The temperature drop expressed as Δ temperature/Δ time was also significantly higher in patients with PNI. Low temperature during the early phases of the freezing cycle (less than -38°C at 40 s) predicted PNI with a sensitivity of 80.5%, a specificity of 77%, and a negative predictive value of 97.9%. Among patients with a fast temperature drop during RSPV ablation, an RSPV diameter >23.55 × 17.95 mm significantly predicted PNI occurrence.

CONCLUSION

The analysis of the temperature course within the first 40 s after the initiation of the freezing cycle showed that the temperature dropped significantly faster in patients with PNI during ablation in the RSPV.

[Cryoablation: Clinical applications in cardiac electrophysiology from their biophysical bases]

Cryoablation is an energy alternative to radiofrequency for ablation of various arrhythmias, where its unique biophysical properties offer a greater safety profile. Since its first use for the surgical treatment of different arrhythmias until its conceptualization in the current technical transcatheter, cryoablation has proven not to be only a safe source of energy, but also an effective source in the long-term. While the radiofrequency has been the energy most used for isolation of pulmonary veins in atrial fibrillation ablation, technological advances in cryoballon have managed to simplify the procedure without sacrificing its effectiveness. Cryoablation has been widely used for arrhythmias located in high-risk locations, such as the ablation of the atrioventricular nodal reentrant tachycardia and septal accessory pathways, due to its theoretical null risk of complete AV block. This review intends to give the clinical applications of the cryothermy through a thorough understanding of their biophysical basis.

Anatomical predictors for successful pulmonary vein isolation using balloon-based technologies in atrial fibrillation

PURPOSE

We evaluated the correlation between pulmonary venous (PV) anatomy and acute and long-term success of PV isolation (PVI) with two balloon-based ablation catheter techniques.

METHODS

One hundred consecutive patients were analyzed in two equal groups treated with either the second-generation cryoballoon (CRYO) catheter or the visually guided laser ablation (VGLA) catheter. All patients underwent multi-detector computed tomography (CT) imaging. The primary and secondary efficacy endpoints were the procedural achievement of proven electrical isolation of all veins and freedom from atrial fibrillation (AF) within a 1-year follow-up period, respectively.

RESULTS

Variant PV anatomy was observed in 32% of patients in the CRYO group and in 40% of patients in the VGLA group. All PVs were targeted with either the CRYO catheter (n = 199) or the VGLA catheter (n = 206). One hundred ninety-three of 199 PVs (97%) were successfully isolated in the CRYO group and 194 of 206 PVs (94%) in the VGLA group (p = 0.83). Over a 12-month follow-up, AF recurrence was documented in 11/45 (24%) and 7/43 (16%) patients in the CRYO and the VGLA groups, respectively (p = 0.21). In the CRYO group, a larger left inferior PV size was associated with worse long-term outcome (p = 0.001). In the VGLA group, a larger left superior PV size (p = 0.003) and more oval right inferior PV were associated with worse acute success (p = 0.038). There was no absolute cutoff between PV anatomy and clinical success.

CONCLUSIONS

The variability of PV anatomy did not significantly compromise acute success of PVI or patient outcomes.

Outcomes Of Cryoballoon Ablation Of Atrial Fibrillation: A Comprehensive Review

Over the last decade, cryoballoon ablation has emerged as an effective alternate strategy to point-by-point radiofrequency ablation for treatment of symptomatic atrial fibrillation. There are several reasons for this. First, the acute and long-term safety and efficacy associated with cryoablation appear comparable to that of radiofrequency ablation in patients with both paroxysmal and also persistent atrial fibrillation. Second, cryoablation offers certain advantages over conventional radiofrequency ablation including a gentler learning curve, shorter ablation and procedure times as well as lack of need for costly electroanatomical mapping technologies commonly utilized with radiofrequency ablation. Lastly, with the recent advent of the second-generation cryoballoon, the effectiveness of cryoablation has further improved dramatically. This comprehensive review examines the gradual evolution of the cryoablation tools as well as the rationale and data in support of the currently-available cryoballoon technologies for catheter ablation of atrial fibrillation.

Effect of cryoballoon inflation at the right superior pulmonary vein orifice on phrenic nerve location

BACKGROUND

Cryoballoon catheter ablation was developed to simplify ablation for atrial fibrillation (AF). Initial enthusiasm for its widespread use has been dampened by phrenic nerve (PN) injury (PNI).

OBJECTIVE

The purpose of this study was to assess the effect of cryoballoon inflation at the right superior pulmonary vein (RSPV) orifice on PN location and to elucidate the potential mechanism of PNI.

METHODS

Twenty patients with paroxysmal atrial fibrillation underwent ablation performed with a second-generation 28-mm cryoballoon catheter. Before ablation, the pacing-determined PN course was delineated along the right atrium. PN location and its relation to the RSPV as well as RSPV surface distortions after balloon inflation were established with a NavX mapping system.

RESULTS

During RSPV ablation, the inflated balloon surface extended anteriorly 6.3 ± 1.8 mm outside the RSPV. This narrowed the distance between the PN capture points in the RSPV vs PN location from 11.4 ± 5.0 mm to 7.5 ± 5.0 mm (P = .0002) and increased the PN capture area from 1.9 ± 1.3 cm(2) to 3.2 ± 1.8 cm(2) (P = .0004). Furthermore, the PN capture points shifted toward the orifice within the RSPV and after balloon inflation were located significantly closer to the orifice in the 3 patients with transient PNI than in those without PNI.

CONCLUSION

Cryoballoon inflation at the RSPV orifice alters PV/left atrial surface geometry, reducing the distance between the energy delivery source and the PN and increasing PN area, possibly explaining the mechanism of PNI. PN pacing within the RSPV after balloon inflation may be useful for preventing PNI.

Two-year outcome after pulmonary vein isolation using the second-generation 28-mm cryoballoon: lessons from the bonus freeze protocol

BACKGROUND

Pulmonary vein isolation (PVI) using the second-generation cryoballoon (CB2) in patients with paroxysmal and persistent atrial fibrillation (AF) has demonstrated encouraging acute and mid-term results. Follow-up data on outcome beyond 1-year is lacking. The purpose of this analysis was to investigate the 2-year clinical outcome after CB2-based PVI.

METHODS

Sixty patients (age 62 ± 11 years) with paroxysmal [45/60 (75%) patients] or short-standing persistent AF [15/60 (25%) patients] underwent 28-mm CB2-based PVI. Freeze-cycle duration was 240 s. After successful PVI, a bonus freeze-cycle of the same duration was applied. Follow-up was based on outpatient clinic visits at 3, 6, 12, 18, and 24 months including 24 h Holter-ECGs and telephone interviews. Recurrence was defined as any symptomatic and/or documented atrial tachyarrhythmia (ATA) episode >30 s following a 3-month blanking period.

RESULTS

A total of 231 pulmonary veins (PV) were identified and 230/231 (99.6%) PVs were successfully isolated. Phrenic nerve palsy occurred in 2/60 (3.3%) patients. No other periprocedural complications occurred. Follow-up was available for 59/60 (98%) patients with a mean duration of 838 ± 67 days. A total of 43/59 (73%) patients remained in stable sinus rhythm. In 10/16 (63%) patients with ATA recurrence, a repeat procedure was performed using radiofrequency energy. The overall success rate after a maximum of two ablation procedures and a follow-up period of 838 ± 67 days was 88% (52/59) patients.

CONCLUSIONS

Patients with paroxysmal or short-persistent AF undergoing PVI using the 28-mm CB2 demonstrated a 73% 2-year single-procedure clinical success rate.

A long-term evaluation of cryoballoon ablation in 205 atrial fibrillation patients: a single center experience

BACKGROUND

Atrial fibrillation is the most prevalent cardiac arrhythmia with significant healthcare impact with regards to treatment costs, morbidity, and mortality. Many of the focal electrical activities that initiate and sustain atrial fibrillation have been found to reside within or near the pulmonary veins. Consequently, pulmonary vein isolation by catheter ablation has emerged as an effective method to eliminate the focal triggers associated with atrial fibrillation.

METHODS

In this single-center study, 205 patients were ablated for atrial fibrillation using a cryoballoon catheter and followed-up long-term by retrospective chart examination to evaluate their post-procedural freedom from atrial fibrillation.

RESULTS

Patients were followed for up to 6 years with a cohort median of 3 years of post-ablation evaluation. Overall, at 12, 24, and 36 months post-ablation, 71, 49, and 31% of evaluated patients were free of atrial fibrillation, respectively. We found the type of atrial fibrillation (paroxysmal vs. persistent) as an independent predictor for arrhythmia recurrence (HR 1.97; 95% CI: 1.24-3.13, P  = 0.006). The cohort median atrial fibrillation-free survival time was 24 months (27 months for paroxysmal atrial fibrillation patients and 14 months for persistent atrial fibrillation patients). There were a total of 37 (18%) complications, 8 (3.9%) were categorized as major complications, all without permanent sequels. The most common complication was phrenic nerve palsy which occurred in 14 (6.8%) patients.

CONCLUSION

Long-term outcomes in this study suggest that the pulmonary vein isolation using the cryoballoon technique is relatively an effective method especially in the treatment of paroxysmal atrial fibrillation.

Ablation of atrial fibrillation

Ablation is increasingly used to treat AF, since recent trials of pharmacological therapy for AF have been disappointing. Ablation has been shown to improve maintenance of sinus rhythm compared to pharmacological therapy in many multicenter trials, although success rates remain suboptimal. This review will discuss several trends in the field of catheter ablation, including studies to advance our understanding of AF mechanisms in different patient populations, innovations in detecting and classifying AF, use of this information to improve strategies for ablation, technical innovations that have improved the ease and safety of ablation, and novel approaches to surgical therapy and imaging. These trends are likely to further improve results from AF ablation in coming years as it becomes an increasingly important therapeutic option for many patients.

Intracardiac Echocardiography in Catheter Ablation for Atrial Fibrillation: It Is Better to See What You Are Doing?

Current advanced technology allows the accurate three-dimensional reconstruction of cardiac structures using multiple images from two-dimensional intracardiac echocardiography (ICE). This technology is applicable to atrial fibrillation (AF) ablation and provides real-time anatomical information on relevant atrial structures and myocardial thickness as well as suitable sites for transseptal puncture. ICE allows radiofrequency to be delivered away from structures resistant to ablation and the monitoring of possible complications during AF ablation. Visualization of the inside of both atria during the procedure may contribute to safe and effective AF ablation. The purpose of this review was to elucidate the utility of ICE in AF ablation.

Persistence of Phrenic Nerve Palsy Following 28-mm Cryoballoon Ablation: A Four-Year Single Center Experience

BACKGROUND

Phrenic nerve palsy (PNP) is the most frequently observed complication in the setting of cryoballoon (CB) ablation (Arctic Front, Medtronic Inc., Minneapolis, MN, USA). Although, usually transient, resolving before the end of the procedure, persistent PNP (not resolving before the end of procedure) can occur. Literature on persistent PNP after second generation CB ablation is relatively sparse.

METHODS

A total of 316 consecutive patients having undergone large 28-mm CB ablation as index procedure in the Heart Rhythm Management Center, UZ Brussels, Belgium, from January 2009 to December 2013 were retrospectively reviewed for the study. Of these 117 patients were treated with the first generation CB (CB1) and 199 patients with the second generation CB (CB2).

RESULTS

PNP occurred in 10% of the total population. Persistent PNP was only observed following CB2 ablation which occurred in 4.5% of the group. At a mean follow-up of 11 months, diaphragmatic contraction in persistent PNP patients resumed in 78% (7/9) of the patients. In a final follow-up at 5 and 20 months, PNP persisted in two patients, respectively. PNP during ablation in the right inferior pulmonary vein was only observed in the CB2 group. No predictors of persistency of PNP were observed.

CONCLUSION

Persistence of PNP only occurred in the CB2 group in 4.5% of patients. The majority of patients with persistent PNP were asymptomatic. In most of the patients having persistent PNP after ablation, complete phrenic nerve function resumed during follow-up (78%).

Balloon Devices for Atrial Fibrillation Therapy

Ablation of atrial fibrillation (AF) is an established treatment option for symptomatic patients refractory to antiarrhythmic medication. In patients with paroxysmal AF, ablation can be offered as first-line therapy when performed in an experienced centre. The accepted cornerstone for all ablation strategies is isolation of the pulmonary veins. However, it is still challenging to achieve contiguous, transmural, permanent lesions using radio-frequency current (RFC) based catheters in conjunction with a three-dimensional mapping system and the learning curve remains long. These limitations have kindled interest in developing and evaluating novel catheter designs that incorporate alternative energy sources. Novel catheters include balloon-based ablation systems, incorporating different energy modalities such as laser (Heartlight(™), CardioFocus, Marlborough, MA, US), RFC (Hot Balloon Catheter, Hayama Arrhythmia Institute, Kanagawa, Japan) and cryo-energy (ArcticFront, Medtronic, Inc., Minneapolis, MN, US). While the cryoballoon (CB) and the radiofrequency hot balloon (RHB) are single-shot devices, the endoscopic ablation system (EAS) allows for point-by-point ablation. The CB and EAS are well established as safe, time-efficient and effective ablation tools. Initial studies using the RHB could also demonstrate promising results. However, more data are required.

Electromyographic monitoring for prevention of phrenic nerve palsy in second-generation cryoballoon procedures

BACKGROUND

Electromyography-guided phrenic nerve (PN) monitoring using a catheter positioned in a hepatic vein can aid in preventing phrenic nerve palsy (PNP) during cryoballoon ablation for atrial fibrillation. We wanted to evaluate the feasibility and efficacy of PN monitoring during procedures using second-generation cryoballoons.

METHODS AND RESULTS

This study included 140 patients (43 women) in whom pulmonary vein isolation was performed using a second-generation cryoballoon. Electromyography-guided PN monitoring was performed by pacing the right PN at 60 per minute and recording diaphragmatic compound motor action potential (CMAP) via a quadripolar catheter positioned in a hepatic vein. If a 30% decrease in CMAP amplitude was observed, cryoapplication was discontinued with forced deflation to avoid a PNP. Monitoring was unfeasible in 8 of 140 patients (5.7%), PNP occurred in 1. Stable CMAP amplitudes were achieved before ablation in 132 of 140 patients (94.3%). In 18 of 132 patients (13.6%), a 30% decrease in CMAP amplitude occurred and cryoablation was discontinued. Each time, recovery of CMAP amplitude took <60 s. In 9 of 18 cases, a second cryoapplication in the same pulmonary vein was safely performed. We observed no PNP or complication related to electromyography-guided PN monitoring.

CONCLUSIONS

Electromyography-guided PN monitoring using a catheter positioned in a hepatic vein seems feasible and effective to prevent PNP during cryoballoon ablation using second-generation cryoballoon.

[Innovative techniques in atrial fibrillation therapy]

Pulmonary vein isolation (PVI) is the established cornerstone in most catheter-based ablation treatment strategies for atrial fibrillation (AF); however, it is still a challenge to create contiguous, transmural and permanent ablation lesions using radiofrequency current in combination with three-dimensional mapping systems. To overcome these limitations, innovative spiral mapping and ablation catheters as well as balloon-based ablation catheters incorporating alternative energy sources, such as cryoenergy and laser were developed and evaluated and have proved their potential for safe and clinically effective PVI. In addition, novel ablation strategies, such as identification and ablation of AF-inducing foci and/or AF-perpetuating rotors using either endocardial or epicardial mapping systems were introduced and are currently under clinical evaluation. The identification and modulation of atrial ganglionic plexi (GP) and, therefore, of the autonomous nervous system is another additive ablation approach which requires further clinical evaluation.

Incidence and characteristics of phrenic nerve palsy following pulmonary vein isolation with the second-generation as compared with the first-generation cryoballoon in 360 consecutive patients

AIMS

The second-generation cryoballoon (CB2) with increased surface cooling has recently become available. The aim was to investigate the incidence and characteristics of phrenic nerve palsy (PNP) during pulmonary vein isolation (PVI) using the CB2 as compared with the first-generation balloon (CB1).

METHODS AND RESULTS

A total of 360 consecutive patients with atrial fibrillation underwent PVI with the CB1 (106 patients) or the CB2 (254 patients). Right PN function was monitored by continuous stimulation and palpation during septal PV ablation. Persistent PNP (present at discharge) occurred in 2.8 and 1.9% (P = 0.63) of patients, transient PNP (full recovery before discharge) in 5.9 and 3.8% (P = 0.41) of patients in the CB2 and CB1 group, respectively. Phrenic nerve palsy during ablation at the right inferior PV was observed in 0% (CB1) and 4.3% (CB2, P = 0.03) of patients. Using the CB2, a trend of reduced incidence of persistent PNP over quartiles of consecutive patients was observed [4.8% (Q1) vs. 0% (Q4); P = 0.077]. At the culprit PV, PNP occurred after 3.5 ± 2.1 (CB1) and 1.1 ± 0.4 applications (CB2; P = 0.036). Complete recovery of PN function occurred after 29 ± 11 (CB1) and 259 ± 137 days (CB2; P = 0.004).

CONCLUSIONS

The rate of transient/persistent PNP associated with the use of the CB2 was 5.9 and 2.8%, respectively. Time to restitution of PN function was longer using the CB2.

Pulmonary vein isolation as index procedure for persistent atrial fibrillation: One-year clinical outcome after ablation using the second-generation cryoballoon

BACKGROUND

No data are available about the clinical outcome of pulmonary vein isolation (PVI) as an index procedure for persistent atrial fibrillation (PersAF) ablation using the second-generation cryoballoon (CB-Adv).

OBJECTIVE

The purpose of this study was to assess the 1-year efficacy of PVI as an index procedure for PersAF ablation using the novel CB-Adv.

METHODS

Sixty-three consecutive patients (45 male [71.4%], mean age 62.7 ± 9.7 years) with drug-refractory PersAF undergoing PVI using the novel CB-Adv were enrolled. Follow-up was based on outpatient clinic visits including Holter ECGs. Recurrence of atrial tachyarrhythmias (ATas) was defined as a symptomatic or documented episode >30 seconds.

RESULTS

A total of 247 PVs were identified and successfully isolated with a mean of 1.7 ± 0.4 freezes. Mean procedural and fluoroscopy times were 87.1 ± 38.2 minutes and 14.9 ± 6.1 minutes, respectively. Among 26 of 63 patients (41.3%) presenting with AF at the beginning of the procedure, 7 of 26 (26.9%) converted to sinus rhythm during ablation. Phrenic nerve palsy occurred in 4 of 63 patients (6.3%). At 1-year follow-up, after a 3-month blanking period (BP), 38 of 63 patients (60.3%) were in sinus rhythm. Because of ATa recurrences, 9 patients underwent a second procedure with radiofrequency ablation showing a pulmonary vein reconnection in 4 right-sided PVs (44.4%) and 3 left-sided PVs (33.3%). Multivariate analysis demonstrated that PersAF duration (P = .01) and relapses during BP (P = .04) were independent predictors of AT recurrences.

CONCLUSION

At 1-year follow-up, freedom from ATas following PersAF ablation with the novel CB-Adv is 60%. Phrenic nerve palsy is the most common complication. PersAF duration and relapses during the BP appear to be significant predictors of arrhythmic recurrences.

Contact-force guided radiofrequency vs. second-generation balloon cryotherapy for pulmonary vein isolation in patients with paroxysmal atrial fibrillation-a prospective evaluation

AIMS

In the setting of paroxysmal atrial fibrillation (AF), there are no available data comparing the mid-term outcome of patients undergoing pulmonary vein isolation (PVI) catheter ablation using contact-force (CF)-guided radiofrequency (RF) vs. second-generation balloon cryotherapy.

METHODS AND RESULTS

Prospective single-centre evaluation, carried out from March 2011 to February 2013, comparing CF radiofrequency (Thermocool(®) SmartTouch™, Biosense Webster, Inc.) (CF group) with cryoballoon ablation (Arctic Front Advance™ 28 mm cryoballoon, Medtronic, Inc.) (CB group), in regards to procedural safety and efficacy, as well as recurrence at 12 months. Overall, 150 consecutive patients were enrolled (75 in each group). The characteristics of patients of both the groups were similar (61.2 ± 9.9 years, women 25.3%, mean AF duration 4.1 ± 4.0 years, mean CHA2DS2-VASc score 1.4 ± 1.3, mean HAS-BLED 1.4 ± 0.6). Duration of the procedure was significantly lower in the CF group (110.7 ± 32.5 vs. 134.5 ± 48.3 min, P = 0.001), with a lower duration of fluoroscopy (21.5 ± 8.5 vs. 25.3 ± 9.9 min, P = 0.017) and X-ray exposure (4748 ± 2411 cGy cm² vs. 7734 ± 5361 cGy cm², P = 0.001). In contrast, no significant difference was found regarding significant procedural complication (2.7 vs. 1.3% in CF and CB groups, respectively; P = 0.56), and PVI was eventually achieved in all cases. At 12 months, AF recurrence occurred in 11 patients (14.7%) in the CB group and in 9 patients (12.0%) in the CF group (HR = 1.20 95% CI 0.50-2.90; log rank P = 0.682).

CONCLUSIONS

Our preliminary findings suggest that CF-guided radiofrequency and cryotherapy present very similar performances in the setting of paroxysmal AF catheter ablation.

New Technologies In Atrial Fibrillation Ablation

Atrial fibrillation (AF) is a major public health issue worldwide, the incidence of which is likely to continue to rise. With the birth of pulmonary vein isolation(PVI), cardiac ablation has emerged as key strategy for the treatment of AF. PVI using traditional point by point radiofrequency ablation is time consuming and technically challenging. Refining patient selection for PVI also remains an important goal. New ablative strategies using catheter-based balloon technologies, such as cryothermy and laser-based systems, may simplify PVI. In addition, new MRI-based techniques offer the hope of refining patient selection prior to ablation. Lastly, FIRM mapping represents an entirely new approach to AF ablation via the targeting of mechanisms that perpetuate AF rather than simply targeting triggers alone.

Major complications of cryoballoon catheter ablation for atrial fibrillation and their management

Atrial fibrillation (AF) is the most common symptomatic and sustained cardiac arrhythmia. It affects approximately 2-3 million people in the USA alone with an increased incidence and prevalence worldwide. It is associated, in addition to worsening quality of life, with increased morbidity and mortality especially in poorly controlled AF, affecting mostly those older than 65 years of age. Radiofrequency ablation was found to be a good strategy for focal isolation of pulmonary veins triggering from the vulnerable atrial substrate but is a time-consuming procedure and carries the risk of multiple complications like tamponade which could be fatal, atrioesophageal fistula and local thrombus formation at the site of ablation. Cryoballoon ablation with pulmonary vein isolation has emerged in the past few years as a breakthrough novel technology for the treatment of drug-refractory AF. It is a relatively simple alternative for point-by-point radiofrequency ablation of paroxysmal AF and is associated with fewer incidences of fatal complications such as cardiac perforation. As experience with this new tool accumulates, the field faces new challenges in the form of rare compilations including gastroparesis, phrenic nerve palsy, atrioesophageal fistula, pulmonary vein stenosis, thromboembolism pericardial effusion, and tamponade.

[Advances in cryoballoon technology: benefits and risks in daily practice]

BACKGROUND

Cryoballoon ablation is nowadays a standard approach for pulmonary vein isolation in symptomatic atrial fibrillation. The second generation cryoballoon was introduced in 2012 and modifications and enhancement to the system promised a higher efficiency.

OBJECTIVES, MATERIALS AND METHODS

A comprehensive overview of advances in cryoballoon ablation is provided and the consequences for daily practice are described based on a PubMed literature search, taking into account own experiences.

RESULTS AND CONCLUSION

Advances in cryoballoon ablation result in a significantly higher efficiency. To maintain the overall safety of the procedure and to avoid phrenic nerve palsy and esophageal lesions, special care needs to be taken by following some safety aspects and cut-off criteria. More data are necessary to clarify if recommendations for cryoenergy titration with the new balloon are reasonable. Ongoing prospective studies comparing cryoballoon and radiofrequency (RF) ablation will give answers to the question which energy source is more favorable, and upcoming studies will evaluate the impact of cryoballoon ablation as a first line treatment option.