Reduced incidence of esophageal lesions by luminal esophageal temperature–guided second-generation cryoballoon ablation

Machine learning identifies esophageal luminal temperature patterns associated with thermal injury in catheter ablation for atrial fibrillation

INTRODUCTION

Luminal esophageal temperature (LET) monitoring during atrial fibrillation (AF) ablation is widely used to reduce the incidence of endoscopically detected esophageal lesion (EDEL). We sought to assess whether specific patterns of LET variation are associated with EDEL.

METHODS

A high-fidelity multisensor probe was used to record LET in AF patients undergoing radiofrequency ablation (RFA) or cryoballoon ablation (CBA). Explainable machine learning and SHapley Additive exPlanations (SHAP) analysis were used to predict EDEL and assess feature importance.

RESULTS

A total of 94 patients (38.3% persistent AF, 71.3% male, 72 RFA, and 22 CBA) were included. EDEL was detected in 11 patients (10 RFA and one CBA). In the RFA group, the highest LET recorded was similar between patients with and without EDEL (40.6 [40.1-41]°C vs. 40.2 [39.1-40.9]°C; p = .313), however, the rate of LET rise for the highest recorded peak was higher (0.08 [0.03-0.12]°C/s vs. 0.02 [0.01-0.05]°C/s; p = .033), and the area under the curve (AUC) for the highest peak was smaller (412.5 [206.8-634.1] vs. 588.6 [380.4-861.1]; p = .047) in patients who had EDEL. In case of CBA, the patient with EDEL had a faster LET decline (0.12 vs. 0.07 [0.02-0.14]°C/s), and a smaller AUC for the lowest trough (2491.3 vs. 2629.3 [1712.6-5283.2]). SHAP analysis revealed that a rate of LET change higher than 0.05°C/s and an AUC less than 600 were more predictive of EDEL in RFA.

CONCLUSION

The rate of LET change and AUC for the recorded temperature predicted EDEL, whereas absolute peak temperatures did not.

Safety of the Radiofrequency Balloon for Pulmonary Vein Isolation: A Focus on Lesion Metric Analysis of Posterior Electrodes

Previous clinical studies on pulmonary vein isolation (PVI) with radiofrequency balloons (RFB) reported safe and effective procedures for a 20 s RF delivery via posterior electrodes. Recent recommendations from the manufacturer suggest reducing the application time to 15 s on the posterior wall (PW) when facing the esophagus region. Here, we retrospectively assess whether 15 s of RF delivery time on posterior electrodes is safe while still ensuring lesion metrics of sufficient quality. This retrospective study included 133 patients with paroxysmal and persistent atrial fibrillation who underwent PVI using an RFB (Heliostar, Biosense Webster, Inc., Irvine, CA, USA) at two European centers. The ablation protocol was set for an RF duration of 20 s/60 s for the posterior/anterior electrodes. A multielectrode temperature probe was systematically used. In the case of an esophageal temperature rise (ETR) above 42 °C (ETR+), an endoscopic evaluation was performed. All posterior electrode lesion metric dynamics (temperature (T) and impedance (Z)) were collected from the RFB generator and analyzed offline. In total, 2435 posterior electrode applications were analyzed. With an RF delivery of 19.8 (19.7-19.8) s, the median impedance drop was 18.4 (12.2-25.2) Ω, while the temperature rise was 11.1 (7.1-14.9) °C. Accordingly, impedance (84.6 (79.3-90.2) Ω) and temperature plateaus (38 (35.3-41.1) °C) were reached at 13.9 (10.6-16) s and 16.4 (12.6-18.5) s, respectively. Overall, 99.6% and 95.8% of electrodes reached 90% (16.6 Ω) and 95% (17.5 Ω) of their impedance drops within 15 s of RF delivery, while 97.2% and 92.8% achieved 90% (34.2 °C) and 95% (36.1 °C) of their temperature rise to reach the plateaus within 15 s of RF delivery. An ETR >42 °C occurred in 37 (30.1%) patients after 17.7 ± 2.3 s of RF delivery. In the ETR+ group, the impedance drop and temperature rise on the posterior electrodes were higher compared to patients where ETR was <42 °C. Two asymptomatic thermal esophageal injuries were observed. In conclusion, 15 s of RF delivery on the posterior electrodes provides a good balance between safety, with no esophageal temperature rise, and efficacy with high-profile lesion metrics.

Outcomes of pulmonary vein isolation with radiofrequency balloon vs. cryoballoon ablation: a multi-centric study

AIMS

Cryoballoon (CB) ablation is the mainstay of single-shot pulmonary vein isolation (PVI). A radiofrequency balloon (RFB) catheter has recently emerged as an alternative. However, these two technologies have not been compared. This study aims to evaluate the freedom from atrial tachyarrhythmias (ATas) at 1 year: procedural characteristics, efficacy, and safety of the novel RFB compared with CB for PVI in patients with paroxysmal atrial fibrillation (AF).

METHODS AND RESULTS

This prospective multi-centre study included consecutive patients with symptomatic drug-resistant paroxysmal AF who underwent PVI with RFB or CB between July 2021 and January 2022 from three European centres. A total of 375 consecutive patients were included, 125 in the RFB group and 250 in the CB. Both groups had comparable clinical characteristics. At 12.33 ± 4.91 months, ATas-free rates were 83.20% and 82.00% in the RFB and CB groups, respectively (P > 0.05). Compared with the CB group, the RFB group showed a shorter procedure time [59.91 (45.80-77.12) vs. 77.0 (35.13-122.71) min (P < 0.001)], dwell time [19.59 (14.41-30.24) vs. 27.03 (17.11-57.21) min (P = 0.04)], time to isolation, and thermal energy delivery in all pulmonary veins (P < 0.001). First-pass isolation was comparable. No major complications occurred in either group, with no stroke, atrio-oesophageal fistula, or permanent phrenic nerve injury. Transient phrenic nerve palsy occurred more frequently with CB than RFB (7.20% vs. 3.20%; P = 0.02). Oesophageal temperature rise occurred in 21 (16.8%) patients in the RFB group, and gastroscopy showed erythema in two of them with complete recovery after 30 days.

CONCLUSIONS

The RFB appears to have a safety and efficacy profile similar to that of the CB for PVI. Shorter procedural times appear to be driven by shorter left atrial dwell and thermal delivery times.

Efficacy and safety in patients treated with a novel radiofrequency balloon: a two centres experience from the AURORA collaboration

AIMS

A novel irrigated radiofrequency (RF) balloon (RFB) for pulmonary vein (PV) isolation (PVI) was released in selected centres. We pooled the procedural data on efficacy and safety of RFB-PVI from two high volume German centres.

METHODS AND RESULTS

Consecutive patients with RFB procedures were enrolled. A 3D electroanatomical left atrial map guided the RFB navigation. Every RF delivery lasted 60 s, and duration was automatically reduced to 20 s for electrodes facing the posterior wall. Procedural data and post-procedural endoscopy data (<48 h) were analysed. Data from 140 patients were collected (57% male, 67 ± 11 years, 57% paroxysmal atrial fibrillation). There were 547 PVs identified, and 99.1% could be isolated using solely the RFB. Single-shot PVI was recorded in 330/547 (60%) PVs. Median time to isolation during the first application was 10 s (IQR 8-13). A total of 2.1 ± 1.8 applications per PV were delivered, with the left superior PV requiring more application compared to other PVs. Median procedure and fluoroscopy time were 77 min (61-99) and 13 min (10-17), respectively. Major safety events were recorded only in the first 25 cases at each centre and included 1/140(0.7%) cardiac tamponade, 1/140(0.7%) phrenic nerve palsy, and 2/140 strokes (1.4%). An oesophageal temperature rise was recorded in 81/547 (15%) PVs, and endoscopy detected oesophageal lesions in 7/85 (8%) patients undergoing endoscopy.

CONCLUSION

The RFB showed a high efficacy allowing for fast PVI procedures, and 60% of PVs could be isolated at the first application. Most safety events were recorded during the learning phase. An oesophageal temperature monitoring is suggested: oesophageal lesions were detected in 8% of patients.

Pulmonary vein isolation with the radiofrequency balloon catheter: a single centre prospective study

AIMS

The multielectrode radiofrequency balloon catheter (RFB) has been developed to achieve safe and effective pulmonary vein isolation (PVI) for atrial fibrillation (AF) ablation. This single-centre study aimed to evaluate the midterm clinical outcome and predictors of single-shot PVI with the novel RFB.

METHODS AND RESULTS

All consecutive patients with symptomatic paroxysmal or persistent AF undergoing first-time PVI with the RFB were prospectively included. Clinical and procedural parameters were systematically collected. The primary safety endpoint was defined as any major periprocedural complications. The primary efficacy endpoint consisted of freedom from any atrial tachyarrhythmias (ATas) lasting >30 s during the follow-up after a 3-month blanking period. Persistent single-shot PVI was defined as PVI achieved with a single RFB application without acute reconnection.  A total of 104 consecutive patients (mean age 64.3 ± 11.4 years, 56.7% males) were included. 15 patients (14.4%) presented with persistent AF. The procedure time was 59.0 min with a dwell time of 20.0 min. One major complication occurred in one patient. At a mean follow-up of 10.1 ± 5.3 months, freedom from ATas was 82.9%. ATas occurred in 14 patients, 11/69 patients (15.9%) with paroxysmal AF and 3/13 (23.1%) with persistent AF. The best cut-offs to predict persistent single-shot PVI were impedance drop >19.2 Ω [area under the receiver operator characteristic curve (AUC) 0.74] and temperature rise >11.1° C (AUC 0.77).

CONCLUSION

In a large cohort of patients undergoing PVI with the RFB, the complication rate was 1%. At a mid-term follow-up of 10.1 ± 5.3 months, freedom from ATas was 82.9%. Specific cut-offs of impedance drop and temperature rise may be useful to predict persistent single-shot isolation.

Protecting Against Collateral Damage to Non-cardiac Structures During Endocardial Ablation for Persistent Atrial Fibrillation

Injury to structures adjacent to the heart, particularly oesophageal injury, accounts for a large proportion of fatal and life-altering complications of ablation for persistent AF. Avoiding these complications dictates many aspects of the way ablation is performed. Because avoidance involves limiting energy delivery in areas of interest, fear of extracardiac injury can impede the ability of the operator to perform an effective procedure. New techniques are becoming available that may permit the operator to circumvent this dilemma and deliver effective ablation with less risk to adjacent structures. The authors review all methods available to avoid injury to extracardiac structures to put these developments in context.

Impact of a time-to-effect guided ablation protocol in cryoballoon ablation on durability of pulmonary vein isolation

BACKGROUND

Cryoballoon (CB) based pulmonary vein isolation (PVI) has proven to be as effective as radiofrequency (RF) based ablation. Different ablation protocols took the individual time-to-isolation (TTI) into account aiming at shorter but equally or even more effective freeze-cycles. The current study sought to assess the impact of the TTI on PVI durability in patients undergoing a repeat procedure for recurrence of atrial tachyarrhythmia (ATA).

METHODS AND RESULTS

In 205 patients with ATA recurrence after previous CB-based PVI a total of 806 PVs were identified. One hundred-twenty-six out of 806 PVs (16%) were previously treated with a TTI guided ablation (protocol #1; TTI+120 sec.), in 92/806 (11%) PVs TTI was only monitored (m) but fixed freeze-cycles were applied (protocol #2; mTTI) and in 588/806 (73%) a fixed freeze-cycle was applied without TTI-monitoring. There was no difference in the PV-reconduction rate between the groups (p=0.23). The right inferior pulmonary vein (RIPV) showed overall significantly higher reconduction rates compared to the other PVs (RIPV - left inferior PV (LIPV) p<0.003, -left superior PV (LSPV) p<0.001, - right superior PV RSPV p<0.013). Twenty-one patients (10%) were demonstrated to have only electrical reconduction of the RIPV, while all other PVs were still electrically isolated.

CONCLUSIONS

TTI based CB ablation did not show significant differences regarding PV-reconduction rates compared to the other protocols. This article is protected by copyright. All rights reserved.

Preventing esophageal complications from atrial fibrillation ablation: A review

Atrioesophageal fistula is a life-threatening complication of ablation treatment for atrial fibrillation. Methods to reduce the risk of esophageal injury have evolved over the last decade, and diagnosis of this complication remains difficult and therefore challenging to treat in a timely manner. Delayed diagnosis leads to treatment occurring in the context of a critically ill patient, contributing to the poor prognosis associated with this complication. The associated mortality risk can be as high as 70%. Recent important advances in preventative techniques are explored in this review.

Preventative techniques used in current clinical practice are discussed, which include high-power short-duration ablation, esophageal temperature probe monitoring, cryotherapy and laser balloon technologies, and use of proton pump inhibitors. A lack of randomized clinical evidence for the effectiveness of these practical methods are found. Alternative methods of esophageal protection has emerged in recent years, including mechanical deviation of the esophagus and esophageal temperature control (esophageal cooling). Although these are fairly recent methods, we discuss the available evidence to date. Mechanical deviation of the esophagus is due to undergo its first randomized study. Recent randomized study on esophageal cooling has shown promise of its effectiveness in preventing thermal injuries. Lastly, novel ablation technology that may be the future of esophageal protection, pulsed field ablation, is discussed.

The findings of this review suggest that more robust clinical evidence for esophageal protection methods is warranted to improve the safety of atrial fibrillation ablation.

The established and the challenger: A direct comparison of current cryoballoon technologies for pulmonary vein isolation

INTRODUCTION

Cryoballoon (CB) ablation for pulmonary vein isolation (PVI) is an effective treatment of atrial fibrillation (AF). Recently, a novel cryoablation system was introduced. The aim of the study was to compare the safety, efficacy and biophysical characteristics of a novel cryoablation system (POLARx™; Boston Scientific) to a commonly used and clinically well characterized system (Arctic Front Advance Pro™, AFA; Medtronic).

METHODS AND RESULTS

Fifty consecutive patients with symptomatic AF, who underwent CB-based ablation with the POLARx were compared to 50 consecutive patients treated with the AFA. Acute PVI was achieved in 99.8% (POLARx 99.5%, AFA 100%, p = 1.00). Time to isolation (TTI) was comparable in both groups (POLARx 35 [27, 48] s, AFA 30 [21, 43] s, p = 0.165). The POLARx showed a lower balloon temperature at TTI (POLARx -44 [-50, -36] °C, AFA -31 [-38, -21] °C, p < 0.001) and lower nadir temperature (POLARx -60 [-65, -55] °C, AFA -48 [-54, -45] °C, p < 0.001). Procedure time (POLARx 80 [60, 105] min, AFA 62 [42, 80] min, p < 0.001), fluoroscopy time (POLARx 17 [13, 22] min, AFA 11 [7, 16] min, p < 0.001) and freeze cycles per patient (POLARx 5 [4, 6], AFA 4.5 [4, 5], p = 0.002) were higher in the POLARx group. Two cerebral ischemic events occurred in the POLARx group, two patients in each group had phrenic nerve injury.

CONCLUSION

Both systems enable effective isolation of pulmonary veins. The POLARx required longer procedure and fluoroscopy times. Larger, prospective and randomized studies are needed to assess long-term efficacy and safety of this technology.

[Practical guide for safe and efficient cryoballoon ablation for atrial fibrillation : Practical procedure, tips and tricks]

In the current guidelines on treatment of atrial fibrillation, cryoballoon-based catheter ablation of atrial fibrillation is recommended in addition to radiofrequency ablation and has become established as a standard procedure in the clinical routine of many centers for index pulmonary vein isolation. A safe, simplified and often durable pulmonary vein isolation can be achieved by a systematic approach. This review article provides a practical guide for all steps of cryoballoon-based pulmonary vein isolation, including preprocedural preparation and postinterventional follow-up. Both cryoballoon systems currently available on the market are considered.

Prevalence of gastric hypomotility after additional cryoballoon ablation of the left atrial roof

INTRODUCTION

Gastric hypomotility (GH) is a major complication of atrial fibrillation (AF) ablation. We aimed to clarify whether additional cryoballoon ablation (CBA) of the left atrial (LA) roof is associated with GH.

METHODS AND RESULTS

This study included 54 patients with non-paroxysmal AF who underwent CBA for pulmonary vein isolation and of the LA roof line. GH was defined according to the results of esophagogastroscopy performed 2 days after ablation. GH was observed in 10 patients. There were significant differences in LA diameter (LAD), right inferior pulmonary vein (RIPV) diameter, and the height of the LA roof from the point where the LA posterior wall and esophagus make contact between patients with (GH+) and without GH (GH-) (LAD: 41.0 [36.3-41.8] mm vs. 46.5 [42.8-50.0] mm, p < .01; RIPV diameter: 19.7 [19.0-20.5] mm vs. 23.2 [21.2-24.9] mm, p < .01; height of LA roof: 5.7 [5.1-6.1] mm vs. 8.8 [7.1-11.2] mm for, p < .01, respectively). Multivariate analysis revealed that LA roof height was a predictor of GH. Moreover, Patient Assessment of Upper Gastrointestinal Disorders-Symptom Severity Index (PAGI-SYM) scores increased significantly 1 week after ablation (from 1.0 [0.0-2.8] to 5.0 [3.0-11.0], p = .03) in patients with GH.

CONCLUSION

The height of the LA roof may be a predictor of GH after CBA of the LA roof line. Additionally, GH-related symptoms may still appear 1 week after ablation.

Cryoballoon Versus High-Power, Short-Duration Radiofrequency Ablation for Pulmonary Vein Isolation in Patients With Paroxysmal Atrial Fibrillation: A Single-Center, Prospective, Randomized Study

[Figure: see text].

Optimizing cryoballoon pulmonary vein isolation: lessons from >1000 procedures- the Frankfurt approach

AIMS

Cryoballoon (CB) pulmonary vein isolation (PVI) is an accepted ablation strategy for rhythm control in atrial fibrillation (AF). We describe efficacy and safety in a high volume centre with a long experience in the use of the second-generation CB (CB2).

METHODS AND RESULTS

Consecutive paroxysmal AF (PAF) or persistent AF (persAF) patients undergoing CB2-PVI were enrolled. Procedural data, efficacy, and safety issues were systematically collected. The 28 mm CB2 was used in combination with an inner lumen spiral catheter, a luminal oesophageal temperature (LET) probe was used with a cut-off of 15°C, the phrenic nerve (PN) monitored during septal PVs ablation. Freeze duration was mainly set at 240 s with a bonus application in case of delayed time-to-isolation (TTI > 75 s). A total of 1017 CB2 procedures were analysed (58% male, 66 ± 12 years old, 70% with PAF). 3964 PVs were identified, 99.8% PVs isolated using solely the 28 mm CB. Mean procedure time was 69 ± 25 min, TTI during the first application was recorded in 77% of PVs after a mean of 48 ± 31 s. We recorded 0.2% cardiac tamponade, 4.8% PN injury (1.6% of PN palsy), and 19% of LET < 15°C. Among 725 patients with follow-up data, 84% with PAF and 75% with persAF were in stable SR at 1 year. Shorter freezing duration and longer TTI were procedural predictors for recurrence.

CONCLUSION

Cryoballoon procedures are fast and associated with a benign safety profile. Shorter TTI and longer freeze durations are associated with sinus rhythm during follow-up.

Rationale and Outcomes of Cryoballoon Ablation of the Left Atrial Posterior Wall in Conjunction with Pulmonary Vein Isolation

There is strong evidence in support of pulmonary vein isolation (PVI) with concomitant left atrial (LA) posterior wall (PW) isolation (PWI) for the treatment of patients with persistent atrial fibrillation (persAF). While this may be achieved using surgical and catheter-based strategies, there is growing interest in performing this approach using the cryoballoon. There are several potential advantages to this strategy. First, lesions created using the current-generation cryoballoons are typically large and durable. Second, cryoballoon ablation offers a simple technique to directly ablate and debulk the LAPW. Moreover, some consider cryoenergy a safer modality specifically with regard to collateral structures (ie, the esophagus). Based on the available data, cryoballoon PVI + PWI is associated with greater intraprocedural AF terminations and reductions in long-term AF recurrence (typically by ~20%), as compared to PVI alone in patients with persAF, but with similar rates of adverse events. As such, PVI + PWI has emerged as a significant predictor of freedom from recurrent AF (odds ratio: 3.67, 95% confidence interval: 1.44-9.34; p = 0.006) as well as all atrial arrhythmias (hazard ratio: 2.04, 95% confidence interval: 1.15-3.61; p = 0.015). Adjunct radiofrequency ablation to complete PWI is required in at least one-third of the patients, and this need is highly predicted by the LA size (significantly increased with an LA diameter > 48 mm). LAPW reconnection also seems to be associated with LA dimension, particularly an LA diameter greater than 48 mm (negative predictive value: 89.7%). Nevertheless, based on the analysis of patients who underwent repeat electrophysiology study for arrhythmia recurrences, cryoballoon PVI + PWI yields acceptable long-term durability (> 80%).

Increased procedural safety of cryoballoon pulmonary vein isolation with a double 120 s freeze protocol

BACKGROUND

Recently a double 120 s freeze cryoballoon (CB) pulmonary vein isolation (PVI) protocol proved to be non inferior to a double 240 s freeze protocol in terms of atrial fibrillation (AF) recurrences. We hypothesized that this approach could also result in an increased procedure safety.

METHODS

Eighty consecutive patients treated with a double 120 s freeze protocol (Group CB120) were compared with 80 previous consecutive patients treated with a single 240 s freeze protocol (Group CB240). Procedures were performed with a temperature probe to monitor the luminal esophageal temperature (LET), using a cut off for cryoenergy interruption of 15°C. During ablation at the septal pulmonary veins (PVs), the phrenic nerve (PN) function was monitored by pacing.

RESULTS

In CB120 and CB240 the rate of single shot isolation was similar in all PVs. Time to isolation was not different between the two groups. Mean minimal esophageal temperature was lower in LSPV and LIPV of the CB240 group. A total of 4/80 patients (5%) of the CB120 group experienced a PN injury, but no persistent form was recorded; 11/80 patients (14%) of the CB240 group experienced a PN injury, three in a persistent form (p = .10). A LET <15°C was recorded in 3/80 patients (4%) in the CB120 group and in 16/80 patients (20%) in the CB240 group (p < .01). Composite rate of energy-related safety events (LET <15°C and PN injury) was significantly lower in the CB120 (34% vs. 9%, p < .01).

CONCLUSIONS

Safety of second generation CB PVI can be increased using a double 120 s freeze protocol.

Pulsed field ablation selectively spares the oesophagus during pulmonary vein isolation for atrial fibrillation

Aims

Extra-atrial injury can cause complications after catheter ablation for atrial fibrillation (AF). Pulsed field ablation (PFA) has generated preclinical data suggesting that it selectively targets the myocardium. We sought to characterize extra-atrial injuries after pulmonary vein isolation (PVI) between PFA and thermal ablation methods.

Methods and results

Cardiac magnetic resonance (CMR) imaging was performed before, acutely (<3 h) and 3 months post-ablation in 41 paroxysmal AF patients undergoing PVI with PFA (N = 18, Farapulse) or thermal methods (N = 23, 16 radiofrequency, 7 cryoballoon). Oesophageal and aortic injuries were assessed by using late gadolinium-enhanced (LGE) imaging. Phrenic nerve injuries were assessed from diaphragmatic motion on intra-procedural fluoroscopy. Baseline CMR showed no abnormality on the oesophagus or aorta. During ablation procedures, no patient showed phrenic palsy. Acutely, thermal methods induced high rates of oesophageal lesions (43%), all observed in patients showing direct contact between the oesophagus and the ablation sites. In contrast, oesophageal lesions were observed in no patient ablated with PFA (0%, P < 0.001 vs. thermal methods), despite similar rates of direct contact between the oesophagus and the ablation sites (P = 0.41). Acute lesions were detected on CMR on the descending aorta in 10/23 (43%) after thermal ablation, and in 6/18 (33%) after PFA (P = 0.52). CMR at 3 months showed a complete resolution of oesophageal and aortic LGE in all patients. No patient showed clinical complications.

Conclusion

PFA does not induce any signs of oesophageal injury on CMR after PVI. Due to its tissue selectivity, PFA may improve safety for catheter ablation of AF.

Pulsed Field Ablation of Paroxysmal Atrial Fibrillation: 1-Year Outcomes of IMPULSE, PEFCAT, and PEFCAT II

OBJECTIVES

This study sought to determine whether durable pulmonary vein isolation (PVI) using pulsed field ablation (PFA) translates to freedom from atrial fibrillation recurrence without an increase in adverse events.

BACKGROUND

PFA is a nonthermal ablative modality that, in preclinical studies, is able to preferentially ablate myocardial tissue with minimal effect on surrounding tissues. Herein, we present 1-year clinical outcomes of PFA.

METHODS

In 3 multicenter studies (IMPULSE [A Safety and Feasibility Study of the IOWA Approach Endocardial Ablation System to Treat Atrial Fibrillation], PEFCAT [A Safety and Feasibility Study of the FARAPULSE Endocardial Ablation System to Treat Paroxysmal Atrial Fibrillation], and PEFCAT II [Expanded Safety and Feasibility Study of the FARAPULSE Endocardial Multi Ablation System to Treat Paroxysmal Atrial Fibrillation]), paroxysmal atrial fibrillation patients underwent PVI using a basket or flower PFA catheter. Invasive remapping was performed at ∼2 to 3 months, and reconnected PVs were reisolated with PFA or radiofrequency ablation. After a 90-day blanking period, arrhythmia recurrence was assessed over 1-year follow-up.

RESULTS

In 121 patients, acute PVI was achieved in 100% of PVs with PFA alone. PV remapping, performed in 110 patients at 93.0 ± 30.1 days, demonstrated durable PVI in 84.8% of PVs (64.5% of patients), and 96.0% of PVs (84.1% of patients) treated with the optimized biphasic energy PFA waveform. Primary adverse events occurred in 2.5% of patients (2 pericardial effusions or tamponade, 1 hematoma); in addition, there was 1 transient ischemic attack. The 1-year Kaplan-Meier estimates for freedom from any atrial arrhythmia for the entire cohort and for the optimized biphasic energy PFA waveform cohort were 78.5 ± 3.8% and 84.5 ± 5.4%, respectively.

CONCLUSIONS

PVI with a "single-shot" PFA catheter results in excellent PVI durability and acceptable safety with a low 1-year rate of atrial arrhythmia recurrence. These data mitigate concern that the nonthermal ablative mechanism of PFA might mask undiscovered compromises to clinical success. (IMPULSE: A Safety and Feasibility Study of the IOWA Approach Endocardial Ablation System to Treat Atrial Fibrillation, NCT03700385; A Safety and Feasibility Study of the FARAPULSE Endocardial Ablation System to Treat Paroxysmal Atrial Fibrillation, NCT03714178; PEFCAT II Expanded Safety and Feasibility Study of the FARAPULSE Endocardial Multi Ablation System to Treat Paroxysmal Atrial Fibrillation [PEFCAT II], NCT04170608).

Segmental nonocclusive cryoballoon ablation of pulmonary veins and extrapulmonary vein structures: Best practices III

Although cryoballoon ablation of atrial fibrillation (AF) traditionally has been guided by pulmonary vein (PV) occlusion, there is evidence and growing interest in performing segmental, nonocclusive cryoballoon ablation to target not only large/common PVs but extra-PV structures such as the left atrial (LA) roof and posterior wall in conjunction with PV isolation. A number of studies have demonstrated improved clinical efficacy associated with nonocclusive cryoballoon ablation of the LA roof and posterior wall in addition to PV isolation, particularly in patients with persistent AF. Not only can the cryoballoon be used for targeting extra-PV structures through segmental, nonocclusive ablation, but the large size and durability of cryolesions coupled with the enhanced stability afforded through cryoadhesion render the cryoballoon an effective tool for such an approach. This article reviews the rationale and practical approach to segmental, nonocclusive cryoballoon ablation of large/common PV antra and the LA roof and posterior wall.

Novel Cryoballoon Ablation System for Single Shot Pulmonary Vein Isolation - The Prospective ICE-AGE-X Study

BACKGROUND

The arctic front cryoballoon (AF-CB) provides effective and durable pulmonary vein isolation (PVI) associated with encouraging clinical outcome. The POLARx cryoballoon incorporates unique features and design changes that may translate into improved efficacy, safety and further simplified balloon-based procedures. Efficacy and safety of the novel POLARx cryoballoon was compared to the fourth generation AF-CB (AF-CB4).Methods and Results:Twenty-five consecutive patients with paroxysmal or persistent atrial fibrillation were prospectively enrolled, underwent POLARx-based PVI (POLARx group) and were compared to 25 consecutive patients treated with the AF-CB4 (AF-CB4 group). All PVs were successfully isolated utilizing the POLARx and AF-CB4. A significant difference regarding the mean minimal cryoballoon temperatures reached using the AF-CB4 and POLARx (-50±6℃ vs. -57±7℃, P=0.004) was observed. Real-time PVI was visualized in 81% of POLARx patients and 42% of AF-CB4 patients (P<0.001). Utilizing the POLARx, a trend towards shorter median procedure time (POLARx: 45 [39, 53] min vs. AF-CB4: 55 [50, 60] min; P=0.062) was found. No differences were observed between AF-CB4 and POLARx concerning catheter maneuverability, catheter stability and periprocedural complications.

CONCLUSIONS

The novel POLARx showed similar safety and efficacy compared to the AF-CB4. A higher rate of real-time PV recordings and significantly lower minimal balloon temperatures were observed using the POLARx.

Duration of Applications Affects the Long-Term Efficacy of Cryoballoon Ablation Pulmonary Veins

Aim      To evaluate the effect of cryo-exposure duration and the use of the Achieve circular mapping catheter on efficacy of cryoballoon ablation (CBA).Material and methods  CBA of pulmonary vein ostia (PVO) is a major method for heart rhythm control in patients with atrial fibrillation (AF). Since the inception, the PVO CBA method has evolved; the recommended application time was changed, and the Achieve circular catheter appeared. We performed a retrospective analysis of PVO CBA administered to patients with AF in the I.V. Davydovsky Municipal Clinical Hospital from 2017 through 2019. The study included 100 patients with available clinical and demographic characteristics and remote results of the intervention. Three patient groups were analyzed based on differences in surgical techniques: group 1, Guidewire / 240 (n=31) with the cryoballoon placing on a guidewire and PVO exposure duration of 240 s; group 2, Guidewire / 180 (n=26) with the cryoballoon placing on a guidewire and PVO exposure duration of 180 s; and group 3, Achieve / 180 (n=43) with the cryoballoon placing on the mapping catheter Achieve and PVO exposure duration of 180 с. The follow-up period was 33.2±4.5, 15.2±6.1, and 12.2±4.1 months in the Guidewire / 240, Guidewire / 180, and Achieve / 180 groups, respectively. The intervention was considered effective when there was no relapse at the time of interview. A relapse of AF was determined as one or more paroxysms recorded on electrocardiogram (ECG) or during 24-h ECG monitoring; the "blind period" (first 3 months after the procedure) was excluded from the follow-up. Safety evaluation included clinically significant complications, such as phrenic nerve damage, hemopericardium, gastroparesis, hemoptysis, acute cerebrovascular disease, and formation of atrio-esophageal fistula. Effects of independent factors were determined with binary logistic regression.Results In the Guidewire / 240 group, efficacy of PVO CBA for the maximum follow-up period was 74.4%, which was significantly different from the value for the Guidewire / 180 group (57.7 %, р=0.015). At the same time, the difference between the Guidewire / 240 and Achieve / 180 groups was statistically non-significant for a comparable follow-up period (р=0.144). Clinically significant complications were absent in all 3 groups. The independent factors that significantly increased the PVO CBA efficacy were the cryo-exposure duration of 240 s compared to 180 s (р= 0.018) and the use of the Achieve catheter (р=0.014).Conclusion      Decreasing the cryo-exposure duration to less than 240 s is impractical (in absence of Achieve mapping catheter) since it impairs the long-term efficacy of PVO CBA and does not influence the risk of complications.

Initial experience and procedural efficacy of pulmonary vein isolation using the fourth-generation cryoballoon - a step forward?

Background: Cryoballoon (CB)-based pulmonary vein isolation (PVI) is an established treatment modality for patients suffering from paroxysmal or persistent atrial fibrillation (AF). Recently, the novel fourth-generation cryoballoon (CB4) was introduced which mainly provides a 40% shorter distal tip as compared to the second-generation cryoballoon (CB2). This two-centre analysis sought to assess the primary efficacy of the 28 mm CB4 for PVI and the feasibility of real-time signal recordings from the PVs considering the time-to-isolation (TTI).Methods and results: Eighty-four patients with paroxysmal or short-standing persistent AF underwent CB4-based PVI at two different hospitals. Individual freeze-cycle duration was set at TTI + 120 seconds. No bonus freeze was applied. A total of 331 pulmonary veins (PVs) including five left common PVs were identified and all PVs were successfully isolated. Mean freeze-cycle duration was 165.7 ± 31.5 seconds. The mean minimal CB temperature was -45.6 ± 7.6 °C with a real-time PVI visualisation rate of 78% (67/84 (79.8%) RSPVs, 55/84 (65.5%) RIPVs, 67/79 (84.8%) LSPVs, 66/79 (83.5%) LIPVs and 2/5 (40%) LCPV). Transient phrenic nerve palsy occurred in 2/84 (2.4%) patients during cryo-application along the RSPV.Conclusions: The novel CB4 provides both, a high acute efficacy and a high rate of real time electrical PV-recordings, thus facilitating individual ablation strategies based on TTI.

Keeping it Simple: Balloon Devices for Atrial Fibrillation Ablation Therapy

Atrial fibrillation is a common disease of increasing prevalence. Catheter ablation has evolved into an established therapeutic option that mainly aims to electrically isolate the pulmonary veins from atrial myocardium. The traditional method comprises point-by-point radiofrequency current ablation guided by electroanatomical mapping and has proven to be effective and safe in experienced hands. However, this approach is technically highly demanding and associated with a long learning curve, limiting its widespread utilization. To address these shortcomings, simplified ablation tools for pulmonary vein isolation are needed. In this context, balloon devices promise to ease the procedure by approaching the entire orifice of a targeted pulmonary vein in a single maneuver. This requires less catheter manipulation in the left atrium and often allows ablation of a large volume of tissue with a single application of ablative energy. Two balloon devices-one using cryoenergy, the other laser energy-have already been established in clinical routine and have demonstrated noninferiority when compared with radiofrequency ablation in large randomized trials. More balloon devices are on the verge of being introduced into clinical practice and bear the potential to expand the interventional electrophysiologist's armamentarium when treating atrial fibrillation. The authors review the use of the established balloon devices available for atrial fibrillation ablation and provide a detailed outlook on upcoming balloon technologies, including 3 different balloons utilizing radiofrequency energy as well as a novel cryoballoon.

High incidence of (ultra)low oesophageal temperatures during cryoballoon pulmonary vein isolation for atrial fibrillation

Background

Low oesophageal temperatures (OTs) during cryoballoon pulmonary vein isolation (PVI) have been associated with complications. This study assessed the incidence of low OT in clinical practice during cryoballoon PVI and verified possible predictive values for low OT.

Methods

Consecutive patients who underwent PVI using the second-generation cryoballoon were retrospectively included. The distance from the oesophagus to the different pulmonary veins (PVs) (OP distance), body mass index (BMI), sex, age, balloon temperature and application time were studied as potential predictors of low OTs. Computed tomography was performed before the procedure to determine the OP distance. OT was measured using an oesophageal temperature probe. Applications were ended prematurely if the OT reached <16 °C. Low and ultralow OT were defined as OT <20 and <16 °C respectively.

Results

Two hundred and four patients were included. Low OT was observed in 54 patients (26%) and 27 patients (13%) reached ultralow OTs. OP distance was the only predictor of low OTs after multivariate analysis. A cut-off value of 19 mm showed 96.2% sensitivity and 37.8% specificity in predicting low OTs. No clinically relevant relation was found between low OTs and BMI, age, sex, balloon temperature or application duration.

Conclusions

The incidence of low OT was 26% for cryoballoon PVI. OP distance was the only predictor of low OTs. Since an OP distance <19 mm was present in all patients in at least one PV, we recommend routine OT measurement during PVI cryoballoon therapy to prevent oesophagus-related complications.

Long-term durability of posterior wall isolation using the cryoballoon in patients with persistent atrial fibrillation: a multicenter analysis of repeat catheter ablations

PURPOSE

There is a growing interest in performing pulmonary vein isolation (PVI) with concomitant posterior wall isolation (PWI) using the cryoballoon for the treatment of patients with persistent atrial fibrillation (AF). However, there is little known about the long-term durability of PWI using this approach.

METHODS

In this multicenter study, we retrospectively examined the durability of PVI + PWI using the 28-mm cryoballoon by investigating the outcomes from consecutive patients referred for repeat catheter ablation.

RESULTS

Altogether, 81/519 patients (15.6%) were referred for repeat catheter ablation. Repeat ablation was associated with a longer AF duration, hypertension, heart failure, multiple cardioversions, and antiarrhythmic therapy as well as larger left atrial (LA) diameters (49 ± 4 mm versus 43 ± 5 mm; P < 0.001) and greater need for "touch-up" (adjunct) radiofrequency ablation (44.4% versus 18.3%; P < 0.001). LA diameter also emerged as a significant predictor for adjunct radiofrequency ablation (P < 0.001). Durable PVI was observed in 66/81 patients (81.5%) and PWI in 67/81 patients (82.7%). Those with incomplete PWI exhibited larger LA diameters, particularly > 48 mm (negative predictive value = 89.7%). Lastly, an atypical LA posterior wall/roof flutter represented the third most common cause of arrhythmia recurrence and essentially every patient with incomplete PWI exhibited such an arrhythmia.

CONCLUSION

PWI performed using a 28-mm cryoballoon in conjunction with PVI exhibits long-term durability in the vast majority of patients with persistent AF. While LA diameter (particularly > 48 mm) is a significant predictor for the need for adjunct radiofrequency ablation when performing this technique, those with incomplete PWI invariably present with an atypical flutter using this substrate.

Current Status of Esophageal Protection

Catheter ablation of atrial fibrillation necessitates ablation on the posterior left atrium. The anterior esophagus touches the posterior left atrium, although its course is highly variable. The proximity of the left atrium to the esophagus confers risk of injury with radiofrequency and cryoablation owing to the heat transfer that occurs with thermal ablation. Early detection of esophageal temperature changes with probes may decrease the extent of damage to the esophagus, but evidence is mixed. Avoiding ablation on the esophagus with esophageal deviation and modifying ablation approaches may decrease the risk of injury.

Prevention of left atrium esophagus fistula: Appraisal of existing technologies and strategies

Catheter ablation has emerged as an effective treatment for atrial fibrillation (AF). Atrial esophageal fistula (AEF) is a rare, but feared complication. With increasing utilization of ablation therapy for AF, the understanding of the relationship between AEF and ablation has been improved in recent years. Efforts to reduce the risk of AEF have focused on decreasing the risk of severe esophageal injury (EI) and the presumed subsequent progression from EI to AEF, including esophageal temperature monitoring, esophageal cooling systems, esophageal deviation devices, and decreasing and/or curtailing ablation energy delivery. Periprocedural assessment may help identify higher risk patients and detect early esophageal lesions. This review systematically summarizes and evaluates the current strategies and techniques utilized to reduce the risk of AEF in the clinical workflow for AF ablation. We expect that this review will help clinicians to better understand the principles, advantages, and disadvantages of these methods, and to find suitable strategies using current available tools.

Esophageal injury associated with catheter ablation for atrial fibrillation: Determinants of risk and protective strategies

Catheter ablation has become an important element in the management of atrial fibrillation. Several technical advances allowed for better safety profiles and lower recurrence rates, leading to an increasing number of ablations worldwide. Despite that, major complications are still reported, and esophageal thermal injury remains a significant concern as atrioesophageal fistula (AEF) is often fatal. Recognition of the mechanisms involved in the process of esophageal lesion formation and the identification of the main determinants of risk have set the grounds for the development and improvement of different esophageal protective strategies. More sensitive esophageal temperature monitoring, safer ablation parameters and catheters, and different energy sources appear to collectively reduce the risk of esophageal thermal injury. Adjunctive measures such as the prophylactic use of proton-pump inhibitors, as well as esophageal cooling or deviation devices, have emerged as complementary methods with variable but promising results. Nevertheless, as a multifactorial problem, no single esophageal protective measure has proven to be sufficiently effective to eliminate the risk, and further investigation is still warranted. Early screening in the patients at risk and prompt intervention in the cases of AEF are important risk modifiers and yield better outcomes.

Second-generation cryoballoon-based pulmonary vein isolation: Lessons from a five-year follow-up

BACKGROUND

Pulmonary vein isolation (PVI) using the second-generation cryoballoon (CB2) for atrial fibrillation (AF) treatment has demonstrated encouraging procedural success rates and mid-term results. However, long-term follow-up data on outcome is sparse. The current study is reporting on five-year clinical outcomes following CB2-based PVI in patients with paroxysmal AF (PAF) and persistent AF (PersAF).

METHODS

A total of 139 patients underwent index CB2-based PVI patients (PAF: n = 105, 76% and PersAF: n = 34, 34%) in two electrophysiology centers. Freeze-cycle duration was 240 s. After successful PVI a bonus freeze-cycle of the same duration was applied in the first 71 patients while the bonus-freeze was omitted in 68 following patients. Three patients (2.2%) were lost to follow-up.

RESULTS

After a median follow-up duration of 60 months (interquartile range: 46, 72 months) 74/136 (54.4%) patients remained in stable sinus rhythm (PAF: 62/104, 59.6%; PersAF: 15/32, 46.9%). Significant differences were observed concerning 5-year clinical outcome between PAF and PersAF patients (p = 0.0315). After a mean of 1.32 ± 0.6 procedures (2nd and 3rd procedure by radiofrequency ablation) and a median follow-up duration of 60 (37, 68) months 90/136 (66.2%) patients remained in stable sinus rhythm (PAF: 72/104 (69.2%), PersAF: 21/32 (65.6%), p = 0.0276). For the comparison of bonus-freeze vs no-bonus-freeze protocols no differences were observed (53.5% vs 57.4%, p = 0.650).

CONCLUSIONS

The five-year single-procedure success rate for CB2-based PVI was 54.4% and increased to 66.2% following repeat RF-based procedures. No differences were detected comparing bonus-freeze and no-bonus-freeze protocols.

A comparative study of pericardial effusion and pleural effusion after cryoballoon ablation or radiofrequency catheter ablation of atrial fibrillation

INTRODUCTION

The incidence and clinical outcome of pericardial and pleural effusion after cryoballoon ablation (CBA) or radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF) have not been fully investigated.

METHODS

A total of 60 patients with paroxysmal AF were treated with either CBA (n = 30) or RFCA (n = 30) groups, with assessment of serum troponin I level, left atrial pulmonary vein computed tomography (CT) angiography and echocardiography within 24 hours before ablation, and serum troponin I level at 12 hours, and chest CT and echocardiography within 24 hours postablation. Repeat chest CT was performed 1 month after the index procedure in patients with pericardial or pleural effusion.

RESULTS

With similarly distributed baseline characteristics, the CBA group relative to the RFCA group had postablation: higher serum troponin I level (13.48 vs 1.84 µg/L, P < .001); similarly high pericardial effusion rates on chest CT (80% vs 93.3%, P > .05), with chest CT yielding significantly higher detection rate than echocardiography; similarly high pleural effusion rates on chest CT (73.3% vs 80%, P > .05); and smaller maximum depths on chest CT cross-section of pericardial effusion (5.21 ± 3.37 vs 7.13 ± 2.68 mm, P < .05) and pleural effusion bilaterally (left: 4.16 ± 4.90 vs 6.96 ± 5.42 mm; right: 5.04 ± 4.46 vs 7.55 ± 4.95 mm, both P < .05). The effusions self-resolved within a mean period of 1 month.

CONCLUSIONS

Both CBA and RFCA were associated with high rates of pericardial and pleural effusion, with RFCA yielding numerically higher incidence and significantly higher effusion extent, and chest CT significantly higher detection rates than echocardiography.

Novel three-dimensional imaging approach for cryoballoon navigation and confirmation of pulmonary vein occlusion

BACKGROUND

Cryoballoon apposition is crucial for durable pulmonary vein isolation (PVI) in atrial fibrillation, yet the balloon is difficult to visualize by conventional mapping systems, and pulmonary venography may miss small or out-of-plane leaks. We report a novel imaging system that offers real-time 3D navigation of the cryoballoon within atrial anatomy that may circumvent these issues.

METHODS AND RESULTS

A novel overlay guidance system (OGS) registers already-acquired segmented atrial cardiac tomography (CT) with fluoroscopy, enabling real-time visualization of the cryoballoon within tomographic left atrial imaging during PVI. Phantom experiments in a patient-specific 3D printed left atrium showed feasibility for confirming PV apposition and leaks. We applied OGS prospectively to 68 PVs during PVI in 17 patients. The cryoballoon was successfully reconstructed in all cases, and its apposition was compared to concurrent PV venography. The OGS uncovered leaks undetected by venography in nine veins (eight cases), which enabled repositioning, confirming apposition in remaining 68 veins. Concordance of OGS to venography was 83.8% (χ² , P < .01) CONCLUSIONS: We report a new system for real-time imaging of cryoballoon catheters to ensure PV apposition within the tomography of the left atrium. While providing high concordance with other imaging modalities for confirming balloon apposition or leak, the system also identified leaks missed by venography. Future studies should determine if this tool can provide a new reference for cryoballoon positioning.

Current Status of Atrial Fibrillation Ablation with Balloon Strategy

Catheter ablation of atrial fibrillation (AF) has been established worldwide and is recommended for symptomatic paroxysmal AF patients according to international guidelines. Importantly, the cornerstone of any AF ablation represents pulmonary vein isolation (PVI). Traditional radiofrequency (RF) point by point ablation within a 3D electroanatomic left atrial (LA) map requires profound understanding of LA anatomy and electrophysiology. This ablation strategy can be highly efficient and safe if performed in experienced hands and centers. However, procedural complexity causes a long learning curve and has limited its wide spread utilization. In contrast, balloon based PVI ablation strategies are based on an anatomic principle. Currently, two balloon types (cryoballoon and laserballoon) have been adopted to clinical routine. Both balloons are positioned at the target PV and circumferential energy ablation is enabled. This simplified anatomic approach facilitates reaching the procedural endpoint of PVI and demonstrated less operator dependency. Therefore, balloon PVI appears to be associated with improved procedural reproducibility and safety. Importantly, large scale randomized trials proved non-inferiority of balloon guided AF ablation (cryothermal and laser energy) vs. experienced operators using traditional “gold standard” RF ablation in paroxysmal and persistent AF. Ongoing technological refinements of both balloons as well as the introduction of novel energy dosing strategies and ablation targets may potentially impact the current way of ablating AF in future. This review will summarize current clinical experience of contemporary balloon devices and will look into future developments.

Significant Radiation Dose Reduction Using a Novel Angiography Platform in Patients Undergoing Cryoballoon Pulmonary Vein Isolation

OBJECTIVES

Cryoballoon pulmonary vein isolation (cPVI) in patients with atrial fibrillation requires fluoroscopic guidance, causing a relevant amount of radiation exposure. Strategies to reduce radiation exposure in electrophysiologic procedures and specifically cPVI are of great importance. The aim of this study was to evaluate a possible reduction of radiation dose using the novel Azurion 7 F12 x-ray system compared with its predecessor Allura FD10.

METHODS

In February 2017, the Philips Azurion angiography system was introduced, combining the Allura Clarity radiation dose reduction technology with a more powerful generator, improved image resolution, and a large screen display. In 173 patients undergoing cPVI by a single experienced operator in our institution between December 2016 and April 2018, dose area products (cGy×cm) and image quality were compared using Azurion 7 F12 or Allura FD10 angiography system.

RESULTS

A significant reduction in total radiation dose expressed as a dose area products of 524 (332; 821) cGy×cm on the Allura system compared with 309 (224; 432) cGy×cm on the Azurion system was observed (P<0.001). The number of imaging scenes recorded were 14.7 versus 13.9, and mean overall imaging quality scores (grading 4.85±0.4 with Azurion vs. 4.80±0.4 with Allura, P=0.38) and scores based on specific quality parameters were similar in both groups.

CONCLUSION

Use of the new Azurion 7 F12 angiography system substantially reduced radiation doses compared with the previous generation reference system, Allura Clarity, without compromising imaging quality in patients undergoing cryoballoon pulmonary vein isolation.

The influence of cryoballoon manipulation on luminal esophageal temperature during ablation for atrial fibrillation

BACKGROUND

Esophageal injury is related to a reduction in luminal esophageal temperature (LET) in second-generation cryoballoon (CB) ablation; however, methods to prevent these reductions in temperature have not been well characterized.

METHODS

Esophageal temperature was continuously monitored using a LET probe in patients undergoing pulmonary vein (PV) isolation using the second-generation CB. A rotational maneuver of the CB was performed if the initial ablation resulted in a decrease of more than 4℃ in LET. The refrigerant injector near the distal CB pole was used as a fluoroscopic marker to measure the nearest distance between the CB and the LET probe.

RESULTS

A total of 52 consecutive patients were enrolled in this study. The rotation was applied in 19 patients and 20 PVs (seven left superior pulmonary veins [LSPVs], seven left inferior PVs [LIPVs], and six right inferior PVs [RIPVs]) with a reduction in LET of more than 4℃ during freezing. The nadir temperature of CB applications was similar before and after CB rotation in all PVs. There was significant difference in the minimum LET before and after rotation during freezing in LSPVs (28.4 ± 3.7 vs 32.4 ± 2.3℃, P = .02), LIPVs (28.4 ± 1.4 vs 32.6 ± 2.7, P = .01) and RIPVs (26.1 ± 4.3 vs 34.0 ± 1.3℃, P = .002). The differences in mean balloon to LET distance were measured for all veins before and after rotation; LSPV (right anterior oblique [RAO], 11.0 ± 1.7 vs 13.8 ± 4.5 mm, P = .05); LIPV (RAO, 10.7 ± 4.3 vs 14.6 ± 6.1 mm, P = .03); RIPV (LAO, 11.8 ± 5.5 vs 14.2 ± 5.7 mm, P = .01).

CONCLUSIONS

CB rotational maneuvers during ablation can prevent significant reduction in LET and may prevent esophageal injury during the procedure.

Single freeze per vein strategy with the second-generation cryoballoon for atrial fibrillation: a propensity score-matched study between 180- and 240-s application time in a large cohort of patients

Aims

The single-freeze strategy using the second-generation cryoballoon (CB-A, Arctic Front Advance, Medtronic, Minneapolis, MN, USA) has been reported to be as effective as the recommended double-freeze approach in several single-centre studies. In this retrospective, international, multicentre study, we compare the 3-min single-freeze strategy with the 4-min single-freeze strategy.

Methods and results

Four hundred and thirty-two patients having undergone pulmonary vein isolation (PVI) by means of CB-A using a single-freeze strategy were considered for this analysis. A cohort of patients who were treated with a 3-min strategy (Group 1) was compared with a propensity score-matched cohort of patients who underwent a 4-min strategy (Group 2). Pulmonary vein isolation was successfully achieved in all the veins using the 28-mm CB-A. The procedural and fluoroscopy times were lower in Group 1 (67.8 ± 17 vs. 73.8 ± 26.3, P < 0.05; 14.9 ± 7.8 vs. 24.2 ± 10.6 min, P < 0.05). The most frequent complication was PNP, with no difference between the two groups (P = 0.67). After a mean follow-up of 13 ± 8 months, taking into consideration a blanking period of 3 months, 85.6% of patients in Group 1 and 87% of patients in Group 2 were free from arrhythmia recurrence at final follow-up (P = 0.67).

Conclusion

There is no difference in acute success, rate of complications, and freedom from atrial fibrillation recurrences during the follow-up between 3-min and 4-min per vein freeze strategies. The procedural and fluoroscopy times were significantly shorter in 3-min per vein strategy.

Irreversible electroporation for catheter-based cardiac ablation: a systematic review of the preclinical experience

INTRODUCTION

Irreversible electroporation (IRE) utilizing high voltage pulses is an emerging strategy for catheter-based cardiac ablation with considerable growth in the preclinical arena.

METHODS

A systematic search for articles was performed from three sources (PubMed, EMBASE, and Google Scholar). The primary outcome was the efficacy of tissue ablation with characteristics of lesion formation evaluated by histologic analysis. The secondary outcome was focused on safety and damage to collateral structures.

RESULTS

Sixteen studies met inclusion criteria. IRE was most commonly applied to the ventricular myocardium (n = 7/16, 44%) by a LifePak 9 Defibrillator (n = 9/16, 56%), NanoKnife Generator (n = 2/16, 13%), or other custom generators (n = 5/16, 31%). There was significant heterogeneity regarding electroporation protocols. On histological analysis, IRE was successful in creating ablation lesions with variable transmurality depending on the electric pulse parameters and catheter used.

CONCLUSION

Preclinical studies suggest that cardiac tissue ablation using IRE shows promise in delivering efficacious, safe lesions.

Predictors of freedom from atrial arrhythmia recurrence after cryoballoon ablation for persistent atrial fibrillation: A multicenter study

AIMS

We sought to assess (1) clinical outcomes of second-generation cryoballoon (CB) ablation for persistent atrial fibrillation (AF), and (2) the association of baseline and procedural covariates with atrial arrhythmia recurrence (AAR) after ablation.

METHODS

A total of 135 patients (63 ± 11 years, 96 men [71%]) with persistent AF underwent CB ablation at three experienced electrophysiology centers. Freedom from AAR was estimated with the Kaplan-Meier method. A Cox proportional-hazards model was used to estimate the effects of baseline and procedural covariates on the likelihood of AAR.

RESULTS

Freedom from AAR at 6, 12, and 18 months was estimated at 91% (95% confidence interval [CI] 86%-96%), 75% (95% CI, 67%-83%), and 53% (95% CI, 43%-65%), respectively. The presence of an implantable cardiac device (Hazard ratio [HR] 3.09; 95% CI, 1.37-7.00; P = .007), a left atrial (LA) diameter > 50 mm (HR 1.69; 95% CI, 1.02-2.79; P = .043), and absence of antiarrhythmic drug (AAD) therapy before the ablation procedure (HR 3.12; 95% CI, 1.72-5.64; P < .001) were associated with AAR. A trend toward an increased risk of AAR was revealed for women (HR 1.73; 95% CI, 0.96-3.11; P = .069).

CONCLUSIONS

CB ablation for persistent AF resulted in freedom from AAR about that reported for RF ablation. The presence of an implantable cardiac device, LA size, and absence of AAD therapy at baseline were associated with the risk of AAR.

Long-term outcomes of cryoballoon pulmonary vein isolation for paroxysmal and persistent atrial fibrillation in Chinese patients

PURPOSE

We aimed to study the long-term outcomes of cryoballoon (CB) pulmonary vein isolation (PVI) in treating Chinese patients with atrial fibrillation (AF).

METHODS

A total of 122 patients (48 women, mean age 57.4 ± 11.3) underwent CB PVI (first generation CB 44.3%, second generation CB 55.7%) for AF (paroxysmal 65.6%, persistent 10.7% and long-standing persistent 23.8%).

RESULTS

PVI was achieved in 113 (92.6%) patients with CB alone, and it was achieved in all patients with additional touch-up by 8-mm-tip cryocatheter. The mean procedural and fluoroscopic duration were 171.9 ± 41 and 46.6 ± 14.6 min respectively. The recurrence-free survival for paroxysmal and non-paroxysmal AF was 77% and 59% respectively at 1 year and progressively declined over time to reach a plateau of 52% and 30% for paroxysmal and non-paroxysmal AF respectively at 5 years. In patients undergoing PVI with second-generation CB, the recurrence-free survival was 75% for paroxysmal AF and 45% for non-paroxysmal AF at 5 years. With multivariate Cox regression analysis, the types of CB (use of second-generation CB: HR 0.49; 95% CI 0.28-0.85; p = 0.011) and size of left atrium (LA) (larger LA size: HR 1.52; 95% CI 1-2.14; p = 0.017) independently predicted recurrence. Transient phrenic nerve injury (PNI) occurred in four (3.3%) patients and persistent PNI occurred in four (3.3%) patients. Other complications occurred in 10 (8.2%) patients with no procedure-related death.

CONCLUSIONS

Long-term success of CB PVI for AF declined over time and reached a plateau at 5 years. CB types and LA size are independent predictors for long-term recurrence.