Time-to-effect guided pulmonary vein isolation utilizing the third-generation versus second generation cryoballoon: One year clinical success

Incidence of Long-Term Pulmonary Vein Reconnection after a 2-Minute Cryoballoon Freeze for Pulmonary Vein Isolation—Invasive Insights of TTI-Dependent Cryoenergy Titration

Introduction: The optimal freeze duration in cryoballoon pulmonary vein isolation (PVI) is unknown. TTI-based titration of cryoenergy allows individualized freeze duration and has emerged as a favorable ablation strategy in PV cryoablation. In a recent study, we demonstrated that omission of a bonus freeze and reduction in freeze duration to a minimum of 2 min in the case of short TTI led to comparable arrhythmia recurrence rates. Whereas clinical outcome seems to be comparable to fixed freeze duration, evidence of long-term PV reconnection rates in patients undergoing TTI-based cryoballoon ablation is sparse. Aim of the study: To evaluate the procedural efficacy of a single 2-min freeze for PVI, we assessed PV conduction recovery after cryoballoon PVI with a TTI-guided titration of freeze duration compared to a fixed ablation protocol. Methods and Results: We included consecutive patients with atrial fibrillation (AF) recurrence undergoing a second ablation procedure after the initial cryoballoon procedure. The second AF ablation procedure was performed by the 3D-mapping system and radiofrequency ablation technique. A total of 219 patients (age: 66.2 ± 10.8 years, 53% female, paroxysmal AF: 53%) treated with the TTI-guided protocol (174 patients, 685 PV) or fixed protocol (45 patients, 179 PV) showed comparable total reconnection rates (TTI: 36.9% vs. fixed: 31.8%, p = 0.21). The PV reconnection rate was not statistically different for PVs treated with a 2-min freeze in case of short TTI, compared to longer freeze duration. Interestingly, the PV reconnection rate was lower in LIPVs treated with the fixed protocol (13% vs. 31%, p = 0.029). In the TTI group, 17 out of 127 patients (15%) had durable isolation of all PVs, whereas in 8 out of 40 patients (20%) in the fixed group, all PVs were still isolated (p = 0.31). Conclusions: overall reconnection rate was not different using a TTI-guided ablation protocol compared to a fixed ablation protocol, whereas the LIPV reconnection rate was significantly lower in patients treated with a fixed ablation protocol.

Phrenic Nerve Injury During Cryoballoon-Based Pulmonary Vein Isolation: Results of the Worldwide YETI Registry

Supplemental Digital Content is available in the text.

Background:

Cryoballoon-based pulmonary vein isolation (PVI) has emerged as an effective treatment for atrial fibrillation. The most frequent complication during cryoballoon-based PVI is phrenic nerve injury (PNI). However, data on PNI are scarce.

Methods:

The YETI registry is a retrospective, multicenter, and multinational registry evaluating the incidence, characteristics, prognostic factors for PNI recovery and follow-up data of patients with PNI during cryoballoon-based PVI. Experienced electrophysiological centers were invited to participate. All patients with PNI during CB2 or third (CB3) and fourth-generation cryoballoon (CB4)-based PVI were eligible.

Results:

A total of 17 356 patients underwent cryoballoon-based PVI in 33 centers from 10 countries. A total of 731 (4.2%) patients experienced PNI. The mean time to PNI was 127.7±50.4 seconds, and the mean temperature at the time of PNI was −49±8°C. At the end of the procedure, PNI recovered in 394/731 patients (53.9%). Recovery of PNI at 12 months of follow-up was found in 97.0% of patients (682/703, with 28 patients lost to follow-up). A total of 16/703 (2.3%) reported symptomatic PNI. Only 0.06% of the overall population showed symptomatic and permanent PNI. Prognostic factors improving PNI recovery are immediate stop at PNI by double-stop technique and utilization of a bonus-freeze protocol. Age, cryoballoon temperature at PNI, and compound motor action potential amplitude loss >30% were identified as factors decreasing PNI recovery. Based on these parameters, a score was calculated. The YETI score has a numerical value that will directly represent the probability of a specific patient of recovering from PNI within 12 months.

Conclusions:

The incidence of PNI during cryoballoon-based PVI was 4.2%. Overall 97% of PNI recovered within 12 months. Symptomatic and permanent PNI is exceedingly rare in patients after cryoballoon-based PVI. The YETI score estimates the prognosis after iatrogenic cryoballoon-derived PNI.

Registration:

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03645577.

Graphic Abstract:

A graphic abstract is available for this article.

Comparison for the efficacy and safety of time-to-isolation protocol and conventional protocol of cryoballoon in the treatment of atrial fibrillation: a meta-analysis and systematic review

BACKGROUND

Cryoballoon (CB) has been widely utilized in the treatment of drug-refractory atrial fibrillation (AF), but the balance point between efficacy and safety has been unclear. The protocol based on the time-to-isolation (TTI) was expected to provide patients with individualized ablation strategies.

METHODS

All studies up to June 2020 comparing the CB of TTI-based protocol (TTIP) and conventional protocol (ConP) in PubMed, Embase, and Cochrane Library databases were searched. The pooled OR or SMD with 95% CIs for each outcome were calculated with inverse-variance random effect model. The Egger method was used to evaluate the publication bias and the subgroup analysis was conducted according to the type of atrial fibrillation.

RESULTS

Six studies enrolling a total of 1770 patients with drug-refractory AF were included. The pool real-time recording of pulmonary veins potential was 71% (95% CI: 61 ~ 81%, I2 = 97.9%) and a similar incidence of freedom from ATs after 1 year (OR: 1.12; 95% CI: 0.86 ~ 1.46, I2 = 0.0%, P = 0.481) was observed between two protocols. No difference was observed in complications (OR: 0.67; 95% CI: 0.43 ~ 1.04, I2 = 0.0%, P = 0.717) and phrenic nerve palsy (OR: 0.70; 95% CI: 0.37 ~ 1.35, I2 = 0.0%, P = 0.807). TTIP could significantly decrease the CB freezes per patient (SMD: - 2.44; 95% CI: - 4.46 to approximately - 0.41; I2 = 99.5%, P = 0.00) and shorten the cryotherapy application time (SMD: - 3.04; 95% CI: - 4.18 to approximately - 1.89; I2 = 97.4%, P = 0.00), procedure time (SMD: - 1.51; 95% CI: - 2.08 to approximately - 0.94; I2 = 95.4%, P = 0.00), and fluorescence time (SMD: - 0.70; 95% CI: - 1.25 to approximately - 0.15; I2 = 95.7%, P = 0.00).

CONCLUSION

TTIP is safe and effective and it opens a new chapter in the field of individualized protocol of CB for patients with AF.

Earliest pulmonary vein potential-guided cryoballoon ablation is associated with better clinical outcomes than conventional cryoballoon ablation: A result from two randomized clinical studies

INTRODUCTION

With regard to short-term outcome in atrial fibrillation (AF), the benefit of cryoballoon ablation (CBA) by pressing a balloon against the earliest pulmonary vein (PV) potential site during PV isolation (earliest potential [EP]-guided CBA) has been previously demonstrated. The present study aimed to evaluate the long-term outcome of the EP-guided CBA.

METHODS AND RESULTS

This study included 136 patients from two randomized studies, who underwent CBA for paroxysmal AF for the first time. Patients were randomly assigned to the EP-guided and conventional CBA groups in each study. In the EP-guided CBA group, we pressed a balloon against the EP site when the time-to-isolation (TTI) after cryoapplication exceeded 60 and 45 s in the first and second studies, respectively. We compared the clinical outcomes for 1 year after the procedure between the EP-guided CBA group (68 patients) and the conventional CBA group (68 patients). The primary endpoint was the recurrence of atrial arrhythmia after ablation. No significant differences in baseline characteristics were observed between the two groups. Compared with the conventional CBA group, the EP-guided CBA group had a significantly higher success rate at TTI ≤ 90 s (98.5% vs. 90.0%, p < .001); lower touch-up rate and total cryoapplication; and shorter procedure time, and fluoroscopy time. The recurrence at 1 year after ablation was significantly lower in the EP-guided CBA group than in the conventional CBA group (6.0% vs. 19.4%; p = .019).

CONCLUSIONS

The EP-guided CBA approach can facilitate the ablation procedure and achieve low recurrence at 1 year after ablation.

Experience and procedural efficacy of pulmonary vein isolation using the fourth and second generation cryoballoon: The shorter, the better?

BACKGROUND

The second-generation cryoballoon (CB2) provides effective and durable pulmonary vein isolation (PVI) associated with encouraging clinical outcome. The novel fourth-generation cryoballoon (CB4) incorporates a 40% shorter distal tip. This design change may translate into an increased rate of PVI real-time signal recording, facilitating an individualized ablation strategy using the time to effect (TTE).

METHODS AND RESULTS

Three hundred consecutive patients with paroxysmal or persistent atrial fibrillation were prospectively enrolled. The first 150 consecutive patients underwent CB2 based PVI (CB2 group) and the last 150 consecutive patients were treated with the CB4 (CB4 group). A total of 594/594 (100%, CB4) and 589/594 (99.2%, CB2) pulmonary veins (PVs) were successfully isolated utilizing the CB4 and CB2, respectively (p = .283). The real-time PVI visualization rate was 47% (CB4) and 39% (CB2; p = .005) and the mean freeze cycle duration 200 ± 90 s (CB4) and 228 ± 110 s (CB2; p < .001), respectively. The total procedure time did not differ between the groups (CB4: 64 ± 32 min) and (CB2: 62 ± 29 min, p = .370). No differences in periprocedural complications were detected.

CONCLUSIONS

A higher rate of real-time electrical PV recordings are seen using the CB4 as compared to CB2, which may facilitate an individualized ablation strategy using the TTE.

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.

Stroke and left atrial thrombi after cryoballoon ablation of atrial fibrillation: incidence and predictors. Results from a long-term follow-up

Stroke after catheter ablation (CA) of atrial fibrillation (AF) is a potential complication with long term consequences. Aim of this study was to determine incidence and potential predictors of stroke and left atrial appendage (LAA) thrombi after AF ablation with cryo-energy. Two hundred nine consecutive patients with symptomatic drug refractory AF (65% male; 61 ± 11 yo, 69% paroxysmal AF, mean CHA₂DS₂-VASc score 2 ± 1.4) were enrolled between October 2012 until December 2015. Long term follow-up was performed with outpatient clinic visits at 6-month intervals. Incidence of stroke after CA was 1.4% (3/209 pts) at long term follow-up. Two out of 3 pts experienced stroke during the first 3 month after CA and one after 36 months. At long term follow-up LAA thrombi were found in two patients (1%) that were on therapeutic oral anticoagulation. Recurrence of AF was found in 4 out of 5 pts with stroke or LAA thrombi. Patients with stroke or LAA thrombi did not differed from those without in term of age, gender, CV risk factors, LA size and AF type. They differed only for EHRA score (2.4 vs 1.3, p = 0.01) before CA. At multivariate analysis after correction for age, gender, LA size, LVEF and AF type, only EHRA score (β 1.92, 95% C.I. 1.3-35 p = 0.02), was an independent predictor of stroke/LAA thrombi. Incidence of stroke after cryoablation is low, with a relative higher prevalence during the first 3 months after CA. Prospective, multicenter long-term registries are needed for a better stroke risk stratification.

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.

Feasibility, safety, and acute efficacy of the fourth-generation cryoballoon for ablation of atrial fibrillation: Another step forward?

Background

The second‐generation cryoballoon (CB2) is widely used for pulmonary vein (PV) isolation (PVI) in patients with paroxysmal atrial fibrillation (AF). Recently, the novel fourth‐generation CB (CB‐Advance PRO) was introduced, incorporating a shortened catheter tip.

Hypothesis

The aim of this study was to evaluate the feasibility and acute efficacy of PVI using the CB‐Advance PRO.

Methods

A total of 200 consecutive patients were analyzed. Hundred patients who underwent PVI due to symptomatic, drug‐refractory AF were treated with the CB‐Advance PRO (group I) and were included into this multicenter analysis. A group of 100 patients were treated with the CB2 and acted as controls (group II).

Results

In total, 739 of 739 PVs (100%) were successfully isolated. There was a nonsignificant trend in the incidence of online registration of PV signals between both groups (group I: 77.9% vs group II: 71.4%, P = .09). Median time to PVI (time to isolation [TTI]) and mean total freezing time were significantly shorter when using the CB‐Advance PRO (group I: 33 [23, 50] vs group II: 40 [26, 60] seconds and group I: 166 ± 29 vs group II: 183 ± 38 seconds, P < .01). In three of 100 (3%) patients of group I and one of 100 (1%) patients of group II, a transient phrenic nerve palsy occurred (P = .62).

Conclusion

The use of the novel CB‐Advance PRO is feasible and associated with a significant reduction in mean TTI and mean total freezing time as compared to the CB2.

Comparison of cryoballoon ablation for atrial fibrillation guided by real-time three-dimensional transesophageal echocardiography vs. contrast agent injection

Background:

Pulmonary vein (PV) occlusion generally depends on repetitive contrast agent injection when cryoballoon ablation for atrial fibrillation (AF). The present study was to compare the effect of cryoballoon ablation for AF guided by transesophageal echocardiography (TEE) vs. contrast agent injection.

Methods:

Eighty patients with paroxysmal AF (PAF) were enrolled in the study. About 40 patients underwent cryoballoon ablation without TEE (non-TEE group) and the other 40 underwent cryoballoon ablation with TEE for PV occlusion (TEE group). In the TEE group during the procedure, PVs were displayed in 3-dimensional images to guide the balloon to achieve PV occlusion. The patients were followed up at regularly scheduled visits every 2 months.

Results:

No differences were identified between the groups in regard to the procedure time and cryoablation time for each PV. The fluoroscopy time (6.7 ± 4.2 min vs. 17.9 ± 5.9 min, P < 0.05) and the amount of contrast agent (3.0 ± 5.1 mL vs.18.1 ± 3.4 mL, P < 0.05) in the TEE group were both less than the non-TEE group. At a mean of 13.0 ± 3.3 mon follow-up, success rates were similar between the TEE group and non-TEE group (77.5% vs. 80.0%, P = 0.88).

Conclusions:

Cryoballoon ablation with TEE for occlusion of the PV is both safe and effective. Less fluoroscopy time and a lower contrast agent load can be achieved with the help of TEE for PV occlusion during procedure.

Impact of atrial rhythm on pulmonary vein signals in cryoballoon ablation - Sinus rhythm predicts real-time observation of pulmonary vein isolation

Purpose

Real-time observation of pulmonary vein (PV) potentials with a spiral mapping catheter has emerged as a key electrogram-based procedural parameter to estimate lesion quality and titrate cryoenergy application during PV isolation (PVI) with the cryoballoon. Whether correct PV electrogram interpretation and thus PVI real-time observation rate depends on atrial rhythm during cryoballoon PVI is unknown. We compared observation rates of time-to PV isolation (TTI) during sinus rhythm (SR group) and during atrial fibrillation (AFib group) in cryoballoon PVI.

Methods

We prospectively included 157 consecutive patients undergoing cryoballoon PVI and compared the incidence of PVI real-time recording of each pulmonary vein during SR and in AFib.

Results

Overall PVI real-time observation rate was 82.1% (491/598 PV) with significantly higher TTI observation rate in the SR group (315/365 PV, 86.3%) compared to the AFib group (176/233 PV, 75.5%; p < 0.001). Per vein analysis demonstrated that only TTI observation rate in the left superior pulmonary vein (LSPV) was significantly higher during SR (85/92, 92.4%) compared to AFib (37/54, 68.5%; p < 0.001). Regression analysis revealed that atrial rhythm is a strong and independent predictor of PVI real-time observation in the LSPV with an odds ratio of 4.98 (95%-CI: 1.86–13.34, p = 0.001) to detect TTI during SR.

Conclusions

Our results demonstrate that correct interpretation of PV electrograms and thus PVI real-time observation is more likely in SR than in AFib. Hence, cardioversion of patients in AFib at the beginning of the procedure should be considered to yield higher PVI real-time observation rates facilitating TTI guided cryoenergy titration.