Comparing learning curves of two established "single-shot" devices for ablation of atrial fibrillation

Safety and effectiveness of the first balloon-in-basket pulsed field ablation system for the treatment of atrial fibrillation: VOLT CE Mark Study 6-month results

AIMS

Pulsed field ablation (PFA) is a growing ablation modality for pulmonary vein isolation (PVI) in atrial fibrillation (AF) patients. This study assesses the 6-month safety and effectiveness of a novel balloon-in-basket, mapping-integrated PFA system, with a purpose-built form factor for PVI.

METHODS AND RESULTS

The VOLT CE Mark Study is a prospective, multi-center, pre-market study. A total of 150 patients with drug-refractory paroxysmal (PAF) or persistent AF (PersAF) were enrolled between 8 November 2023 and 14 March 2024, of which 146 patients (age 64.1 ± 10.0 years, 63.0% male, 70.5% PAF) underwent PVI with the balloon-in-basket PFA catheter and system featuring integrated electroanatomic mapping with contact-sensing. Study endpoints were the rate of primary serious adverse events within 7 days as well as acute procedural effectiveness and 6-month freedom from recurrence. Acute effectiveness was achieved in 99.1% (573/578) of treated PVs (98.6% of patients, 144/146) with 17.6 ± 5.7 PFA applications/patient. Procedure, fluoroscopy, LA dwell, and transpired ablation times were 100.4 ± 33.0, 17.3 ± 12.1, 39.4 ± 20.6, and 31.4 ± 16.8 min, respectively. There were 4 (2.7%; 4/146) primary serious adverse events. The rate of freedom from documented atrial arrhythmias was 88.2% in PAF patients and 76.7% in PersAF patients (freedom from symptomatic recurrence was documented in 90.2% of PAF patients and 74.4% of PersAF patients) through 6-months post-index procedure.

CONCLUSION

The VOLT CE Mark Study primary results demonstrate the safety and effectiveness of the novel balloon-in-basket PFA system to perform PVI in PAF and PersAF.

Temperature to time Catch-Up: a novel procedural endpoint to predict durable pulmonary vein isolation after cryoballoon ablation of paroxysmal atrial fibrillation

BACKGROUND

Cryoballoon ablation is a widely used single-shot technique for pulmonary vein isolation (PVI) in the treatment of paroxysmal atrial fibrillation (AF). Procedural endpoints ensuring maximal PVI durability are important.

OBJECTIVE

To assess the performance of cryoablation procedural markers to predict long-term PVI.

METHODS

In a single center, consecutive patients who underwent redo ablation with high-density mapping for symptomatic AF recurrence after cryoballoon ablation were included and cryoballoon procedural data were collected, including temperature values at 30 and 60 s, time to isolation, nadir temperature and the velocity of temperature decline estimated with the temperature/time catch-up point (T2T-Catch-Up) defined as positive when the freeze temperature in minus degree equals the time in seconds after cryoablation initiation (e.g. - 15 °C in the first 15 s of the ablation impulse).

RESULTS

47 patients (62% male; 58.3 ± 11.2 years) were included. Overall, 38 (80.9%) patients had ≥ 1 reconnected PV. Among 186 PVs, 56 (30.1%; 1.2 per patient on average) were reconnected. Univariate analysis revealed T2T-Catch-Up in 103 (56%) and more frequent in durably isolated than in reconnected PVs (93 [72%] vs 10 [19%], p < 0.0001). Among binary endpoints, T2T-Catch-Up had the highest specificity (82%) and predictive value for durable PVI at redo ablation (90%). In multivariable analyses, absence of T2T-Catch-Up (Odds-ratio 0.12, 95% CI [0.05-0.31], p < 0.0001) and right superior PV (Odds-ratio 3.14, 95% CI [1.27-7.74], p = 0.01) were the only variables independently associated with PV reconnection.

CONCLUSION

T2T-Catch-Up, a new and simple cryoballoon procedural endpoint demonstrated excellent predictive value and strong statistical association with durable PVI.

Feasibility and efficacy of a novel size adjustable cryoballoon for ablation of atrial fibrillation

The aim of the present case series was to characterize the feasibility of a novel size adjustable cryoballoon system (PolarX Fit, Boston Scientific, Marlborough, MA, USA). This cryoballoon catheter can be inflated to two different diameters (28 mm and 31 mm) within the same procedure allowing vein adapted PVI. In summary, the novel size adjustable cryoballoon shows similar characteristics as the established versions. The intraprocedural flexibility of balloon size led to employment of the larger variant in the majority of freeze applications. Of note, in all but one procedure, both sizes were employed to ensure optimal occlusion for all veins. This initial series suggests that the size adjustable balloon offers more flexibility of obtain optimal occlusions in particular, in challenging anatomies, including common pulmonary vein ostia.

The Incidence, Electrophysiological Characteristics and Ablation Outcome of Left Atrial Tachycardias after Pulmonary Vein Isolation Using Three Different Ablation Technologies

Background: Left atrial tachycardias (LAT) are a well-known outcome of pulmonary vein isolation (PVI). Few data are available on whether the catheter used to perform PVI influences the incidence, as well as the characteristics of post PVI LAT. We present data on LAT following PVI by the following three ablation technologies: (1) phased multi-electrode radiofrequency catheter (PVAC), (2) irrigated single-tip catheter (iRF), and (3) cryoballoon ablation. Methods: Using a prospectively designed single-center database, we analyzed 650 patients (300 iRF, 150 PVAC, and 200 cryoballoon) with paroxysmal (n = 401) and persistent atrial fibrillation (AF), who underwent their first PVI at our center. Results: The three populations were comparable in their baseline characteristics; however, the cryoballoon group comprised a higher percentage of patients with persistent AF (p = 0.05). The LAT rates were 3.7% in the iRF group (mean follow-up 22 ± 14 months), 0.7% in the PVAC group (mean follow-up 21 ± 14 months), and 4% in the cryoballoon group (mean follow-up 15 ± 8 months). The predominant mechanism of LAT was macro-reentrant tachycardia. Reconnection of at least one pulmonary vein was observed in 87% of the patients who underwent 3D mapping. No predictors for LAT occurrence were identified. Conclusion: The occurrence of LAT post PVI is rare; the predominant mechanism was macro-reentrant tachycardia. Reconnection of at least one pulmonary vein was observed in nearly all the LAT patients. In our retrospective analysis, the lowest rate of LAT was observed with the PVAC. No predictors for LAT occurrence were identified.

Quantifying Left Atrial Size in the Context of Atrial Fibrillation Ablation: Which Echocardiographic Method Correlates to Outcome of Pulmonary Venous Isolation?

INTRODUCTION

Multiple studies have shown that left atrial (LA) enlargement is a strong predictor of poor outcome after catheter ablation of atrial fibrillation (AF). LA size is commonly approximated as the diameter in the parasternal long axis. It remains unknown whether more precise echocardiographic measurements of LA size allow for better correlation with outcome after pulmonary vein isolation (PVI).

METHODS AND RESULTS

We performed a retrospective study of 131 consecutive patients (43 females, 60% paroxysmal AF, mean CHA2DS2-Vasc score 1.6, mean age 61 ± 12 years) referred for PVI. Measurements of the LA were carried out by a single observer in transthoracic echocardiograms (TTE) performed prior to ablation. We calculated diameter of the LA in the parasternal long axis (PLAX), LA area in the 2- as well as 4-Chamber (CH) view. LA volume was computed using the disc summation technique (LAV) and indexed to body surface area (LAVI). Procedural and follow-up data were gathered from a prospective AF database. Ablation was performed exclusively using the second generation cryoballoon by the same operators. Follow-up visits at 3, 6 and 12 months showed freedom from AF in 76%, 73% and 73% respectively. Mean values of LA calculations were LAPLAX: 37.9 mm ± 6.3 mm, 2CH area: 22.5 cm² ± 6.7 cm², 4CH area: 21.4 cm² ± 5.5 cm², LAV: 73.7 mL ± 26.1 mL and LAVI: 36.2 mL/m² ± 12.7 mL/m², respectively. C statistic revealed the best concordance of LAVI with outcome after 12 months (C = 0.67), LAV also exhibited a satisfactory value (C = 0.61) in comparison to surfaces in 2CH (C = 0.59) and 4CH (C = 0.57). PLAX showed the worst correlation (C = 0.51). Additionally, different binary logistic regression models identified three independent predictors of AF outcome after cryoballoon PVI: gender (OR = 0.95 per year; p = 0.01); LAV (OR = 1.3/10mL; p = 0.02) and LAVI (OR = 1.58/10 mL/m²; p = 0.02). In all models, PLAX and area measurements were not predictive.

CONCLUSIONS

Our data add further to evidence that LA size lends itself well as a predictor of PVI outcome. LAVI and LAV were independently predictive of rhythm outcome after PVI. This did not hold true for more commonly used measurements, such as PLAX diameter and surfaces of the LA, irrespective of the view chosen.

[Innovations in invasive electrophysiology : What awaits us?]

Technological developments in percutaneous catheter ablation for the treatment of cardiac arrhythmias have progressed from direct current shock ablation over the introduction of radiofrequency ablation to routine clinical procedures. Invasive electrophysiology is characterized by continuous technical innovation and an accompanying increasing understanding of underlying electrophysiologic mechanisms. A number of technical developments were promising, e.g., laser ablation, multipolar biphasic ablation, cryoballoon ablation, contact force, high density three-dimensional (3D) mapping, and the concept of rotors for atrial fibrillation ablation. Despite intense progress, one of the main challenges of catheter ablation is still the creation of tissue-specific chronic transmural lesions and avoidance of collateral damage. The purpose of this review is to present a status quo of catheter ablation of supraventricular tachycardia, atrial fibrillation, and ventricular tachycardia and to discuss future technical innovations and strategies. In the presence of the intense dynamic developments, this review can not consider all new approaches but will rather highlight some of the most promising innovations. Topics of discussion include the use of nonfluoroscopic catheter navigation, the introduction of new ablation tools, the development of alternative energy sources, the integration of new imaging modalities, and the establishment of novel ablation strategies.

Learning curves in atrial fibrillation ablation - A comparison between second generation cryoballoon and contact force sensing radiofrequency catheters

OBJECTIVE

To examine the learning curves of atrial fibrillation (AF) ablation comparing the cryoballoon (CB) and radiofrequency (RF) catheters.

METHODS

We performed a retrospective data analysis from the initiation of AF ablation program in our center. For CB ablation, a second generation 28 mm balloon was utilized and for RF ablation.

RESULTS

A total of 100 consecutive patients (50 in each group) have been enrolled in the study (male 74%, mean age 58.9 ± 10 years, paroxysmal AF 85%). The mean procedure time was shorter for CB (116.6 ± 39.8 min) than RF group (191.8 ± 101.1 min) (p < 0.001). There was no difference in the mean fluoroscopy time, 24.2 ± 10.6 min in RF and 22.4 ± 11.7 min in CB group, (p = 0.422). Seven major complications occurred during the study; 5 in RF group (10%) and 2 in CB group (4%) (p = 0.436). After the mean follow up of 14.5 ± 2.4 months, 15 patients in RF group (30%) and 11 in CB group (26%) experienced AF recurrences (P = 0.300).

CONCLUSION

When starting a new AF ablation program, our results suggest that CB significantly shortens procedure while fluoroscopy time and clinical outcomes are comparable to RF ablation.

Cryoballoon Ablation for Patients With Paroxysmal Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical practice and induces cardiac dysfunction and stroke. The development of AF requires a trigger and also an electroanatomic substrate capable of both initiating and perpetuating AF. In the past decade, ectopic beats originating from the pulmonary veins (PV) have been identified as a source of paroxysmal AF. Thus, strategies that target the PV, including the PV antrum, are the cornerstone of most AF ablation procedures. Recently, alternative technologies to radiofrequency catheter ablation for paroxysmal AF such as balloon ablation modalities have been developed. The purpose of this review is to discuss cryoballoon ablation for paroxysmal AF.