Cryoballoon Ablation of Atrial Fibrillation Without Demonstration of Pulmonary Vein Occlusion-The Simplify Cryo Study

Nonocclusive Ablation Technique Using a Novel Cryoballoon for Failed Left Superior Pulmonary Vein Isolation Despite Complete Occlusion

BACKGROUND

An indicator of successful cryoballoon (CB)-assisted pulmonary vein (PV) isolation is complete PV occlusion. However, CBs may exhibit a weaker freezing effect on the equatorial plane. This study investigates the predictors of failed left superior PV (LSPV) isolation despite complete occlusion with novel CBs.

METHODS

This retrospective analysis enrolled 300 consecutive patients who underwent first-time ablation with POLARx or POLARxFIT between November 2021 and October 2023. Of the total, complete occlusion of the LSPV was achieved in 200 patients. Patients in whom LSPV isolation was achieved with additional nonocclusive freezing of the LSPV roof due to nonisolation of LSPV despite complete occlusion (Group A) were compared with those in whom isolation was achieved with complete PV occlusion alone (Group B).

RESULTS

Group A had a larger LSPV diameter (21.5 ± 4.6 mm vs. 18.8 ± 3.3 mm, p = 0.052), larger left atrial volume on CT (142.3 ± 47.8 cc vs. 117.8 ± 39.0 cc, p = 0.028), higher nadir temperature (-54.1 ± 5.1°C vs. -60.2 ± 4.4°C, p < 0.001), and smaller northern latitude of the balloon contact site on the LSPV roof side (20.9° ± 3.8° vs. 38.9° ± 6.7°, p < 0.001) compared with Group B. A 27.5° north latitude was observed in most of Group A (sensitivity, 100%; specificity, 96%).

CONCLUSIONS

Adequate contact positioning of the northern hemisphere to the LSPV is critical for effective isolation, particularly when isolation is challenging despite complete occlusion. In such cases, nonocclusive cryoablation against the LSPV roof might be effective.

A single-beat algorithm to discriminate farfield from nearfield bipolar voltage electrograms from the pulmonary veins

BACKGROUND

Superimposition of farfield (FF) and nearfield (NF) bipolar voltage electrograms (BVE) complicates the confirmation of pulmonary vein (PV) isolation after catheter ablation of atrial fibrillation. Our aim was to develop an automatic algorithm based on a single-beat analysis to discriminate PV NF from atrial FF BVE from a circular mapping catheter during the cryoballoon PV isolation.

METHODS

During freezing cycles in cryoablation PVI, local NF and distant FF signals were recorded, identified and labelled. BVEs were classified using four different machine learning algorithms based on four frequency domain (high-frequency power (PHF), low-frequency power (PLF), relative high power band, PHF ratio of neighbouring electrodes) and two time domain features (amplitude (Vmax), slew rate). The algorithm-based classification was compared to the true identification gained during the PVI and to a classification by cardiac electrophysiologists.

RESULTS

We included 335 BVEs from 57 consecutive patients. Using a single feature, PHF with a cut-off at 150 Hz showed the best overall accuracy for classification (79.4%). By combining PHF with Vmax, overall accuracy was improved to 82.7% with a specificity of 89% and a sensitivity of 77%. The overall accuracy was highest for the right inferior PV (96.6%) and lowest for the left superior PV (76.9%). The algorithm showed comparable accuracy to the classification by the EP specialists.

CONCLUSIONS

An automated farfield-nearfield discrimination based on two simple features from a single-beat BVE is feasible with a high specificity and comparable accuracy to the assessment by experienced cardiac electrophysiologists.

Practical guidance to reduce radiation exposure in electrophysiology applying ultra low-dose protocols: a European Heart Rhythm Association review

Interventional electrophysiology offers a great variety of treatment options to patients suffering from symptomatic cardiac arrhythmia. Catheter ablation of supraventricular and ventricular tachycardia has globally evolved a cornerstone in modern arrhythmia management. Complex interventional electrophysiological procedures engaging multiple ablation tools have been developed over the past decades. Fluoroscopy enabled interventional electrophysiologist throughout the years to gain profound knowledge on intracardiac anatomy and catheter movement inside the cardiac cavities and hence develop specific ablation approaches. However, the application of X-ray technologies imposes serious health risks to patients and operators. To reduce the use of fluoroscopy during interventional electrophysiological procedures to the possibly lowest degree and to establish an optimal protection of patients and operators in cases of fluoroscopy is the main goal of modern radiation management. The present manuscript gives an overview of possible strategies of fluoroscopy reduction and specific radiation protection strategies.

Safety and efficacy of intracardiac echocardiography-guided zero-fluoroscopic cryoballoon ablation for atrial fibrillation: a prospective randomized controlled trial

AIMS

The development of intracardiac echocardiography (ICE) has enabled fluoroless atrial fibrillation (AF) ablation using three-dimensional electroanatomical mapping systems. However, fluoroless cryoballoon ablation (CBA) remains challenging, mainly because of the lack of a visual mapping system. Hence, this study aimed to investigate the safety and efficacy of fluoroless CBA for AF under ICE guidance.

METHODS AND RESULTS

Patients (n = 100) who underwent CBA for paroxysmal AF were randomly assigned to zero-fluoroscopic (Zero-X) and conventional groups. Intracardiac echocardiography was used to guide the transseptal puncture and catheter and balloon manipulation in all enrolled patients. The patients were prospectively followed for 12 months after CBA. The mean age was 60.4 years, and the left atrial (LA) size was 39.4 mm. Pulmonary vein isolation (PVI) was achieved in all patients. In the Zero-X group, fluoroscopy was used in only one patient because of unstable phrenic nerve capture during right-sided PVI. The procedure time and LA indwelling time in the Zero-X group were not statistically different compared with that in the conventional group. Fluoroscopic time (9.0 vs. 0.008 min) and radiation exposure (29.4 vs. 0.02 mGy) were significantly shorter in the Zero-X group than in the conventional group (P < 0.001). The complication rate did not differ between the two groups. During a mean follow-up of 663.3 ± 172.3 days, the recurrence rate was similar (16.0 vs. 18.0%; P = 0.841) between the groups. Multivariate analysis revealed that LA size was the only independent predictor of clinical recurrence.

CONCLUSION

Intracardiac echocardiography-guided fluoroless CBA for AF was a feasible strategy without compromising acute and long-term success or complication rates.