BACKGROUND:The safety and effectiveness of the variable loop circular catheter (VLCC) pulsed field ablation (PFA) system was shown in atrial fibrillation (AF) registrational trials. OBJECTIVE:Assess acute safety and effectiveness of first-time pulmonary vein isolation (PVI) with the VLCC in standard clinical practice in the VARIPURE substudy of the ongoing, prospective, multicenter, observational SECURE postmarket follow-up study. METHODS:Data were extracted from Electronic Data Capture and the CARTONET data analytics software. Primary safety was the incidence of primary adverse events related to the VLCC and/or procedure. Primary effectiveness was acute procedural success, confirmed by electrical isolation of all targeted PVs. RESULTS:Among 1022 AF patients (mean age 64.9 years, 63.3% male, 63.5% paroxysmal AF; mean CHA2DS2-VASc 2.2; 22 European centers, 74 operators), 29.5% underwent ablations beyond the PVs (PVI+). The mean ± standard deviation procedure, left atrial dwell, and fluoroscopy times were 60.1 ± 21.9, 38.0 ± 15.6, and 5.2 ± 5.6 minutes, respectively. The primary adverse event rate was 0.8%, with no stroke, cerebrovascular accident, or transient ischemic attack. No ST elevation, coronary spasm, or acute kidney injury were reported. Acute reconnection was assessed per physician preference in a subset of patients (18.5% [78/421]). Acute PVI was achieved in 99.8% of patients. Using CARTONET (868 cases), the recommended workflow of 16-28 ablations for PVI was followed in 83.1% of patients with a 4-PV anatomy. CONCLUSION:In the largest real-world VLCC yet, PFA with the VLCC exhibits favorable safety, high acute efficacy, procedural efficiency, and recommended workflow adherence. Results may provide a strong foundation for future studies of this PFA technology upon 12-month follow-up completion. CLINICAL TRIAL REGISTRATION:ClinicalTrials.gov Identifier: NCT04750798 (https://clinicaltrials.gov/study/NCT04750798).

Abstract Background Pulse-field ablation (PFA) is regarded as a non-thermal ablation modality, but there is an increasing range of complications that could be due to thermal effects. Methods The hydrogel undergoes permanent colour change when a target temperature is reached allowing direct visualisation of the surface thermal footprint and depth. Comparative lesion sets using a variable loop circular catheter (VP), circular over-the-wire catheter (PS) and pentaspline catheter (FP) were performed. Protocols included single and stacked applications with variation of force, irrigation, and voltage. The hydrogel lesions were analysed en-face and by section using digital image analysis. Results All 3 PFA catheters tested had significant thermal footprints. The VP catheter had the largest mean surface footprint (156.1mm 2 ) and thermal depth (1.31mm) compared to the other two catheters (PS 55.4mm 2 & 1.1mm, FP 29.8mm 2 & 1.05mm, p<0.005). Increasing irrigation showed a trend to reduce thermal footprint but did not achieve statistical significance. Increasing voltage increased thermal footprint, but increasing force had negligible effect. Stacked lesions incrementally increased thermal lesion footprint and depth in all catheters. Thermal depths of up to 2.4mm were observed. Areas of darkening and degradation of the hydrogel were observed with the VP and FP catheters, consisting of up to 47% of lesion area. No darkening was observed with the PS catheter. Conclusions There are significant thermal footprints in all the systems tested. Temperatures exceeding 60°C have been demonstrated, comparable to radiofrequency ablation, and this may explain the mechanism of injury in some reports of collateral damage during PFA.

Pulse field ablation (PFA) is an ablation modality based on irreversible electroporation and is typically used to isolate the pulmonary veins in the treatment of atrial fibrillation (AF). The safety and efficacy of PulseSelect PFA for other linear lesions is less well substantiated in the literature. We describe a novel use of this circular, over-the-wire PFA catheter for the ablation of the cavotricuspid isthmus (CTI), mitral isthmus (MI), and posterior wall isolation (PWI) as part of ablation for AF. Data was collected prospectively on consecutive patients undergoing AF ablation using the PulseSelect catheter. CTI, MI, and PWI ablation was performed as based on patient factors and if there was documented atrial flutter. Acute bidirectional block was tested for both the CTI and MI, and isolation of the posterior wall was demonstrated during remapping. Continuous periprocedural ECG monitoring was performed. Patients underwent clinical follow-up at 3, 6, and 12 months. 62 patients were included in this dataset. 61 patients had PVI, 52 patients had CTI ablation, 36 had MI ablation, and 38 had PWI. Successful PVI was observed in all patients where the veins were targeted. Acute CTI block was observed in 98

BACKGROUND:Linear ablation lesions are used in multiple ablation strategies including left atrial roof lines, and mitral and tricuspid isthmus lines. A continuous and transmural line is mandatory for effective lesions. A proposed catheter employs cryo-anchoring: the tip initially freezes to adhere to the tissue, permitting the shaft of the catheter to be applied firmly against tissue to create linear lesions. METHODS:Ex vivo tests were performed in a 35°C water bath on turkey skeletal muscle, lamb, and porcine myocardial tissue. The experimental setup allowed the quantification of force exerted from the catheter onto the tissue with bidirectional strain-gauge measurement. Five protocols evaluated: force for tissue or equipment failure during traction, consistency experiments to evaluate the safe level of traction, force for tissue failure in forward pressure, contact force effect on time to transmural lesion, and contact force effect on lesion depth. RESULTS:Tissue failure in traction occurred at the lowest force of 3.9 kg. This occurred at the ventricular apex of a lamb heart, whereas atrial samples tolerated > 10 kg of force before failure. Correlations between force, lesion thickness, and time to the formation of a transmural lesion were observed. Lesions of 3-4 mm depth occurred at 45 g forward pressure with 60 s lesions. The time required to attain this depth fell to 20 s with forces over 200 g. CONCLUSION:There is a broad safety margin between the force required to enhance lesion formation during cryotherapy and the force that can disrupt tissue, both for traction and forward pressure.

BACKGROUND:Transvenous lead extraction (TLE) plays a significant role in maintaining device therapy. Conventional extraction involves advancing an extraction sheath via the implanting vein over the targeted lead, however advanced techniques involve the use of the jugular and femoral accesses which provide geometrical advantages. Femoral extraction can be used as a "bail-out" and a primary extraction strategy but with significant challenges. METHOD:We present a novel technique, transferring a 20-year-old passive fixation atrial lead with a deployed locking stylet from the subclavian vein to the femoral site, to complete the extraction of an infected system. RESULT:Transfer of the lead from the implanting vein to the femoral vein, permitted linear alignment of the femoral sheath to the passive fixation atrial lead, safely enhancing the application of traction and counter-traction. The lead was extracted without sequalae. CONCLUSION:The femoral pull-through technique is safe and effective, with potential application in a range of scenarios.

ABSTRACT Background and Aims The need for transvenous lead extraction (TLE) is rising due to increased cardiovascular device implantation and an aging population. While the superior access is standard, complex cases may benefit from the Tandem approach, combining femoral and superior access to improve efficacy and safety. This study evaluates outcomes and predictors associated with the Tandem approach as a primary strategy. Methods A retrospective analysis was conducted on 148 patients who underwent Tandem TLE at a high‐volume UK center between September 2020 and December 2024. Data on procedural success, complete lead removal, complications, and outcome predictors were collected. The Needle's eye snare (NES) learning curve was assessed via fluoroscopy time. Results Median patient age was 72.4 years, with 42.6% considered high‐risk (EROS 3). 319 leads were targeted, with 81.2% extracted via the Tandem approach. Clinical procedural success was 97.3%, and complete lead removal 93%. Use of Medtronic leads was the sole independent predictor of complete lead removal. Major complications occurred in 3.4% of cases, with no procedural mortality. BMI < 25 kg/m² and extraction of ≥ 3 leads were predictors of complications and 30‐day mortality. NES proficiency improved significantly after 40 leads ( p < 0.001), confirming a learning curve. Conclusion The Tandem approach is a safe and effective primary strategy for complex TLE, particularly in cases involving passive fixation, shock, and long dwell times leads. However, widespread use may be limited by resource intensity, increased fluoroscopy exposure, and the need for experienced operators.

INTRODUCTION:Pulsed Field Cryoablation (PFCA) is a dual-energy cardiac ablation modality consisting of short-duration ultra-low temperature cryoablation (ULTC) followed immediately by pulsed field ablation (PFA) delivered from the same catheter. It is hypothesized that PFCA may improve contact stability during PFA, while maintaining lesion depth and effectiveness of ULTC. METHODS:PARALELL is a first-in-human multicenter study evaluating safety and effectiveness of a novel PFCA catheter and system in patients with persistent atrial fibrillation (PsAF) using the combination of pulmonary vein (PVI) and posterior wall (PWI) isolation. RESULTS:Sixty-six patients were ablated at six sites. One groin hematoma and one intubation-related hospitalization were the only serious procedure- or device-related adverse events recorded in the study. Per protocol, acute effectiveness was evaluated in 46 patients, including 31 patients with post-hoc analysis of cryogenic energy per lesion. After an average of 21.1 ± 9.3 lesions per patient the rates of PVI and PWI were 95.7% (176/184) and 97.7% (42/43), respectively. The average cryogenic energy per patient was highly predictive of acute isolation success with ROC AUC = 0.944% and 100% rates of both PVI and PWI in 24 patients in the optimal energy cohort. Grade I microbubbles and faint muscle contractions were detected in 1.1% and 0.5% of ablations, respectively. CONCLUSION:This initial multi-center experience suggests that PFCA can be efficiently performed for PVI and PWI using a single versatile catheter system, with high acute success and good early safety profile. The evaluation of the chronic 12-month effectiveness of PFCA is ongoing.

Catheter ablation is a well-established treatment for atrial fibrillation (AF), effectively reducing AF burden, improving quality of life, and decreasing cardiovascular risk. The efficacy and the safety between point-by-point radiofrequency (RF) and one-shot techniques such as cryoablation or pulsed field ablation are similar. Recently, a novel ultra-low temperature cryoablation (ULTC) has been introduced, achieving temperatures as low as -196°C versus -89°C with traditional cryoballoon ablation. This cryogenic energy can potentially create deeper, transmural lesions and thus, more durable. To compare the long-term outcomes of a novel ULTC catheter system vs RF catheter ablation for the management of paroxysmal (PAF) and persistent (PsAF) atrial fibrillation. Between 2022 and 2023, 19 patients with PAF/PsAF who underwent ultra-low temperature ablation (Group A) were propensity matched in 1:1 ratio with 19 patients treated with RF ablation (Group B). Patients with previous AF ablation or a follow-up period less than 12 months were excluded from the study. Primary endpoint was defined as the freedom from a redo-AF procedure within the study period. Propensity score matching was performed in 1:1 ratio based on age (61.9 ± 10.6 years in group A vs 62.2 ± 9.4 years in group B, p = 0.938), sex (4 females in each group) and AF type (n=7 for PAF and n=12 for PsAF in each group) (Figure 1). Pulmonary vein isolation was successfully achieved in all patients (n=38). As for the additional lesions, there was no difference between the two groups in terms of the posterior line (n=8 in group A and group B), the roof line (n=9 in group A and group B), and the mitral annulus line (n=4 in group A and n=3 in group B, p = 0.676) (Figure 1). Mean follow-up was 23.5 ± 7.8 months for group A and 24.1 ± 8.9 months for group B (p = 0.837, Figure 1). During this period, freedom from redo-AF ablation was significantly higher in group A (n=16 patients) than in group B (n=10 patients) (p = 0.017, Figure 2). In this single-centre retrospective study, freedom from redo-AF ablation with a novel ultra-low temperature cryoablation appears to be higher compared to the traditional radiofrequency ablation, indicating greater procedural durability beyond 12 months. Further randomised trials with larger number of patients are warranted to confirm these findings.Baseline and ablation characteristics Graphical abstract

A patient with shocks from his ICD related to AF underwent redo ablation. The only identifiable target was the superior vena cava. This was isolated using ultra-low cryotherapy, eliminating episodes of AF.

The temperature-sensing catheter with microelectrodes and 6 thermocouples delivers radiofrequency ablation in very-high power short-duration (vHPSD, 90W/4s) or conventional-power temperature-controlled modes (CPTC, ≤50W). CARTONET, a cloud-based data management and artificial intelligence-powered insights system is being used to evaluate ablation characteristics of the 2 modalities in Afib cases performed on SECURE, a prospective observational study.