Ablation Mode Research Articles

LA strain analysis in patients undergoing atrial fibrillation ablation using cryoballoon or pulsed-field-ablation

Abstract Background Catheter ablation for atrial fibrillation (AF) is increasing as rhythm control therapy. Besides thermal ablation approaches, such as cryoballoon ablation (CBA), a novel non-thermal and tissue-specific ablation modality – pulsed field ablation (PFA) – has been introduced. Left atrial reservoir strain (LArS) has been suggested to predict arrhythmia recurrences after AF ablation. Up to now, data describing LArS in patients undergoing their first AF ablation using PFA or CBA are sparse. Purpose To compare LArS in patients undergoing first catheter ablation for AF using either PFA or CBA. Methods Patients with transthoracic echocardiography prior to their first catheter ablation for AF were included. Patients in AF during transthoracic echocardiography, with poor 2D image quality and those that did not have a transthoracic echocardiography after AF ablation were excluded. Clinical characteristics and echocardiography parameters were analyzed. LArS was measured before and after AF ablation and was correlated with the recurrence of atrial arrhythmias in the follow-up period. Results Of 267 patients undergoing their first AF ablation, 67 patients (69% male, 65 ± 11 years) fulfilled the inclusion criteria and were further analyzed. AF ablation was performed using PFA in 55% and CBA in 45% of patients. Baseline characteristics were similar in both groups. Before ablation LArS was similar for PFA (17.69 ± 6.92%) and CBA patients (19.38 ± 9.42%, P=0.45). After AF ablation, LArS did not change significantly compared to the values before (before ablation: 20.96 ± 15.9 vs. after ablation: 19.87 ± 9.38, P=0.18), irrespective of the ablation mode (PFA before: 17.69 ± 6.92%vs. PFA after: 18.06 ± 8.9%, P=0.53; CBA before: 19.38 ± 9.42% vs. CBA after: 21.08 ± 9.48%, P=0.36). After a median of 190 days [95% confidence interval: 89 - 454 days], 25 patients (37%) experienced an arrhythmia recurrence (PFA: 38%, CBA: 37%). Comparing patients with and without arrhythmia recurrences, LArS before catheter ablation was lower in those experiencing an arrhythmia recurrence (16.02 ± 6.8%) compared to those without arrhythmia recurrence (25.58 ± 20.32%, P=0.02). However, this was independent from the ablation mode (PFA: AF-recurrence: 16.51 ± 4.27 vs. no recurrence: 21.31 ± 15.9, P=0.19; CBA: AF-recurrence: 15.48 ± 9.03 vs. no recurrence: 27.34 ± 22.14, P=0.07). Univariable regression analysis - including sex, age and comorbidities - revealed a trend for baseline LArS being associated with arrhythmia recurrence (HR 0.92, 95% CI: 0.86 – 1.01; P=0.065). Conclusions This hypothesis generating study indicates that LArS is not affected by AF ablation irrespective of the ablation mode. Patients with lower LArS before ablation had more arrhythmia recurrences independent of the ablation mode. A larger patient population is needed to assess the association of LArS and arrhythmia recurrences after AF ablation using different ablation modalities.

Atrial fibrillation ablation with temperature-controlled very high-power short-duration, with conventional-power, or with combined modes in clinical practice: 12-month outcomes from SECURE

Abstract Background/Introduction QDM is a contact force-sensing catheter optimized for temperature-controlled radiofrequency ablation in very high-power short-duration (vHPSD; 90 W/4 s), conventional-power (CP; ≤50 W), or vHPSD/CP combined modes. Purpose Evaluate 12-month (M) safety and effectiveness of atrial fibrillation (AF) ablations performed with 3 different ablation modes using the QDM catheter, a frequently used single tip catheter in Europe. Methods SECURE is an observational, prospective, post-market study collecting data on procedures performed per standard-of-care with up to 12M follow-up, in 16 enrolling sites in 8 countries across Europe and Israel. Index pulmonary vein (PV) isolation procedures are reported here. The primary safety endpoint is the incidence of primary adverse events (PAEs); the primary effectiveness endpoint is PV isolation (entrance block) of targeted PVs. Additional endpoints include acute reconnections, incidence of char and steam pop, 12M recurrence, repeat ablation, and healthcare utilization (HCU). Ablation strategy, impedance drop, and catheter stability were analysed with a cloud-based data management and artificial intelligence-powered algorithm. Results Since Feb 2021, 291 patients (70% male, 61±11 yrs, CHA2DS2-VASc 1.9±1.5) completed 12M follow-up in 11 sites. Most patients (175 [60.1%]) were treated for paroxysmal (PAF), 85 (29.2%) for persistent (PsAF), and 31 (10.7%) for long-standing persistent (LsPsAF) AF, under general anaesthesia (44.0%) or sedation (55.7%). A combined workflow was used in 66.0% of ablations, while vHPSD-only and CP-only were used in 13.4% and 20.6% of cases, respectively. Four (1.4%) patients reported a PAE; all resolved, and none were catheter related. Acute effectiveness was achieved in all targeted veins; 5.0% of PVs had acute reconnections, with the most common being the left superior PV. No steam pops were reported; 2 counts of char were noted in PsAF ablations with combined modes. Freedom from documented recurrence were 95.8% for PAF, 88.1% for PsAF, and 73.5% for LsPsAF (Fig 1). Freedom from repeat ablation post-blanking and freedom from cardioversion were both 96.8%. Cardiovascular hospitalization and emergency room visits decreased by 65.3% and 76.5% from 12M pre- to 12M post-procedure, respectively. Application-level analyses showed larger impedance drop and greater catheter stability with vHPSD. In procedures using a combined workflow, vHPSD was used preferentially for most PV segments, except anteriorly on the left wide area circumferential ablation (Fig 2). Conclusions Real-world data demonstrates that AF ablation with the QDM catheter is safe and effective with a low PAE rate, high 12M effectiveness, and reduced HCU. Most procedures were done with combined modes, where vHPSD was used preferentially, except at left anterior thicker regions. Larger impedance drop and greater catheter stability were observed with vHPSD applications.

Incidence of acute pericarditis after pulsed-field ablation for the treatment of atrial fibrillation

Abstract Introduction Pulsed-field ablation (PFA) has emerged as a novel treatment strategy for patients with atrial fibrillation (AF). While traditional thermal ablation modes such as radiofrequency energy or cryoballoon energy showed an acute pericarditis rate of 0.5 – 4%, little is known about the incidence of acute pericarditis after PFA. Purpose To assess the incidence of acute pericarditis using PFA for the treatment of AF. Method Patients undergoing catheter ablation for AF using PFA were consecutively enrolled in a prospective registry in a tertiary referral center between January 2022 and January 2024. After PFA, all patients received a clinical assessment for cardiothoracic symptoms including cardiac auscultation, 12-lead ECG and transthoracic echocardiography. A clinical diagnosis of acute pericarditis was established according to the 2015 European Society of Cardiology (ESC) guidelines by the presence of at least 2 of the following criteria within 90 days after PFA: 1) pleuritic chest pain; 2) friction rub; 3) new widespread ST-elevation or PR depression on ECG; 4) pericardial effusion. Suspected acute pericarditis was diagnosed if 1 criterion was fulfilled. Results A total of 388 patients with AF (median age 67.5 years, 32% female) underwent pulmonary vein isolation using PFA. 0 (0%) patients fulfilled ≥ 2 ESC criteria required for diagnosis of acute pericarditis. Suspected acute pericarditis within 90 days after the procedure was found in 17 (4.4%) patients. 29 (7.5%) patients reported some sort of cardiothoracic symptoms (chest pain, chest tightness, chest discomfort, shortness of breath or pleuritic chest pain). Among them, 6 (1.5%) patients received anti-inflammatory drug treatment due to suspected pericarditis. 0 (0%) patients had a friction rub, 6 (1.5%) patients showed PR depression (no ST-elevation) and 5 (1.3%) patients demonstrated pericardial effusions. None of the pericardial effusions required drainage. Conclusion In this large cohort of patients undergoing PFA for AF, no patients suffered acute pericarditis according to current ESC criteria. Any type of cardiothoracic symptoms after PFA were noted in 7.5% of patients with 1.5% of patients requiring drug therapy.Graphical Abstract

Efficacy of Fractional Versus Fully Ablative CO2 Laser for Distolateral Onychomycosis: Experience With 20 Patients.

Oral antifungals are the treatment choice for onychomycosis, and topical therapies are favored in cases of limited nail involvement. Recently, carbon dioxide (CO2) laser treatment has emerged as an option to enhance the effectiveness of topical therapies. Our objective was to compare the efficacy of fractional ablative and fully ablative CO2 laser treatments for distolateral subungual onychomycosis affecting a single toenail and caused by dermatophytes. The records of 10 patients treated with a single fully ablative CO2 session were matched with those of 10 patients who underwent a single CO2 fractional treatment. All had previously failed topical antifungal lacquers and were discharged with the prescription of topical ciclopirox nail lacquer (8%) for 3 months. The clinical response rates were 80% for the fully ablative group and 60% for the fractional group. Additionally, the mean reduction in Onychomycosis Severity Index from baseline to 8.6±1.6 weeks after treatment completion was 6.9±5.4 in the fully ablative group and 3.6±6.6 in the fractional group. The relapse rate among responders was 12.5% in the fully ablative and 33.3% in the fractional group after a mean follow-up time of 29.4±2.3 weeks. Fractional and fully ablative CO2 laser in combination with ciclopirox lacquer could increase the response rate in onychomycosis resistant to topical antifungals when systemic therapy is contraindicated or not yet pursued. Fully ablative mode therapy is significantly more effective than fractional (P < 0.05). Further studies are needed to identify prognostic response factors and assess the long-term effectiveness of CO2 laser treatment.

Application of high-power ablation mode in patients with idiopathic ventricular extrasystole

Background. A new method of high-power short-duration ablation (HPSDA) with high impact energy, ranging from 60 to 90 W, is becoming widespread in the world. However, the number of studies on the use of HPSDA in patients with idiopathic ventricular arrhythmias (IVA) is limited. It is relevant to study the feasibility of using HPSDA to improve the outcomes of radiofrequency ablation (RFA) in patients with IVA. The aim of the study: to evaluate the immediate results of HPSDA in RFA for IVA and to compare it with the classic ablation mode. Materials and methods. We have retrospectively analyzed the results of RFA in 54 patients with symptomatic IVA. Their average age was 45.0 ± 11.7 years. The majority were men (72.3 %). Given the possible effect of intracardiac mapping on the results of ablation, the patients were divided into two groups. Group I include 27 (50 %) participants in whom mapping was performed using 3D navigation. Group II include 27 (50 %) patients in whom 3D navigation was not used. The decision to use HPSDA or classic ablation was made empirically, without considering any factors or characteristics of a patient. The following ablation parameters were used during HPSDA: temperature 45 °C, exposure time 7 seconds, energy 70 W. Results. In group I, where 3D navigation was used to localize the substrate, HPSDA was performed in 12 patients (44.4 %), and the classic mode was used in 15 cases (55.6 %). With conventional mapping, HPSDA was applied in 10 (37.0 %) patients, and the classic mode in 17 (63.0 %). Сlassic ablation allowed to achieve complete arrhythmia suppression in all patients, regardless of the mapping method. When using only HPSDA, the disappearance of arrhythmia was observed only in 45.5 % of cases. With the use of the classic mode, recurrence of IVA during the control time was observed in 16.6 % of patients, while with the use HPSDA in 33.3 %. Conclusions. The high-power regimen demonstrated significantly lower efficacy for permanent suppression of IVA compared to classic ablation methods (p = 0.007). The use of HPSDA to suppress IVA is associated with a high risk of arrhythmia recurrence during control time (p = 0.0010). It is advisable to convert the ablation mode for complete suppression of arrhythmia when the HPSDA is ineffective.

Personalized pulmonary vein isolation with very high-power short-duration lesions guided by left atrial wall thickness: the QDOT-by-LAWT randomized trial.

Pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) using very high-power short-duration (vHPSD) radiofrequency (RF) ablation proved to be safe and effective. However, vHPSD applications result in shallower lesions that might not be always transmural. Multidetector computed tomography-derived left atrial wall thickness (LAWT) maps could enable a thickness-guided switching from vHPSD to the standard-power ablation mode. The aim of this randomized trial was to compare the safety, the efficacy, and the efficiency of a LAWT-guided vHPSD PVI approach with those of the CLOSE protocol for PAF ablation (NCT04298177). Consecutive patients referred for first-time PAF ablation were randomized on a 1:1 basis. In the QDOT-by-LAWT arm, for LAWT ≤2.5 mm, vHPSD ablation was performed; for points with LAWT > 2.5 mm, standard-power RF ablation titrating ablation index (AI) according to the local LAWT was performed. In the CLOSE arm, LAWT information was not available to the operator; ablation was performed according to the CLOSE study settings: AI ≥400 at the posterior wall and ≥550 at the anterior wall. A total of 162 patients were included. In the QDOT-by-LAWT group, a significant reduction in procedure time (40 vs. 70 min; P < 0.001) and RF time (6.6 vs. 25.7 min; P < 0.001) was observed. No difference was observed between the groups regarding complication rate (P = 0.99) and first-pass isolation (P = 0.99). At 12-month follow-up, no significant differences occurred in atrial arrhythmia-free survival between groups (P = 0.88). LAWT-guided PVI combining vHPSD and standard-power ablation is not inferior to the CLOSE protocol in terms of 1-year atrial arrhythmia-free survival and demonstrated a reduction in procedural and RF times.

Durable pulmonary vein isolationwith optimized high-power and very high-power short-duration temperature-controlled ablation: A step-by-step guide.

Through systematic scientific rigor, the CLOSE guided workflow was developed and has been shown to improve pulmonary vein isolation durability. However, this technique was developed at a time when using power-controlled ablation catheters with conventional power ranges was the norm. There has been increased adoption of a high-power and very high-power short-duration ablation practice propelled by the availability of the temperature-controlled radiofrequency QDOT MICRO catheter. There are fundamental differences in biophysics between very high-powered temperature guided ablation and conventional ablation strategy that may impact patient outcomes. The catheter's design and ablation modes offer flexibility in technique while accommodating the individual operator's clinical discretion and preference to deliver a durable, transmural, and contiguous lesion set. Here, we provide recommendations for 3 different workflows using the QDOT MICRO catheter in a step-by-step manner for pulmonary vein isolation based on our cumulative experience as early adopters of the technology and the data available in the scientific literature. With standardization, temperature-controlled ablation with the QDOT MICRO catheter provides operators the flexibility of implementing different ablation strategies to ensure durable contiguous pulmonary vein isolation depending on patient characteristics.

Ultrafast laser ablation of tungsten carbide: Quantification of threshold range and interpretation of feature transition

AbstractTungsten carbide was manufactured by picosecond laser in this study. Shapes of the ablated craters evolved from parabolic‐like (less than 10 pulses) to Gaussian‐like (more than 500 pulses) as the pulse number increased. The shape changes were closely associated with the discontinuous diameter expansion of ablated crater. To explain these phenomena, two thresholds were identified: an upper threshold of 0.129 J/cm2 and a lower threshold of 0.099 J/cm2. When the laser energy exceeded the upper threshold, ablation occurred under the laser‐energy‐dominated mode. When the laser energy fell between the upper and lower thresholds, ablation occurred under the cumulative‐effect‐dominated mode. The transition of ablation mode contributed to the diameter expansion and shape change. In addition, elemental composition varied significantly at the ablated crater and heat‐affected zone (HAZ), which were related to the degrees of reactions that occurred at different distances from the laser. Finally, surface hardness decreased from base material (32.52 GPa) to edge of crater (11.59 GPa) due to the escape of unpaired interstitial C atoms from the grain boundaries.

Picosecond laser drilling grids in aluminium foil at 532 and 355 nm wavelengths

Ultra-short laser drilling technique enables production of filters, membranes, microfluidic, photonic, and biomedical devices. Micro-hole grids were drilled in aluminum foil using a 28 picosecond Nd:YAG laser operated at wavelength of 532 and 355 nm with energy up to 18 and 12 mJ, respectively. Varying pulse energy and number, micro-holes obtained at 355 nm and 3.6–9 mJ had the appropriate mean diameter of 36–86 μm. However, the circularity changed in 0.5–0.94. For the 2nd harmonic the mean diameter varied 15–61 μm at 0.36–9 mJ with the circularity of 0.81–0.92. The morphology of the area surrounding micro-holes investigated by scanning electron microscopy exhibited distribution of droplets dominated size 0.9–10 μm, which is feasible for filtration of contaminated liquids. Local elemental composition of the area determined by energy dispersive spectroscopy discovered significant increase in the concentration of C and O, and also emergency of F, depending on laser fluence under vapor-dominated ablation mode, where nuclear reactions are excited in hot plasma.

Atomistic modeling of high-speed laser action on thin gold film: determination of main mechnaisms of ablation

The action of an ultrashort laser pulse on a thin gold film was studied using a single-speed nonequilibrium combined continuum-atomistic model, which was further developed in the work. Three ablation modes were studied: supercritical expansion, phase explosion and mechanical spallation. The simulation results are compared with experimental data. The dependence of the amount of removed substance on the fluence of laser radiation was obtained.

Comparison of Electrothermal Ablation and Electrolyte Plasmalization Devices Based on the Mechanical Properties of Anterior Cruciate Ligament Femoral Attachment Following Partial Debridement: A Biomechanical Study Using a Porcine Model.

Purpose This study aimed to clarify whether differences in ablation devices used in the knee joint during partial debridement of the proximal end of the femoral attachment of the anterior cruciate ligament (ACL) affect the mechanical properties of the femur-ACL-tibia complex. Methods Electrothermal ablation was generated from Vulcan for the left knees, and radiofrequency ablation was generated from Werewolf Flow 50 Wand for the right knees. The probes were set to the default setting of 120 W and 150 W for Vulcan and Werewolf Flow 50 Wand, respectively. To mimic partial debridement in remnant tissue-preserving (RTP) ACL reconstruction, the bipolar ablation mode and serpentine movements were employed while in contact with the femoral fan-like extension fibers of the ACL. To simulate the arthroscopic environment, the model was immersed in a saline solution. The probes were applied for 60 s, and their biomechanical properties were evaluated. Results A significant difference was observed in the upper yield load between the two groups (Vulcan group, 107.1 ± 93.4 N; Werewolf group, 177.9 ± 108.8 N; P = 0.045). However, no significant differences were noted in linear stiffness (Vulcan group, 47.6 ± 30.9 N/mm; Werewolf group, 50.1 ± 30.5 N/mm; P = 0.85), maximum load (Vulcan group, 276.2 ± 171.8 N; Werewolf group, 397.7 ± 150.8 N; P = 0.26), or elongation at failure (Vulcan group, 6.1 ± 0.9 mm; Werewolf group, 11.6 ± 10.4 mm; P = 0.20) between the two groups. Conclusion The mechanical properties of the ACL after partial ACL femoral attachment debridement for RTP-ACL reconstruction were better when an electrolyte plasmalization device was used. When performing RTP-ACL reconstruction, surgeons must consider that the device used for partial femoral ACL stump debridement may affect the mechanical properties of the ACL remnant tissue. Clinical relevance When performing RTP-ACL reconstruction, surgeons must consider that the device used for partial femoral ACL stump debridement may affect the mechanical properties of the ACL remnant tissue.

Subclinical Dysfunction of Left Atrial Compliance after Cryoballoon versus Radiofrequency Ablation for Paroxysmal Atrial Fibrillation.

It has been suggested that cryoballoon (CB) ablation for paroxysmal atrial fibrillation (PAF) may lead to more extensive left atrial (LA) injury than radiofrequency (RF) ablation; however, results are conflicting. We sought to address this issue using modern echocardiographic techniques estimating the LA function after successful CB and RF ablation for PAF. A total of 90 patients (66% males, mean age 57 ± 10 years) successfully treated (no AF recurrences confirmed in serial 4-7 day ECG Holter monitoring) with RF (51%) or CB (49%) ablation for PAF were retrospectively studied. Echocardiography with speckle tracking (STE) was performed before and 12 months after the procedure. The peak longitudinal LA strain (LAS) and strain rate (LASR) during the reservoir (r), conduit (cd), and contraction (ct) phases were measured in sinus rhythm. Analysis of covariance was applied to compare changes in the echocardiographic parameters over time with the baseline measurements as covariance and the type of ablation as the factor. The parallelism of the slopes of the covariance was tested. The LA diameter decreased (38.3 ± 4.1 mm vs. 36.8 ± 3.6 mm, p < 0.001) in the whole study group at 12 months after ablation. The LASRr and LASRcd increased (1.1 ± 0.3 s-¹ vs. 1.3 ± 0.3 s-¹, p < 0.001 and 1.1 ± 0.3 s-¹ vs. 1.2 ± 0.3 s-¹, p < 0.001, respectively) whereas other LA strain parameters remained unchanged in the whole study group at 12 months after ablation. In the analysis of LA function at 12 months after the procedure regarding the mode of ablation, the worsening of parameters reflecting LA compliance was observed in patients with better pre-served baseline values in the CB ablation subgroup. For baseline LAScd >28%, the difference ΔCB - ΔRF was -7.6 (11.7; -3.4), p < 0.001, and for baseline LAScd >16%, ΔCB - ΔRF was -1.8 (-3.2; -0.4), p = 0.014. The traditional Doppler-derived parameter e' showed the same trend-for baseline e' ≥12 cm/s, ΔCB - ΔRF was -1.7 (-2.8; -0.6), p = 0.003. We conclude that worsening of parameters reflecting LA compliance was observed 12 months after CB ablation compared to RF ablation for PAF in patients who underwent a successful procedure and had better-preserved baseline LA function. This might suggest subclinical dysfunction of LA after the CB ablation procedure. The clinical significance of these findings warrants further investigations.

Subclinical dysfunction in left atrial compliance after successful cryoballoon versus radiofrequency ablation for paroxysmal atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): The Medical Centre of Postgraduate Education. Purpose It has been suggested that cryoballoon ablation (CB) for paroxysmal atrial fibrillation (PAF) may lead to more extensive left atrial (LA) injury than radiofrequency ablation (RF), however, results are conflicting. The aim of our study was to estimate the LA function after successful CB and RF for PAF using transthoracic echocardiography (TTE). Methods 90 pts (66% males, mean age 57±10 years) successfully treated (no AF recurrences confirmed in serial 4–7 day ECG Holter monitoring) with RF (51%) or CB (49%) for PAF were prospectively studied. TTE with speckle tracking (STE) and tissue doppler was performed before and 12 months after the procedure in sinus rhythm. The peak longitudinal LA strain (LAS) during the reservoir (r), conduit (cd) and contraction (ct) phases were measured. The global LAS for each LA phase was calculated by averaging the values observed in all LA segments in the 4- and 2-Chamber views. We set the zero strain point as the time from the beginning of the QRS wave. The velocities of the early (e') and late (a') diastolic phases at the mitral annular septal and lateral corners were measured. Analysis of covariance was applied to compare changes over time with the baseline measurement as covariance and the type of ablation as the factor. The parallelism of the slopes of the covariance was tested. Results Parameters of LA function regarding the mode of ablation at 12 months after the procedure are shown in the table. Significant decrease in LAScd and e’ was observed in the CB subgroup with better preserved baseline values (≥16% and ≥12cm/s respectively). Conclusion Worsening of parameters reflecting LA compliance was observed 12 months after successful CB vs RF ablation for PAF. This might suggest subclinical dysfunction of LA after CB procedure. Clinical significance of this finding warrant further long-term observation.

Laser-Metal Interaction with a Pulse Shorter than the Ion Period: Ablation Threshold, Electron Emission and Ion Explosion.

The laser energy per unit surface, necessary to trigger material removal, decreases with the pulse shortening, becoming pulse-time independent in the sub-picosecond range. These pulses are shorter than the electron-to-ion energy transfer time and electronic heat conduction time, minimising the energy losses. Electrons receiving an energy larger than the threshold drag the ions off the surface in the mode of electrostatic ablation. We show that a pulse shorter than the ion period (Shorter-the-Limit (StL)) ejects conduction electrons with an energy larger than the work function (from a metal), leaving the bare ions immobile in a few atomic layers. Electron emission is followed by the bare ion's explosion, ablation, and THz radiation from the expanding plasma. We compare this phenomenon to the classic photo effect and nanocluster Coulomb explosions, and show differences and consider possibilities for detecting new modes of ablation experimentally via emitted THz radiation. We also consider the applications of high-precision nano-machining with this low intensity irradiation.

Single-center outcome after ablation of atrial fibrillation using very high-power short duration pulmonary vein isolation

Abstract Funding Acknowledgements Type of funding sources: None. Background Catheter ablation of atrial fibrillation is (AF) an established second line therapy for patients with symptomatic paroxysmal (PAF) and persistent AF (persAF). Novel ablation catheters with integrated thermocouples allow fast application of radiofrequency lesions with powers up to 90W. We aimed to describe primary and secondary outcomes after very high-power short duration (vHPSD) ablation. Methods 201 consecutive patients (127 PAF, 68 persAF, 6 longstanding persistent AF) underwent pulmonary vein isolation (PVI) using the QDOT Micro Catheter (Biosense Webster) with the ablation mode QMODE+ (90W, 4s, interlesion distance ≤4mm anterior, ≤6mm posterior). Results Mean age was 62±10 years, 38% were female, median CHA2DS2-VASc Score was 2 (0, 7). Median follow up duration was 196 (30, 461) days. 35% of patients had additional ablation of typical right atrial flutter. Primary success rate to achieve pulmonary vein isolation was achieved in all patients, no catheter-related complications (e.g., charring, steam pop) occurred. First pass isolation of all 4 PVs was achieved in 53% of patients, re-ablations were necessary in the carina regions (right: 27% of cases, left: 20%), 34% at multiple regions including the ridge, 12% in other regions around the PVs. Median procedure for PVI only were 110 (36-344) minutes. Arrhythmia-free survival was 79,3%. 21 patients underwent re-do procedures during follow-up showing most commonly showing gaps in the right PVs (RSPV 52%, RIPV 43%), the left inferior PV (48%), as well as the LSPV (38%) and the ridge (24%); with 91% of patients with recurrence showing more than one site reconnected. Conclusion Very high-power short duration ablation allows safe and quick pulmonary vein isolation. However, first pass isolation rate is low due to gaps in the carina regions. Arrhythmia-free survival is comparable to other pulmonary vein isolation techniques.

Safety and effectiveness of very-high-power, short-duration ablation in patients with atrial fibrillation: Preliminary results

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary vein isolation (PVI) is at the forefront of rhythm control strategies in patients with atrial fibrillation (AF). A very-high-power, short-duration (vHPSD) catheter was designed to improve the effectiveness of AF ablation within a shorter procedure time. We aimed to compare the effectiveness and safety of PVI ablation between this vHPSD ablation mode (90W/4s) and conventional index-guided ablation (up to 40W/indexed). Methods This single-center, retrospective, observational study enrolled 148 patients with AF, referred for catheter ablation between December 16, 2019 and July 29, 2022. In 77 procedures (mean age: 59.7±12.0 years; 61.0% male; 74.0% paroxysmal), a vHPSD catheter was used (vHPSD-group), and 71 patients (mean age: 58.1±11.6 years; 70.4% male; 67.6% paroxysmal) were treated with a ablation index catheter (AI-group). The study assessed the recurrence of AF at 3- and 6-months after ablation. The outcomes also included the amount of opioids administered during the procedure and the incidence of treatment-emergent adverse events. Additionally, procedural factors, such as total procedure time, fluoroscopy time and radiofrequency application time were compared between the groups. Results At 3 months, AF was found to recur in 14.29% (11/77) of patients in the vHPSD-group and in 30.99% (22/71) of patients in the AI-group (p=0.02). At 6 months, 18.31% (13/71) patients reported AF recurrence in the vHPSD-group and 32.73 % (18/55) in the AI-group (p=0.09). There was no difference in treatment-emergent adverse events between the two groups (3.9% vs. 2.8%; p=1.00). One severe adverse event (a cerebral vascular accident) was observed in the vHPSD-group. The mean dose of remifentanil was reported to be lower during vHPSD-based PVI (p&amp;lt;0.0001). The vHPSD-based PVI was associated with shorter radiofrequency application time (p&amp;lt;0.0001), fluoroscopy time (p&amp;lt;0.0001), and total procedure time (p&amp;lt;0.0001). Conclusions This study suggests that the vHPSD-quided PVI is equally effective and safe with reference to short-term clinical observation as conventional ablation. Also, the vHPSD ablation may allow to reduce the dosage of analgesics during significantly shorter procedures.

PO-02-193 A COMPARISON OF THIRD GENERATION CRYOABLATION VERSUS X3 LASER BALLOON SYSTEMS FOR PULMONARY VEIN ISOLATION FOR TREATMENT OF ATRIAL FIBRILLATION

As the incidence of atrial fibrillation (AF) increases operators are looking to improve the efficiency of pulmonary vein isolation (PVI) with similar clinical outcomes. In a recent study the 2nd generation cryo-balloon (CB) and the 1st and 2nd generation laser balloon (LB) was compared with similar clinical efficacy but with shorter procedure time in the CB group. Improvements were made to both modalities in subsequent generation catheters. The 3rd generation CB (CB3) has a 40% shorter tip that allows for improved stability during cryo-applications. The X3 LB (LB3) introduced a “rapid” ablation mode which utilizes a motorized handle to allow for continuous 360-degree energy delivery to decrease ablation time and improve lesion effectiveness We sought to compare if these improvements impacted the overall efficacy, procedural and/or fluoroscopy time between the two modalities. To compare clinical outcomes of CB3 and X3 LB ablation in patients with AF in a multi-center prospective registry. Between November 2019 and November 2020, 69 patients with atrial fibrillation underwent ablation with either CB3 or LB3 at two large US medical centers. Patients were followed for at least 180 days after index procedures. The primary outcome was time to recurrence of AF. Secondary outcomes included time to anti-arrhythmic drug (AAD) therapy after the 90-day blanking period, and procedural characteristics. A total of 69 patients were enrolled in the study (baseline characteristics in Table 1). Forty patients (58%) underwent PVI ablation with CB3, and 29 patients (42%) underwent PVI ablation with LB3. There was no significant difference in the time to recurrent AF between treatment groups (p=0.865) (Figure 1). There was also no significant difference in the time to treatment with AAD therapy after the 90-day blanking period (p=0.125). Both procedural and fluoroscopy time were significantly shorter in the LB group (mean procedure time was 122 minutes in CB3 group versus 104 minutes in LB3 group and mean fluoroscopy time of 19.4 minutes in CB3 group versus 6.7 minutes in LB3 group) which was statistically significant for both parameters (p<0.001). There was no significant difference in adverse events between the two groups. LB and CB are safe and effective PVI modalities. Using the X3 LB system, procedure and fluoroscopy time were shorter than with the CB3 system with similar efficacy and safety. Larger prospective randomized studies are needed to confirm these results.

Stereotactic percutaneous cryoablation technique for spinal tumor lesion: pilot study

INTRODUCTION: Percutaneous cryoablation is a method of minimally invasive treatment of patients with metastatic bone lesions, which is also used for lesions of the vertebrae. The spine is one of the most difficult anatomical areas for ablation due to the risk of mechanical and thermal damage to the spinal cord and adjacent structures. OBJECTIVE: Consideration of methodological aspects of performing minimally invasive percutaneous cryoablation in metastatic lesions of the vertebrae, clarification and systematization of puncture stereotaxic approaches. MATERIALS AND METHODS: The cryoablation procedure was performed in 10 patients. The sizes of metastatic lesions varied from 8 to 45 mm (34.6±9.7 mm). Positioning of cryoprobes was performed in sequential mode using the «free hand» method or using a robotic navigation attachment to a CT scanner. The process of installing cryoprobes and ablation was monitored using a multislice computed tomograph. Number and diameter of cryoprobes determined taking into account the characteristics of the lesion; in one procedure used from 1 to 3 cryoprobes. The PCA procedure included two cooling cycles to a temperature of –190 four °C with an exposure of 10 and 7 minutes, with automatic temperature maintenance at the set parameters and continuous temperature monitoring between cycles. After the end of ablation, active and passive thawing modes were used. Dimensions ice ball was assessed at periodic CT scans with an interval of 2–3 minutes. RESULTS: Two patients without previous pain syndrome using costovertebral and transforaminal approaches after the procedure developed a pain syndrome of 4–5 points on a digital analogue scale, which required medical analgesic correction using, among other things, narcotic analgesics. In a patient in the case of transforaminal access, the pain syndrome completely resolved within 7 days; in the second case, the pain decreased to 2 points, but persisted for 3 weeks. In 4 patients with previous pain syndrome after PCA, its decrease to 0–2 points was noted. These changes in 2 patients persisted throughout the entire observation period (more than 6 months), in 2 patients the effect was observed for 1 and 3 months; the resumption of pain was due to the local progression of the tumor process. In general, local tumor control was achieved in 7 patients (follow-up period 6–14 months). In 3 patients, according to the control CT scan, continued growth of metastases was established, while in all these clinical cases, the size of the foci before PCA exceeded 4 cm. DISCUSSION: In PCA of the vertebrae, a wide range of puncture approaches can be used: transpedicular, costovertebral, transforaminal, posterolateral, and posterior. The choice of the optimal variant depends on the spine and the features of localization, shape, size and structure of the lesion. CONCLUSION: When performing PCA of metastatic foci in the thoracic and lumbar spine, most of the known puncture approaches can be used. In case of marginal destruction of the vertebral body, posterolateral (in the thoracic region) and posterior (in the lumbar region) puncture approaches can be used, in which the cryoprobe is installed paravertebral, without direct perforation of the bone.

Different power modes of microwave ablation for hepatocellular carcinoma: Evaluation of recurrence rate and factors related to recurrence

PurposeTo evaluate the safety and efficacy of different power modes(constant power and variable power) percutaneous microwave ablation (MWA) for treating hepatocellular carcinoma (HCC) and to predict the risk factors of recurrence after MWA. Materials and methodsIn this retrospective study, a total of 112 patients with solitary HCC were included from January 2015 to January 2021. All patients received MWA through a percutaneous approach that was guided by ultrasound, 45 patients received variable power MWA, and the remaining 67 were treated with constant power MWA. The complete ablation rates, local recurrence rates, complications, and short-term survival were analyzed. Possible risk factors for tumor recurrence were analyzed. ResultsThe complete ablation rates were 95.9% for the first ablation and 100% for the second ablation for ≤3 cm lesions. The complete ablation rates were 84.2%(95.9% versus 84.2%, p = 0.039) for the first ablation and 94.7% (100% versus 94.7%, p = 0.113) for the second ablation for 3–5 cm lesions. Local and distant recurrence rates were 18.7%(21/112) and 14.3%(16/112). The 1-, 2-year survival rates were 86.3 and 66.3%, respectively. Subgroup analysis showed that 1-, 2-year survival rates were 91.1% and 78.5% in ≤3 cm group, and were 74.4% and 40.9% in 3–5 cm group, respectively. Univariate analysis revealed that a positive correlation existed between the HBV DNA replication(p = 0.007), AFP level of pre-MWA(p = 0.001) and post-MWA(p<0.001), tumor diameter(p<0.001), irregular shape(p = 0.014), proximity to the risk location(p = 0.008), poor differentiation(p = 0.003), constant power(p = 0.028), length(p<0.001) and width of ablation zone(p = 0.001), and present complication(p<0.001), and early recurrence. Multivariate analysis identified HBV DNA replication(OR = 0.266, p = 0.036), AFP level of pre-MWA (OR = 4.001, p = 0.036), tumor diameter (OR = 2.153, p = 0.042), tumor location (OR = 0.910, p = 0.046), and width of ablation zone(OR = 2.530, p = 0.044) were independent prognosis factors causing postoperative HCC recurrence. ConclusionVariable power MWA of HCC appears to be a safe and effective treatment. HBV DNA, AFP level of pre-MWA, tumor diameter, tumor location, and width of ablation range appear to be independent predictors of tumor recurrence.

Magnetic resonance assessment of left atrial scar formation following a novel very high-power short-duration workflow for atrial fibrillation ablation.

Atrial fibrillation (AF) ablation protocols using energy delivery with very high power and short duration (vHPSD) have been introduced to improve lesion formation. This study reports procedural data of vHPSD ablation in AF patients and analyses characteristics of ablation-induced left atrial (LA) scar formation from cardiac magnetic resonance imaging (MRI). Sixty consecutive patients undergoing index pulmonary vein isolation following our institutional Q4U-AF workflow were prospectively enrolled. Ablation was conducted using a contact force sensing catheter allowing for vHPSD ablation using a temperature-controlled ablation mode. Thirty patients underwent cardiac late gadolinium enhancement MRI of the LA 3 months after ablation to assess LA scar. Mean procedural duration was 66.5 ± 14.8 min. Mean ablation time was 4.7 ± 0.9 min with a mean number of 69.9 ± 14.2 applications. First-pass isolation was achieved in 51 patients (85%) for the right pulmonary veins (RPVs), in 37 patients (61.7%) for the left pulmonary veins (LPVs), and in 34 patients (56.7%) for both pulmonary veins (PVs). Magnetic resonance imaging at 3 months post-ablation demonstrated a mean scar width of 14.4 ± 2.6 mm around RPVs and 11.9 ± 1.9 mm at LPVs (P > 0.05). Complete PV encirclement was observed in 76.7% for RPVs, in 76.7% for LPVs, and in 66.7% for both PV pairs. During a mean follow-up of 4.7 ± 1.4 months, arrhythmia recurrence was observed in 3.3% of the patients. Pulmonary vein isolation following a novel vHPSD workflow resulted in short procedure duration and high acute and mid-term efficacy. Magnetic resonance imaging demonstrated durable and transmural PV lesions with homogeneous and contiguous scar formation.