Parasystole Research Articles

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.

Feasibility and efficacy assessment of a novel size-adjustable cryoballoon for ablation of atrial fibrillation in a multicenter clinical setting

Abstract Background The POLARx-FIT cryoballoon (CB) system introduces a unique feature, allowing the selection of two distinct balloon sizes within a single catheter. This innovation holds promise for treating larger pulmonary veins (PV), providing increased flexibility to achieve optimal occlusions. However, there is a scarcity of clinical data supporting its application in this context. Purpose To compare the benefits and safety of the new POLARx-FIT system to those of the existing POLARx system currently in use for PV isolation (PVI) in patients with atrial fibrillation (AF). Methods The first 140 consecutive patients who underwent CB-based PVI with the POLARx-FIT system were retrospectively compared with 300 consecutive patients treated with the POLARx system. Protocol-directed cryoablation was delivered for 180 sec or 240 sec according to operator’s preference for isolation achieved in ≤60 sec, or 240 sec if isolation occurred >60 sec or when time to isolation was not available. The ablation endpoint was PVI as assessed by entrance and exit block. In the POLARx-FIT group the choice of balloon size (28 or 31 mm) was determined during the procedure while attempting to occlude each vein. Results Two-thousand one-hundred fifty-five cryo-applications (CBA) from 440 patients were analysed (300, 68.2% POLARx; 140, 31.8% POLARx-FIT). PVI was achieved with cryoablation only in all patients. The mean number of freeze applications per patient was similar between groups (5.0±1.4 in the POLARx-FIT vs 5.3±1.8 in the POLARx group, p=0.207) whereas the number of PVs treated in a single-shot fashion was higher in the POLARx-FIT group (444, 80.7% with one shot; 75, 13.7% with 2 shots; 31, 5.6% with more than 2 shots) than in the POLARx one (1168, 70.2% with one shot, p=0.0002; 294, 17.7% with two shots and 143, 8.6% with more than two shots). Among the POLARx-FIT cases, in 54.2% (n=298) of applications, the 31-mm diameter was employed as a first choice, while in the remaining 45.8% (n=252) of applications, the 28-mm diameter was adopted. A switch to a different balloon diameter was applied in 11.6% of cases. The first pass isolation (i.e. a single shot CBA to achieve PVI) was slightly higher when using a 31 mm diameter (n=250, 83.9%) than a 28 mm diameter (n=194, 77.0%, p=0.05). Three (0.7%) transient phrenic nerve palsy were observed (all in the POLARx group, 0.9%, p=0.554), with full recovery in the 48-h post procedure; no major procedure-related adverse events were reported at 30 days post-procedure. Conclusion In this first multicentric experience in a clinical practice setting, this novel cryo-balloon system proved to be safe and effective and resulted in a high proportion of successful single-freeze isolation. The intraprocedural flexibility of balloon size contributed to its versatility, leading to a variation in balloon diameter in about 12% of freeze applications.

Role of 3D-electro-anatomical mapping on procedural characteristics and outcomes in pulsed-field ablation for atrial fibrillation

Abstract Introduction While the utilization of dedicated 3D-electro-anatomical mapping (EAM) systems for catheter ablation of atrial fibrillation (AF) is crucial using radiofrequency, its potential benefits in pulsed-field ablation (PFA) remain uncertain. This is of particular interest, since some PFA ablation systems will soon be available with integrated 3D-EAM capabilities. Objectives To compare the procedural characteristics and outcomes of patients undergoing PFA for pulmonary vein isolation (PVI) with mapping and with no mapping. Methods We prospectively enrolled patients undergoing their first PVI at a tertary referral center. In patients undergoing PVI with mapping, a multipolar mapping catheter was used to create voltage maps during sinus rhythm pre- and post-ablation. In the non-mapping group PVI was confirmed by assessing entrance block via the PFA catheter. The first 30 cases with mapping were excluded to account for a potential learning curve. Results A total of 197 consecutive patients were included (age 65 [interquartile range (IQR) 58 – 72] years; indexed left atrial volume 40 [IQR 35 – 44] mL/m2). Among these, 127 patients (64%) underwent PVI with mapping and 70 patients (36%) with no mapping. The median procedure duration, left atrial dwell time and the fluoroscopic time for the mapping vs the non-mapping group were 55 [IQR 45 – 67] min vs. 28 [IQR 23 – 35] min (p < 0.001), 38 [IQR 30 – 49] min vs. 15 [IQR 11 – 21] min (p < 0.001), 11 [IQR 9 – 14] min vs. 8 [IQR 7 – 11] min (p < 0.001), respectively. In the mapping group in 9% (11/127 patients) at least 1 PV was incompletely isolated and required additional applications. Acute PVI success was 100%. There were two complications in the mapping group (one stroke, one coronary artery air embolism) and none were observed in the non-mapping group. The recurrence rate of atrial arrythmias during a median follow-up of 267 [IQR 164 – 419] days was 14% in the mapping group and 17% in the non-mapping group, p = 0.728. Conclusion In conclusion, the use of PFA with no mapping was associated with a significant decrease in procedural characteristics, while AF-recurrence was not significantly different. The routine use of mapping for PFA-PVI may not be needed.Figure 1

Lesion size index-guided radiofrequency catheter ablation using an impedance-based three-dimensional mapping system to treat sustained atrial tachycardia in a horse.

Sustained atrial tachycardia at an atrial rate of 191/min on the surface ECG was detected in a 6-year-old Warmblood mare. The vectorcardiogram obtained from a 12-lead ECG suggested a caudo-dorsal right atrial origin of the arrhythmia. Impedance-based three-dimensional electro-anatomical mapping, using the EnSite™ Precision Cardiac Mapping System revealed a clockwise macro-reentry around a line of conduction block in the caudomedial right atrium. Ten radiofrequency applications were applied to isolate the caudal vena cava myocardial sleeves at a power of 35 W and mean contact force of 14 ± 3 g until a lesion size index of 6 was reached. Sinus rhythm was restored at the first energy application. Successful isolation was confirmed by demonstrating entrance and exit block. Holter monitoring 5 days post-ablation revealed no abnormalities. To date, 9 months after treatment, no recurrence has been observed. The use of lesion size index-guided ablation and isolation of the arrhythmogenic substrate in the caudal vena cava may minimise the risk of recurrence.

Three-dimensional mesoscale analysis of the dynamic tensile behavior of concrete with heterogeneous mesostructure

This paper investigates the dynamic tensile behavior of concrete under high strain rates. An optimized random concrete mesostructure generation procedure is established using the 3D entrance block (3D E(A, B)) algorithm to account for the intrinsic material heterogeneity. This approach avoids repetitive and complicated polyhedral aggregate overlapping checks in traditional methods, resulting in a highly efficient aggregate packing process. The nucleation, propagation, and coalescence of cracks are captured by a properly developed rate-dependent cohesive constitutive law. The mesoscale model is validated through comparison with experimental results. The crack evolution in the concrete under dynamic direct tensile loading conditions is explicitly presented, and the effects of the aggregate volume fraction and ITZ properties on the dynamic tensile strength enhancements are studied. The results indicate that material heterogeneity significantly influences the fracturing process and damage distribution. The dynamic tensile strength of concrete exhibits a two-strain rate regime dependence on the aggregate volume fraction concerning the strain rate. The influence of the mechanical properties of the ITZ on the dynamic tensile strength of concrete increases with the increasing strain rate.

Pulsed field ablation of atrial fibrillation using a large area focal catheter with a novel contact detection algorithm. A first-in-human experience using the QuickShot catheter

Abstract Background/Introduction Pulsed field ablation (PFA) is emerging as a safe and effective alternative energy modality for cardiac ablation. Data have shown that while tissue contact is critical for PFA, the amount of contact force is less important. Single-shot catheters have shown comparable results to current thermal methods for pulmonary vein isolation (PVI), however, are limited to anatomical-based ablation strategies and have limited ability to detect tissue contact. The investigational QuickShot™ large-area focal catheter (Galvanize Therapeutics, Redwood City, CA) combines high-density mapping with large-area focal ablation guided by contact detection. Purpose The QuickShot PEF-AF study was a prospective, single-arm, first-in-human study performed at a single European center to evaluate the safety and performance of the QuickShot catheter (see Figure 1, panel A) combined with the CE-marked CENTAURI™ System (Galvanize Therapeutics, Figure 1, panel B) for catheter ablation of atrial fibrillation (AF). Methods Subjects with paroxysmal or persistent AF underwent a PVI procedure under deep sedation (fentanyl, midazolam, propofol) guided by Rhythmia™ HDx (Boston Scientific, Marlborough, MA, Figure 1, panel D). Irrigation was set to a constant 6 mL/min during the procedure. Focal, monopolar, biphasic PFA lesions were delivered asynchronously at 33 Amps and a 10 mm inter-lesion spacing (center to center with 10 mm lesion tag size). Catheter-tissue contact was confirmed by ICE/fluoroscopy and a novel impedance-based contact detection system (Figure 1, panel C). The acute performance endpoint was PVI, assessed by entrance and exit block using high-density mapping. Procedural safety assessments included microbubble detection via ICE, induction of VT/VF, muscle stimulation, phrenic nerve function, and NIHSS post-procedure. Results Twenty (20) subjects (60% PAF, 60 ± 12 years, 75% male, 4.3 ± 0.52 cm LA AP diameter) were enrolled and treated. Acute PVI was achieved in 100% of patients and targeted PVs (82/82), with first-pass isolation in 88% of targeted PVs. The PVI time was 31 ± 10 min with 46.7 ± 11.4 PFA applications. There were no device- or procedure-related adverse events, and no documented incidence of microbubble formation, arrhythmia induction, muscle stimulation, phrenic nerve dysfunction, esophageal injury, or change in NIHSS post-procedure. Conclusion The QuickShot catheter enables safe and effective large-area focal PFA for subjects requiring PVI. The catheter design enables efficient and flexible focal lesion placement with the ability to ensure adequate apposition to targeted tissues using its novel contact detection algorithm. Future studies will investigate the use of this novel catheter for PFA strategies beyond PVI.

Left atrial posterior wall isolation during catheter ablation with the pulsed field ablation in patients with persistent atrial fibrillation

Abstract Background Few data are available on pulsed-field ablation (PFA) targeting left atrial posterior wall (LAPW) in persistent atrial fibrillation (PeAF) patients. Purpose We sought to explore the role of PFA in persistent AF patients beyond pulmonary vein isolation (PVI), extending the lesion set to obtain LAPW isolation. Methods We enrolled consecutive patients referred for persistent AF catheter ablation using the Farapulse PFA system at nine Italian centers. Complete 3D mapping was performed before and immediately after LAPW isolation to validate our workflow in all cases. To analyze lesions' formation and residual gaps, the line around each pair of PVs was divided into 7 distinct sections in accordance with the literature, while the roof line, the floor line, and the two longitudinal posterior wall lines were equally divided into three parts. The PW was overall divided into nine regions. This scheme has been illustrated in Figure 1, Panel A. Results Fifty patients meeting inclusion criteria were included. PVI was achieved in all 202 (100%) PVs (1 patient exhibited a left common trunk, 2 patients exhibited a right middle cardiac PV). One-hundred ninety-eight (98.0%) PVs were acutely isolated on first pass, as confirmed by both entrance and exit block on subsequent 3D-mapping with the mapping catheter. A total of 7 PV gaps were detected through 3D mapping: 4 at the RSPV, 2 at the RIPV and 1 at the LSPV. When considering LAPWI, overall LAPW ablated area was 20.0±6 cm2 with lesions being deployed with the PFA catheter maneuvered in the flower configuration from one LAPW area to another. First-pass roof area (sectors #1 to #3) block was achieved in 44 (88%), first-pass floor area (sectors #7 to #9) block in 43 (86%) and inner-area (sectors #3 to #6) block in 45 (90%). A total of 23 residual LAPW activity gaps were detected through validation using high-output pacing and 3D mapping. Remapping examples has been reported in Figure 1, panel B-C-D. Evaluation of individual segments of the LAPW via signals’ assessment from the PFA splines demonstrated an accuracy of 94.9% (437 out of 450 sectors), compared to the results of subsequent high-output pacing and 3D mapping. Following PFA consolidation in these areas, LAPW isolation was successfully achieved in all cases (100%) using PFA alone, with no need for radiofrequency touch-ups. No major procedure-related adverse events were reported. Conclusion A structured workflow with the novel Farapulse PFA system allowed for a reliable, safe, and fast LAPW isolation, as confirmed by ultra-high-density 3D mapping.

Role of high-density voltage map guiding parosysmal atrial fibrillation ablation

Abstract Background High-density mapping of the pulmonary vein antra has been demonstrated to improve the detection of conduction gaps in wide antral catheter ablation (WACA) approach for the treatment of paroxysmal atrial fibrillation (AF). Purpose We aimed to compare the AF recurrencies in patients treated with WACA for pulmonary veins isolation (PVI) guided by high-density bipolar voltage map (BVM) vs WACA guided by a standard 20-pole circumferential mapping catheter (CMC-20). Methods This prospective study included patients scheduled for AF ablation in a single center. In group A (85 patients) PVI was achieved with a conventional approach using CMC-20; in group B (96 patients) high density BVM was acquired by sequential multielectrode mapping through Pentaray Catheter (Biosense Webster). More than 1000 voltage points per map were acquired. Acute PVI was defined as an entrance and exit block after ≥ 20 min waiting period. In both groups WACA was perfomed using a contact force sensing catheter targeting an interlesion distance ≤6 mm and ablation index ≥400 at posterior wall and ≥550 at anterior wall. The primary endpoint was the AF recurrencies in the two groups. Results A total of 181 patients were included (mean age 64.9±10.6 years, 33.1% female): in 85 patients AF ablation was guided by CMC-20, in 96 patients AF ablation was guided by BVM; WACA PVI was achieved in all patients. There were no significant differences in the clinical characteristics of the two groups (table 1). At 12-month follow-up, AF recurrencies were significantly lower in the BVM group compared with CMC-20 group [11/96 (11.4%) vs 19/85 (22.3%) respectively, p=0.01]. Conclusions High-density BVM might increase success rate of AF ablation compared with a conventional 20-pole circumferential mapping approach.

Impact of pulmonary vein variant anatomy during cryo-ablation in paroxysmal and persistent AF patients: 1-year outcome from a nationwide multicenter clinical setting

Abstract Background Complete electrical pulmonary vein isolation (PVI) by cryo-balloon approach is a well-established ablation strategy of atrial fibrillation (AF). While contrast findings exist regarding the influence of variant pulmonary vein (PV) anatomy on predicting AF recurrence, limited data are currently available specifically for cases involving the POLARx cryoablation system during PVI. Purpose We report the real-world experience of POLARx in the context of de novo AF ablation in a multicenter Italian registry. Methods Consecutive patients undergoing AF ablation from the CHARISMA registry at 10 Italian centres were included. Protocol-directed cryoablation was delivered for 180 sec or 240 sec according to operator’s preference for isolation achieved in ≤60 sec, or 240 sec if isolation occurred >60 sec or when time to isolation was not available. The ablation endpoint was PVI as assessed by entrance and exit block. All patients were followed-up for at least 12 months after the procedure. Results Four-hundred twenty-nine patients were included (n=358, 83.4% paroxysmal AF, n=71, 16.6% persistent AF, mean age 60.7±10 years, 28.3% female, mean LVEF 58±8%). PVI was achieved in all pts using only cryoablation. Twenty-eight (6.6%) patients exhibited an anatomical variant: 17 (4.0%) a common ostium and 11 (2.6%) an adjunctive PV. The mean number of freeze applications per patient was 5.1 (1.2 for LSPV, 1.3 for LIPV, 1.2 for RSPV and 1.3 for RIPV). Over a median of 398[370-461] days of follow-up, 14 (3.2%) patients experienced an early recurrence of AF during the 90-day blanking period. Overall, 63 patients (14.7%) suffered an AF recurrence after the 90-day blanking period (median time to recurrence 342[171-381] days). The proportion of patients exhibiting AF/AT recurrences was higher in the persistent AF group (17 out 71, 23.9%) than in the paroxysmal AF group (46 out 358, 12.8%, p=0.026), with a hazard ratio of 2.02 (95%CI: 1.2 to 3.5, p=0.0137) whereas patients with anatomy variant showed a similar AF/AT recurrence rate (5 out 28, 17.9%) than in the standard anatomy group (58 out of 401, 14.5%) with a hazard ratio of 1.43 (0.6 to 3.6, p=0.441). Four (0.9%) transient phrenic nerve palsy were observed, both with full recovery in the 48-h post procedure; no major procedure-related adverse events were reported. Conclusion In this multicenter study, the cryo-balloon system demonstrated safety and efficacy in treating both paroxysmal and persistent AF patients, yielding a low incidence of AF/AT recurrence during follow-up, regardless of the presence of variant PV anatomy.

Meta-contact analysis based on contact theory in three-dimensional discontinuous deformation analysis

Accurate contact analysis between nonspherical blocks, such as polyhedral blocks, is crucial for modeling jointed rock masses. The Contact Theory provides a rigorous foundation for contact detection. However, designing a robust and efficient algorithm that conforms to the original Contact Theory remains challenging. This study introduces the meta-contact concept for polyhedral blocks, which corresponds to the contact cover on the entrance block of the Contact Theory. Using the meta-contact concept, contact type identification, determination of contact points and plans, and contact force calculation can be formulated while retaining the advantages of Contact Theory in dealing with irregular blocks with small edges and large penetration.

Successful caudal vena cava and pulmonary vein isolation in healthy horses using 3D electro-anatomical mapping and a contact force-guided ablation system.

Recently, treatment of equine atrial tachycardia by three-dimensional electro-anatomical mapping (3D EAM) and radiofrequency catheter ablation (RFCA) has been described. Myocardial sleeves in the caudal vena cava and pulmonary veins are a potential trigger for initiation and perpetuation of atrial tachycardia and atrial fibrillation in the horse. Isolation of these myocardial sleeves by RFCA may be an effective treatment for these arrhythmias. To describe the feasibility of 3D EAM and RFCA to isolate caudal vena cava and pulmonary veins in adult horses using 3D mapping and a contact force (CF)-guided ablation system. In vivo experiments. 3D EAM and RFCA was performed in five horses without cardiovascular disease under general anaesthesia, using the CF-guided system CARTO®3. Point-by-point RFCA aimed for isolation of caudal vena cava and pulmonary veins. Radiofrequency energy was delivered in power-controlled mode with a target power of 45 W, CF between 10 and 15 g and 30 mL/min irrigation rate, until an ablation-index of 450-500 was reached. In the right atrium, myocardial sleeves of the caudal vena cava were isolated (n = 5). In the left atrium, isolation of ostium II (n = 3), ostium III (n = 1) and ostium I, II and III en bloc (n = 1) was performed. Successful isolation was confirmed by entrance and exit block. Horses were euthanised at the end of the procedure, so long term effects such as potential reconnection of isolated veins could not be studied. This is the first description of 3D EAM and RFCA with CARTO®3 in horses, thereby showing the technical feasibility and successful caudal vena cava and pulmonary vein isolation. CF measurement allowed monitoring of catheter-tissue contact, resulting in efficient acute lesion creation as confirmed by entrance and exit block. This is a promising treatment for cardiac arrhythmias in horses.

Long-term success rates of a stable, low pressure cryo balloon for the treatment of paroxysmal atrial fibrillation - results of the prospective, international, multicenter POLAR-ICE study

Abstract Background/Introduction Pulmonary vein isolation (PVI) using a cryo balloon is well-established for the treatment of paroxysmal atrial fibrillation (PAF). Compared to other available technologies, the usage of a stable, low pressure cryo balloon (POLARx, Boston Scientific) has demonstrated lower nadir temperatures and longer thawing times. However, long term efficacy and safety still needs to be proven. Purpose The aim of the POLAR-ICE Study was to evaluate long-term efficacy and safety outcome of cryo balloon ablation in patients with paroxysmal atrial fibrillation. Methods POLAR ICE, a prospective, non-randomized, international, multicenter study, enrolled 399 patients across 19 centers, between Aug 2020 and May 2021. Patients with paroxysmal atrial fibrillation undergoing de novo PVI were included into the study. During the index procedure, procedural characteristics, such as time to isolation (TTI), cryoablations per pulmonary vein, balloon nadir temperature, and occlusion grade were recorded. Procedural success was defined as successful isolation of each vein proven by entrance block. Follow up visits were at 3, 6, and 12 months. Recurrence is defined as any documented (ECG/Holter) episode of atrial fibrillation / atrial tachycardia longer than 30sec. after a blanking period of 3 months. Results 399 patients (mean age 61 years, 36% female) were included into the study. After 12 months, freedom from any arrhythmia was 83.5% and freedom from atrial fibrillation 88.1% (Figure 1). Procedure/ablation related Serious adverse events occurred in 8.7% of patients, and included access complications (2.6%), cardiac tamponade (0.5%), air embolism (0.3%), AV block (0.3%), effusion (0.3%) phrenic nerve palsy (0.3%), stroke (0.3%), transient ischemic attack (0.3%). Redo procedures have been conducted in 19 patients. In 14/19 pts reconnection of at least one PV could be identified (RSPV n=8, RIPV n=12, LSPV n=9, LIPV n=11). Freedom from any arrhythmia was associated with lower nadir temperature (p=0.008) and longer time to thaw (p=0.05) during the index procedure. Conclusions In this prospective, non-randomized, international, multicenter study, isolation of the pulmonary veins using a stable, low pressure cryo balloon was highly effective and safe in patients treated for paroxysmal atrial fibrillation. Lower nadir temperatures and a longer thawing time were predictors of clinical success.

Contact-force local impedance algorithm to guide effective pulmonary vein isolation in AF patients: 1- year outcome from an international multicenter clinical setting

Abstract Background The combination of highly localized impedance (LI) and contact force (CF) may improve tissue characterization and lesion prediction during radiofrequency (RF) pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF). Objective We report the outcomes of our acute and long-term clinical evaluation of CF-LI guided PVI in consecutive AF ablation cases from an international multicenter clinical setting. Methods Consecutive patients (pts) from 16 European centers undergoing de novo AF RF catheter ablation with the Stablepoint catheter endowed of CF and LI measurement capabilities were enrolled in the CHARISMA registry. Ablation was guided by the magnitude and time-course of LI drop during RF delivery. The maximum distance between each ablation spot (center-to-center) was suggested to be ≤6 mm. Procedural endpoint was the achievement of the PVI as assessed by entrance and exit block. Post-ablation, all patients were monitored with ambulatory event monitoring. Additional ECG monitoring was performed as indicated by patient symptoms. Data are reported as mean±SD. Results From a total of 212 consecutive pts, 151 were followed-up for at least 12 months after the procedure and were included in this 1-year outcome analysis (61.6% paroxysmal AF, 38.4% persistent AF, 78.8% de novo procedures, 21.2% redo procedures). Baseline LI was 161.2±19 Ω with LI drop of 21.9±9 Ω (LI drop rate=3.1±2 Ω/s). The first pass isolation rate per vein was 93.3%. LI drop was predicted by baseline LI (r=0.56, 95%CI:0.55 to 0.57, p<0.0001). Effective ablation spots showed both higher baseline LI and LI drop compared with PV gap spots (161.4Ω vs 153.0Ω, p<0.0001 for baseline LI; 22.1Ω vs 14.4Ω, p<0.0001 for LI drop). No steam pops or complications, including atrio-esophageal fistula or tamponade were reported during or after the procedures. At the end of the procedures all PVs were successfully isolated in all study patients. During a median follow-up of 377 [365 – 402] days, 11 (7.3%) patients experienced an early recurrence of AF during the 90-day blanking period. Overall, 21 pts (13.9%) suffered an AF recurrence after the 90-days blanking period (10.8% with paroxysmal AF vs 19% with persistent AF, p=0.226; 10.9% for de novo procedures vs 25.0% for redo procedures, p=0.079). De novo paroxysmal AF pts showed the lowest rate of recurrence (5 out 69 pts, 7.2%). The time to recurrence was comparable among AF type (HR=1.73; 0.73 to 4.05; p=0.210 for persistent vs paroxysmal AF) whereas was shorter in repeated AF ablation procedures (HR=2.49; 1.04 to 5.98; p=0.042 for redo vs de novo procedure). Early recurrence was not associated with late recurrence (HR=2.29; 0.68 to 7.76; p=0.182). Conclusions In our experience, the magnitude of LI drop is predictive of PV segment isolation. An ablation strategy for PVI guided by CF-LI technology was safe and effective, and resulted in a low recurrence rate of AF at 1-year follow-up irrespective of underlying AF type.

Development of three-dimensional numerical manifold method with cover-based contact theory

Numerical manifold method (NMM) is a typical continuous-discontinuous coupling method. It unifies the continuous and discontinuous theories in the same program framework. In the present work, based on the cover-based contact theory, the specific solution of contact covers under five different positional relationships is given in detail, and the contact judgement conditions and contact cover solution formulas under each positional relationship are proposed. By converting the contact into the relationship between reference point a0 and the outer boundary of entrance block E (A, B), the contact algorithm between 3D blocks is implemented and programmed. The developed code is initially calibrated by two simple models, and its correctness is quantitatively verified by the motion of the inclined sliding model. Finally, it is applied to more complex structural deformation and dynamic collision problems. The 3D-NMM developed in the present work can be used for structural kinematics, structural deformation and dynamic collision problems, and has broad application prospects in the field of structural mechanics.

Impact of a standardized pacing protocol on end point verification and first pass isolation using a multipolar pulsed-field ablation catheter for pulmonary vein isolation

Pulsed-field ablation (PFA) has emerged as a novel treatment strategy for patients with atrial fibrillation (AF) ( 1 Badertscher P, Weidlich S, Serban T, et al. Pulsed-field ablation versus single catheter high-power short-duration radiofrequency ablation for atrial fibrillation: procedural characteristics, myocardial injury and midterm outcomes. Heart Rhythm 2023. Google Scholar , 2 Reddy VY, Dukkipati SR, Neuzil P, al. Pulsed Field Ablation of Paroxysmal Atrial Fibrillation: 1-Year Outcomes of IMPULSE, PEFCAT, and PEFCAT II. JACC Clin Electrophysiol 2021; 7(5):614–627. Google Scholar ). In general, acute pulmonary vein isolation (PVI) may be confirmed by entrance and exit block ( 3 Duytschaever M. Meyer G de Acena M. et al. Lessons from dissociated pulmonary vein potentials: entry block implies exit block. Europace. 2013; 15: 805-812 Crossref PubMed Scopus (25) Google Scholar ). The penta-spline PFA catheter only provides larger electrodes and wider inter-electrode distance making such an assessment less reliable. Little is known about the required number of applications when using PFA as systematically assessed via exit block testing. Likewise, since close proximity of the PFA catheter to the PV ostium seems to be of importance ( 2 Reddy VY, Dukkipati SR, Neuzil P, al. Pulsed Field Ablation of Paroxysmal Atrial Fibrillation: 1-Year Outcomes of IMPULSE, PEFCAT, and PEFCAT II. JACC Clin Electrophysiol 2021; 7(5):614–627. Google Scholar ), catheter positioning might be optimized by pacing before the first PFA application and adjusting contact depending on the ability to capture atrial myocardium. Thus, our aim was to assess the number of PFA applications per PV until acute PVI was observed and to assess the impact of a standardized pacing protocol on first pass isolation (FPI) confirmed via electroanatomical mapping (EAM). We prospectively enrolled consecutive patients undergoing their first PVI. In brief, the PFA 31 mm Farawave© catheter (Boston Scientific, Marlborough, MA) was inserted into the left atrium via a single transseptal puncture. PVI was performed as described previously ( 2 Reddy VY, Dukkipati SR, Neuzil P, al. Pulsed Field Ablation of Paroxysmal Atrial Fibrillation: 1-Year Outcomes of IMPULSE, PEFCAT, and PEFCAT II. JACC Clin Electrophysiol 2021; 7(5):614–627. Google Scholar ). In group 1 no standardized pacing protocol was applied prior or after PVI. In group 2, pacing was performed prior to the first application across all five bipoles to assess proximity of the PFA catheter to the PV ostium. Entrance and exit block were then assessed after each PFA application per PV separately. PVI was subsequently confirmed via EAM. The study was approved by the local ethics committees and adhered to the Helsinki Declaration.

Local impedance technology for effective PVI with a novel ablation catheter: results from a large, international, multicenter registry

Abstract Funding Acknowledgements Type of funding sources: None. Background Highly localized impedance (LI) measurements in combination with a catheter-tissue contact force (CF) during atrial fibrillation (AF) ablation may improve tissue characterization and lesion prediction during pulmonary vein isolation (PVI). Purpose This analysis explores the relationship between LI parameters, ablation spot locations and procedural success during ablation of PVs in a large population of consecutive AF patients. Methods Two-hundred twelve consecutive patients from 16 European centers undergoing de novo AF radiofrequency (RF) catheter ablation with a novel open-irrigated tip catheter enabled by CF and LI measurement capabilities (Stablepoint) were included. Ablation was guided by the magnitude and time-course of LI drop during RF delivery. The interlesion distance between each ablation spot was set ≤6 mm. First pass isolation (FPI) was defined as successful PVI at or before completion of the first encircling lesion set regardless of visual gaps. Procedural endpoint was the achievement of the PVI as assessed by entrance and exit block. Data are reported as mean±SD. Results A total of 13891 ablation spots performed around PVs were analyzed (baseline LI=161.2±19 Ω; LI drop=21.9±9 Ω; LI drop rate=3.1±2 Ω/s; RF Delivery time=9.2±4 s; CF=12.5±7 g). LI drop was predicted by baseline LI (r=0.56, 95%CI:0.55 to 0.57, p<0.0001). A total of 80 PV gaps were detected, mostly at the right pairs of the PV (63.7%, p=0.013). The FPI rate per vein was 93.3% resulting from 180 patients (84.9%) with FPI. PV gaps were located at anterior (31.3%), posterior (31%), and carina (16%) sites after the FPI evaluation. At successful ablation spots, both baseline LI and LI drop were larger than at PV gap spots (161.4Ω vs 153.0Ω, p<0.0001 for baseline LI; 22.1Ω vs 14.4Ω, p<0.0001 for LI drop), whereas RF delivery time was shorter (9.1s at successful ablation spots vs 10.1s at PV gap spots, p<0.0001). CF values seem to be higher at successful ablation spot that at PV gap spots (12.5g vs 11.4g, p=0.0592). On the basis of the receiver-operating characteristic curve (ROC) analysis, the best LI drop that predicts successful ablation spots was >20Ω (Sensitivity=56.8%, Specificity=93.2%, PPV=99.7%, Area under the ROC curve=0.7841, p<0.0001). Optimal LI drops were identified by left atrial region and were >21Ω at anterior sites and >18Ω at posterior sites. No steam pops or complications were reported during the procedures. All PVs were successfully isolated in all study patients Conclusions In a large, international population of consecutive de novo AF cases, an ablation strategy guided by LI and CF information results in a very high first pass isolation rate. LI drop is predictive of PV segment isolation. A regional approach to RF ablation guided by LI information may be useful in patients with AF.

Implementation of CLOSE protocol for pulmonary vein isolation in paroxysmal atrial fibrillation by young electrophysiologists in real world clinical practice

Abstract Funding Acknowledgements Type of funding sources: None. Background Paroxysmal atrial fibrillation (AF) is widely treated by radiofrequency (RF) catheter ablation. The CLOSE protocol has been proposed and accepted to guide a successful, safe and durable pulmonary vein isolation in patients with paroxysmal AF. However, the reproducibility of the protocol in real clinical practice and on less experienced hands is less established. Objective To assess the acute effectiveness, safety and reproducibility of RF catheter ablation based on the CLOSE protocol for pulmonary vein isolation in paroxysmal AF patients, performed by young electrophysiologists with less than 5 years of experience. Methods Fifty consecutive patients (25 men, aged 61±11 years) with symptomatic paroxysmal AF were enrolled during the period 2020- 2021. RF catheter ablation based on the CLOSE protocol, using a conventional contact force sensing catheter (Thermocool SmartTouch ST D/F) and a circumferential multipolar catheter (Lasso) after double transseptal puncture (2 SL0 long sheaths), under general anesthesia and oesophageal temperature monitoring was performed in all patients. Results Pulmonary vein isolation demonstrated by entrance and exit block was achieved in all patients. Total procedure time was 147 ± 29 minutes, exposure X-ray time was 5.36 ± 4.46 minutes and exposure dose was 922 ± 1616 cGy*cm2. Left pulmonary veins (LPVs) first pass isolation (94%) was numerically higher than the right pulmonary veins (RPVs) first pass isolation (82%). There were not safety issues. In comparison with the results reported by the authors of the CLOSE protocol, the procedure time was similar (p= 0.84), however, the exposure X-ray time and the exposure dose were significantly lower in our study (p<0.0001 and p=0.01, respectively). The rates of first pass isolation of left and right pulmonary veins did not differ when compared to the respective rates reported by the CLOSE protocol authors (82% vs CLOSE 100% for RPVs and 94% vs CLOSE 97% for LPVs, p> 0.05 for both). Conclusions RF catheter ablation in paroxysmal AF patients using the CLOSE protocol is highly effective, safe and reproducible not only by experienced but also by young electrophysiologists. Adaptation of an ablation strategy for pulmonary vein isolation based on the CLOSE protocol may improve the workflow of the procedure and the training curve of young electrophysiologists without compromising the efficacy and safety.

Novel pulsed-field ablation technology for pulmonary vein isolation in patients with atrial fibrillation: preliminary experience from a large multicenter clinical practice

Abstract Funding Acknowledgements Type of funding sources: None. Background Complete electrical pulmonary vein isolation (PVI) by thermal energy sources is a well-established ablation strategy of atrial fibrillation (AF). Recently, a non-thermal ablation approach by means of irreversible cellular electroporation has been made available for clinical use. Purpose We report the preliminary experience of a new pulsed-field ablation (PFA) system in the context of AF ablation in a multicenter Italian setting. Methods All consecutive patients (pts) undergoing AF ablation with PFA at 7 Italian centres were included. Protocol-directed PVI was delivered using 2000 V with eight applications per vein, that is, four applications each in the basket and flower poses. Applications were delivered in pairs at any given catheter position, rotating by ≈30–40° after the first two applications in each configuration. Additional lesions were performed at the operator’s discretion. The ablation endpoint was PVI as assessed by entrance and exit block. Data are reported as median [IQ range]. Results With a median of 32[25-38] pts treated per center, a total of 205 cases were included (n=150 73.2%, paroxysmal AF, n=55, 26.9% persistent AF). Of them 187 (91.2%) were de novo cases, whereas 18 (8.8%) were redo cases. A mapping system was used in 55 (21.5%) procedures and an intracardiac echocardiography in 65 (31.7%) cases. The number of PFA applications to reach PVI was 32[32-36]. Procedural parameters were: fluoroscopy time = 16[12-22] min, skin-to-skin time = 60[55-85] min, support time (preparation plus skin-to-skin) =75[64-95] min, lab occupancy time was 97[75-120] min and PFA LA dwell time was 23[20-28] min. The first pass isolation (FPI) rate per vein was 99.6% resulting from 202 patients (98.5%) with FPI. At the end of the procedure, PVI was achieved in all pts (100%) using only PFA. Additional PFA delivery outside PVs was performed in 19% (n=39) of the cases, mostly at the posterior wall area only (n=34, 87%), requiring 16[12-24] PFA deliveries. All the additional lesion sets were validated through differential pacing and/or 3D mapping. The learning curve was extremely fast. After only 5 cases time to PVI and total support time have significantly improved, whereas we did not notice any additional improvement after 10 or 20 cases (LA dwell time: 27[22-32] min during the first 5 cases vs 23[19-27] min after the first 5 cases, p=0.0172; support time: 100[65-120] min vs 75[65-90] min, p=0.0181, respectively). In 13 (6.3%) cases a transient bradycardia or asystole occurred after the first PFA application requiring temporary high-output pacing. No major procedure-related adverse events were reported. Conclusion In this first multicentric experience, the novel PFA system proved to be safe and effective in both paroxysmal and persistent AF patients. The learning curve seems to be very fast according with procedural parameters.

Cardiac Troponin I kinetic after pulmonary vein isolation for atrial fibrillation ablation with pulsed-field ablation and cryo-energy

Abstract Funding Acknowledgements Type of funding sources: None. Background Previous studies have demonstrated that cardiac biomarkers elevate after both cryoballoon (CB) and radiofrequency atrial fibrillation (AF) ablation, depending on the amount of energy delivered and the site of ablation. To date no comparison has been made between these thermal energy source and a novel non-thermal pulsed-field ablation (PFA) technology based on cells electroporation. Purpose Our analysis aims to compare acute myocardial injury through cardiac troponin I variation after pulmonary vein isolation (PVI) performed with different technologies (PFA vs CB). Methods All consecutive patients undergoing paroxysmal AF ablation with CB and PFA at our center from July to November 2022 were included. Protocol-directed cryoablation (CBA) was delivered for 180 sec or 240 sec according to operator’s preference for isolation achieved in ≤60 sec, or 240 sec if isolation occurred >60 sec or when time to isolation was not available. A standard PFA protocol-directed PVI was applied using 2kV with eight applications per vein (four applications each in the basket and flower poses). The ablation endpoint was PVI as assessed by entrance and exit block. Pre- and post-procedure samples of cardiac troponin I (CTpI) were collected before CBA/PFA and at 24h after ablation. Only patients with normal baseline values for myocardial injury were included. Results A total of 71 patients met inclusion criteria and were included in this analysis. The CBA group consists of 50 (70%) patients and the PFA group comprises 21 (30%) patients. The number of CBA applications to reach PVI was 5.0±1.4 and the number of PFA applications to achieve PVI was 32±4. All (100%) patients were in sinus rhythm at the time of the procedure. Evaluating the kinetic of CTpI, baseline values were homogeneous between CBA and PFA groups (p=0.979) whereas CTpI values significantly rose from baseline (7±2 ng/L) to 24h (8979±3691 ng/L, p<0.0001) and were significantly different between groups after CBA/PFA (8148±3311 ng/L for CBA vs 11900±7143 ng/L for PFA, p=0.0056). PVI was achieved in all patients (100%) using only CB or PFA. No major procedure-related adverse events were reported. Conclusion Our preliminary results showed that cardiac troponin I enzyme level increased after PVI by means of both cryoballoon and pulsed-field ablation and were higher after cellular electroporation by PFA than cryoablation.

General anesthesia in spontaneous respiration with intravenous ketamine in patients undergoing pulsed-field ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background Thermal ablation of atrial fibrillation (AF) by means of radiofrequency or cryo-balloon is usually performed under general anesthesia, deep sedation, or conscious sedation at operator’s discretion and based on the general condition of the patient. However, a standardized sedation protocol when performing a non-thermal ablation, such as pulsed-field ablation (PFA) through irreversible cellular electroporation, has not been well established. Purpose We report our preliminary experience of a general anesthesia in spontaneous respiration protocol with ketamine used at a high-volume center during ablation of AF with a new PFA system. Methods All consecutive patients (pts) undergoing AF ablation with PFA at our center were included. Our sedation protocol consists of intravenous administration of midazolam (1+1 mg), fentanyl (25+25+25+25 mcg/kg) at low doses before local anesthesia with lidocaine (200mg) administration. Patients underwent sedation under spontaneous respiration by administering oxygen (4-6 l/min) through a face mask with nasal cannula. Local anesthesia was performed before the percutaneous femoral venous access. Soon after the trans-septal puncture, heparin (1 mg/kg) and atropine (1 mg, to mitigate anticipated bradycardia) were injected, followed by a second bolus of midazolam (1 mg). Ketamine adjunct (1 mg/kg) was then injected about 5 minutes before the first PFA delivery which was titrated to effect based on patient’s condition, response and changes in vital signs (total ketamine adjunction of 2 mg/kg). For quantitative assessment the Numeric Rating Scale for Pain (NRS) was applied. For qualitative assessment a 3-levels satisfaction evaluation was retrieved. The ablation endpoint was PVI as assessed by entrance and exit block. Results Forty-two pts were included in this analysis (mean age of 66±9 years,72% were male, CHA2DS2VASc score=2 [IQR 1–3], median body mass index 24[20-48]kg/m2, 35% had respiratory diseases – e.g. asthma, OSAS, COPD –). At baseline, before sedation, mean systolic blood pressure was 140.5+20.1mmHg and mean oxygen saturation was 97.9+2.1%. PVI was achieved in all the patients. The number of PFA applications to reach PVI was 33.4+3 (time to PVI = 25+4min). In two cases additional PFA lesion sets were deployed outside the PVs. Lab occupancy time was 122±32min, skin-to-skin time was 78±35min and fluoroscopy time was 23±14min. All the patients achieved a NRS ≤ 3. Satisfaction level was found to be acceptable in all procedures by both the patient and the primary operator (Score equal to 0). No major procedure-related adverse events were reported. Conclusion The PFA procedure has a short execution time. The standardized anesthetic protocol with the administration of drugs with rapid onset and pharmacological offset at low doses was effective and safe with an optimal degree of patient and operator satisfaction.