Electroanatomic Mapping System Research Articles

First experience with a vendor-neutral three-dimensional mapping system for cardiac magnetic resonance-guided electrophysiological procedures: a case report

Abstract Background Fluoroscopy-guided catheter ablation has become the gold standard for treatment of cardiac arrhythmias. High resolution electro-anatomical mapping systems have become fundamental to perform these procedures. Recently, interventional cardiac magnetic resonance (iCMR) has been proposed as an alternative for fluoroscopy to guide atrial flutter ablations. The clinical experience with iCMR and dedicated three-dimensional mapping systems is growing. NorthStar is currently the first available vendor-neutral mapping system. Case summary We performed a real-time CMR-guided cavotricuspid isthmus (CTI) catheter ablation (CA) on a 69-year-old man using a novel mapping system (NorthStar Mapping System, Imricor Medical Systems, MN, USA). Starting from the CMR imaging, a pre-rendered segmentation model was loaded on NorthStar and used to guide the catheters, display voltage and activation maps, show mapping and ablation points. NorthStar can also take full control of the CMR scanner (i.e. start/stop sequences for anatomical information, tissue characterization, and catheter visualization) and communicate with the recorder/stimulator system (Advantage-MR EP, Imricor Medical Systems, MN, USA). With comparable procedural time to standard fluoroscopy-guided CA, CTI bidirectional block was achieved, without any complication. Discussion Using the NorthStar Mapping System, we managed to achieve a successful CMR-guided CTI ablation without any complication. Its further use should be explored, especially in more complex arrhythmias where a substrate-guided ablation is critical, as it could significantly improve results in terms of arrhythmia recurrence.

Stereotactic arrhythmia radioablation for refractory ventricular tachycardia. A retrospective analysis and optimisation of the planning phase

Abstract Introduction Stereotactic arrhythmia radioablation (STAR) is used as a rescue treatment for refractory ventricular tachycardia (VT). However, the planning phase to accurately delineate the clinical target volume (CTV) still suffers from limitations due to the incompatibility of data formats between 3D electro-anatomical mapping systems (EAM) used for VT ablation and STAR planning software. The concordance between the CTVs as defined by the planning software (CTVSTAR) and the CTV based on EAM data (CTVEAM) remains unknown. Purpose Within the STOPSTORM European consortium, we compared the concordance between CTVSTAR and CTVEAM in our series of 13 patients (pts) treated by STAR for refractory VT. We also evaluated need for redo ablation of VT after STAR. Method Using the software Slicer3D, two protocols were retrospectively compared: Protocol 1 comprised the manual contouring of the CTVSTAR based on 4D-CT SCAN drawn side-by-side using EAM (Carto3, Biosense Webster) screenshots and diagnostic reports. Protocol 2 comprised semiautomatic segmentation of CTVEAM based on 4D-CT SCAN using imported EAMs annotated with landmarks for VT substrate delimitation. The delineation of CTVEAM included 3 steps: (1) semiautomatic segmentation of ventricular myocardium (VM), the blood-pool of the concerned ventricle and at least 2 additional cardiac cavities; (2) 3D-alignment of EAM with the segmented cavities; and (3), 3D-delineation of CTVSTAR identified as the transmural section of VM segment surrounding the EAM’s VT substrate delimited by STAR tags (Figure 1). Volume overlap (Dice coefficient, 100% meaning complete overlap) and volume absolute difference (VAD, 0% meaning similar volumes) between CTVs were compared. The following cumulative averages were computed over time: redo ablation (RedoA) and CTV. Results Figure 1 illustrates the last treated patient (#13) in whom the delineated volumes, CTVSTAR (red) and CTVEAM (blue), displayed good matching (Dice 72% and VAD 4. Figure 2 shows the comparison between CTVSTAR and CTVEAM for the 13 pts (65±7 yo) treated with STAR, resulting in a mean Dice of 47±17% and mean VAD of 40±51%. Figure 3 shows the cumulative RedoA and the cumulative averaged CTVSTAR and CTVEAM over time. Interestingly, the need for redo ablation decreased with increasing CTVs. Conclusion Our study demonstrates the efficacy of STAR treatment for refractory VT. Our confidence in STAR led to higher CTVs and lower RedoA over time. The high variability of CTV delineation using two different protocols suggests that STAR planning phase can be optimised by appointing intraprocedural anatomical landmarks to the VT substrate.

SLAM-guided catheter ablation of AVNRT: single-center experience

Abstract Aims Three-dimensional mapping systems have been utilized to reduce fluoroscopy and minimize complications in patients with AVNRT. Recently, voltage-gradient mapping has been introduced to visualize low-voltage bridges. However, there are some limitations of voltage assessment due to catheter contract. Therefore, new Slow pathway Late Activation Mapping (SLAM) has been recently used to reveal slow conduction zone in AVNRT patients. Method and materials Seven adult patients with diagnosis of typical AVNRT were included. Electro anatomical mapping systems was used in all patients. Voltage and late activation mapping were performed with high-definition multipolar catheter. His cloud was also tagged in all patients. Voltage of 0.20-0.50 mV was used to delineate voltage-bridges. Latest activation in the SP area along with voltage-guided bridges were targeted with either radiofrequency ablation (RFA) or focal cryoablation (Figure 1 and 2). Results Limited fluoroscopy was used in 4 patients. Acute success was achieved in all patients. Patients had no structural heart disease. Detailed clinical and procedural data was depicted in Table. Cryoablation was used in 2 patients due to very small Koch triangle. Each cryolesion applied for 240 secs and overall, 3-4 lesions were delivered. Ablation at late activation areas successfully eliminated slow pathway. In most of cases, one ablation lesion was adequate to see junctional beats and elimination of dual AV nodal physiology. Conclusion SLAM is effective in guiding catheter ablation of AVNRT, with a complete acute success rate and no recurrences at short-term follow-up.

The procedural characteristics of radiofrequency ablation points in patients undergoing atrial fibrillation ablation: comparison between standard vs very high-power short-duration

Abstract Introduction Atrial fibrillation ablation has a central role in the treatment of atrial fibrillation. Radiofrequency (RF) ablation is one of the possible energy sources used for the procedure. Recently, the development of new catheters has made it possible to modify the amount of power delivered by moving from a standard ablation to a very high-power short-duration (VHPSD). The objective of the study is to compare the delivery features of the RF points between standard RF vs VHPSD. Methods All the patients underwent RF ablation of paroxysmal atrial fibrillation. The procedure was performed using an electroanatomical mapping system under conscious sedation. All patient received a heparin bolus for ACT>300. The anatomy of the left atrium was reconstructed with a high-density catheter. Radiofrequency (RF) was applied following a wide antral circumferential approach (WACA) obtaining the isolation of the veins. The use of the ablation catheter was at the discretion of the operator and the choice was between a standard open-irrigated catheter with force sensor (Smartouch SF) and an irrigated, temperature-controlled contact-force sensing capable of delivering VHPSD (QDOT MICRO). For every patient, data from each individual RF delivery point were collected and analysed. Results A total of 72 consecutive patients were collected (26 QDOT group vs 46 standard group). Average total number of ablation point for obtaining complete pulmonary vein isolation with WACA was lower in the QDOT group (QDOT group 37,8±11 vs 42,1±18 standard group). As expected, the average duration (QDOT group 3.9±0.1s vs 12.7±2.4s standard group) and the average power delivered was significantly different between the two group (QDOT group 89,8±0.8W vs 33.0±1.4W standard group). Average basal impedence was similar (QDOT group 133.2±11,6 ohm vs 122.4±11,4ohm standard group) while impedence drop was significantly different (QDOT group 12.2±2.4 vs 9.9±2.4s standard group). Conclusion VHPSD ablation allows isolation of the pulmonary veins to be achieved with fewer ablation points and more quickly. It is also associated with a greater impedence drop during delivery. More studies are needed to see if this also corresponds to a lower number of recurrences after ablation.

Electrophysiological characteristics and durability of index pulsed field ablation lesions from redo procedures for atrial arrhythmia recurrences

Abstract Background Catheter ablation for atrial fibrillation (AF) has been performed using mainly thermal energy sources (radiofrequency, cryo, or laser). Pulsed field ablation (PFA) is a novel energy with interesting safety and effectiveness demonstrated in previous preclinical and clinical trials. Purpose We sought to assess the electrophysiological characteristics and durability of PFA index procedure procedures using a pentaspline PFA catheter as assessed based on redo procedures in patients with AT/AF recurrences. Methods A total of 169 patients (paroxysmal AF (PAF), 120; persistent AF (PsAF), 49) who underwent PFA using a pentaspline PFA catheter in the index procedure from November 2021 to July 2023 were studied. Pulmonary vein isolation (PVI) was performed with PFA in all patients with additional PFA lines: i)posterolateral mitral isthmus (MI) ablation in 25, ii) posterior line in 40 patients. Twenty-seven patients (PAF, 11; PsAF, 16) had atrial arrhythmia (atrial tachycardia (AT) or AF) recurrence after a 3-month blanking period (16%). We analyzed the electrophysiological characteristics of previous PFA lesions in 18 (PAF, 8; PsAF, 10) out of 27 patients in whom an activation and voltage mapping using 3-D electroanatomical mapping system was available. Results PV reconnections were identified in 7 of 18 patients (13PVs/69PVs ,18.8%) at the PV-LA junctions and carina regions of both left PVs and right PVs, mainly at the anterior aspect of right PV carina (n=6). In 6 out of 10 redo cases, posterolateral MI line using PFA was performed in the index procedure based on our strategy for PsAF ablation. In these 6 cases with previous MI line using PFA for PsAF ablation endocardial PFA was combined with marshall vein ethanolization(Et-VOM). Additional RF endocardial ablation and in the CS was needed to achieve MI block in 2 (33%) in the index procedure. 3D mapping of redo cases showed MI line gaps in 6/6 (100%). In 3 of those patients, the clinical arrhythmia recurrence was a perimitral AT (50%). Nine of the 10 PsAF patients who underwent a redo procedure had an index procedure complete posterior line. Remapping demonstrated durable block in 7/9 (78%). One of these patients presented with a roof dependent AT diagnosed in the redo procedure. Durable posterior lines received a significantly larger number of PFA deliveries during the index procedure: 16.4±3.3 vs 10.0±2.8 respectively, p=0.041). Conclusion This study based on redo cases after PFA using a pentaspline PFA catheter shows that PFA is associated with high durability for PVI and posterior line ablation. However the durability of MI line are poor, even when combined with VOM ethanolization. Further research is needed to define the optimal number of deliveries required to achieve durable posterior line block.

Feasibility and safety of cavotricuspid isthmus ablation using exclusive intracardiac echocardiography guidance: a proof-of-concept, observational trial

Abstract Introduction Catheter ablation is the preferred treatment for typical atrial flutter (AFl), although it can pose challenges due to anatomical abnormalities. The integration of 3D electroanatomical mapping systems (EAMS) has notably diminished the need for fluoroscopy in AFl ablation procedures. Intracardiac echocardiography (ICE) has also demonstrated advantages in reducing radiation exposure during AFl ablation. Nevertheless, there is a lack of evidence on the feasibility of ICE-guided, zero-fluoroscopy AFl ablation without the use of EAMS. Methods In this prospective study, we enrolled 80 patients with CTI-dependent AFl. The initial 40 patients underwent ablation guided by standard fluoroscopy along with ICE (Standard ICE group), whereas the remaining 40 patients underwent zero-fluoroscopy ablation exclusively using ICE (Zero ICE group). Procedure outcomes, including acute success, procedural duration, fluoroscopy duration, radiation dose, and any associated complications, were compared between the groups. Results Both groups achieved a 100% acute success rate. In the Zero ICE group, the zero-fluoroscopy approach was successfully executed in 39 out of 40 cases (97.5%). There were no significant differences in procedure time (55.5 (46.5; 66.8) min vs. 51.5 (44.0; 65.5), p=0.50) and puncture to first ablation time (18 (13.5; 23) min vs. 19 (15; 23.5) min, p=0.50) between the groups. The Zero ICE group had significantly lower fluoroscopy time (57 (36.3; 90) sec vs. 0 (0; 0) sec, p<0.001) and dose (3.17 (2.27; 5.63) mGy vs. 0 (0; 0) mGy, p<0.001 compared to the Standard ICE group. Total ablation time was longer in the Standard ICE group (597 (447; 908) sec vs. 430 (260; 750), p=0.02), but total ablation energy (22458 (14836; 31116) Ws vs. 17043 (10533; 29302) Ws, p=0.10) did not differ significantly. First-pass bidirectional conduction block of the CTI and acute reconnection rates were comparable between the groups. No complications or recurrences were noted during the follow-up period. Conclusion ICE-guided, zero-fluoroscopy CTI ablation for AFl using only ICE is feasible and safe. This method effectively eliminates radiation exposure without compromising procedural duration, total ablation time, or acute success rates.isthmus ablation by ICE

Digital health in the electrophysiological lab: Initial experience, safety and feasibility using remote support for arrhythmia ablation-Results of REMOTE-VA study

Abstract Background In most electrophysiology (EP) labs, electroanatomical mapping (EAM) systems are operated on site by qualified staff or field technical engineers (FTE). Due to lack of skilled personnel, the FTE usually must travel between different hospitals and procedures must be planned in advance. Ablation of ventricular arrhythmias (VA) represents the most complex procedure in the field. The use of remote support (RS) to guide complex EP procedures has the potential to increase flexibility, reduce travel times and maximise healthcare resources. Purpose To evaluate the safety and feasibility of RS as compared to on-site support guided catheter ablation procedures for VA. Methods All patients undergoing ventricular tachycardia (VT) or premature ventricular complex (PVC) ablation using remote support were included. The electronical system of the hospital was searched for 30 days postprocedural emergency department (ED) visits, unplanned ambulatory presentations, and readmissions. RS guided three-dimensional (3D) mapping was achieved by connecting the EAM software with an integrated audio-visual solution for remote support. Internet connection-based headphones and high-resolution cameras ensured the communication between the operator and the FTE, who worked exclusively from home office. The control group consisted of an equal number of patients matched for the type of procedure and undergoing on-site guided procedures. All ablations were performed using high density 3D mapping, as per institutional standard. Results Between October 2022 and October 2023, a total of 25 patients underwent VT (32%) or PVC ablation in our centre using RS and were compared to 25 patients undergoing the same procedures under on-site guidance. In the RS group one patient underwent epicardial VT ablation and another one bipolar ablation for VT Storm. The demographic data were similar between the groups. The median procedure time was 120 (93, 143) minutes in the RS group and 112 (95, 138) minutes in the control group (p=0.95), while the fluoroscopy time was 11.4 (7.0, 14.0) and 7.26 (5.0, 10.9) minutes respectively (p=0.08). The procedural success was achieved in 96% procedures in the RS group and in 100% in the control group. No technical issues or changes to on-site support were reported. One minor intraprocedural complication was noted among the control patients, while 24% of the patients in each group developed minor complications until discharge. Two patients in the RS group and one in the control group had ED visits, while only one patient in the control group had an unplanned ambulatory presentation. One unplanned readmission was reported in the control group (Table 1). Conclusions Even in the most complex procedures including epicardial ablation, the use of RS was feasible and safe in this single centre study. This approach has the potential to increase the feasibility in case of emergency procedures, reduce travel times, and maximise healthcare resources.

Imageless electrocardiographic imaging for atrial electrophysiological characterization: a validation study

Abstract Background The mechanisms responsible for atrial fibrillation (AF) are not yet fully understood and treatment strategies remain suboptimal. Electrocardiographic imaging (ECGi) could provide new insights into the arrhythmogenic substrate’s characterization. Objective To validate a novel imageless ECGi technique against electroanatomical mapping (EAM) systems to evaluate its use in guiding therapeutic decisions. Methods Periprocedural ECGi was implemented on 12 patients submitted for pulmonary vein isolation with EAM arriving in sinus rhythm. As opposed to current methods requiring patient-specific torso-heart geometries from CT/MRI scans, the employed ECGi system computes a cardiac anatomical model from a 3D-camera torso reconstruction. Both ECGi signals and intracavitary recordings were acquired simultaneously during catheter stimulation from a single atrial site at two different pacing cycles and local activation time (LAT) maps were derived. As a result, an ECGi and an EAM map were obtained for both 300 and 600 ms distal coronary sinus pacing for each patient. These were then compared by splitting the left atrial geometries from both mapping methodologies into 7 predefined, clinically relevant regions and identifying the earliest and latest activation sites in each. Results For all 24 LAT maps under consideration, the pacing sites identified by non-invasive ECGi maps were consistent with those determined through EAM as 100% accuracy was obtained in terms of detecting the first activated region. As well as the correct stimulation area, according to the corresponding EAM instance, the earliest ECGi activations were also found in one of its immediate neighbours in 38% of the maps, indicating a broader region of interest. Regarding the latest activation sites, ECGi achieved an accurate localisation in 92% of the activation sequences and, similarly, other neighbouring regions showed the maximum LAT in one third of the studied maps. Conclusions Considering the spatial resolution constraints inherent to its non-invasive nature, imageless ECGi activation patterns are congruent with the gold-standard technique for substrate mapping without the need for prior medical imaging.

Real-world multicenter registry on a novel focal lattice tip catheter toggling between pulsed electric field and radiofrequency for atrial tachyarrhythmia ablation

Abstract Background Pulsed field ablation (PFA) has emerged as a novel non-thermal energy source for cardiac tissue ablation. A novel focal 9mm lattice tip catheter, namely Sphere-9 (Affera Inc), has recently received regulatory approval; the technology is part of a technology that allows the delivery of either pulsed electric field or radiofrequency energy and incorporates a proprietary 3D electroanatomical mapping system. Purpose To describe the first real-world, multicenter experience with the AfferaTM system. Methods Consecutive AF patients undergoing first-time or redo atrial tachyarrhythmia ablation with the AfferaTM system in two different centres between August and November 2023 were prospectively enrolled. PFA was always used to ablate the posterior left atrium, whereas anterior applications were performed using either radiofrequency energy (RF/PF strategy) or PFA (PF/PF strategy) based on operator's discretion. Data on first-pass pulmonary vein isolation (PVI) and posterior wall isolation (PWI), as well as success rate of extrapulmonary ablation were reported. Primary safety endpoint included any technology-related periprocedural complications. Results 46 patients (mean age: 67±10; 41.3% males, 60.8% non-paroxysmal AF) were included. 5 (10.8%) patients were in atrial flutter (AFlu) at the beginning of the procedure, whereas AF was the rhythm at presentation in 19 (41.3%) others. First-time PVI was performed in 37 (80.4%) patients, 68.4% of whom received concomitant PWI. PVI was performed with PFA-only in 27% of them. First-pass isolation was achieved in 97.3% and 100% of PVI and PWI cases, respectively. Additional lesions included an anterior or posterior mitral line (6 and 15 patients), CTI (4 patients) or substrate ablation in 3 patients. Evidence of first-pass line block was documented in 96.4% of patients. The remaining 9 (19.6%) patients had already undergone a previous ablation; remapping showed 27.7% of PVs requiring reisolation. PWI was performed in 88.9% of them, for the first time (75%) or due to reconnection (25%). Additional lesions included an anterior or posterior mitral line (3 and 3 patients) or CTI in 2 patients. Evidence of first-pass line block was documented in 100% of patients. In 3 AFlu patients, the arrhythmia was mapped and termination was achieved while performing an AML (2 patients) and CTI (1 patient). Procedural duration was 96.5±15.6 min for first time and 97.8±12.6 min for redo procedures. Mean left atrial dwelling and fluoroscopy times were 75.4±17.6 min and 7.36±2.1 min, respectively. No technology-related complications were documented. Conclusions AF ablation with the focal 9-mm lattice tip catheter Sphere-9 confirmed high efficacy and safety in a real-world population.

Safety and feasibility of zero-fluoroscopy technique in ablation-index guided pulmonary vein isolation: a prospective, single center trial

Abstract Introduction Pulmonary vein isolation (PVI) represents the cornerstone of catheter ablation procedures in patients with symptomatic paroxysmal/persistent atrial fibrillation (AF). Conventionally, PVI is performed using fluoroscopy, but it can also be performed using the zero-fluoroscopy (ZF) technique with the assistance of electroanatomical mapping systems and intracardiac ultrasound, achieving fluoroscopy-free procedures. Purpose Our study aimed to compare procedural data of ablation-index guided point-by-point radiofrequency (RF) PVI performed with non-zero-fluoroscopy (NZF) vs. ZF approaches. Methods We enrolled 100 consecutive patients undergoing PVI for antiarrhythmic drug- refractory AF in our prospective observational study. In the first 50 cases, PVI was performed using the NZF technique, and in the other 50 cases, the ZF technique was applied. Procedural time, fluoroscopy exposure, ablation parameters, and the occurrence of complications were compared between the two groups. Results Compared to the NZF group, procedural time (59.6±10.7 min vs. 74.6±13.2 min, p<0.0001) was significantly shorter in the ZF group. This difference was mainly driven by the time from puncture to the beginning of left atrial mapping, which was significantly longer in the NZF group (17 [16; 20] min vs. 31 [23; 34.5] min, p<0.001). No differences were found between the two approaches in the number of RF applications (81 [73; 103] vs. 83 [71; 91], p=0.67), total ablation energy (54986 ± 13093 Ws vs. 55500 ± 11907 Ws, p=0.48), and the left atrial dwelling time (41.5 [36; 52.5] min vs. 40.5 [35; 46], p=0.14). No complications occurred in either group. In the ZF group, complete elimination of fluoroscopy was achieved in all cases, resulting in significant differences in fluoroscopy time (0 [0; 0] sec vs. 132 [100; 160] sec, p<0.0001] and dose (0 [0; 0] mGy vs. 4.8 [4.1; 8.2] mGy, p<0.0001) compared to the NZF technique. The acute success rate was 100% in the study population, and no complications occurred during the study period. Conclusion Ablation-index guided ZF PVI is feasible and safe. Using this technique, the procedure time can be shortened besides achieving a similar acute success rate without increasing complications.

Left ventricular wall thickening predicts left atrial low voltage areas in patients undergoing catheter ablation for atrial fibrillation

Abstract Background The success rate of circumferential pulmonary vein isolation (CPVI) remains suboptimal in patients with paroxysmal and persistent atrial fibrillation; moreover, the detection of low voltage areas (LVA) in the left atrium does predict an even higher recurrence rate of atrial tachyarrhythmias after the procedure. Left ventricular wall thickening (LVWT) is known to correlate with left atrial volume; however, no data is available whether LVWT is predictive of the presence of left atrial LVA. Purpose The aim of this study was to investigate whether LVWT is predictive of left atrial LVA and to verify that the presence of LVA confer a higher arrhythmia recurrence rate after catheter ablation for atrial fibrillation. Methods A total of 374 patients who undervent CPVI with the use of 3D electroanatomical mapping system as a primary procedure were enrolled in the study. Transthoracic echocardiography was performed in all patients prior the procedure with measurement of the thickness of the septum and the posterior wall. Patients were classified based on LVWT as normal (females:≤9mm, males:≤10mm), borderline (females:10-11mm, males: 11-12mm) and increased (females:≥12mm, males:≥13mm). A detailed left atrial voltage map was obtained in all patients prior to ablation with the identification of LVA (bipolar voltage <0.5mV with an area >5cm2). Arrhythmia recurrence was defined as documented atrial fibrillation or atrial tachycardia lasting for at least 30 seconds. Results Among 374 patients (mean age: 59.0±10.2 years, 131 females) 94, 195 and 85 were considered to be normal, borderline and increased based on LVWT, respectively. LVA were found in 29.9% (112/374) of patients. According to LVWT, LVA were detected in 16.0% (15/94), 31.3% (61/195) and 42.4% (36/85) in patients with normal, borderline and increased wall thickness, respectively, p=0.005. Patients with left atrial LVA had a higher [60.7% (68/112)] arrhythmia recurrence compared to those without low voltage areas [35.1% (92/262)] during a mean follow-up of 2.1±1.9 years, p<0.0001. Conclusions Left ventricular wall thickening predicts the presence of left atrial low voltage areas in patients undergoing catheter ablation for atrial fibrillation. Low voltage areas confer a higher arrhyhtmia recurrence rate during follow-up.

Optimized workflow for pulmonary vein isolation using very high power short duration radiofrequency ablation

Abstract Background Point-by-point radiofrequency ablation is the most used invasive treatment of atrial fibrillation (AF). However, single-shot technologies are largely widespread due to their proved safety and efficacy. QDOT MICRO (QDM) is a novel contact force–sensing catheter optimized for temperature-controlled radiofrequency (RF) ablation that allows to maintain target temperature during 90 W ablations for ≤4 seconds. Purpose This study evaluates procedural safety and effectiveness as well as long-term effects of an optimized procedural workflow using QDM catheter to perform wide atrial circumferential ablation in patients with paroxysmal AF. Methods Consecutive patients referred for paroxysmal AF first ablation through pulmonary vein isolation (PVI) were prospectively enrolled. Every procedure was performed in general anesthesia by using CARTO3 Electroanatomical Mapping System BiosenseWebster QDM catheter and Deflectable Sheet VIZIGO as single sheet in left atrium. VHPSD was performed to encircling the posterior wall, while conventional-power temperature-controlled (CPTC) mode was used to encircling the anterior wall. The primary safety endpoint was incidence of primary adverse events within ≤7 days of ablation. The primary effectiveness endpoint was freedom from documented atrial tachyarrhythmia recurrence and acute procedural, repeat ablation, and antiarrhythmic drug failure. Results 120 enrolled participants (61 ± 12 years, 45% female) met eligibility criteria. Median procedural skin-to-skin time and RF application for ablating PVs were 56 and 17 minutes, respectively. Median ablation time was 22 minutes. First-pass isolation (entrance and exit block validation) was obtained in 98 % and inter-lesion distance was 4,8 ± 0,8 mm. In 100% of patients PVI was obtained without adverse events. The Kaplan-Meier estimated 12-month rate for clinical success (freedom from symptomatic recurrence of AF) was 93%, freedom from AF was 89% Conclusions PVI performed with point by point optimized workflow using VHPSD RF catheter in combination with steerable sheet is highly efficient and effective without compromising safety.

Single-centre experience with an electrogram-based artificial intelligence software system to identify drivers in pulsed field ablation of persistent atrial fibrillation

Abstract Background Ablation of persistent atrial fibrillation (AF) beyond pulmonary vein isolation (PVI) remains challenging, despite increasing numbers of eligible patients. Previous studies suggest a possible role for non-PVI lesions targeting atrial drivers, but their identification can be difficult and subject to inter-operator variability. Purpose We investigated feasibility for an electrogram-based artificial intelligence software system to assist in the identification of left or right atrial dispersion sites as ablation targets for persistent AF using the penta-spline multi-electrode pulsed-field ablation (PFA) catheter, a recent technique which is more conventionally employed for PVI. Methods This is a single-centre retrospective descriptive study of a cohort of patients with persistent AF, who underwent their first-time ablation from May to November 2023 using the Farawave PFA catheter (Boston Scientific) and the VX1 system (Volta Medical). This system relies on off-line pre-training of multiparametric machine learning algorithms on a database of annotated AF intracardiac electrograms. It connects to cardiac electrophysiology recording systems via a custom data cable to receive analogue data and digitize them through an integrated converter. Its algorithms analyse signals in the cardiac chamber of interest to adjudicate the local presence or absence of dispersion and provides relevant visual cues to operators in order to target energy delivery. Results We identified 16 patients who underwent PFA for persistent AF (long-standing in 5/16, 31.3%), including PVI and further ablation guided by VX1. See table 1 for baseline population characteristics and table 2 for procedural characteristics. All underwent ablation with uninterrupted anticoagulation, general anaesthesia, use of the Rhythmia electroanatomic mapping system and its Orion mapping catheter (Boston Scientific) to feed signals into the VX1 system. VX1-guided electrogram localization and ablation mostly targeted the anterior region of the left atrium (16 segments), followed by its septal region (6 segments) and its lateral region (4 segments); the median number of applications per procedure was 88 [IQR 68-108], including a median of 76 [61-85] in the left atrium and 12 [0-15] applications in the right atrium. The median procedure duration was 123 [114-137] minutes; the median fluoroscopy time was 32 [26-40] minutes and the median radiation dose was 12.5 Gy∙cm2 [10.0-25.8]. Sinus rhythm was restored either during ablation or by electrical cardioversion (see Table 2). Two complications occurred one femoral arteriovenous fistula requiring stenting and one tamponade requiring drainage. At a three-month follow-up, 87.5% did not present AF recurrences. Conclusion Real-time detection and annotation of electrograms to track dispersion using AI-assisted technology to support PFA with a multipolar catheter is feasible. The interest of the approach should be validated by further studies.Table 1.Table 2.

Use of a novel, mode-switching electroanatomic mapping function and its effect on procedure and fluoroscopy duration in de novo AF procedures

Abstract Background Electroanatomical mapping systems utilize either an impedance-primary (IP) or magnetic-primary (MP) coordinate system for navigation. IP systems allow visualization of metal within the impedance field and can be scaled with supplemental magnetic information. MP systems collect information from catheters with a magnetic sensor, and supplementary impedance information is used to visualize catheters without a sensor. One commercially available mapping system offers both IP and MP navigation modes; however, operators must select a mode at procedure start. A novel software function allowing for near-instant transition between modes was recently introduced; its impact on procedural metrics has not yet been quantified. Objective Assess the impact of a mode-switching software function (MS) on acute procedural metrics in de novo paroxysmal atrial fibrillation (PAF) cases in which both the IP and MP modes were used, compared to procedures in which IP or MP was used alone. Methods Observational data was collected from 309 de novo PAF cases performed at 63 centers in Europe, the US, and Australia. Ablation technology used, procedure duration, fluoroscopy time, and acute outcomes were collected. Results Of 309 cases analyzed, 157 (50.8%) used MS, 97 (31.4%) used MP alone, and 55 (17.8%) used IP alone. Radiofrequency ablation (RFA) was used in 291 (94.2%) cases, while the remaining 18 (5.8%) used cryoablation. Irrigated, contact force sensing RFA catheters were used in 153 (97.4%) MS, 89 (91.8%) MP, and 29 (52.7%) IP cases. Mean procedure durations for MS and MP cases were similar: 106.2±51.6 min and 106.8±53.0 min, respectively (p=0.93). However, IP cases were significantly longer than both MS and MP cases, 134.2±53.8 min (p=0.002). Fluoroscopy time was significantly less in the MS group compared to MP and IP groups: 3.9±5.5, 6.1±5.2, and 7.8±6.4 min, respectively (p<0.001). No fluoroscopy was used in significantly more MS compared to MP or IP cases: 72 (45.9%) MS, 10 (10.3%) MP, and 8 (14.5%) IP cases (p<0.001). When these 90 cases were excluded, mean fluoroscopy times were similar between MS, MP, and IP cases (7.1±5.6, 6.8±5.0, and 9.2±5.9 min, respectively (p=0.05)). Acute success rates were not significantly different between modes: 98.6% MS, 100% MP, and 100% IP (p=0.49). Conclusions In this analysis of international usage of a novel software function, cases utilizing MS had significantly shorter fluoroscopy durations with similar acute success rates and procedure durations than those using MP or IP. When zero fluoroscopy cases were excluded, there was no significant difference in fluoroscopy times; however, there were significantly more zero fluoroscopy cases in the MS group, indicating that, while MS supports and may encourage low-fluoroscopy workflows, differences in procedural metrics seen may be biased by operator preference. Future analyses are warranted to provide insight into operator-specific metrics when using MS.Fluoroscopy Duration Comparison

Intermittent hypoxia is significantly associated with low-voltage areas in patients with atrial fibrillation complicated by obstructive sleep apnea

Abstract Background Obstructive sleep apnea (OSA) is one of risk factors for atrial fibrillation (AF); however, how OSA affects the structural and electrical atrial remodeling is not well described. This study aimed to determine the association of OSA with left atrial (LA) size and LA low-voltage area (LVA), a known arrhythmogenic substrate for AF. Methods Eighty-three patients undergoing catheter ablation of AF (forty-nine with OSA [apnea–hypopnea index: AHI ≥ 5/h] and thirty-four control patients without OSA by full polysomnography or portable monitor) were studied. In all cases, LA maps were created using a three-dimensional electro-anatomical mapping system in sinus rhythm or pacing from the right atrium. LVA was defined as a bipolar voltage < 0.5 mV. %LVA is defined as ratio of LVA to LA area. Results LVA and %LVA were larger in OSA group as compared to Control group (6.0 ± 6.6 vs. 2.6 ± 3.2 cm2, P = 0.003 and 7.5 ± 8.5 vs. 3.5 ± 4.6 %, P = 0.008, respectively). On the other hand, there was no difference in LA size between the two groups. In addition, 3% oxygen desaturation index (ODI) was significantly correlated with %LVA (r = 0.282, P = 0.010), but not with LA size (r = 0.053, P = 0.637). Multiple regression analysis demonstrated that 3%ODI ≥ 30 (3.088, 1.078-8.851, P = 0.036) was significantly associated with %LVA after adjustment. Conclusion In patients with AF complicated by OSA, significant enlargement of the LVA was observed, but there was no evidence of enlargement in LA size. Intermittent hypoxia may be one of the mechanisms of this atrial electro-anatomical remodeling.figure 1figure 2

Impact of inter-lesion distance and first-pass isolation on outcomes of pulmonary venous isolation for paroxysmal atrial fibrillation.

Contiguity of ablation lesions is a critical determinant of success for paroxysmal atrial fibrillation (PAF) ablation. Evidence supports maintaining an inter-lesional distance (ILD) ≤ 6mm during pulmonary venous isolation (PVI). Meanwhile, first-pass isolation (FPI) on PVI outcome in follow-up was not deeply studied. The impact of ILD and FPI on PAF ablation outcomes was investigated. Consecutive PAF patients who underwent first-time antral PVI were recruited. Coordinates of ablation points were extracted from the electro-anatomical mapping system and analyzed using custom-developed software to determine the ILD. A gap is defined as ILD greater than 6mm. FPI was defined as the achievement of PVI by encircling the ipsilateral veins while simultaneously recording their electrical activity using a multipolar catheter. The primary endpoint was freedom from documented atrial arrhythmias including AF, atrial tachycardia (AT), or atrial flutter (AFL) lasting longer than 30s during follow-up. A total of 105 patients underwent first-time antral PVI. During 13.3 ± 0.6months of follow-up, atrial arrhythmias recurrence was noted in 22.9% of the patients. Atrial arrhythmia recurrence was significantly higher in patients with more gaps (> 2) (37.0% versus 11.9%, P < 0.01), and the number of gaps was an independent predictor of AF/AT/AFL recurrence. (Hazard ratio [HR] 1.20, 95% CI 1.03-1.40, P = 0.02). The group with FPI for at least one ipsilateral pair of PVs exhibited a decreased number of gaps (2.0 versus 7.0, P < 0.01) and demonstrated a significant correlation with a reduction of recurrence (HR 0.26, 95% CI 0.09-0.71, P = 0.01). Among 16 patients who underwent repeat ablation, the number of gaps during the index PVI was associated with PV reconnection (PVR) (P < 0.01). Gaps created during PVI are a modifiable determinant of AF/AT/AFL recurrence, and avoidance of gaps is crucial to improve clinical outcomes of PAF ablation. In addition, FPI exhibited a strong predictive capability for clinical success in patients with PAF.

Targeting Wavefront Discontinuity Linesfor Scar-Related Ventricular Tachycardia Ablation: A Novel Functional Substrate Ablation Approach.

The boundaries of critical isthmuses for re-entrant ventricular tachycardia (VT) are formed by wave-front discontinuities (fixed lines of block, slow propagation, and rotational propagation) seen during baseline rhythm. It is unknown whether wavefront discontinuities can be automatically identified and targeted for ablation using electroanatomic mapping systems. The purpose of this study was to assess the electrophysiologic characteristics of automatically projected wavefront discontinuity lines (WADLs) and outcomes of an ablation strategy targeting WADLs in a mixed cohort of VT patients. Late activation substrate maps were analyzed from 1 or more baseline rhythm wavefronts. WADLs were identified using the Carto Extended Early Meets Late module. Number, total length, and distance to critical VT sites were measured. VT recurrence and VT-free survival were followed. In total, 49 patients underwent 52 ablations with 71 unique substrate maps analyzed (18.8% epicardial; 62.0% right ventricular paced, 28.2% sinus rhythm, 9.9% left ventricular paced). A total of 28 VT critical sites were identified in 24 patients. WADLs were present in 49 of 71 (69.0%) maps. WADLs were present regardless of cardiomyopathy etiology, mapping wavefront, or surface. At a WADL threshold of 30%, 73.9% of critical VT sites were in close proximity (≤15mm) to a WADL. VT-free survival was 62% at 1 year, with a competing risk model estimating a 1-year risk of VT recurrence of 23%. WADLs can be automatically projected in a majority of patients in a mixed cohort of cardiomyopathy etiology, mapped wavefronts, and myocardial surfaces mapped. Targeting WADLs results in low rate of VT recurrence at 1 year.

ROLE OF CARDIOVASCULAR IMAGING IN CARDIO-ONCOLOGY: A LITERATURE REVIEW

Antitumor drugs are toxic to the cardiovascular system and directly affect cardiac function and anatomy. During the treatment of oncology, patients may experience complications in the form of asymptomatic myocardial dysfunction, severe heart failure, exacerbation of symptoms of coronary heart disease, thromboembolic complications, arterial and pulmonary hypertension, pericardial complications, valve defects and arrhythmias. A number of diagnostic tools are currently available to cardio-oncologists to detect cardiotoxicity, and the choice of imaging method depends on the availability of the specific diagnostic modality and its resolution. The main method for assessing the condition of the heart in cancer patients is echocardiography - a widely available method that enables to assess the structure of the heart and hemodynamics without exposing the patient to an additional dose of ionizing radiation. If imaging is insufficient, the recommended method for assessing cardiac structure and function is magnetic resonance imaging. Computed tomography of the chest, heart and coronary arteries is also used to diagnose complications of cancer treatment. In addition, nuclear medicine techniques, including gated radionuclide ventriculography, are also used to diagnose cardiotoxicity. Electroanatomical mapping systems combined with remote navigation are promising. Early detection of subclinical left ventricular myocardial dysfunction in cancer patients receiving potentially cardiotoxic drugs is advisable and aimed at secondary prophylaxis and prevention of mortality from cardiovascular diseases.

A real-time signal processing software package for the electrophysiology laboratory.

Real-time signal processing has to date been difficult to implement in the clinical electrophysiology laboratory. To date, no open access software solutions are available in electrophysiology (EP) laboratories to facilitate real-time intraprocedural signal analysis. We aimed to develop an open access, scalable Python plug-in to allow real-time signal processing during human EP procedures. A Python-based plug in for the widely available EnsiteX mapping system was developed. This plug-in utilized the LiveSync feature of the system to allow real-time signal analysis. An open access library was developed to allow end-users to implement real-time signal analysis using this platform, implemented in the Python programming language https://github.com/anand9176/WaveWatch5000Public. We have developed and demonstrated the feasibility of a readily scalable and open-access Python-based plug in to an electroanatomic mapping system (EnSiteX) to allow real-time processing and display of electrogram (EGM) based information for the procedural electrophysiologist to view intraprocedurally in the electrophysiology laboratory. The availability, to the clinician, of traditional and novel EGM-based metrics at the time of intervention, such as atrial fibrillation ablation, allows for key mechanistic insights into critical unresolved questions regarding arrhythmia mechanism.

Use of three-dimensional electroanatomic mapping for epicardial access: needle tracking, electrographic characteristics, and clinical application.

Pericardiocentesis is usually completed under fluoroscopy. The electroanatomic mapping (EAM) system allows visualizing puncture needle tip (NT) while displaying the electrogram recorded from NT, making it possible to obtain epicardial access (EA) independent of fluoroscopy. This study was designed to establish and validate a technique by which EA is obtained under guidance of three-dimensional (3D) EAM combined with NT electrogram. 3D shell of the heart was generated, and the NT was made trackable in the EAM system. Unipolar NT electrogram was continuously monitored. Penetration into pericardial sac was determined by an increase in NT potential amplitude and an injury current. A long guidewire of which the tip was also visible in the EAM system was advanced to confirm EA. Epicardial access was successfully obtained without complication in 13 pigs and 22 patients. In the animals, NT potential amplitude was 3.2 ± 1.0 mV when it was located in mediastinum, 5.2 ± 1.6 mV when in contact with fibrous pericardium, and 9.8 ± 2.8 mV after penetrating into pericardial sac (all P ≤ 0.001). In human subjects, it measured 1.54 ± 0.40 mV, 3.61 ± 1.08 mV, and 7.15 ± 2.88 mV, respectively (all P < 0.001). Fluoroscopy time decreased in every 4-5 cases (64 ± 15, 23 ± 17, and 0 s for animals 1-4, 5-8, 9-13, respectively, P = 0.01; 44 ± 23, 31 ± 18, 4±7 s for patients 1-7, 8-14, 15-22, respectively, P < 0.001). In five pigs and seven patients, EA was obtained without X-ray exposure. By tracking NT in the 3D EAM system and continuously monitoring the NT electrogram, it is feasible and safe to obtain EA with minimum or no fluoroscopic guidance.