High-density Mapping Catheter Research Articles

High-density mapping-guided ventricular tachycardia ablation in patients with ischemic cardiomyopathy: outcomes from a tertiary center cohort in Switzerland

Abstract Background Substrate-based ablation has emerged as a successful technique for VT ablation, especially in patients with ischemic cardiomyopathy with markedly reduced left ventricular function. High-density mapping catheters provide high-resolution electroanatomical maps and better discrimination of abnormal substrates and local activation in the heart chambers, making them a valuable and safe resource in the electrophysiology laboratory. Purpose The purpose of this study was to investigate differences in procedural characteristics and clinical outcomes of VT ablation with ischemic cardiomyopathy. VT ablations were guided by two mapping strategies: high-density mapping using a high-density mapping catheter and conventional mapping using an ablation catheter. Methods Patients with ischemic cardiomyopathy receiving VT ablation at our center between January 2018 and June 2023 were retrospectively included. Procedural characteristics and clinical outcomes were compared between patients receiving high-density mapping with a multielectrode-mapping catheter vs conventional mapping with a single-tip irrigated ablation catheter. Results Eighty-four patients with ischemic cardiomyopathy who underwent VT ablation were consecutively included (mean age 67 ± 12 years, mean LVEF 32 ± 11 %, 79 (94%) males). Fifty-seven (68 %) procedures were performed using high-density mapping, and 27 (32 %) conventional mapping. In the high-density mapping and conventional mapping group, the total procedure time was 256 ± 77 min vs. 232 ± 61 min (P < 0.05) and the total fluoroscopic dose was 1643 ± 204 μGy.m2 vs. 948 ± 105 μGy.m2 (P < 0.05), respectively,. However, there was no difference between the two groups in terms of acute success (84% vs 80%, P > 0.05) or major complications (5% vs 4%, P > 0.05). The mean duration of follow-up was 2.6 years (4 - 51 months). The 1-year mortality rates were 4% vs 7% in the high-density mapping and conventional mapping groups, respectively (P < 0.05). The 3-month and 1-year single-procedural sustained VT/VF-free rates were 77% vs 59% and 74% vs 63%, respectively (P < 0.05). The 1-year incidence of sustained VT/VF recurrence was 7.0 per 100 person-years in high-density mapping group, compared with 7.4 per 100 person-years in the conventional group. Conclusions VT ablation in patients with ischemic cardiomyopathy using high-density mapping appears to be superior to conventional mapping in terms of reducing postprocedural VT/VF recurrence and a subsequent reduction of overall mortality.Figure 1Figure 2

The role of high density mapping in cathether ablation of paroxysmal atrial fibrillation - preliminary results

Abstract Introduction Despite technical progress and numerous approaches in ablation strategies, long-term success in paroxysmal atrial fibrillation (PAF) treatment is still suboptimal. Non-transmural ablation lesions in antral isolation lines, causing late electrical reconnection between pulmonary veins (PVs) and left atrium (LA) could present one of the potenital issues for reduced effectiveness of radiofrequency cathether ablation (RFCA). Potentially, these lesions can be identified with high-density (HD) mapping as low voltage, fragmented electrocardiograms (LFEGMs) representing gaps in antral isolation lines. Purpose To compare the long-term pulmonary vein isolation (PVI) durability of two PVI verification methods (circumferential vs high-density mapping catheter) after catheter ablation of PAF. Methods Thirty-three patients with PAF were prospectively randomized to PVI verification by either circumferential mapping catheter (CM group) or HD mapping catheter (HD group). Patients in both groups underwent PVI according to the CLOSE protocol with PVI verification after a 30 minute waiting period. Additionally, in the HD group antral ablation lines were mapped to search for LFEGMs that were defined as fragmented signals (at least 3 deflections) and/or conduction to the LA during stimulation on the ablation line (10 mA at 1 msec) and/or voltage amplitude above 0.1 mV. If LFEGMs were found, additional ablations were performed until electrical inactivity was confirmed with the HD catheter. To monitor AF reccurence 6-day continuous holter ECG was performed after 3, 6, and 12 months after the initial procedure. Arrhythmia recurrence was defined as any atrial tachyarrhythmia lasting more than 30 seconds. Patients also underwent a mandatory second procedure 12 months after the initial PVI, during which HD re-mapping was performed to test durability of PVI and absence of conducting gaps in antral isolation lines. Results There were 16 patients in the CM group and 17 patients in the HD group. Baseline characteristics (gender, age, body mass index, LA volume index, left ventricular ejection fraction, CHA2DS2VASc score) did not significantly differ between the groups. Procedural characteristic are summarized in Table 1. There were significantly more isolated PVs at the remapping procedure in the HD group compared to the CM group (91.2% (62/68) vs 75.0% (48/64); P=0.021). There were also significantly more patients with all PVs durably isolated in the HD group (82.4% (14/17) vs 37.5% (6/16); P=0.008). However, arrhythmia recurrence rate was similiar between the CM and HD group (43.8% (7/16) vs 35.3% (6/17); P=0.640). Conclusion HD mapping improved PVI durability after 12 months compared to standard CM verification. However, lower number of isolated PVs in the HD group did not have an impact on arrhythmia reccurence.

Transbaffle or retrograde aortic approach for atrial arrhythmias ablation in patients with D-TGA treated with atrial switch surgery

Abstract Introduction Patients with D- transposition of the great arteries (TGA) treated with Senning or Mustard surgeries have high incidence of supraventricular tachycardias (SVTs). Accessing to the pulmonary venous atrium (PVAt) is frequently required to perform the ablation, however it can be challenging. Aim To investigate the differences between a retrograde aortic approach (Re-Aa) and transbaffle approach (TBa) for PVAt ablation in this set of patients. Methods Prospective observational study in a third level hospital since April 2018 until October 2022, with a medium-term follow-up. All consecutive patients (pt) with history of SVT and atrial switch surgery that underwent electrophysiologic study (EP) and electroanatomic mapping using a high-density Grid mapping catheter and a contact-force ablation catheter were included. Results A total of 25 EPs were performed in 20 pt (13 (52%) Female, median age 37 y.o [IQR 34-41], median follow-up time 13 month [IQR 10-37]). In 14 pt the PVAt was mapped and ablated via Re-Aa, and in 11 with TBa. Table 1 shows basal patients characteristics, note that no significant differences between groups were found. In 19 pt (76%) a CTI-dependent flutter was documented (10 (71%) in Re-Aa group and 9 (82%) in TBa, p=0.6). Furthermore, in 7 pt other tachycardia circuits were found. Accurate mapping of all the CTI walls were achieved with both strategies, however, the posterior PVAt wall and the pulmonary veins were suboptimal mapped with Re-Aa due to a lack of catheter contact. Acute ablation success was 83% in Re-Aa and 100% in TBa (p=0.5). Despite a higher recurrence rate in the Re-Aa in the first months (20% vs 0%), no significant differences in recurrences were found between groups within 1 year of follow-up (HR 1.3 [95%CI: 0,2-7], p=0.8) (FIGURE). Complication rate was 20% in Re-Aa and 0% in TBa. All complications were directly related to the arterial vascular access (1 femoral pseudoaneurysm, 1 iliac dissection, 1 mediastinal hematoma), and were successfully treated. Conclusion In D-TGA treated with atrial switch surgery, PVAt mapping and ablation is feasible with both strategies with a high acute success rate and without significant differences in recurrences at mid-term follow up. However, TBa is associated with a lower complications rate and also with a better catheter contact and accurate mapping in the PVAt posterior wall.

Inter-patient variability of local cycle length and duty cycle distribution of the atrial fibrillation substrate beyond pulmonary vein isolation

Abstract Appropriate targets for catheter ablation of atrial fibrillation (AFib) beyond pulmonary vein isolation (PVI) are still controversially discussed. Various approaches such as ablation of complex fractionated atrial electrograms (EGMs), areas with spatio-temporal dispersion, and areas with increased rotor density have not been reproducible or failed to improve clinical success rates. The local cycle length (CL) and duty cycle (DC) distribution during AFib offer novel measures to characterize the atrial substrate. This study aims at providing first insights into the inter-individual variability of observed CL and DC distributions, their interdependence, and their correlation to the duration of AFib episodes to improve the individual characterization of the AFib substrate and tailor ablation strategies in future. In patients with recurrence of AFib despite PVI, a high-resolution 3D map was recorded at baseline during AFib. Intracardiac EGMs were preprocessed to improve local signal quality and far field suppression. EGMs were recorded with the multipolar, basket-shaped high-density mapping catheter. Local CL and DC distribution were visualized using a scatter plot and histograms. CL quantifies the time between subsequent local activations, DC quantifies the fraction of CL with local EGM activity, and the confidence (conf) feature quantifies the spatiotemporal consistency of EGM morphology. Only EGMs with conf > 0.6 are analysed. Feature calculation does not only take into account single EGMs but a weighted conglomerate of all acquisitions within a series of beats. Adjustable CL and DC thresholds allow highlighting regions within the 3D map for individual spatial analysis. 14 patients (7x paroxysmal AFib, 7x persistent AFib) were enrolled. All subjects underwent repeat ablation after PVI due to recurrence of AFib. CL and DC histograms were of highly individual shape. The most prevalent feature value varied from 158ms to 263ms for CL and from 38% to 96% for DC; histogram widths (inter-quartile-range) from 10ms to 34ms and from 26% to 36%, respectively. Normal distributions, multimodal distributions, and skewed distributions exhibiting a dominant peak were observed for CL. Both the most prevalent CL and the width of the distribution were highly individual. DC was observed to be normally to equally distributed with mostly broad bandwidths. Linear regression revealed a positive dependency between the most prevalent CL and the width of CL distributions. The most prevalent value and the width of both CL and DC did not differ significantly for the paroxysmal and persistent subgroup. Compare figure for detailed results. CL and DC distributions can help to characterize the highly individual type of AFib. The presented results suggest that there will not be a one-size-fits-all ablation approach for the AFib substrate. Further research is needed to identify clusters of similar pattern and individually adjust the ablation strategy.

Omnipolar mapping and vector mapping in premature ventricular contractions ablation: a comparison with bipolar mapping

Abstract Background Omnipolar Mapping, with HD Grid high-density mapping catheter, overcomes the dependency of EGM characteristics to wavefront orientation, reconstructing the highest peak-to-peak voltage attainable within the electric field and the real wavefront direction, displayed in the form of a local activation vector [1][2]. Methods Consecutive patients who underwent radiofrequency ablation of PVCs from October 2021 to August 2023 at the Hospital Clinic of Barcelona were included in the study. EAM was performed with EnsiteX mapping system, Advisor HDgrid was used as mapping catheter. An activation map was performed if enough PVC burden. The area of interest was determined by earliest activation time combined with the morphology of unipolar electrogram during activation mapping. RF was delivered at the area of interest with target temperature of 45°C and maximum power of 50W. Both bipolar and omnipolar maps were analysed retrospectively. The reviewer was blinded to the ablation set for this analysis. A window of interest was created uniformally for all maps by defining a caliper within 15 ms before the onset of PVC. Activation vectors were displayed on the map and visually analysed. Three specific patterns were identified: Starburst, Homogeneous and Chaotic. Area of the earliest activation was measured. Earliest site of bipolar and omnipolar maps and specific location of star burst pattern were tagged. The site of the effective RF ablation was identified and the distance between points was determined. Results 18 patients were included. Overall, 11(61%) were males; age: 57,9±15,2 ys, 6(33%) patients haven't structural heart disease, 4(22%) presented PVC-induced cardiomyopathy. Mean left ventricular ejection fraction was 46±10. Mean PVC burden was 27±10%. In 9(50%) patients, PVCs were ablated from RVOT, 4(22%) in LVOT, 1(5%) in the left superior fascicle, 1(5%) in the antero-lateral papillary muscle, 2(10%) in the perihissian area and 1(5%) in the aortomitral continuity. Compared with bipolar, omnipolar mapping showed a smaller area of earliest activation(2,13±1,9mm2 vs 3,34±2,1 mm2,p<0,001), a shorter distance of the earliest point to starburst region(4,2±4,1mm vs 7,8±4,2mm,p<0,001) and shorter distance to the effective ablation site(6,1±3,9 mm vs 8,33±4,2mm, p<0,07). No significative difference was found between the effective RF ablation site and the starburst area compared to the distance between the effective RF ablation site and the omnipolar earliest deflection (6,11±3,9mm vs 6,5±4,3mm, p=0,6). No statistical significative difference was found between the timing of the earliest deflection in both settings (33,2±12,5 ms vs 31,5±12 ms, p=0,2) Conclusions Omnipolar mapping allows a better identification of the area of interest in PVC’s ablation compared to bipolar mapping. Vector mapping is a valuable asset to identify the earliest activation point to guide PVCs catheter ablation.Retrospective EAM analysisArea/distance measurements

Temporal stability of local cycle length and duty cycle distribution during atrial fibrillation

Abstract Appropriate targets for catheter ablation of atrial fibrillation (AFib) beyond pulmonary vein isolation (PVI) are still controversially discussed. Since available parameters to analyze the vulnerable substrate are very limited, there is the need to define and understand tailored features. Mapping during AFib can be particularly challenging due to its non-repetitive nature. Amongst others, temporal stability despite changing activation sequences is an essential requirement for features applied to AFib maps. The local cycle length (CL) and duty cycle (DC) offer novel measures to characterize the atrial substrate during AFib. This study aims at providing first insights into the temporal stability of CL and DC during AFib in order to assess the suitability of both features for the characterization of the individual substrate and tailor ablation strategies in future. In patients with recurrent AFib after PVI, two high-resolution 3D electro-anatomical maps were recorded sequentially during AFib before any ablation. Intracardiac electrograms (EGMs) were preprocessed to improve local signal quality and far field suppression. EGMs were recorded with a multipolar, basket-shaped high-density mapping catheter. Local CL and DC distribution were visualized using scatter plots and histograms. CL quantifies the time between subsequent local activations, DC quantifies the fraction of CL with local EGM activity, and the confidence (conf) feature quantifies the spatiotemporal consistency of EGM morphology. Only recordings with conf > 0.6 are analyzed. Feature calculation is based on a weighted conglomerate of all acquisitions within a series of beats. Adjustable CL and DC thresholds allow highlighting regions within the 3D map for individual spatial analysis. Both the global distributions and the local occurrence of CL and DC were compared in order to assess temporal stability. Four patients (2x paroxysmal AFib, 2x persistent AFib) were enrolled. All subjects underwent repeat ablation after PVI due to recurrence of AFib. Table 1 summarizes mapping parameters for both AFib maps in individual patients. Despite differences in mapping time and the number of EGMs, CL and DC histograms were significantly similar when comparing maps within one patient. For individually selected ranges of CL and DC in the upper left corner of the scatter plot (short CL and high DC), localization of corresponding areas was comparable in both 3D maps. An example is shown for patient I in the left and central column of the figure. CL and DC distributions were temporally stable features for all patients in this study cohort. Localization of EGMs of given CL and DC range within the 3D maps were comparable but not identical for arbitrarily selected ranges. CL and DC can therefore be considered valid features for substrate characterization during AFib. Further studies will need to investigate how ablation strategies can be derived from individual CL and DC distributions.

Role of Sleep-Disordered Breathing and Epicardial Connections in the Recurrence of Atrial Fibrillation.

The presence of epicardial connections (ECs) between the pulmonary veins (PVs) and atrium may contribute to atrial fibrillation (AF) recurrence. This study aimed to determine the impact of sleep-disordered breathing (SDB) on the presence of ECs and the interplay between SDB and ECs on AF recurrence.We retrospectively reviewed 400 consecutive non-valvular AF patients. Among them, 235 patients exhibiting a 3% oxygen desaturation index (ODI) of ≥ 10 events/hour underwent polysomnography to evaluate the SDB severity, measured by the apnea-hypopnea index (AHI). To facilitate the ablation of AF and ECs, a high-density mapping catheter (HDMC) was employed. AF recurrence was evaluated over a 12-month period post-AF ablation.The key findings included: 1) 63% of AF patients with ECs had SDB with an AHI ≥ 20 events/hour. 2) Despite achieving complete PV isolations and precise EC ablation using an HDMC, SDB presence was associated with an increased AF recurrence. 3) Continuous positive airway pressure therapy for SDB improved AF recurrence among the AF patients with both ECs and SDB (57% versus 73%; P = 0.016). 4) AHI (odds ratio [OR] = 1.91, ≥ 28.4 events/hour) and left atrial volume (LAV) (OR = 1.42, ≥ 128.3 mL) were independent predictors of the presence of ECs, and AHI (OR = 1.44, ≥ 27.8 events/hour) was an independent predictor of the presence of AF recurrence.It is essential for physicians to recognise the potential complexity of ECs and SDB in AF patients. Thus, screening and treating SDB in AF patients presenting with ECs might play a pivotal role in suppressing AF recurrence.

Initial clinical experience of atrial fibrillation ablation guided by a cryoballoon-compatible, magnetic-based circular catheter.

The circular catheter compatible with current cryoballoon system for atrial fibrillation (AF) ablation is exclusively sensed by impedance-based electro-anatomical mapping (EAM) system, limiting the accuracy of maps. We aim to investigate the feasibility and safety of a magnetic-based circular mapping catheter for AF ablation with cryoballoon. Nineteen consecutive patients who underwent pulmonary vein isolation (PVI) with cryoballoon for paroxysmal or persistent AF were included. EAMs of left atrium (LA) created by the LASSOSTAR™NAV catheter (Lassostar map) before and after PVI were compared to that generated by a high-density mapping catheter (Pentaray map) from different aspects including structural similarity, PV angle, LA posterior wall (LAPW) and low voltage areas (LVAs), and the amplitude of far field electrograms (FFEs) recorded by catheters. All patients had successful PVI without major complications. With similar mapping time and density, the LA volume calculated from the Pentaray map and Lassostar map were comparable. There were no significant differences in PV angle of all PVs and PW area (16.8 ± 3.2 vs. 17.1 ± 2.8, p = .516) between Pentaray map and Lassostar map. High structural similarity score was observed between two maps (0.783 in RAO/LAO view and 0.791 in PA view). Lassostar map detected lesser but not statistically significant extension of LVA (13.9% vs. 18.3%, p = .07). Amplitude of FFE was larger at the right superior PV on Lassostar map (0.21 ± 0.16 vs. 0.14 ± 0.11 mV, p = .041) compared to that on the Pentaray map. In our initial experience, PVI with cryoballoon and magnetic-based circular LASSOSTAR™NAV catheter was safe and effective based on the accurate LA geometry it created.

Identification of the fossa ovalis by voltage mapping using a high-density mapping catheter

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Transseptal puncture (TP) is routinely performed under fluoroscopy and/or echocardiography guidance. Additional methods to localize the fossa ovalis (FO) may decrease radiation exposure, as well as periprocedural risk. In the recent years, high-density mapping (HDM) catheters have been used for mapping and ablation of left atrial (LA) arrhythmias. Purpose The aim of this study is to determine whether a HDM catheter can reliably identify the specific FO electrogram (EGM) patterns. Methods During atrial fibrillation (AF) ablation, a voltage map of the right-sided atrial septum was created using a HDM catheter (Pentaray, Biosense Webster, USA, spacing 2-6-2 mm). The location of the FO was identified by transesophageal echocardiogram and fluoroscopy guidance prior to TP. At the end of the procedure, a 3D phantom was created during catheter retrieval from the left to the right atrium through the TP. Post ablation analysis was done to evaluate whether the HDM catheter was able to record EGM characteristics of the FO. Results Fifteen patients were included (male 63%, mean age 61.2±11.7 y. o.); 80% of the cases were in sinus rhythm, 53% had a normal LA size, and the mean CHADS2-VA2SC score was 1.5 ± 1.6. One patent fossa ovalis and one septal pouch of the left atrium were seen. In all patients, an area of low voltage could be identified in the vicinity of the transseptal puncture. In 74%, the location of transseptal puncture was inside of the area of low voltage. The mean voltage value of this area was 0.6 ± 0.3 mV, whereas the mean voltage value of the myocardium surrounding the "low voltage area" was 4.3 ± 2.1 mV (P<0.01). The surface of the low voltage could be best demarcated using a scale from 0.05 -1.5 mV with an area measured at 3.8 ± 2.6 cm2 [Figure 1]. At other voltage scales, the FO surface demonstrated smaller areas of low voltage (scale/surface [mV/cm2] : 0.05-0.5/ 0.8 ± 1.3; 0.05-1.0/2.2 ± 1.8; 0.5-1.0/2.3±1.6). In 63%, fractionated potentials were recorded in the area of the FO [Figure 1]. Conclusions Based on its EGM characteristics, the fossa ovalis can be accurately localized with a high-density mapping catheter. This finding will certainly help to implement radiation free procedure particularly when echocardiographic modalities are not available. Figure 1: Mapping of the region of the fossa ovalis with a high density mapping catheter revealed an area of low voltage with fractionnated electrogram. Fossa ovalis was identified by transseptal puncture. TP: phantom of the catheters, CS: coronary sinus, H: His, IVC: inferior vena cava, SVC: superior vena cava, * fractionnated electrogram

Omnipolar mapping improves substrate characterization and critical isthmus identification in atypical atrial flutters

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Characterizing atrial substrate and conduction properties is crucial to treat complex arrhythmias during catheter ablations. Unipolar and bipolar electrogram signals are routinely used with significant limits due to low detailed mapping, the impact of poor contact and far-field electrical signals. Moreover, signals morphology is dependent on the relative orientation of the catheter inter-electrode axis to the direction of activation. Omnipolar signals try to overcome this direction-dependence by using three adjacent electrodes to infer directional information about the local electric field. Purpose We compared omnipolar mapping (OM) signals with the traditional high-density bipolar mapping (BM) ones. Methods All the procedures were performed using a high-density grid-designed mapping catheter. The atypical left atrial flutters were mapped using both OM and BM configuration. All the analysis about voltage and potential duration are related to the entire left atrial surface excluding pulmonary veins. Results Ten atypical atrial flutters were mapped in the left atrium in seven patients (median age 70 y, 5 males). OM identified 7 double loops and 3 triple loops while BM identified 7 double loops, 2 triple loops and 1 single loop, missing 2 critical circuits (an example is shown in figure 1) Significant differences were present also in potentials amplitude (peak-to-peak voltage amplitude) in the critical isthmus with OM higher than BM (OM median 0.22 mV IQR [0.16 – 0.30] vs BM median 0.19 mV IQR [0.13 – 0.24], P= 0.002). Dense scar area (defined as voltage amplitude <0.05 mV) identified with OM was smaller compared to BM (1.3 cm2 IQR [0.13-1.73] vs 1.7 cm2 IQR [0.23-3.10]; P= 0.06). OM showed longer signal duration (+10.1%) compared to BM in the entire left atrium and in particular the mean signal duration in the critical isthmus (OM median 79.1 ms IQR [70.7 – 88.9] vs BM median 62.5 ms IQR [55.2 – 85.2], P= 0.006). Percentage of tachycardia cycle lenght (TCL) mapped at the critical isthmus (maximum signal duration at the isthmus/ TCL) was greater with OM than BM (OM mean 60% ± 11%, BM mean 54% ± 12% (P= 0.02)(a summary of the results are shown in table 1). Conclusions OM identifies higher amplitude and longer signal duration especially in the critical isthmus region also reducing the extension of dense scar area. This finding may be crucial in the definition of complex and localized reentrant activities, leading to a faster and more precise catheter ablation.

PO-04-027 A DAUNTING ASCENT: MAKING THE DIFFICULT CLIMB TO THE LEFT VENTRICULAR SUMMIT

Premature ventricular contractions (PVCs) originating from the left ventricular (LV) summit continue to be a challenging target for operators mainly due to inaccessibility. Alternate vantage points for PVC ablation should be explored. We describe two cases of LV summit PVCs presenting with inaccessible targets, necessitating different endocardial vantage points and strategies for successful ablation. N/A A 61-year-old woman presented from an outside medical facility. Despite a prior PVC ablation and use of antiarrhythmics, she was still experiencing symptomatic frequent PVCs (26% burden) along with a PVC (left bundle branch morphology with transition between V2 to V3, pseudo-delta wave, inferior axis) induced cardiomyopathy. This PVC was mapped with a high density mapping catheter in the right ventricular outflow tract (RVOT), left ventricular outflow tract (LVOT) and coronary sinus (CS) with a 2mm multi-polar catheter. Fractionated electrograms (EGMs) were detected at -52msec pre-QRS from the LV summit. The RVOT and LVOT were not early. Even though the LVOT site was not early, we were able to get our closest endocardial vantage point opposite to the earliest site, inferior to the left coronary cusp where successful ablation was achieved. In our second case, a 16-year-old male presented with symptomatic frequent PVCs (right bundle branch morphology and small R wave in V1, inferiorly directed) with high burden (26%). This PVC was mapped initially in the RVOT and LVOT. The LVOT EGM was -20msec pre-QRS but ablation at this site did not eliminate the PVC. Further mapping with our 2mm multi-polar catheter into the CS and its venous branches showed the earliest EGM of -28msec pre-QRS at the LV summit. Due to tortuosity of the venous system, our ablation catheter was not able to be driven at this site. Further mapping beyond the RVOT into the left pulmonary artery vantage point showed only -20msec pre-QRS (97% pace map match) just opposite to the LV summit. Ablation at this vantage point was successful due to spatial proximity to the LV summit. Despite innovations in ablative techniques operators are still in need of novel ablation maneuvers. Mapping catheters and ablation systems are limited in their utility by individual anatomy, necessitating exploration of alternative vantage points. Our cases highlight two instances where, despite not being earliest to the clinical PVC, a different vantage point with spatial proximity to the LV summit led to successful ablation.

PO-03-101 PEAK FREQUENCY INITIAL US AND EUROPEAN EXPERIENCE: A NOVEL MEASURE TO DISTINGUISH NEAR-FIELD FROM FAR-FIELD EGM COMPONENTS

Discrimination between near-field (NF) vs. far-field (FF) components in electrograms (EGMs) is mostly based upon intuitive perception of local EGM sharpness. As high-density mapping catheter use has expanded, the difficulty of discerning sub-components across many EGMs in realtime has increased. To date no mapping system had employed a means to quantify this distinction. A novel detection algorithm was designed to identify sharpness of NF EGM components by annotating the highest Peak Frequency (PF) of a signal. To provide insight into first clinical use cases of NF annotation algorithm and PF data. Acute procedure data were prospectively collected from 32 operators at 16 institutions in the US and Europe. All cases were performed on EnSite X system with EnSite OT Near Field software (Abbott). PF information was used as an adjunct to activation or voltage maps via an emphasis layer or as a standalone map (Figure). Choice of mapping tools and technique was at physician discretion. Analysis included ablation cases (n=175) with the following indications: AF (60.6% [54.7% PAF, 45.3%, PsAF; 34.9% redo]), SVT (20.6%), and VT/PVC (18.9%). The NF algorithm was the roving detection option of choice for automated point collection in most cases (96.2% of AF cases, 91.7% SVT, 69.7% VT/PVC). Alternative detections were Last Deflection in VT cases (33%) and First Deflection in PVC cases (29%). When NF was used, correctness of EGM annotation was noted as highly accurate in 93.5% of cases. Standalone PF maps were used as a diagnostic tool in 48 (27.4%) Depth of Activation Insights cases. Bounding values for map display were variable based on use-case to highlight various electrophysiologic phenomena (Table). In an AF use case, PF was used for gap identification (n=6); values were applied at 225±28 Hz, consistent with previously published value of 240Hz (Merino, et al. EHRA 2022). Alternatively in VT/PVC cases, low PF far-field zones were highlighted to assess activation at depth in tissue; mean values were 198±10 Hz. Peak frequency mapping helps distinguish near field from far-field electrograms. PF mapping can be used as (1) a standalone mapping technique to accurately identify near field components and (2) PF mapping can be used as an adjunctive technique to complement activation and voltage maps. PF mapping appears to assist in substrate differentiation, pathway localization, and contact assessment. Further research is warranted on optimal settings for various tissue types and rhythms.Tabled 1Table. Standalone PF mapsValues in HzValues in HzUsed InUsed InUsed InIntention of Map UseColor Range HighColor Range LownAFSVTVT/PVCCritical Isthmus Identification424 +/- 70222 +/- 445YesYesYesDepth of Activation Insights490 +/- 300198 +/- 3010YesYesFF LAA vs NF PV EGM475 +/- 268220 +/- 256YesPV Gap Identification400 +/- 257225 +/- 286YesSlow Pathway Modification231 +/- 4345 +/- 7911YesOther**10YesYesYes Open table in a new tab

3D-electroanatomical mapping of the left atrium and catheter-based pulmonary vein isolation in pigs: A practical guide.

To propose a standardized workflow for 3D-electroanatomical mapping guided pulmonary vein isolation in pigs. Danish female landrace pigs were anaesthetized. Ultrasound-guided puncture of both femoral veins was performed and arterial access for blood pressure measurement established. Fluoroscopy- and intracardiac ultrasound-guided passage of the patent foramen ovale or transseptal puncture was performed. Then, 3D-electroanatomical mapping of the left atrium was conducted using a high-density mapping catheter. After mapping all pulmonary veins, an irrigated radiofrequency ablation catheter was used to perform ostial ablation to achieve electrical pulmonary vein isolation. Entrance- and exit-block were confirmed and re-assessed after a 20-min waiting period. Lastly, animals were sacrificed to perform left atrial anatomical gross examination. We present data from 11 consecutive pigs undergoing pulmonary vein isolation. Passage of the fossa ovalis or transseptal puncture was uneventful and successful in all animals. Within the inferior pulmonary trunk 2-4 individual veins as well as 1-2 additional left and right pulmonary veins could be cannulated. Electrical isolation by point-by-point ablation of all targeted veins was successful. However, pitfalls including phrenic nerve capture during ablation, ventricular arrhythmias during antral isolation close to the mitral valve annulus and difficulties in accessing right pulmonary veins were encountered. Fluoroscopy- and intracardiac ultrasound-guided transseptal puncture, high-density electroanatomical mapping of all pulmonary veins and complete electrical pulmonary vein isolation can be achieved reproducibly and safely in pigs when using current technologies and a step-by-step approach.

Atrial tachycardia in a patient with severe pectus excavatum

A 68-year-old woman underwent catheter ablation of drug-refractory atrial tachycardia (AT; cycle length 490 ms). A computed tomography scan of her chest showed severe pectus excavatum (PEX) (Figure 1A ). A voltage map using a multipolar high-density mapping catheter with the EnSite X mapping system (Abbott Technologies, Minneapolis, MN) revealed severe distortion of the right atrium (RA) and an extensive low-voltage area (LVA; <0.5 mV), which occupied 32% of the RA surface (Figure 1B). The AT demonstrated a centrifugal activation pattern arising at the inferior portion of the cavotricuspid isthmus (Online Supplemental Video 1), and the AT was eliminated by ablation at the earliest activation site on the LVA. In PEX, distortion of the right heart cavities can cause traction on the myocardial wall resulting in wall thinning. 1 Oezcan S. Attenhofer Jost C.H. Pfyffer M. et al. Pectus excavatum: echocardiography and cardiac MRI reveal frequent pericardial effusion and right-sided heart anomalies. Eur Heart J Cardiovasc Imaging. 2012; 13: 673-679 Crossref PubMed Scopus (44) Google Scholar In the present case, an extensive LVA was found in the area apart from the RA free wall and thus in the lower part of the RA and in the entire peri-tricuspid annulus, where more tractions can exert than normal and may result in wall thinning (Figure 1B). This makes it likely that the mechanism of the AT was either abnormal automaticity or microreentry caused by damage to the RA by severe PEX. This report adhered to CARE case report guidelines (https://www.care-statement.org/).

High-density Mapping Catheter (Advisor™ HD Grid) Usage for Intra-atrial Reentrant Tachycardia Ablation in Children and Young Adult Patients with Congenital Heart Disease.

We aimed to share our experience of intra-atrial reentrant tachycardia mapping and ablation with a new grid-style multielectrode high-density mapping catheter (Advisor™ HD Grid) in pediatric and young adult patients with operated congenital heart disease. All patients with operated congenital heart disease and intra-atrial reentrant tachycardia mapping with the new grid-style catheter between October 2019 and December 2022 were included (group 1), and the results were compared to those patients who operated with conventional catheter methods before this period (group 2). All procedures were performed using the EnSite Precision 3D mapping system (Abbott Laboratories, Abbott Park, Ill, USA) with a limited fluoroscopy approach. Data were evaluated retrospectively. In group 1 (n = 16; 9 male), the median age was 21 years (10-36), compared to 19years (9-27) in group 2 (n = 10; 5 male). While irrigated radiofrequency ablation was pre-ferred in all patients, the median number of 15 lesions (8-38) in group 1 was significantly less than the median of 30 lesions (8-71) in group 2 (P =.027). The median procedure duration of 159 minutes (110-233) in group 1 was significantly shorter compared to 280 minutes (180-370) in group 2 (P <.05). Acute procedural success was achieved in all patients (16/16; 100%) in group 1 compared to 8/10 patients (80%) in group 2. During the median follow-up of 27 months (11-36), there was only 1 intra-atrial reentrant tachycardia recurrence in group 1 (1/16; 6.2%) and 2 recurrences (2/8; 25%) in group 2 during the median follow-up of 110 months (56-151). No complications related to the mapping catheter itself occurred. In the intra-atrial reentrant tachycardia ablation of children with congenital heart disease to increase procedural success and shorten the mapping duration, the utility of Advisor™ HD Grid mapping catheter seems to be a feasible alternative.

765 PULSED FIELD ABLATION FOR PULMONARY VEIN ISOLATION: PRELIMINARY RESULTS OF A SINGLE CENTER EXPERIENCE

Abstract Background Pulsed Field Ablation (PFA) is a new and promising non-thermal ablation modality for Pulmonary Vein Isolation (PVI) for the treatment of patients with Atrial Fibrillation (AF). It preferentially ablates myocardial tissue via electroporation leading to minimal effects on surrounding structures. We sought to evaluate safety and efficacy of PFA in our single center experience. Methods PFA was performed at optimized bipolar biphasic waveform using Farapulse system. A protocol of 8 pulses per vein, 4 in the basket configuration and 4 in the flower configuration was followed. The procedure was performed under general anesthesia. Fluoroscopy was used to guide single transseptal puncture. 1 mg of atropine was administered before starting applications. One third of patients underwent CTI ablation using radiofrequency during the same procedure. In one patient we mapped the left atrium before and after ablation using a high-density mapping catheter. Results We prospectively enrolled 21 patients (76% men, age 58,6 ± 9) who underwent PVI using PFA from July to September 2022 for the treatment of Paroxysmal AF (81%) or Persistent AF (19%). Acute pulmonary veins isolation was achieved in the totality of patients. Median skin-to-skin procedure time and catheter dwell time were 56 minutes and 29 minutes respectively. Median fluoroscopy time was 12 minutes. The average number of total applications was 34 ± 4. No adverse events were observed. After a median follow-up of 77 days, we observed early AF recurrence in two patients. Conclusion Preliminary results of our singe center experience confirm that PFA is a safe and effective ablation modality. Pulmonary vein isolation can be achieved very rapidly with short procedural time, catheter dwell time and fluoroscopy time. Further studies are needed to assess durability of the technique.

Characterization of high-density mapping in catheter ablation for persistent atrial fibrillation: results from the Advisor™ HD Grid Mapping Catheter Observational study.

We quantified and characterized the outcomes of ablation in persistent atrial fibrillation (PersAF) subjects, and the utility of electroanatomical mapping with a market-released high-density (HD) mapping catheter. PersAF subjects received electroanatomical mapping with the Advisor™ HD Grid mapping catheter, Sensor Enabled™ (HD Grid) and radiofrequency (RF) ablation to gather data regarding ablation strategies, mapping efficiency, quality, and outcomes. Subjects were enrolled from January 2019 to April 2020 across 25 international sites and followed for 12months after the procedure. Three hundred thirty-four PersAF subjects (average age 64.2years; 76% male; 25.4% previous AF ablation) were enrolled. Multiple map types were generated in a variety of rhythms using HD Grid. Significant differences in low voltage areas were identified in maps generated with the HD Wave Solution™ electrode configuration when compared to the standard configuration, which in some cases, influenced physicians' ablation strategies. PV-only ablation strategy was used in 59.0% of subjects and 34.1% of subjects received PV ablation and additional lesions. Of the subjects, 82.0% were free from recurrent atrial arrhythmias at 12months and new or increased dose of class I/III antiarrhythmic drugs. About 6.0% of subjects experienced a serious adverse event or serious adverse device effect through 12months including 1 event deemed related to HD Grid and the index procedure by the investigator and 1 death unrelated to study devices. The results of this study (NCT03733392) support the safety and utility of electroanatomical mapping with HD Grid in subjects with complex arrhythmias, such as PersAF in the real-world setting.

High-density mapping improves detection of conduction gaps after pulmonary vein isolation ablation with a circular mapping catheter.

High-density (HD) mapping of the pulmonary vein (PVs) has been hypothesized to improve the detection of conduction gaps in the radiofrequency ablation lesions set after pulmonary vein isolation (PVI) for the treatment of atrial fibrillation (AF). We aimed to compare the incidence of gaps after PVI with a standard 20-pole circumferential mapping catheter (CMC-20) and an HD mapping catheter (HD Grid). This prospective study included patients scheduled for high-power short-duration PVI. Acute PVI was defined as an entrance and exit block using the CMC-20 after ≥ 20min waiting period. The left atrium was then remapped using the HD Grid high-density mapping catheter to identify residual conduction gaps in the PVI lines by voltage and activation criteria. The primary endpoint was the number of gaps identified per patient by the HD Grid catheter. A total of 20 patients were included (mean age 59.9 ± 10.8years, 15% female, 70% paroxysmal AF). The new map with the HD Grid identified 6 gaps in 4 patients (20%) or 0.3 ± 0.7 gaps per patient (p = 0.055 when compared to CMC-20). Five gaps (83%) were located at the right PVs. There was no difference in mapping time (CMC-20 12.2 ± 2.6min vs HD Grid 11.7 ± 3.4min, p = 0.452); however, the number of points was significantly higher in the HD Grid map (1662.7 ± 366.1 vs 1171.6 ± 313.6, p < 0.001). HD mapping during AF ablation identified PVI gaps in 1 out of 5 patients. Therefore, HD mapping may have the potential to improve AF ablation success rates in the long term. ClinicalTrials.gov NCT04850508 on April 20, 2021.

Low voltage area as a predictor of recurrence after a single pulmonary vein isolation procedure: results of the WAVE-MAP AF study

Abstract Background/Introduction Pulmonary vein isolation (PVI) is a recommended approach for atrial fibrillation (AF) ablation procedures. Substrate modification beyond PVI has mixed results but identifying and ablating low voltage zones and ablating those targets in addition to PVI may be beneficial. Electroanatomic mapping is critical to identify subjects that may require further substrate modification. Low voltage area may be predictive of optimal treatment approach. Purpose This was a prospective, multicenter, interventional study of a high-density grid-style mapping catheter (HD Grid) to characterize left atrial low voltage substrate during sinus rhythm (SR) and AF and identify associations with 12 month recurrence rates after a single de novo radiofrequency (RF) ablation using a PVI only approach. Methods This study (NCT03882021) enrolled 300 subjects at 18 centers in Europe and Israel. Subjects underwent de novo RF ablation for paroxysmal AF (PAF) (N=113), early persistent AF (PsAF; AF sustained 7 days to 3 months) (N=86) or non-early PsAF (AF sustained &amp;gt;3 months to 12 months) (N=101). High density voltage maps were collected with HD Grid. Two pre-ablation maps, in SR and AF, were created for each subject (N=196) followed by PVI only ablation. Low voltage area (using cutoffs of 0.1 mV to 1.5 mV) was investigated in SR and AF. Follow up visits were at 3, 6 and 12 months post-ablation, with a 24-hour Holter monitor at 12 months. A Cox proportional hazards model was used to identify associations between mapping data and 12 month AF/atrial flutter (AFL)/atrial tachycardia (AT) recurrence after a single PVI procedure. Results At 12 months, 75.5% of subjects were free from AF/AFL/AT recurrence. On average, PsAF subjects had more low voltage area than PAF subjects in SR and AF. However, while univariate analysis found no correlation between recurrence and PAF or PsAF diagnosis (p=0.1261), those with recurrence had a significantly larger percent left atrial low voltage area under 0.5 mV with simultaneous orthogonal bipole wave configuration (HDW) in both AF (p=0.0011) and SR (p=0.0210) than those without recurrence. Using HDW, low voltage area (identified as &amp;lt;0.5 mV) greater than 28% of the left atrium in SR (HR: 4.82, 95% CI: 2.08–11.18, p=0.0003) and greater than 72% in AF (HR: 5.66, 95% CI: 2.34–13.69, p=0.0001) were associated with a higher risk of AF/AFL/AT recurrence at one year. Conclusion(s) Using a standard cutoff of 0.5 mV, a larger percent low voltage area was associated with increased risk of recurrence in both SR and AF. Future analyses will explore optimal low voltage cutoffs and thresholds predictive of recurrence that may necessitate additional substrate modification beyond PVI. Funding Acknowledgement Type of funding sources: Private company. Main funding source(s): Abbott

The high-density grid catheter: A safe adjunctive tool in pediatric and complex congenital heart disease patients.

The safety and utility of the Advisor™ High-Density Grid mapping catheter (HDGC) in children and congenital heart disease (CHD) patients are not well described. A single-center retrospective cohort study of pediatric and CHD patients undergoing electrophysiology study and ablation to determine the effect of HDGC use on outcomes including complications, fluoroscopy use, procedure duration, acute ablation success, and arrhythmia recurrence. HDGC was used in 74/261 (28.3%) cases. HDGC subjects differed by median age (17 vs. 13 years; p < 0.001),weight (68 vs. 50 kg; p < 0.001), and prevalence of significant CHD (42% vs. 3%; p < 0.001). Arrhythmia substrates were dissimilar: HGDC cases had higher frequencies of intra-atrial re-entrant tachycardia (25.7% vs. 0.5%), atrial flutter (8.1% vs. 1.1%), ectopic atrial tachycardia (13.5% vs. 3.7%), and premature ventricular contractions (9.5% vs. 0.5%), and lower incidences of atrioventricular re-entrant tachycardia (16.2% vs. 46.1%). Complications were rare (n = 5, 1.9%) with no significant difference between groups (p = 1.00). Procedure duration-but not fluoroscopy exposure-was significantly longer in HDGC cases (median 256 vs. 216 min, p < 0.001). Acute success was lower (93.2% vs. 99.4%; p = 0.01) and recurrences higher (13.2% vs. 3.8%; p = 0.016) in HDGC compared to non-HDGC cases. HDGC use in children and CHD patients is safe and not associated with higher complication rates. The lower acute success and higher recurrence rates in HDGC cases likely reflect a bias toward HDGC use in more complex arrhythmia substrates rather than less favorable ablation outcomes.