Left Atrial Posterior Wall Research Articles

Additional left atrial lesions improve the effect of cryoballoon pulmonary vein isolation in paroxysmal atrial fibrillation patients

Aim. Cryoballoon ablation (CBA) is one of the methods for catheter pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (AF). Left atrial additional lesion (LAAL) to PVI were proposed to eliminate extrapulmonary AF triggers. Nonetheless whether the additional lesions improve CBA effectiveness is not clear.Methods. Primary CBA procedures performed for paroxysmal AF during 2017-2021 were analyzed. The study group (Algorithm group, n=82) was recruited prospectively in 2019-2021. As the first step CBA PVI were performed in all pts. In those who were on sinus rhythm (SR) after the PVI, AF induction attempts with burst atrial pacing were performed. Pts with induced AF and those who stayed on AF after PVI underwent LAAL at the left ganglionated plexus area. In case of stable SR (non-inducible AF) the procedure finished. If AF was inducible or did not terminate during CBA, the second LAAL set were performed - LA posterior wall lesions. If AF was still inducible or did not terminate, the SR was restored by electrical cardioversion. The control group (Control group, n=94) was formed retrospectively from patients with routinely performed only CBA PVI with achievement of isolation criteria in 2017-2019. If AF continued, sinus rhythm was restored by cardioversion. There were no attempts of induction AF during the procedure.Results. The Algorithm and Control groups were comparable in terms of clinical, demographic and electrophysiological characteristics. At 12 months postoperatively, the effectiveness was higher in the Algorithm group than in the Control group (78.0% vs. 62.8%, p = 0.044). No adverse effects were found.Conclusion. Thus, the stepwise approach with LAAL increases the effectiveness of CBA in the long-term period and does not affect the risk of complications.

Efficacy and durability of posterior wall isolation with ethanol infusion into the vein of Marshall.

Ethanol infusion into the vein of Marshall (EIVOM) is expected to be an adjunctive therapy for mitral isthmus (MI) ablation. Additionally, EIVOM can widely ablate the epicardium via the branches that extend to the left atrialposterior wall (LAPW) and facilitate LAPW isolation. This study aimed to investigate the efficacy and durability of LAPW isolation with EIVOM. Our cohort consisted of 413 patients with atrial fibrillation (AF)who underwent both LAPW and MI ablations. EIVOM was first attempted in 177 (35%) patients with adequate VOMs. The VOM was infused with 5 mL of ethanol with a double coaxial guiding catheter technique. Both ablations were performed only by radiofrequency ablation (the RF group) in the remaining 236 (57%) patients. EIVOM with 5 mL of ethanol was completely achieved in 106 patients (the EIVOM group). The application duration of LAPW isolation did not differ significantly between the two groups (718 ± 276 vs. 709 ± 288 s; p = .78). LAPW debulking ablation was required in 64/106 (60%) and 176/236 (75%) patients in the EIVOM and RF groups, respectively (p < .05). However, AF- or atrial tachycardia-free survival analyses revealed no significant differences between the two groups (log-rank p = .70). Among the cases of recurrence, 17 and 38 patients underwent subsequent ablation sessions; LAPW was reconnected in 9/17 (53%) and 25/38 (53%) patients (p = .36)in the EIVOM and RF groups, respectively. EIVOM reduced the number of cases that required LAPW debulking ablation but did not improve the durability of LAPW isolation or clinical outcomes.

Focal pulsed field ablation and ultrahigh-density mapping — versatile tools for all atrial arrhythmias? Initial procedural experiences

BackgroundFocal pulsed field ablation (FPFA) is a novel and promising method of cardiac ablation. The aim of this study was to report the feasibility, short-term safety, and procedural findings for a broad spectrum of ablated atrial arrhythmias.MethodsPatients (n = 51) scheduled for ablation of atrial arrhythmias were prospectively included and underwent FPFA using the Galvanize CENTAURI generator with energy delivery through commercially available ablation catheters with ultrahigh-density (UHDx) 3D electroanatomic voltage/local activation time map evaluations. Workflow, procedural data, and peri-procedural technical errors and complications are described.ResultsPlanned ablation strategy was achieved with FPFA-only in 48/51 (94%) of the cases. Ablation strategy was first-time pulmonary vein isolation (PVI) in 17/51 (36%), repeat ablation in 18/51 (38%), PVI + in 13/51 (28%), and cavotricuspid isthmus block (CTI)-only in 3/51 (6%). The mean procedure time was 104 ± 31 min (first-time PVI), 114 ± 26 min (repeat procedure), 152 ± 36 min (PVI +), and 62 ± 17 min (CTI). Mean UHDx mapping time to assess lesion formation and block after ablation was 7 ± 4 min with 5485 ± 4809 points. First pass acute (linear) isolation with bidirectional block for anatomical lesion sets was 120/124 (97%) for all PVs, 17/17 (100%) for (any) isthmus, and 14/17 (82%) for left atrium posterior wall (LAPW). We observed several time-consuming integration errors with the used ablation system (mean 3.4 ± 3.7 errors/procedure), one transient inferior ST elevation when ablating CTI resolved by intravenous nitroglycerine and one transient AV block requiring temporary pacing for > 24 h.ConclusionsFPFA was a highly versatile method to treat atrial arrhythmias with high first-pass efficiency. UHDx revealed acute homogenous low-voltage lesions in ablated areas. More data is needed to establish lesion durability and limitations of FPFA.

Effect of right and left-sided programmed atrial extrasystoles on conduction across Bachmanns Bundle and initiation of atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Atrial extrasystoles (AES) originating from the pulmonary veins are notorious for triggering episodes of atrial fibrillation (AF). However, non-pulmonary vein triggers, emerging from e.g. the superior vena cava, left atrial posterior free wall, left atrial appendage (LAA), terminal crest and interatrial septum, play also an important role in a significant part of AF patients. AES provoke conduction disorders due to (dispersion in) refractoriness and enhanced non-uniform anisotropy of atrial tissue, which are related to initiation and perpetuation of AF. Bachmann’s bundle (BB) is the main route for interatrial conduction and plays a key role in AF development. However, the exact mechanistic effects of AES on BB in AF initiation are still unknown. Purpose To examine the impact of programmed electrical stimulation (PES) from the left and right atrium on activation and electrophysiological features of BB. Methods Intra-operative high-resolution epicardial mapping of BB was performed during sinus rhythm (SR) in 30 patients (27 male, 64±10 years). PES included a S1 sequence of 400 ms followed by a S2 of 300, 250 and 200 ms provided from the left and right atrial appendage (LAA/RAA). Electrophysiological features included unipolar voltage, conduction velocity, potential type (single, short/long double and fractionated) and conduction delay/block (CDCB). Features of the shortest captured S2 were compared to the S1 sequence. Results The average cycle length during SR was 962 [869–1085] ms. Compared to SR, during S1 pacing from both the RAA and LAA, voltage (RAA: -0.49 [-1.25–0.06] mV; LAA: -0.17 [-0.97–0.42] mV, P&amp;lt;0.001) and conduction velocity (RAA: -2.72 [-6.85–0.36] cm/s; LAA: -1.28 [-12.37–0.85] cm/s, P&amp;lt;0.001) decreased, and the amount of fractionation increased. In addition, CDCB increased specifically during RAA S1 pacing (+1.8 [0.1–3.2]%, P&amp;lt;0.001), while total activation time increased during LAA pacing (+16 [-1–29] ms, P&amp;lt;0.001). Applying the maximal captured S2, 12 patients had a refractory period of 250 ms, 13 patients of 200 ms and 3 patients &amp;lt;200 ms. In 4 patients, AF was induced by a S2 of 250 or 200 ms from either RAA or LAA. During both RAA and LAA S2 pacing, voltage (RAA: -1.33 [-2.51–-0.64] mV; LAA: -0.91 [-1.64–-0.46] mV, P&amp;lt;0.001) and conduction velocity (RAA: -16.34 [-24.49–-6.70] cm/s; LAA: -8.63 [-19.95–-1.25] cm/s, P&amp;lt;0.001) decreased, while total activation time (RAA: +26 [11–59] ms; LAA: +21 [2–46] ms, P&amp;lt;0.001) and CDCB (RAA: +5.7 [3.5–11.7] %; LAA: +4.1 [0.4–6.5] %, P&amp;lt;0.001) increased. Specifically, the average length of CDCB lines increased remarkably during LAA S2 pacing (+22 [8–39] mm, P&amp;lt;0.001) and even more during RAA S2 pacing (+36 [19–80] mm, P&amp;lt;0.001). Conclusions Premature AES affect interatrial conduction via BB by enhancing conduction disorders. This indicates that BB is involved in AF initiation by ectopic beats, independently of their origin from the right or left atrium.

Insights into level of pulmonary vein isolation using pulsed-field ablation for atrial fibrillation and unexpected effects in the posterior wall

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction Pulse field ablation (PFA) has emerged as an effective, safe and efficient tool for pulmonary vein isolation (PVI). Purpose We studied the extent of PVI, specifically the isolation of PV antrum, carina and left atria’s posterior wall after PFA with an ultrahigh density mapping (UHD). Methods We involved the first patients referred for atrial fibrillation (AF) ablation treated with a PFA multispline catheter. PFA-lesion extension was assessed with a voltage-map UHD mapping performed before and immediately after PVI. Results Sixty-one consecutive patients underwent PVI with PFA (62±10 year old, 23 women, 39 paroxysmal AF). Four out of 61 patients were excluded because their posterior wall was isolated with extra aplications on purpose. Acute results involved a 100% success of PVI and the only safety issue was a pericardial effusion in one patient managed conservatively. Mean procedure and fluoroscopy times were 59±39 min and 16±5 min, respectively. UHD immediately after PVI revealed early reconnection just in one vein (1/228 veins). PFA created wide antral circumferential lesions without electrical activity registered by UHD mapping inside the isolation area. There were no notch-like normal voltage areas at the anterior or posterior side of carinas. As a result of the PVI with this technology, it was observed the existence of a narrow corridor in the posterior wall in 8 patients (14%) and in another 8 cases right and left antral ablation converged at the posterior wall creating an unexpected isolation area. There was a significant relationship between LA posterior inter-carina distance and posterior wall´s level of isolation (77,1±7mm, no affectation; 68,8±7mm narrow corridor; 60,3±1mm posterior wall isolation (fig 1); p=0.036). Finally, it was a significant linear correlation between posterior inter-carina distance and the distance between the ipsilateral, antral levels of isolation at the posterior wall (fig 2, r=0.79, p=0.001) Conclusion(s) PFA creates wide antral circumferential PVI lesions involving the ipsilateral veins carina. Nevertheless, in small left atria it can create an undesired isolation or a narrow corridor in the posterior wall.

PO-01-104 3D MODELING OF PRE-PROCEDURE CT SCAN TO PREDICT SEVERE ESOPHAGEAL HEATING DURING HIGH POWER SHORT DURATION ATRIAL FIBRILLATION ABLATION

The degree of esophageal heating during left atrial posterior wall (LAPW) ablation is a powerful predictor of esophageal injury. Esophageal temperature monitoring has not been shown, however, to reduce esophageal injury risk related to atrial fibrillation (AF) ablation. Esophageal proximity modeling based on pre-procedure CT scan using ADAS 3D software (ADAS3D Medical, Barcelona, Spain) is a novel method of identifying left atrial locations at high risk for severe esophageal heating. Given the mobile nature of the esophagus relative to the LAPW, the predictive value of esophageal proximity mapping is unclear. To determine the predictive value of esophageal proximity mapping to identify LAPW ablation sites at risk for severe esophageal heating. Pre-procedure CT scans were analyzed using ADAS 3D software in 10 patients undergoing AF ablation to create a 3D esophageal proximity model and left atrial tissue thickness map that were merged with a catheter based left atrial electroanatomic map (Ensite X, Abbott, Inc.). Esophageal proximity was defined as: Zone 1 – overlying esophagus, Zone 2 – within 5 mm of esophagus, or Zone 3 – > 5 mm from esophagus. LAPW ablation lesions were created with a contact-force sensing radiofrequency ablation catheter (Tacticath, Abbott, Inc.) at 45W, 10-20g of force, and 6 seconds duration. A 12 sensor esophageal temperature probe (Circa, Circa Scientific, Inc.) recorded the temperature increase related to each LAPW lesion. Ablation lesions in Zone 3 resulted in significantly lower esophageal temperature rise (degrees Celsius) as compared to either Zone 1 (mean 0.11 ± 0.27 vs 1.61 ± 1.39, p value <0.0001) or Zone 2 (mean 0.11 ± 0.27 vs 0.84 ± 1.1, p value <0.0001) (Fig A). Lesions in Zone 2 resulted in lower temperature rise as compared to Zone 1 (mean 0.84 ±1.1 vs. 1.61 ± 1.39, p value <0.0001) (Fig A). Within Zones 1 and 2, lesions with LAPW thickness > 2 mm resulted in significantly less esophageal temperature rise as compared to those on tissue with thickness of ≤ 2 mm (Fig B). Ablation lesions delivered >5mm from esophageal location at time of pre-procedure CT scan are very unlikely to result in significant esophageal heating. Ablation sites overlying esophagus with LAPW thickness ≤ 2mm were at greatest risk of significant esophageal heating. Analysis of pre-procedure CT scans to determine esophageal proximity and LAPW thickness may be useful in developing strategies to avoid esophageal injury during LAPW RF ablation.

AB-452663-3 DISTRIBUTION OF TRIGGERS IN THE LEFT ATRIAL POSTERIOR WALL IN AF PATIENTS UNDERGOING CATHETER ABLATION

Having a common embryologic origin with the pulmonary veins (PVs), left atrial posterior wall (LAPW) is considered to be a source of non-PV triggers that facilitate maintenance of atrial fibrillation (AF). However, the benefits of electrical isolation of the posterior wall (PWI) is still debated with contradictory data originating from different ablation approaches. . We report the distribution of triggers in the LAPW area in AF patients undergoing repeat ablation. Consecutive AF patients undergoing catheter ablation between 2015 and 2022 were included in this analysis. PVs were isolated first. Next, high-dose isoproterenol challenge (up to 30μg/min) was used to disclose triggers in the PW by moving the circular mapping catheter along the PW down to the level of coronary sinus, which were targeted using additional RF energy. We defined lower part of LAPW as the area between the line joining the inferior borders of the inferior PV-encircling lesions and the coronary sinus. The endpoint was to achieve electrical isolation, as documented by absence of any electrical activity in the PW. Of the 10,390 AF ablations performed during the specified time period, 5843 (56.2%) had triggers mapped and ablated in the LAPW area. Triggers were seen to be originating from the part of the PW between the PVs in 3809 (65.2%), from the lower part of the PW in 2028 (34.7%) and focal triggers from all over the PW including the lower part in 1519 (26%) cases. All triggers were targeted for ablation. Figure 1 demonstrates the triggers arising from lower PW. Ectopic triggers in the LAPW were documented to be arising from the lower part of the PW in a large number of cases. Thus, operators should consider extending the ablation to include the lower LAPW area to maximize the benefits of PWI.

AB-452672-4 POINT-BY-POINT PULSED FIELD ABLATION USING A MULTIMODALITY GENERATOR: COMPARISON WITH RADIOFREQUENCY ABLATION IN REMAPPED CHRONIC SWINE HEARTS.

In recent years, Pulsed Field Ablation (PFA) has emerged as a novel non thermal energy source for ablation. To compare lesion durability and collateral damage between unipolar/biphasic PFA and RF delivered through a contact-force sensing catheter both in a point-by-point fashion. A 4 arm pre-clinical study (n=12 swine) was designed with the multimodality generator TRUPULSE™ 2. PFA was delivered with nominal dose (12 pulses) in Group 1 whereas a high PFA dose (24 pulses) was used to evaluate energy safety in Group 2. RF arms served as controls with energy deployed through multimodality (Group 3) or market available (Group 4) generators. A contact-force catheter was used to focally deliver PFA/RF at the right superior pulmonary vein (RSPV), left atrial posterior wall (LAPW) and Roof, mitral isthmus (MI), cavotricuspid Isthmus (CTI), and RA posterior wall (RAPW). Average contact force was 12.7±3.7g. Animals were remapped at immediate post and 28 days post ablation. All animals were euthanized at 28 days and gross necropsy and histology followed. Acute RSPV isolation was achieved in all animals (Figure 1). At 28 days, remapping showed that RSPV isolation was maintained in all but one animal (Group 1) showing an electrical gap confirmed on histology. RAPW, CTI, MI (with exception of 2 animals, 1 in Group 2 and 1 in Group 3), and LAPW were maintained per histology as well. Differently from RF, both PFA arms had essentially similar histopathologic effect showing benign mature scar tissue repair with no necrosis nor inflammation (Figure 1). PFA applied to the RA lateral and posterior wall did elicit phrenic nerve response during ablation confirming ablations were done on the nerve. However, at 28 days remap, the nerve was stimulated and, in all animals, remained intact with no signs of damage on necropsy or histology. Representative samples were selected from the downstream/upstream organs including the brain, rete mirabile, heart, lungs, liver, esophagus, spleen, and kidneys, which showed no evidence of thrombo-embolic events. In swine models, point-by-point unipolar/biphasic PFA ablation showed durable PVI lesions acutely and at remapping without any sign of collateral damage after 28 days remap study. On histology, PFA lesions evolved with scar tissue without signs of necrosis nor inflammation. Further studies are needed to investigate the long-term safety and efficacy of this point-by-point PFA contact force sensing catheter.

AB-452654-3 AVOIDING THERMAL INJURY OF THE ESOPHAGUS BY USING LUMINAL ESOPHAGEAL TEMPERATURE MONITORING DURING HIGH-POWER, SHORT-DURATION RADIOFREQUENCY ABLATION: RESULTS OF A “ZERO TOLERANCE” PROTOCOL

The prevention of esophageal thermal injury (ETI) during atrial fibrillation (AF) ablation is still a challenge and the optimal luminal esophageal temperature (LET) strategy remains to be proved. Recent studies showed a lower incidence (3.5- 6%) of endoscopic ETI during high-power, short-duration (HPSD) AF ablation in which radiofrequency (RF) delivery was tolerated at LET cutoff point of 39-41°C. We investigated whether the LET monitoring with “zero tolerance” towards any rise of temperature is a safe and effective strategy in terms of endoscopic ETI and acute pulmonary vein isolation (PVI) in HPSD ablation. Observational study of consecutive patients with symptomatic AF undergoing HPSD RF ablation. The previously estimated sample size was 87, considering an estimated prevalence of 6%, margin of error of 5%, and 95% of significance level. HPSD RF ablation was defined as maximum temperature at 43°C, power delivery at 50 or 40 W for 5 and 10 seconds, respectively (the lowest power was at the left atrium posterior wall [LAPW]), 20 ml/min., and contact force of 5-30 grams. The applications were monitored by the impedance curve and real-time LET using a 9F insulated single thermocouple temperature probe. The “zero-tolerance” protocol was defined as stopping the point-by-point RF delivery at any LET rise in the LAPW in which the tip of the temperature probe was always positioned, via fluoroscopy vision, at the closest ablation site. The RF application was resumed only after the LET fell back to the baseline. All patients were scheduled to undergo esophageal endoscopy 1-3 days after procedure. We included 87 consecutive patients (59±13 years, 62 [71%] males) with paroxysmal (58[66.6%] and persistence AF (29[33.3%]). PVI was achieved in all patients with 16±7 min. of fluoroscopy time and 168±38 min. of procedure time. The LET rose in 86 (98.8%) patients, with a mean peak temperature of 37.3±1.2°C. There were no major complications. All patients underwent esophageal endoscopy and no ETI was found. They were discharged on the day after the procedure and no complications, including esophagus perforation or atrio-esophageal fistula, were clinically detected in at least 3 months of follow-up. The LET monitoring with “zero tolerance” towards any rise of temperature in HPSD RF ablation of AF prevented the occurrence of endoscopic esophageal thermal lesion without compromising the acute PVI.

PO-02-077 HYBRID CONVERGENT PROCEDURE FOR THE TREATMENT OF PERSISTENT AND LONG-STANDING PERSISTENT ATRIAL FIBRILLATION: A SINGLE CENTER EXPERIENCE

Pulmonary vein isolation by endocardial ablation is an effective treatment strategy for paroxysmal atrial fibrillation (AF). However, its effectiveness for treatment of persistent forms of AF is limited. In patients with advanced AF, there are extra-pulmonary vein foci that initiate and perpetuate AF. The left atrial posterior wall has been shown to have the highest proportion of such triggers. The Hybrid Convergent procedure is a novel procedure that combines epicardial and endocardial ablation to obtain isolation of the left atrial posterior wall and pulmonary veins. There is paucity of real world and long-term outcomes data regarding the Hybrid Convergent procedure. The purpose of this study is to describe the outcomes of Hybrid Convergent procedures for treatment of persistent and long standing persistent atrial fibrillation at 1 and 3 year follow up. A retrospective review of prospectively maintained single center Hybrid Convergent database was performed. Demographics, clinical, procedural, and outcomes data were collected on all patients. Atrial fibrillation burden was tracked using ECGs, wearable monitors, ICDs/pacemakers, implantable recorders and Holter monitors. Fifty patients with persistent and long-standing persistent AF underwent Hybrid Convergent procedure (age 62.6 ±9.1; male: 78%). Prior to ablation, the mean number of failed antiarrhythmic drugs was 2.3, mean number of previous ablations was 1.7, and mean left atrial volume index was 47.5 ± 17.9 ml/m2. 29 of 41 (71%) patients were free from AF recurrence at one year and 16 of 32 (50%) were free from AF at 3 years. The mean pre-operative AF burden for the group was 65.6 ± 40.2% on antiarrhythmics. Postoperatively, the total AF burden at 1 and 3 years were 23. 8 ± 40.9%, and 27.9 ± 41.1%, respectively. The Hybrid Convergent procedure is effective for the treatment of persistent and long-standing persistent AF with a 1- and 3-year freedom from AF recurrence of 71% and 50%, respectively. In this patient population, this procedure was able to reduce the mean burden of AF by 63.7% (41.8% absolute) at 1 year and by 57.4% (37.7% absolute) at 3 years. Our single center experience is consistent with the success rate from the Converge randomized trial at one year and provides additional 3 year follow up data.

MP-453081-11 PULSED FIELD ABLATION OF ATRIAL FIBRILLATION: SAFE TECHNOLOGY WITHOUT COLLATERAL DAMAGE TO THE ESOPHAGUS? FINDINGS OF POST-PROCEDURAL ENDOSCOPY

Severe injuries of the esophagus causing major complications after catheter ablation (CA) of atrial fibrillation are rare. However, endoscopically detected esophageal lesions (EDEL) have been described in up to 30% after radiofrequency current energy ablation. The novel non-thermal ablation technology pulsed field ablation (PFA) allows for unique ablation of the myocardium, sparing adjacent tissues, including the esophagus. Due to the proximity of the esophagus to the left atrial posterior wall (LAPW), this study sought to investigate the safety profile of PFA after left atrial posterior wall isolation (LAWPI) in patients undergoing catheter ablation of AF. Consecutive patients underwent PFA-guided catheter ablation for AF/atrial tachycardia including LAPWI. No esophagus probe was used due to the non-thermal energy form of PFA. To rule out esophageal lesions, all patients underwent post-procedural esophageal endoscopy, possibly, the next day. In total, 44 patients were included in the study. Patients’ mean age was 68 ± 13 years, 32 of 44 patients were male (72.7%) with a median CHA2DS2-VASc Score of 2 (q1-q3:1.5-4). Of all 44 PFA procedures, 13 (29.5%) were first ablation procedures for persistent AF and 31 (70.5%) were re-ablation procedures, including AF and AT. All patients underwent PFA-guided CA with a procedure duration of 113 ± 35.2 mins and a fluoroscopy time of 14.0 ± 5.7 mins. Pulmonary vein isolation (PVI) and/or Re-PVI was performed in 32 (72.3%) of patients. Successful LAPWI with PFA was performed in all patients (100%) including one (1/44, 2.3%)% early reconnection during remapping that required additional PFA. Additional PFA (including roof line, anterior line and mitral isthmus ablation) was performed in 22/44 patients (50%). Post-procedural endoscopy was performed at a median of one day after the procedure (q1-3: 1-2 days). No ablation-associated esophageal lesion was found (0%). There was no tamponade, and only one minor groin complication (2.3%, AV fistula not requiring intervention). After pulsed field ablation, no EDEL were detected on post-procedural esophageal endoscopy. Therefore, AF ablation including left posterior wall isolation performed by pulsed field ablation seems to be safe regarding any collateral damage to the esophagus.

PO-02-033 CALCULATED LUMINAL ESOPHAGEAL TEMPERATURE DATA PREDICT ESOPHAGEAL INJURY FOLLOWING RADIOFREQUENCY PULMONARY VEIN ISOLATION

Luminal esophageal temperature (LET) monitoring does not prevent esophageal injury following pulmonary vein isolation (PVI) but LET excess (i.e. > 41°C) is associated with increased risk for esophageal lesions and fistula. Detailed analysis of LET data may better predict the risk for any esophageal injury (mucosal lesions, periesophageal edema and food retention), and thus to streamline follow-up/therapy to prevent progression to fistula. LET data (S-Cath Circa, 12 thermocouples [Fig. 1A]) of consecutive patients with radiofrequency (RF) PVI (30 Watt at the left atrial posterior wall) were analyzed offline. Ablation was stopped when LET exceeded 41.0°C. LET-maxima, duration of LET rise [Fig. 1B], area under the maximum LET curve of any thermocouple (AUCmax [Fig. 1B]) and summed-up AUC of all individual LET-curves of the 12 thermocouples (3D-AUC [Fig. 1C]) were calculated and correlated with the results of endoscopy (EGD [mucosal lesions, food retention]) and endoscopic ultrasound (EUS [edema]). The calculated parameters were analyzed with regard to their ability to predict (sensitivity) or exclude (specificity) esophageal injury [Fig. 1D]. Following RF-PVI, 81 patients were studied by EGD+EUS (n=73) or EGD alone (n=8). Any esophageal injury was observed in 33/73 (mucosal lesions: 12/81, edema: 27/73, food retention: 13/81). Procedural data of PVI were not different between patients with/without esophageal injury. (1) LET > 41.8°C was associated with mucosal lesions but raw temperatures were not able to predict esophageal injury. (2) Duration of any LET-rise above baseline differed significantly with/without esophageal injury and performed even better for duration above 38.0°C (median time [interquartile range] exceeding 38.0°C 542 [298/668]s with vs. 289 [143/414]s without injury). (3) Summed-up area under the curve for LET exceeding 38.0°C (3D-AUC > 38.0°C) was the best predictive parameter and significantly increased in patients with esophageal injury (882 [448/1181]K.s with vs. 421 [170/691]K.s without injury [sensitivity 70%, specificity 83%, Youden-index 0.52, p<0.001]). AUC of the LET curves best predicted esophageal injury following RF-PVI with sensitivity and specificity ranging from 70-80% (Fig. 1D). Whether online-assessment of AUC is useful to guide PVI strategy and to prevent esophageal injury remains to be seen.

PE-452787-3 INITIAL EXPERIENCE OF PULSED FIELD ABLATION OF ATRIAL FIBRILLATION AND ATRIAL TACHYCARDIA IN ADULT PATIENTS WITH CONGENITAL HEART DISEASE

Prevalence of atrial tachycardias (AT) and atrial fibrillation (AF) is increasing in adult patients with congenital heart disease (CHD) significantly contributing to morbidity. Catheter ablation of AT and AF in the adult CHD population is challenging and recurrence is significant. Pulsed field ablation (PFA) is a new, non-thermal energy source for catheter ablation of AF. Due to its inherent properties of creating effective ablation lesions without permanent affection of non-myocardial tissue, it is attractive for the use in the adult CHD population. To date, its use in the adult CHD population has not been reported. This study describes initial experience of PFA of AT and AF in adult CHD patients. Prospective enrollment of adult CHD patients with a history of recurrent AT/AF, who had prior radiofrequency (RFA)/cryoenergy (Cryo) ablation of AT/AF. A high-density map using a 3D mapping system (EnSite™ Precision; Abbott) in conjunction with a high-density catheter (Advisor™ HD Grid; Abbott) was performed prior and after PFA. PFA was performed using the FARAWAVE™ ablation catheter (Boston Scientific) and applying repeated 2 kV pulses (2.5 s each) to the respective substrate. Procedural success was defined as complete substrate ablation (residual atrial electrograms < 0.05 mV on voltage map). Four adult CHD patients with recurrent AT/AF despite repeated previous RFA/cryoablation were enrolled. 2/4 had interrupted inferior V. cava and a transhepatic access was used to get access to the left atrium. PFA of all pulmonary vein ostia and the left atrial posterior wall was performed in 3 subjects. Additional PFA of a septal low voltage area was achieved in one of these patients. In the fourth patient with Ebstein’s anomaly, PFA of the cavotricuspid isthmus (CTI) and of a conduction gap within the crista terminalis was performed. Complete procedural success was achieved in all patients. Transient, fully reversible spasm of the right coronary artery without ECG changes occurred after PFA within the CTI. No recurrence of AT/AF was observed during follow-up of 5 months. Herein, we report for the first time the use of PFA in adult CHD patients with recurrent AT/AF. PFA turned out to be effective and generally safe. When using it in proximity to the coronary arteries, one must be aware of reversible coronary artery spasm. PFA might be a valuable tool to improve mid- and long-term outcome of AT/AF ablation in the adult CHD population.

PO-04-039 DIELECTRIC IMAGING-GUIDED ULTRA-LOW TEMPERATURE CRYOABLATION FOR ATRIAL FIBRILLATION

Ultra-low temperature cryoablation(ULTC) can be used to create transmural ablation lesions in the left atrium (LA). With a circular catheter configuration, this energy modality can be used to create continuous ablation lesions around the pulmonary veins(PVs). The same catheter configuration can be used to isolate the posterior wall(PW) by creating multiple overlapping circular ablation lesions. Isolation of the PVs and the PW can be assessed using pacing maneuvers. Three-dimensional voltage mapping may provide additional information on the extent of the ablation lesions. A recently introduced dielectric imaging-based mapping system can be used to generate voltage maps and to visualize the ULTC ablation catheter. To evaluate the feasibility of ULTC, guided by dielectric imaging-based electroanatomic mapping. Patients with atrial fibrillation were consented for catheter ablation with the iCLAS cryoablation system(Adagio Medical, Laguna Hills, USA). Ablation included isolation of the PV’s and LA PW if deemed necessary. The KODEX-EPD system(EPD Solutions, Best, the Netherlands) was used in conjunction with a circular mapping catheter to create pre- and postablation voltage maps. If the postablation voltage map revealed incomplete ablation lesions, additional energy applications were applied. Patients visited the outpatient clinic at 3 months post ablation. All patients were enrolled in a prospective registry study that was approved by the local ethics committee. Six patients (4 male, 4 persistent AF, age 66±7 years, LAVI 38±14ml/m2) were treated. The PVs were targeted in all patients, while the PW was targeted in 5 patients. A postablation voltage map was generated in 5 patients, which revealed incomplete PV isolation in 2 patients and incomplete PW isolation in 1 patient. Additional ablation in these patients resulted in acute electrical isolation of all targets. Isolation of the PVs was achieved using a median of 11[IQR:9-15] energy applications and 11[8.5-14] minutes of ablation. Isolation of the PW required 6[6-7] applications and 3[3-3.5] minutes of ablation energy. Total mapping time was 14.5[12.5-22.5] minutes, total fluoroscopy time was 16[12.5-18.5] minutes, and the total procedure time was 107.5[67.25-123.5] minutes. At 3 months follow up, only 1 patient had recurrence of atrial arrhythmia. Longer follow up is ongoing. Dielectric imaging-based electroanatomic mapping can be used to evaluate lesions of ULTC.

PO-04-134 STAR MAPPING METHOD TO IDENTIFY ENDO-EPICARDIAL DISSOCIATION AND DRIVING SITES IN PERSISTENT ATRIAL FIBRILLATION

Recurrence rates following ablation for persistent AF (psAF) remain high with the underlying mechanisms complex and poorly understood. Asynchronous activation of the endocardial and epicardial surfaces during AF, defined as endo-epicardial dissociation (EED) may be a driver for AF. We aim to investigate whether using the novel vector mapping approach, Stochastic Trajectory Analysis of Ranked (STAR) signals, endo- epicardial dissociation and early sites of activation (ESA) can be identified. Six (6) patients underwent endo-epicardial AF ablation utilizing the pericardial percutaneous CO2 insufflation technique. Two AdvisorTM HD Grid mapping catheters were placed in corresponding endocardial and epicardial positions in the left atrium. During AF, 30 second segments were recorded at the base of the left atrial appendage, anterior, inferior, left lateral and posterior LA wall. Fifteen (15) corresponding endo-epicardial segments were analysed using STAR maps and assessed for ESA and variation in direction of activation wavefront between the endocardium and epicardium. Activation wavefront direction was defined as dissociated if there was >40-degree difference between activation direction of simultaneous endo-epicardial wavefronts on STAR mapping. For each 30 second recording if there was more than 1 dominant wavefront direction, the 2 most common were used and an average taken. The overall mean difference in angulation of wavefront between the endocardium and epicardium was 71 ± 55 degrees. Nine (9) of 15 STAR maps (53%) showed activation angulation difference of >40 degrees between the endocardial and epicardial wavefront activation. Of these 9, 3 were on the posterior wall, 3 were at the base of the appendage, 2 were on the left lateral wall and 1 was on the anterior wall. ESA was identified in 6 STAR mapped endo and epicardial segments of AF, with 4 of these 6 (67%) ESAs in the epicardium. STAR mapping identifies activation wavefront discrepancy showing EED in multiple sites of the atrium with the majority of ESAs in the epicardial atrial surface.

AB-453068-3 ESOPHAGEAL TEMPERATURE AND ESOPHAGEAL DAMAGE IN HIGH POWER SHORT DURATION ABLATION SETTINGS

Radiofrequency ablation (RFA) of atrial fibrillation (AF) using high-power short-duration (HPSD) ablation settings (50W, 10s or up to 90W, 4s) are increasingly common, seeking to maximize resistive rather than conductive heating to limit the risk of esophageal damage. The real-time luminal esophageal temperature (LET) response and the risk of esophageal damage of HPSD are not fully established. To investigate the LET and esophageal risk of HPSD RFA on the posterior LA wall. We ablated the deep inferior pulmonary vein (IPV) in close proximity to the esophagus in 14 pigs, using either Termocool SmartTouch Catheter (HPSD 50W/10s, n=7), or QDOT Catheter (HPSD 90W/4s, n=7). LET was monitored with a 12-sensor CIRCA probe. RFA was delivered in the IPV in apposition with the esophagus as verified on 3D maps. We collected LET, ablation parameters; endoscopy, macro- and microscopic examination of the esophagus. In 3 pigs in each group, survival was prolonged 1 month for chronic characterization of esophageal lesions. Total energy delivered (90W/4s vs. 50W/10s) was higher in QDOT group (60.8±18.8W vs. 48.9±0.1W, p<0.005), as was the peak temperature at ablation catheter tip (51.2±3.1°C vs. 25.3±2.8°C, p<0.005). Peak LET was lower in the 90W/4s group than in the 50W/10s group, (38.7±1.5°C vs. 40.5±3.1°C, p<0.005). Temperatures >40°C were reached in 14/90 90W/4s ablations vs 43/94 in 50W/10s ablations (p<0.001). Acute esophageal lesions were found in all pigs. In the 90W/4s group, acute lesions involved affecting outer muscularis layer in 4/4 and up to submucosa in 1/4. However, no chronic lesions were identified in 3/3. In the 50W/10s group: 4/4 acute lesions involved entire muscularis layer into the submucosa, and reaching the mucosa in 2. Chronic lesions were found in only 1 on pig in the 50W/10s group – complete muscularis layer replacement with scar (with submucosal inflammation). All lesions occurred after high LETs. (Figure) HPSD 50W/10s can create high LET and significant acute and chronic esophageal damage. QDOT catheter at 90W/4s leads to lower peak LETs, can lead to acute lesions but no chronic esophageal damage. LET can be used to monitor risk of esophageal damage in both HPSD protocols.

PO-01-003 DIFFERENTIAL ENTRAINMENT PACING FOR A PRECISE DELINEATION OF THE CIRCUIT IN A COMPLEX MACROREENTRANT ATRIAL TACHYCARDIA WITH THE ATRIAL ACTIVATION DURATION EXCEEDING THE TACHYCARDIA CYCLE LENGTH

Precise delineation of macroreentrant AT circuits with an atrial activation duration (AAD) exceeding the TCL is challenging because huge bystander regions adjacent to reentrant circuits can exist that activate extremely late, almost simultaneously with early activation of the next beat within reentrant circuits. Thus, 3D-mapping systems cannot clearly annotate local electrograms outside the window of interest, and activation maps of these ATs often appear confusing with 2 sites of earliest activation, the true earliest site (TES) within the circuit and pseudo-earliest site (PES) in the bystander region. We hypothesized that differential entrainment pacing (DEP) from the TES and PES would be helpful to delineate the precise AT circuit differentiating the TES from the PES. DEP was applied to 9 macroreentrant ATs with TCLs of 258±48ms, in which the 3D-EAM exhibited the earliest activation at 2 remote sites. The AT circuit was determined as follows: mitral isthmus (MI) dependent (n=2), LA roof-dependent (n=1), right atrium scar-related reentry (n=1), PV-gap reentry (n=1), a bi-AT (n=1), and cavotricuspid isthmus dependent (n=3). Entrainment pacing from the TES exhibbited a PPI–TCL <30ms and orthodromic capture of the PES with a long stimulus-electrogram (S-EGM) interval >75% of the TCL in all cases. In contrast, entrainment pacing from the PES exhibited a PPI–TCL >30ms in 7 cases, AT terminated in 1, and failure to capture the TES due to unidirectional block of the PES in 1. A representative example is shown in the Figure. The activation map shows the 2 earliest sites, the LA anterior and posterior walls. An ablation catheter (pacing site 1) and Pentaray catheter (pacing site 2) were positioned at each earliest site, and DEP was performed from pacing sites 1 and then 2. The entrainment pacing from site 1 exhibited a PPI–TCL of 20ms and orthodromic capture of site 2 with a long S-EGM interval (262ms). In contrast, entrainment pacing from site 2 exhibited a PPI–TCL of 120ms and antidromic capture of site 1. Those results indicated that site 1 was the TES within the circuit and site 2 was the PES in a bystander area that activated extremely late. The diagnosis of MI dependent AT with a huge bystander region on the LA posterior wall was made. Correctly annotated, the AAD was 315ms, which was greater than the TCL. DEP from the TES and PES was helpful to delineate the precise circuit of an AT with an AAD exceeding the TCL.

PO-03-098 DIFFERENTIAL PACING FOR IDENTIFYING MULTIPLE INTERATRIAL CONNECTIONS

Interatrial connection (IAC) is reported to be an anatomical structure associated with complex biatrial tachycardias. However, electrophysiological conduction between left atrium (LA) and right atrium (RA) has not been fully investigated. This study was to distinguish multiple IACs by using different pacing sites. Twenty patients with paroxysmal atrial fibrillation who underwent ablation were enrolled. High-density mapping of left and right atrial before ablation were created during continuous pacing from sinus node (SN) or low lateral RA (LL-RA), and LA appendage (LAA) or posterior wall (LA-PW), respectively. Focal activation sites were defined as IAC and breakthrough segments of each atrium were recorded. The average number of total IAC were 4.9±1.3 and 4.1±1.2 for RA-LA and LA-RA, respectively (Figure A1,2). There was no significant difference in number of IACs between each directional connections (cranial pacing, p=0.35; caudal pacing, p=0.62) (Figure B). Connections at the level of interatrial septum (IAS) and Bachmann’s bundle were mostly found as RA-LA connections, however more than one third of the patients had connections in right pulmonary veins, its carina, LA roof and coronary sinus musculature. LA-RA connections were mainly existed in IAS, however superior and inferior vena cava were also frequently related. Only either single site from SN or LL-RA pacing elucidated significantly smaller number of IACs for RA-LA compared to total IACs (SN vs total, 3.2±0.8 vs 4.9±1.3, p<0.001; LL-RA vs total, 3.2±1.5 vs 4.9±1.3, p<0.001) (Figure C1). Similarly, only either LAA or LA-PW pacing revealed significantly smaller number of IACs for LA-RA compared to total IACs (LAA vs total, 3.0±0.8 vs 4.1±1.2, p<0.001; LA-PW vs total, 3.0±0.8 vs 4.1±1.2, p<0.001) (Figure C2). Although difference of pacing sites did not influence the total number of interarial conductions (RA-LA, p=0.09; LA-RA, p=0.85), pacing from cranial and caudal sites preferentially disclosed IAC at upper and lower septal segments, respectively (upper connections of RA-LA, SN vs LL-RA, 73.4% vs 46.9%, p=0.0037; upper connections of LA-RA, LAA vs LA-PW pacing, 66.1% vs 41.0%, p=0.013) (Figure D1,2). Pacing from multiple locations may be required in order to reveal entire interatrial connections.

PO-01-102 RISK FACTORS FOR PROGRESSION OF PAROXYSMAL TO PERSISTENT ATRIAL FIBRILLATION FOLLOWING PV ISOLATION

Progression from paroxysmal (PAF) to persistent atrial fibrillation (PerAF) following effective PV isolation (PVI) has important clinical implications, as it is relevant for subsequent management of the arrhythmia. We evaluated risk factors responsible for progression of PAF to PerAF following successful PVI. Consecutive AF patients that received their first and second catheter ablation at our center were identified (n=1352). Patients were included in group 1 if the diagnosis was PAF at both first and redo procedure (PAF to PAF) and group 2 if PAF at index progressed to PerAF at redo. Two blinded electrophysiologists confirmed AF type before the first and the redo ablation procedure. All patients received PV isolation plus isolation of left atrial posterior wall and superior vena cava at the first procedure. A total of 822 patients remained as PAF at redo (group 1), whereas 530 (39%) progressed from PAF to PerAF at the first repeat procedure (group 2). The first AF ablation was performed early (<12 month after diagnosis) in 690 (84%) and 191 (36%) of group 1 and 2 patients respectively (p<0.001). Clinical characteristics of the study population are presented in table 1. In multivariate analysis, BMI (OR 1.02, 1.01-1.04, p=0.04), hypertension (1.4, 1.08-1.8, p=0.01), heart failure (1.67, 1.03-2.69, p=0.03), LA size (2.75, 2.29-3.31, p<0.001) and LVEF (0.97, 0.95-0.98, p<0.001) were independent predictors of progression of PAF to PerAF. In this series, significantly higher number of patients receiving early ablation remained as PAF compared to those that progressed to PerAF. After successful PVI, progression of PAF to PerAF was mediated by independent risk factors such as high BMI, heart failure, hypertension, larger LA size and lower LVEF.

AB-452663-4 LEFT ATRIAL POSTERIOR WALL ABLATION USING PULSED FIELD ABLATION AS ADJUNCTIVE THERAPY DURING RE-DO PROCEDURES AFTER MULTIPLE FAILED PULMONARY VEIN ISOLATIONS USING THERMAL ENERGY

Pulmonary vein isolation (PVI) is the cornerstone for patients with atrial fibrillation (AF). Long-term efficacy is limited because of high PV reconnection rates. Ablation targets and strategies beyond PVI in re-do left atrial (LA) procedures have failed to improve outcome. Pulsed field ablation (PFA) has recently been introduced as a novel ablation technology. We report the first experience of re-do PVI with adjunctive LA posterior wall ablation (LAPWA) in patients with multiple failed LA procedures using thermal energy (RF /cryo). After high-density bipolar 3D voltage maps using a pentaspline diagnostic catheter, ablation was performed in conscious sedation using a steerable sheath and a pentaspline over-the-wire basket and flower PFA catheter. After re-do PVI (irrespective of PV status), the pentaspline catheter was visualized in the 3D mapping system. The posterior wall was ablated using the PFA catheter in the flower configuration (Figure). Projected catheter images overlapped approx. 30% between sites across the posterior wall. Per ablation site, 4 applications were administered. Post ablation, 3D voltage maps confirmed complete PVI and LAPWA. Bidirectional PVI was also documented using pacing. Procedural parameters, acute success, in-hospital safety and arrhythmia recurrence were assessed. Between Sept. 2021 and Nov. 2022, 17 patients were enrolled. Mean age was 68±8 years. Time since first AF diagnosis was 72±46 months. Mean number of previous LA procedures was 3±1. Acute PVI and LAPWA were 100% successful. Median procedural time was 160±62 min (including 47±10 min for pre and post mapping). LA dwell time of the PFA catheter was 46±19 min. Fluoroscopy time and dose area product were 24±09 min and 13±13 Gy.cm2. All patients tolerated this approach without procedural interruption. There were no acute or chronic complications. After a follow-up of 163±105 days, 12/17 (71%) patients were free of documented AF, atrial flutter or tachycardia. In patients with multiple failed LA ablations for AF, re-do PVI (irrespective of PV status) and LAPWA using PFA seems to be a safe and feasible approach with promising short-term results. Larger studies are needed to investigate long-term efficacy and safety in this patient group with otherwise very limited therapeutic options.