Mitral Isthmus Research Articles

The impact of empirical Marshall vein ethanol infusion as a first-choice intraoperative strategy on the long-term outcomes in patients with persistent atrial fibrillation undergoing mitral isthmus ablation.

Marshall vein ethanol infusion (MVEI) as an additional therapy to conventional catheter ablation (CA) has been proved to be efficacious in patients with persistent atrial fibrillation (PeAF). However, whether empirical MVEI could be the first-line strategy in mitral isthmus (MI) ablation has seldom been investigated. Here, we aim to compare the efficacy, safety, and long-term outcomes between provisional and empirical MVEI in PeAF patients undergoing the index MI ablation procedure. We enrolled 133 patients with PeAF either in the provisional group (n = 38, MVEI was performed when conventional endocardial and/or epicardial ablation procedures were inadequate to achieve bidirectional MI block) or in the empirical group (n = 95, MVEI was performed empirically before MI CA). All of the baseline characteristics were comparable. Less spontaneous or inducible atrial tachycardias (ATs) were encountered in the empirical group of patients (P < 0.001). More epicardial ablations were applied (26.3% vs. 9.5%, P = 0.016) and a higher incidence of CA-facilitated restoration of sinus rhythm was recorded (86.8% vs. 11.7%, P < 0.001) in the provisional group of patients. Although more fluoroscopy time (6.4[4.2, 9.3] vs. 9.5[5.9, 11.6] min, P = 0.019) and radiation exposure (69.0[25.3, 160.2] vs. 122.0[62.5, 234.1] mGy, P = 0.010) were documented in the empirical group with comparable procedure time, less time (455.9 ± 192.2 vs. 366.5 ± 161.3 s, P = 0.038) was consumed to achieve bidirectional MI block during endocardial ablation in the provisional group. Incidences of procedure-related complications were similar between the two groups. During a 16.5 ± 4.4-month follow-up, the empirical group of patients showed a significantly higher rate of freedom from AT recurrence (95.8% vs. 81.6%, log-rank P = 0.003), while the rate of freedom from AF or atrial tachyarrhythmias (combining AF and AT) was similar. Both univariate (HR 0.19, 95% CI 0.05-0.64, P = 0.008) and multivariate (HR 0.25, 95% CI 0.07-0.92, P = 0.037) Cox regression analyses indicated that empirical MVEI was independently associated with lower long-term AT recurrence. Among patients with PeAF who underwent the index MI ablation procedure, empirical MVEI could reduce endocardial MI ablation time and provide greater long-term freedom from AT recurrence.

Novel Technique for Creating a Mitral Isthmus Line

Novel Technique for Creating a Mitral Isthmus Line

Pulsed-Field Ablation on Mitral Isthmus in Persistent Atrial Fibrillation: Preliminary Data on Efficacy and Safety

BackgroundPulsed-field ablation (PFA) is a new and promising modality of ablation that has been shown to specifically ablate cardiac tissue while sparing other anatomic structures, thus avoiding thermal ablation–related complications. Recent studies have certified safety and efficacy of PFA for pulmonary vein isolation (PVI) in the setting of paroxysmal atrial fibrillation (AF). However, there are very limited data assessing the feasibility and safety of PFA ablation of different substrates within the left atrium in the setting of persistent AF. ObjectivesThe purpose of this study was to evaluate the feasibility and safety of mitral isthmus (MI) ablation in addition to PVI and posterior wall (PW) ablation with PFA in patients with persistent AF. MethodsWe prospectively included all consecutive patients with persistent AF who underwent a first ablation procedure with PFA. We performed in all these patients a substrate ablation strategy comprising PVI, PW, and MI ablation with the use of PFA only. The primary feasibility endpoint was obtaining a persistent MI block at the end of the procedure. The safety endpoint was a composite of major safety events. ResultsFrom November 2021 to September 2022, we included 45 patients. Complete MI block was achieved in all 45 (100%). Three patients presented with complications, among them 2 cases (4.4%) of reversible and nonfatal coronary spasm. During a mean follow-up time of 107.8 ± 59.5 days, a 20% recurrence rate was observed. ConclusionsPFA is a feasible and safe ablation approach for mitral isthmus ablation in addition to PVI in patients with persistent AF.

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.

Radiofrequency ablation for longstanding persistent atrial fibrillation: long-term outcome of a prospective randomized comparison of mapping with multipolar catheter vs. 4-pole ablation catheter

Abstract Funding Acknowledgements Type of funding sources: None. Background In patients with longstanding persistent atrial fibrillation (LSPAF), mapping with multipolar catheter can enhance identification of arrhythmogenic sources during ongoing AF/converted atrial tachycardia (AT), reduce procedure time, and improve outcome of catheter ablation. Purpose To compare procedural characteristics and long-term outcome of radiofrequency catheter ablation (RFA) for LSPAF between two mapping approaches in a prospective randomized bi-centric study. Methods Between 1/2019-9/2021, RFA was performed in in 172 patients with LSPAF. Mapping with multipolar catheter Pentaray (group 1, n=85) vs. mapping with ablation catheter Navistar STSF (group 2, n=87) were compared. Stepwise ablation to the desired AF termination included pulmonary vein isolation (PVI), electrogram guided left atrial (LA) ablation, CS isolation, and right atrial electrogram guided ablation. PVI, mitral isthmus, LA roof, and CTI block were Intermediate endpoints proved at the procedure end. Sinus rhythm (SR) restoration by ablation was the desired procedure endpoint. Follow-up included 7-day ECG monitoring every 3 months during the first year, and every 6 months afterwards. Results In groups 1 vs. 2, AF was terminated (into SR or AT) in 70 (82%) vs. 68 (78%) patients (p=0.81); and SR was restored by ablation in 54 (64%) vs. 46 (53%) patients(p=0.46), respectively. Procedure, fluoroscopy, and RF delivery times (min) were 251±46 vs. 257±45 (p=0.35); 10,4±2,8 vs. 11,0±3,1 (p=0.17), and 70±21 vs. 70±24 (p=0.98), respectively. At the end of 13-45 months follow-up, stable SR was present in 72 (85%) vs. 69 (79%), patients following repeat ablation in 42 (49%) vs. 42 (48%) patients. Only 29 (34%) vs. 26 (30%) patients remained free from any AF/AT recurrence (&amp;gt;30 s) after single ablation (all p=NS). Conclusion Mapping with multipolar catheter vs. standard ablation catheter was associated with nonsignificant differences in procedural characteristics and clinical results of RF catheter ablation for LSPAF.

Mitral annular electrogram morphology - a balanced signal does not identify the anatomical annulus

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): British Heart Foundation Background Electrogram morphology is used to identify the atrio-ventricular annuli during catheter ablation procedures with a "balanced" signal considered to represent the annuli. However, anatomical studies highlight a significantly greater mass of ventricular myocardium compared to atrial myocardium at the valve plane suggesting the correct electrical signature of the anatomical annulus may not be a balanced signal. Purpose To identify the relationship between atrial and ventricular electrogram components at the anatomically defined mitral valve annulus. Methods Mapping of the mitral annulus was performed in patients undergoing ablation for paroxysmal atrial fibrillation. Following femoral venous access and trans-septal puncture, left atrial anatomy was defined using rotational angiography performed using a 100ml contrast injection 4 seconds prior to X-ray acquisition, during rapid pacing and apnoea while covering 200 degrees at 40 degrees/s. A SmartTouch SF ablation catheter (Biosense Webster) was advanced into the left atrium and used to record intracardiac electrograms at four positions around the mitral annulus and at five predetermined levels ranging from ventricular to atrial (Figure, panel A). Data analysis was performed using OpenEP (https://openep.io). For each electrogram, the distance to the mitral valve plane and the amplitudes of atrial and ventricular electrogram components were calculated (Figure, panel B and C). Mean electrogram component amplitudes were calculated including all points recorded within ±2.5mm of the mitral valve plane. For each patient, a linear regression model was fitted and used to identify the atrial/ventricular ratio at the anatomically defined mitral valve annulus (Figure, panel D). Results The protocol was completed in 9 patients, including analysis of 240 atrial or ventricular electrogram components. Within ±2.5mm of the anatomically defined mitral valve annulus, the mean recorded amplitudes of atrial and ventricular electrogram components was 0.15±0.17mV and 1.35±1.27mV, respectively (A/V ratio 1:9). Using the linear regression model, the ventricular electrogram component was calculated to be 16.5±11.6 times greater in amplitude than the atrial electrogram component at the mitral valve plane (A/V ratio 1:16). The use of a balanced signal to identify the mitral valve annulus resulted in a positional error of -7.9±9.5mm (i.e. identifying a level which is approximately ~8mm too "atrial" compared to the anatomically defined annulus). Conclusion The conventional use of a "balanced" electrogram signal does not identify the anatomical mitral valve annulus. An atrial/ventricular electrogram ratio between 1:9 and 1:16 best approximates the mitral valve annular plane determined by left atrial rotational angiography. These findings have relevance in target site selection for an accessory pathway and the ventricular extent of linear ablation at the mitral isthmus.

Interim analysis of a prospective randomized comparison of pulsed field ablation vs. radiofrequency ablation for longstanding persistent atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Benefits of pulsed field ablation (PFA) compared to radiofrequency ablation (RFA) are not known in patients with longstanding persistent atrial fibrillation (LSPAF). Purpose To present interim procedural and short-term clinical results of an ongoing prospective randomized comparison of PFA vs. RFA in patients with LSPAF. Methods In 9/2021-10/2022, 125 patients underwent catheter ablation for LSPAF using PFA (n=64, 69±8 years, 11 F, continuous AF 32±20 months) vs. RFA (n=61, 68±8 years, 17 F, continuous AF 29±23 months). PFA included pulmonary vein isolation (PVI) and extra-PV left atrial (LA) ablation. RFA included stepwise PVI, electrogram-guided LA ablation, CS isolation, and electrogram-guided right atrial ablation. Intermediate endpoints were PVI, mitral isthmus, LA roof and CTI blocks); sinus rhythm (SR) restoration by ablation was the desired procedural endpoint. Follow-up included 7-day ECG monitoring every 3 months during the first year, and every 6 months afterwards. Results In groups PFA vs. RFA, procedure and fluoroscopy times were 116±32 vs. 204±44 minutes, and 17±5 vs. 8±2 minutes, respectively (both p&amp;lt;0.001). AF termination (into intermediate AT or directly into SR) and SR restoration by ablation were achieved in 30 (47%) vs. 42 (69%) patients (p=0,19), and in 23 (36%) vs. 35 (57%) patients (p=0,15). Of those 48 vs. 50 patients with follow-up ≥3 months (≥6 months in 37 vs. 39 patients), freedom from any AF/AT (&amp;gt;30 s) was achieved in 38 (79%) vs. 23 (46%) patients. Conclusion Interim results of ongoing comparison suggest procedure time reduction and improved AF/AT free survival after PFA as compared to RFA in patients with LSPAF.

Impact of vein of Marshall ethanol infusion on left atrial function: an MRI study

Abstract Funding Acknowledgements Type of funding sources: None. Background Previous data suggested that left atrial (LA) function may be impaired by extensive atrial fibrillation (AF) ablation. Ethanol infusion of Vein of Marshall (EI-VOM) as an adjunctive therapy to pulmonary vein isolation is an emerging therapeutic strategy that has shown to improve efficacy in persistent AF ablation procedures and mitral isthmus line. The impact of EI-VOM scar formation on LA function has not been addressed. Purpose To analyse the effect of EI-VOM on LA function, evaluated by magnetic resonance imaging (MRI) strain parameters. Methods Twelve patients referred for de novo persistent AF or any repeat procedure were included. MRI was performed previous (baseline) and 3-month after AF ablation. MRI images were analyzed off-line with specialized post-processing software. LA volumes, LA strain parameters, including LA global longitudinal strain (GLS), LA reservoir (LASr), conduit (LAScd) and contractile (LASct) strain; LA ejection fraction (LAEF), LA passive emptying function (LAPEF) and LA active emptying function (LAAEF) were measured from SSFPs two-chamber cine sequences. Results Two patients were excluded due to absence of VOM and failed ethanolization. Ten patients (83%) underwent both MRI studies (64 [55-71]years; 80% men; de novo ablation of persistent AF (50%)). Six patients received additional mitral isthmus line and three posterior wall isolation. Mean baseline indexed LA volume was 62.7ml/m2 [47-73]. Baseline LA strain and EF parameters were: LA GLS 17.16±15.3, LASr 17.80±14.9%, LAScd -5.96±3.7%, LASct -10.35±9.5%; LAPEF 5.89±9.8, LAAEF 23.87±17.0 and LAEF 27.6±18.3%. At 3-months follow-up, no AF recurrences were detected. No differences were found regarding LA volume (57.6ml/m2 [42-64], p=0.671), strain parameters (LA GLS Δ0.62, p=0.903; LASr Δ0.02, p=0.991; LAScd Δ-0.84, p=0.563; LASct Δ0.54, p= 0.874) and LAEF parameters (LAPEF Δ4.82, p=0.592; LAAEF Δ3.03, p=0.903; and LAEF Δ7.0, p=0.213). Conclusions EI-VOM appears as a safe adjunctive strategy in AF ablation in terms of LA function. The present study did not show impairment in the main MRI strain parameters.

Usefulness of simultaneous isolation of the coronary sinus and the left atrial inferior wall for persistent atrial fibrillation refractory to box isolation

Abstract Funding Acknowledgements Type of funding sources: None. Background In patients who are refractory to box isolation (BoxI) and have atrial fibrillation (AF) substrate in left atrial inferior wall (LAIW), LAIW isolation is effective, but the procedure is highly difficult because the connection between LAIW and coronary sinus (CS) is dense. In this study, we report four cases of persistent AF in which simultaneous isolation of LAIW and CS was so effective. Methods and Results Case 1 is a 76-year-old female with persistent AF who had undergone BoxI and failed mitral isthmus block (MIB) creation. However, AF and atrial tachycardia (AT) persisted. In the 4th session, chemical ablation of Marshall vein was performed, and AF/AT was terminated, and MIB was created. Thereafter, multiple ATs were still inducible by rapid atrial pacing. Because AT substrate seemed to be confined to LAIW, we attempted to isolate LAIW by performing linear ablation between the right inferior pulmonary vein (RIPV) and posteroseptal mitral annulus (MA) near CS ostium, and linear ablation parallel to CS along posterior MA. However, LAIW isolation could not be achieved. Finally, CS ostial ablation from right atrium (RA) succeeded in simultaneous isolation of LAIW and CS. CS burst pacing could induce AT confined to LAIW and CS although RA maintained sinus rhythm (SR). Rapid RA pacing could not induce AT/AF. Case 2 is a 78-year-old female with persistent AF who completed BoxI and MIB creation. Raid RA pacing induced AF. Because cycle length of LAIW was apparently shorter than RA, we attempted to isolate LAIW. Firstly, we performed linear ablation from RIPV ostium to posterior MA. During linear ablation, AF converted to AT, and finally RA returned to SR while AT was still sustained within LAIW and CS. This tachycardia was a reentrant tachycardia circling LAIW and CS. After this AT returned to SR by linear ablation within LAIW, LAIW and CS were not isolated during SR. CS ostial ablation from RA succeeded in simultaneous LAIW and CS isolation. Case 3 is a 74-year-old female with persistent AF refractory to BoxI. Although non-pulmonary vein (non-PV) trigger was documented in LAIW, the precise origin of non-PV trigger could not be identified due to infrequency. Case 4 is a 64-year-old male with persistent AF refractory to BoxI. He had undergone catheter ablation three times. Fractionation map showed that AF substrate was likely located in LAIW. Therefore, we attempted to isolate LAIW in Case 3 and 4. We performed MI ablation, linear ablation between RIPV ostium and posteroseptal MA, and CS ostial ablation from RA, which succeeded in simultaneous isolation of LAIW and CS in both cases. AF has never recurred in Case 1 and 2. SR could be maintained with antiarrhythmics in Case 3 and 4. Conclusions In patients with persistent AF refractory to BoxI, if LAIW has AF/AT substrate or non-PV triggers, simultaneous isolation of LAIW and CS may be a new therapeutic strategy. Simultaneous isolation of LAIW and CS requires ablation at CSos from RA.

Spontaneous left-sided atypical flutter: revising the mechanisms in patients not submitted to prior linear ablation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction The decrease in the use of linear ablation for atrial fibrillation treatment has reduced the frequency of iatrogenic feft-sided atypical flutters (AFl). However, AFl are becoming increasingly frequent, associated with population age and risk factors for atrial scar. Revising the mechanisms of non-iatrogenic AFl may lead to a better procedure workflow. Purpose To describe the mechanisms of non-iatrogenic AFl. Methods Retrospective single-center study of AFl patients (pts) submitted high-density mapping from 2018 to 2022. Patients submitted to any prior left atrial linear ablation were excluded. Map collection was performed just visualizing the voltage map and a comprehensive workflow was applied for activation map interpretation, starting by facing the mitral annulus and following the sequence of colors to systematically identify all potential circuits, their common-isthmuses, and eventual slow-conduction sites. Entrainment maneuvers were performed to confirm the circuit interpretation if sinus rhythm was not restored with the completion of the planned ablation set. Results A total of 59 pts were included (male: 56% male; 67 ± 13 years), 28 previously submitted to atrial fibrillation ablation, restricted to pulmonary vein (PV) isolation. About 88% presented a macro-reentrant mechanism, either restricted to the left atrium (N=50) or biatrial (N=2) and involving 2 or 3 loops in 61% - Figure 1. Perimitral loop was the most frequent reentrant circuit, representing 60% of macro-reentrant arrhythmias (N=30) and exhibiting an evident out-of-proportion predominance of counterclockwise rotations (73% versus 27%). Among perimitral flutters with at least one additional loop, a balanced distribution was recognized of rotations around the left and right PVs (10 versus 10). As a result of the existence of additional loops producing common-isthmuses locations in various atrial regions, the classical inferior mitral isthmus line (from the mitral annulus to the left inferior PV) would only terminate as much as 53% of the perimitral AFl. The mechanism-tailored ablation strategy, particularly targeting the AFl common-isthmuses, resulted in restoration of sinus rhythm in 96.6% of pts (N=57). Conclusions In pts not previously submitted to linear ablations, AFl are predominantly caused by macro-reentrant circuits involving a perimitral rotation but not necessarily possible to treat with a conventional mitral isthmus line. With current high-density mapping tools, a comprehensive analysis of the substrate and activation maps and a mechanism-tailored ablation strategy results in an unprecedently high acute success rate.

Re-do ablation procedure characteristics after pulmonary vein isolation using pulsed field ablation for atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulsed field ablation (PFA) has recently been introduced as a novel routine ablation technology for paroxysmal atrial fibrillation (PAF). A few small clinical studies and registries have reported an initial clinical success rate of approx. 80% after 1 year. Here, we present the results from re-do ablation after PVI using PFA for AF. Methods In symptomatic AF patients, re-do ablation in conscious sedation using a contact force sensing catheter and 45W RF energy was performed. In all patients, pre- and post-ablation high-density bipolar voltage 3D maps using a pentaspline diagnostic catheter were performed. Procedural parameters and acute success were assessed. Results Eighteen patients (age 67 years; 17% female; 56% PAF) from a total of 304 patients (age 67 years; 42% female; 47% PAF) (6%) treated with PFA as initial AF therapy underwent a re-do ablation 212 days after the index procedure. Mean CHA2DS2-VASc-score was 1,7 in the re-do group vs. 2,5 in the index procedure group. Mean duration since first AF diagnosis and BMI were not significantly different. In 12/18 (67%) patients, reconnection of at least 1 PV was found (LSPV 2x; LIPV 4x; RSPV 2x; RIPV 2x, left carina 4x; right carina 2x). All reconnected PVs were successfully reisolated. In 11/18 (61%) of patients, an atrial flutter (AFL) or tachycardia (AT) was identified (roof 5x; mitral isthmus 5x; anterior/septal 3x; cavotricuspid isthmus 5x). In 5/12 (42%) of patient with reconnection of at least 1 PV, AT/AFL occurred. In contrast, in all 6 patients (100%) with persistently isolated PVs AT/AFL occurred. All tachycardias were successfully ablated. Conclusions Re-do ablation rate after PFA for AF was relatively low (6%), involving mostly male patients. PV reconnection rate was 67%, site of PV reconnection was predominantly left-sided. In 61%, predominantly left-sided AT/AFL occurred. Notably, in all patients with persistently isolated PVs AT/AFL was observed.

Pathophysiology of recurrent atrial fibrillation after initial cryoballoon ablation and clinical outcome of the second ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background There are limited clinical studies on recurrent atrial fibrillation (AF) mechanisms after initial cryoballoon ablation (CBA). Purpose We aimed to elucidate the mechanisms of AF recurrence after CBA based on electrophysiological findings obtained during the second ablation and the response to treatment. Methods Of 885 patients who underwent CBA at our hospital between 2016 and 2022, 50 (5.7%) patients (age 68 ± 9.2 years, 62% male, 52 % paroxysmal AF, body mass index (BMI) 25 ± 3.8 kg/m2, left atrial diameter (LAD) 44 ± 5.9mm, left ventricular ejection fraction (LVEF) 66 ± 11%, CHADS2 score 1.9 ± 1.4) were included. All the patients were treated with an Arctic Front Advance™ in the initial CBA. Each pulmonary vein (PV) was treated with a target time of 180 sec. Routine left atrial roof line and posterior wall isolation was not created. However, tricuspid valve isthmus isolation (CTI) and superior vena cava (SVC) isolation were added as required. The findings obtained with the 3D-mapping system during the second ablation were analyzed. Furthermore, the contents of the second ablation and the clinical outcomes were investigated. Results The first ablation successfully isolated PVs in all patients, and additional radiofrequency ablations were CTI ablation in 28 patients and superior vena cava (SVC) isolation in 6 patients. The second ablation was done after 24±16 months. At recurrence, persistent AF was 24%. Furthermore, atrial flutter was recorded in 16% of the 50 cases. The 3D-mapping systems used for guidance were RHYTHMIA HDx™ in 42 cases, CART-XP™ in 5 cases and EnSite NavX™ in 3 cases. Electrical reconnection of PV was detected in 14 patients. They included seven left-superior PVs, two left-inferior PVs, two left-common PVs, four right-superior PVs and five right-inferior PVs. There were 11 cases of conduction only in the carina area, five with left-sided and six with right-sided. All second ablations were treated with high-frequency irrigation catheters. The treatments were PV re-isolation in 14 patients, isolation area expanding in 43 patients, SVC isolation in 24 patients, CTI ablation in 3 patients, and mitral isthmus ablation in 2 patients. After 24.8 ± 14.9 months, treatment outcomes were as follows; AF was completely cured in 23 patients, anti-arrhythmic drugs were required in 23 patients, and no effects in 4 patients. Comparing the completely cured patients’ group (23 patients) with the other (27 patients), age (65.1 ± 9.3 years vs 70.5 ± 8.6 years, p &amp;lt; 0.05) and CHADS2 score (1.5 ± 1.3 vs 2.3 ± 1.3, p &amp;lt; 0.05) have significant differences. There were no differences in the presence of PV reconnection, BMI, LAD, LVEF and second ablation contents. Conclusion In patients with recurrent AF after CBA, less than 30% had PV-reconnection, and its disappearance was not associated with AF disappearance. Non-PV foci, except SVC origin, might cause recurrent AF after CBA.

Pulmonary vein and posterior wall isolation and mitral isthmus block with radiofrequency vs electroporation: comparing a classic to a novel technique for the ablation of persistent atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Persistent atrial fibrillation (PerAF) ablation continues to be a challenge due to the wide variety of approaches and a high arrhythmia recurrence. In our center, the usual strategy for PerAF ablation comprises posterior wall isolation (PWI) and mitral isthmus block (MIB) in addition to pulmonary veins isolation (PVI), with alcoholization of the Vein of Marshall (VoM) if possible. Pulsed-field ablation (PFA) has emerged as a novel and promising source of energy for AF ablation, having proved its feasibility and safety for PVI. However, there is no evidence in terms of feasibility and safety about a combined strategy of PVI, PWI and MIB. Purpose Our aim was to assess the feasibility and safety of PVI, PWI and MIB with PFA for PerAF ablation, and compare it to the same approach carried out with radiofrequency (RF) +/- alcoholization of the VoM, in terms of procedural parameters, acute success and complications rate. Methods All patients who undergone PerAF ablation with PFA and RF between November 2021 and September 2022 were consecutively and retrospectively included in the study. Demographic data, procedural data, rate of acute access (in achieving isolation or block of the targeted substrates) and complications rate were collected. Results Ninety patients with PerAF ablation were included (45 with the classic approach [RF ± VoM] and 45 with PFA). No differences were found in mean age and gender (67.0±9.1 vs 67.0±10.02 y.o, p=0.96 and 26.6% vs 24.4% of women, p=0.8). No differences were found with regard to previous cardiopathy or other comorbidities. There were also no differences in left atrial volume (157±41.1vs145±54.8ml, p=0.26). As for the procedure, the PFA group had shorter procedural time (119.8±26.3vs 84.1±20.0 min, p=0.00) but longer fluoroscopy time (17.8±6.9vs23.6±6.7 min, p=0.0002) and higher fluoroscopy dose (36.1±25.3vs67.3±84.7 Gy.cm2, p=0.02). No differences were found in the acute success rate to achieve PVI (100% in all), PW isolation (97.7%vs100%, p=0.31) or mitral isthmus block (97.7%vs100%, p=0.31) between RF±VoM and PFA groups, respectively. Of note, among the patients in AF rhythm at the procedure, the rate of reversion to sinus rhythm during ablation was much higher in the PFA group (7.14% vs 77.7%, p=0.00), with a lower rate of cardioversion (92.8% vs 22.2%, p=0.00) during the procedure. No significant differences were found with regard to the number of complications (13.3% [6 cases] in the RF±VoM group vs 6.6% [3 cases] in the PFA group, p=0.27). Conclusions PFA shows a good feasibility and safety profile for PVI, PWI and MIB with shorter procedural time and higher rate of conversion to sinus rhythm during ablation compared to the classic strategy with radiofrequency.

Incidence, types and predictors of AF recurrence after AF ablation with pulsed field ablation. A single-centre experience

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulsed field ablation (PFA) is an emerging method for atrial fibrillation (AF) ablation. However, there is little data about incidence, types, and predictors of AF recurrences after PFA for AF ablation. Methods We report our single-centre experience with PFA for AF ablation. Each procedure was performed under unconscious sedation with propofol and fentanyl. If needed, midazolam was added in rare cases. Fifteen minutes before transeptal puncture 70IU/kg of unfractionated heparin were administered, for an ACT level &amp;gt;300sec during the entire procedure. Isolation of pulmonary veins was started after administration of 1mg of atropine with 8 applications per vein (4 in basket, 4 in flower configuration). Afterwards all veins were checked for entrance- and exitblock to confirm isolation during SR. If needed, additional ablation was performed. Results In total, 124 patients undergoing AF ablation therapy with PFA between June 2021 to October 2022 were analysed. Mean age was 61±9 years, 39% were female. Mean CHADS-VASc Score was 2±1. Sixty-two percent had paroxysmal atrial fibrillation (PAF), 34% persistent AF, in 4% patients suffered from long standing persistent AF. In 85% (n=106) of procedures first pass isolation of all veins was possible. Primary success to achieve PV isolation was accomplished in all patients at the end of procedure. In addition to PVI, in 6,5% of patients cavotricuspid isthmus (CTI) was blocked, in another 7,3% the posterior wall was isolated during the first procedure. Mean procedure duration was 76±30 minutes, mean x-ray time 11±22 minutes. During 124 procedures, only one periprocedural complication was documented (vascular complication). Eighteen patients (14,5%) had recurrence of dysrhythmia after a blanking period of 3 months after a mean follow-up period of 167±150 days. Mean time to recurrence was 108±101 days. Patients with recurrences after the blanking period suffered significantly more often from diabetes (OR 0,21 (0,089-0,495); p&amp;gt;0.01) and hyperlipidaemia (OR: 0,198 (0,070-0,498); p&amp;gt;0.01). Until now we performed five re-do procedures of patients with recurrence of dysrhythmia after a PFA first-do procedure. The recurrent arrhythmia was AF (n=2), atypical AT (roof-dependent n=1, one mitral isthmus dependent n=1), and CTI-dependent flutter (n=1). All five patients had PV reconnections, and all could be successfully reablated. Conclusion AF ablation with PFA is associated with high SR success rate, and acceptable procedure duration and complication rates. Randomized studies are needed to further evaluate this new method compared with other ablation techniques.

Incidence of ventricular tachyarrhythmias and clinical outcomes in primary prophylactic ICD patients in relation to localization of myocardial infarction

Abstract Funding Acknowledgements Type of funding sources: None. Introduction According to current guidelines, primary prophylactic ICD implantation is indicated with a class IA recommendation in patients with severely reduced EF &amp;lt; 35% and ischaemic heart disease. However, it is unclear whether there are differences in patient outcomes related to the localization of myocardial infarction. Aim of the study was to compare the incidence of ventricular tachyarrhythmias and clinical outcomes in primary prophylactic ICD-patients with ischaemic heart disease in relation to the localization of myocardial infarction. Methods A total of 448 consecutive ICD patients from a prospective single-centre ICD-registry who underwent primary prophylactic ICD implantation due to ischaemic cardiomyopathy between 1996 and 2021 were analyzed. Patients with previous anterior wall myocardial infarction (AWMI, n = 293) were compared to those with posterior wall myocardial infarction (PWMI, n = 155). Patients with both AWMI and PWMI were excluded. The median follow-up time was 6 years in both groups. Results Patients with AMWI were younger, more often female, and less often received cardiac synchronization therapy (Table 1). Patients with previous PWMI more often had ICD therapy during follow-up (Figure 1) due to the higher incidence of ventricular tachycardias (Table 1). The all-cause mortality rate was similar between both groups. Conclusion Primary prophylactic ICD patients with previous PWMI have a 10% higher incidence of ventricular tachycardias after 6-year follow-up than ICD patients with previous AMWI. This might be explained by the proximity of the inferior infarction to the mitral isthmus and should be considered when ablating VTs in patients with PWMI.

A novel stepwise approach incorporating ethanol infusion in the vein of Marshall for the ablation of persistent atrial fibrillation.

Apart from pulmonary vein isolation (PVI), several step-by-step procedures that aim to modify left atrial substrate have been proposed for the ablation of persistent atrial fibrillation (AF), yet the optimal strategy remains elusive. There are cumulative data suggesting an incremental benefit of adding vein of Marshall (VOM) ethanol infusion to PVI in patients with persistent AF. We sought to evaluate the feasibility and efficacy of a novel stepwise ablation approach, incorporating a VOM alcoholization step, for persistent AF. In this single-center study, we prospectively enrolled 66 consecutive patients with symptomatic persistent AF and failure of at least one antiarrhythmic drug (ADD). The ablation procedure consisted of (i) PVI, (ii) left atrial segmentation with VOM ethanol infusion and the deployment of linear radiofrequency lesions across the roof and the mitral isthmus and (iii) electrogram-based ablation of dispersion zones. The first two steps were performed in all patients, whereas the third step was carried out only in those still in AF at the end of the second step. Atrial tachycardias during the procedure were mapped and ablated. At the end of the procedure, cavotricuspid isthmus ablation was additionally performed in all patients. The primary endpoint was 12-month freedom from AF and atrial tachycardia after a single procedure and an initial three-month blanking period. Total procedure time was 153 ± 38.5 min. Fluoroscopy time was 16 ± 6.5 min and the radiofrequency ablation time was 26.14 ± 0.26 min. The primary endpoint occurred in 54 patients (82%). At 12 months, 65% of patients were off any AAD. In the univariate Cox regression analysis, left ventricular ejection fraction < 40% was the only predictor of arrhythmia recurrence (HR 3.56; 95% CI, 1.04-12.19; p = 0.04). One patient developed a pericardial tamponade and another a minor groin hematoma. A novel stepwise approach, including a step of ethanol infusion in the VOM, is feasible, safe and provides a high rate of sinus rhythm maintenance at 12 months in patients with persistent AF.

MP-453081-7 A COMPARISON OF LEFT CIRCUMFLEX CORONARY VASOSPASM BETWEEN RADIOFREQUENCY ABLATION AND PULSED FIELD ABLATION AT THE MITRAL ISTHMUS

Pulsed field ablation (PFA) is a nonthermal energy modality that largely spares collateral structures like the esophagus and phrenic nerve. However, a recent study indicates that subclinical coronary artery vasospasm is common during PFA of the cavo-tricuspid isthmus. There is also a case report of left circumflex artery (LCx) vasospasm during PFA at the mitral isthmus (MI). To determine the frequency of LCx vasospasm during PFA on the lateral MI and compare to RFA. In a prospective, consecutively enrolled cohort of patients undergoing AF ablation under deep sedation, diagnostic coronary angiography was performed via right femoral arterial access before, during, and after endocardial ablation on the lateral MI with either a PFA catheter (Farawave, Boston Scientific Inc) or an irrigated RFA catheter (Thermocool, Biosense-Webster Inc). When vasospasm was identified on angiography, it was monitored for clinical remission and hemodynamic changes and intervention with nitroglycerin administered if refractory to upfront supportive care. A total of 19 patients received PFA on the lateral MI with acute bidirectional block: 11 along the superior MI (1-2 o’clock on the annulus) and 8 along the inferior MI (3-5 o’clock on the annulus). In total, 7 patients experienced LCx vasospasm (2 mild, 3 moderate, 1 severe). By site, 7 of 11 (64%) and 0 of 8 (0%) were at the superior or inferior MI, respectively. In comparison, 9 patients underwent RFA of the MI (all at the superior MI with coronary sinus lesions in 3 patients), during which there were no instances of LCx spasm. Of note, 5 of 9 patients also received MI PFA due to the absence of MI block after first pass RFA; 3 of these 5 patients did demonstrate LCx spasm during PFA. In none of the instances of MI spasm were there any symptoms or hemodynamic compromise. ECG changes were seen in 1 patient: ST elevations with severe LCx spasm. While PFA confers an important degree of tissue preferentiality and enhanced safety compared to thermal ablation for esophageal/phrenic damage and pulmonary vein stenosis, our data indicate that PFA can cause reversible (mostly) subclinical LCx spasm during MI ablation. Vasospasm occurred during superior MI ablation while inferior MI PFA did not cause spasm; this may be related to the proximity of the PFA catheter to the LCx along its superior-inferior course. Conversely, RFA of the MI does not appear to be associated with a significant risk for LCx spasm.

PO-04-005 LEFT CIRCUMFLEX ARTERY VASOSPASM DURING PULSED FIELD ABLATION AT THE MITRAL ISTHMUS: CHARACTERIZATION OF TIME-TO-RESOLUTION

While pulsed field ablation (PFA) has emerged as a novel energy modality for ablation of atrial arrhythmias and is accompanied by a theoretically safer profile given its tissue selectivity and sparing of collateral structures, a recent study has highlighted the occurrence of subtotal coronary vasospasm during atrial fibrillation (AF) ablation on the cavo-tricuspid isthmus with PFA. While these observations were subclinical, there is at least one case report of left circumflex (LCx) coronary artery vasospasm during PFA at the mitral isthmus (MI) during AF ablation. To evaluate the natural history time-to-resolution of coronary vasospasm of the LCx artery during PFA at the MI. In a prospective, consecutively enrolled cohort of patients receiving AF ablation under deep sedation, diagnostic coronary angiography was performed via right femoral arterial access before, during, and after ablation on the MI with a multi-spline PFA catheter (Farawave, Boston Scientific Inc). LCx spasm was identified, characterized by severity, and monitored for progression and time-to-resolution. A total of 19 patients underwent PFA on the lateral MI with successful bidirectional block. Notably, 7 patients (37%) developed LCx vasospasm during ablation, of which 3 cases were mild (<50% decrease in luminal diameter), 2 were moderate (50 to 90% decrease), and 2 were severe (>90% decrease). All of the mild and moderate spasm occurrences self-resolved, with mild spasm taking on average 5.7 minutes to be relieved, and moderate spasm requiring 5 minutes. Relief of severe spasm required an average of 15 minutes, with both necessitating administration of intracoronary or intravenous nitroglycerin. Electrocardiographic ST changes were only present in one case of severe spasm (which resolved with relief of spasm), and there were no hemodynamic changes during spasm. As PFA becomes an alternative to radiofrequency and cryothermal ablation, it behooves operators to be vigilant for vasospastic effects on adjacent coronary vessels during ablation. Further investigation with larger populations is required to more fully elucidate the injurious potential of PFA-induced coronary vasospasm. This study is one of the first to elaborate on the features of LCx vasospasm during PFA on the MI.Tabled 1Patient CharacteristicsAge, mean±SD, y65.6±10.1Male, n (%)14 (74)Body mass index, mean±SD30.3±4.9Medical HistoryType of atrial fibrillationParoxysmal, n (%)4 (21)Persistent, n (%)15 (79)Duration of atrial fibrillation, mean±SD, months48.2±66.4CHA2DS2-VASc Score, mean±SD2.1±1.4Hypertension, n (%)13 (68)Diabetes, n (%)4 (21)Dyslipidemia, n (%)11 (58)Sleep apnea, n (%)1 (5)Prior stroke or transient ischemic attack, n (%)2 (11)Coronary artery disease, (%)4 (21)Congestive heart failure, n (%)1 (5)Left ventricular ejection fraction, mean±SD, %62.3±3.4Left atrium dimension, mean±SD, mm45.8±9.2MedicationsWarfarin, n (%)12 (63)Non-Warfarin oral anticoagulant, n (%)7 (37)Antiarrhythmic drugs, n (%)Class I7 (37)Class II11 (58)Class III5 (26)Class IV0 (0) Open table in a new tab

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.

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.