Mitral Line Research Articles

AB-452675-1 ELECTROPHYSIOLOGICAL FINDINGS DURING REDO PROCEDURES AFTER PULSED FIELD ABLATION USING A PENTASPLINE CATHETER TO TREAT ATRIAL FIBRILLATION IN ROUTINE CLINICAL PRACTIC

Data from clinical trials of pulsed field ablation (PFA) to treat atrial fibrillation (AF) indicate highly-efficient workflow, an excellent safety profile, good clinical outcomes with few AF recurrences. Also strikingly, protocol-directed invasive remapping procedures revealed a high degree of durability of the pulmonary vein isolation (PVI) lesion sets. While quite favorable, PVI durability in carefully-monitored protocols may not translate to day-to-day clinical practice. Assessing durability with routine invasive remapping is not possible in routine clinical practice, but the “electrical status” of the PVs during clinical redo procedures provides compelling insights into the technical efficacy of the index procedure. To evaluate the electrophysiologic findings during redo procedures in AF patients initially treated with PFA. This single-center study included all redo ablations after an index PFA using the pentaspline catheter (Farapulse; BSC Inc.); patients in clinical trials were excluded. During the redo case, all PVs and any other lesions we assessed. Redo ablation was performed using either RF or PF energy, per operator preference. Between April 2021 (time of PFA approval) and Nov 2022, 863 consecutive AF ablations were performed using the pentaspline PFA catheter in our center. Clinically-indicated redo procedures were performed in 28 (3.2%) patients: mean age 66 yrs, 17M/11W, BMI 29, LA size 46 mm, PAF/PerAF 17/11. Mapping revealed reconductions (gaps) in 33 of 110 (30%) PVs (gaps seen in 18 pts). The distribution of the reconnections was slightly higher in the right PVs: RSPV 9, RIPV 11, LSPV 7, LIPV 6, LCPV 2. For other lesions placed during the index procedure, reconduction was observed in: 3 of 6 (50%) pts with mitral lines, 1 of 6 (17%) pts with posterior box, and 2 of 2 (100%) pts with left atrial appendage isolation. In 2 pts with initially paroxysmal AF and durable PVI, peri-mitral flutter was the clinical tachycardia, in 1 patient the symptomatic tachycardia was typical AVNRT. Only a minimal number (3,2%) of 863 patients (outside of those enrolled in clinical trials) after PF ablation of atrial fibrillation using Farapulse system underwent reablation for recurrent atrial tachyarrhythmia in our center. Even after PF ablation, gaps in the pulmonary veins remain the most common finding – 30% of treated veins were not permanently isolated.

PO-05-155 A CASE OF ALCOHOL LEADING TO ISOLATION IN THE ELECTROPHYSIOLOGY LABORATORY

Ligament of Marshall alcohol ablation is a treatment for refractory atrial fibrillation and left atrial flutter. Left atrial appendage (LAA) isolation resulting from LOM ablation has not been described. To describe a case of LOM alcohol ablation which resulted in left atrial appendage isolation and dissociation of a left atrial appendage reentrant atrial flutter from the atria. A middle aged man with a history of atrial fibrillation and multiple left atrial flutters was referred for repeat ablation after multiple prior unsuccessful ablations. He previously underwent surgical MAZE and 3 endocardial ablations including an anterior mitral line and endocardial and epicardial mitral isthmus line without achieving bidirectional block. He had recurrent, symptomatic atrial flutter despite therapy with dofetilide and metoprolol. The patient presented in an atypical flutter. The ligament of Marshall was cannulated and alcohol was sequentially injected for a total of 3.8 mL. After the first alcohol injection, the tachycardia abruptly terminated on the coronary sinus (CS) catheter and sinus rhythm resumed (Figure, blue arrows), though the surface ECG showed ongoing small atrial flutter waves (Figure, red arrows). Subsequent left atrial mapping confirmed that the left atrial appendage (LAA) was isolated from the remaining left and right atrium and remained in atrial flutter (Figure C). Overdrive pacing from a multipolar catheter in the LAA demonstrated a post-pacing interval within 20 ms of the tachycardia-cycle length (Figure C). Adenosine administration resulted in AV block but no alteration in tachycardia cycle-length. These findings were highly suggestive of a reentrant mechanism. Because 3D mapping was limited by dissociated CS and LAA rhythms, manual activation mapping was performed with earliest activation at the anterior superior LAA. RF ablation at this site resulted in atrial flutter slowing and termination. In a patient with LAA flutter and prior anteroseptal and lateral linear endocardial ablation, LOM alcohol ablation may isolate the LAA. This should be recognized when counseling patients and planning procedures.

PO-01-091 VEIN OF MARSHALL ETHANOL ABLATION AND LATERAL MITRAL ISTHMUS LINE TO IMPROVE EFFICACY OF PERSISTENT AF ABLATION

The optimal approach to ablation of persistent AF has not been well-established, and current strategies are only modestly successful. To assess the efficacy of additional vein of Marshall (VOM) ethanol ablation and lateral mitral isthmus ablation in addition to standard persistent AF ablation strategies using a stepwise approach. Sixty -Five consecutive patients undergoing ablation for persistent AF were included. . All patients underwent PVI with RF ,left atrial roof ablation with confirmed roof line block, and cavotricuspid isthmus ablation were performed. VOM ethanol ablation with concomitant lateral mitral annular ablation ( from the LA endocardium and Coronary sinus as needed) to achieve block were attempted in all patients. Patients underwent follow-up ambulatory monitoring and in -office and telephonic follow-up in a closed health delivery system for at least 12 months f/u from procedure. A total of 38 of 65 patients had successful Vom ethanol injection. .35 of these patients achieved successful mitral annular block. 27 patients did not receive therapy due to venous collateralization (29)%, inability to cannulate, vessel (29%) VOM not identified (19%) and target vessel dissection or extravasation (23%.) With an average follow up of 12 months, patients with successful VOM ethanol ablation and lateral mitral line had an 82% clinical arrhythmia- free survival. In patients with unsuccessful VOM attempt, the arrhythmia free survival was 58%. All patients were off antiarrhythmic drugs, and had only one procedure. One patient with successful VOM ethanol ablation was readmitted with pericarditis without effusion managed with colchicine. The addition of VOM ethanol ablation and lateral mitral isthmus ablation is associated with an improved arrhythmia-free survival in persistent AF ablation.

Anterior mitral line in patients with persistent atrial fibrillation and anterior scar: A multicenter matched comparison—The MiLine study

The benefit of an anterior mitral line (AML) in patients with persistent atrial fibrillation (AF) and anterior atrial scar undergoing ablation has never been investigated. The purpose of this study was to evaluate the outcomes of AML in addition to standard treatment compared to standard treatment alone (no AML) in this subset of patients. Patients with persistent AF and anterior low-voltage zone (LVZ) treated with AML in 3 centers were retrospectively enrolled. The patients were matched in 1:1 fashion with patients having persistent AF and anterior LVZ who underwent conventional ablation in the same centers. Matching parameters were age, LVZ burden, and repeated ablation. Primary endpoint was AF/atrial tachycardia (AT) recurrence. One hundred eight-six patients (age 66 ± 9 years; 34% women) were selected and divided into 2 matched groups. Bidirectional conduction block was achieved in 95% of AML. After median follow-up of 2 years, AF/AT recurrence occurred in 29% of the patientsin the AML group vs 48% in the no AML group (log-rank P = .024). On Cox regression multivariate analysis, left atrial volume (hazard ratio [HR] 1.03; P = .006) and AML (HR 0.46; P = .003) were significantly associated with the primary endpoint. On univariate logistic regression, lower body mass index, older age, extensive anterior LVZ, and position of the left atrial activation breakthrough away from the AML were associated with first-pass AML block. In this retrospective matched analysis of patients with persistent AF and anterior scar, AML in addition to standard treatment was associated with improved AF/AT-free survival compared to standard treatment alone.

Pseudo-Conduction in the Mitral Isthmus After Ablation.

A 56-year-old patient with a history of hypertension, dyslipidaemia, and long-standing atrial fibrillation underwent pulmonary vein isolation, endocardial mitral line ablation, and alcohol ablation of the vein of Marshall in 2018. He complained of palpitation due to recurrent atrial flutter, which was poorly controlled by amiodarone. Therefore, catheter ablation was arranged. Pre-ablation echocardiography showed normal left ventricular ejection fraction and computed tomography demonstrated an enlarged coronary sinus (CS).

Contact force-controlled high power short duration radiofrequency ablation enables efficient creation of roof line and anterior mitral line in course of low voltage areas

Abstract Funding Acknowledgements Type of funding sources: None. Background Linear ablation lines in the left atrium are questionable for treatment of atrial fibrillation (AF). In particular they are challenging, performed with limited success rate and are arrhythmogenic due to recurrence of conduction. Contact force (CF)-controlled high power short duration (HPSD) radiofrequency ablation (RFA) in areas of fibrosis may overcome these limitations. Purpose We investigated the efficiency of contact force (CF)-controlled high power short duration (HPSD) radiofrequency ablation (RFA) for creation of linear lines in case of fibrotic areas in the anterior left atrium. Methods In 530 consecutive patients (pts), age 65±9 years, paroxysmal AF in 45%, persistent AF in 55%, AF-re-ablation in 32% of pts, undergoing HPSD CF-controlled RF ablation of AF. Besides from pulmonary vein isolation (PVI) additional left atrial linear ablation in the anterior left atrium was performed in 28% of patients exclusively in case of low voltage areas in the course of the line or in case of re-ablation of prior performed lines. Fibrosis was defined by areas of less than 0.5mV signals in high density 3D microelectrode mapping. More than 5% low voltage was present in 46% of pts and more than 20% low voltage in 27% of pts. HPSD RF ablation was performed using a power of 50 Watt, duration 5-15s, with CF-controlled catheters, seeking for CF of 10-30g, and an interlesion distance of 6mm. Results A anterior roof line between both upper pulmonary veins was performed in 25% of pts (n=133), and an anterior mitral line in 17% of pts (n=88). The anterior mitral line connected the superior mitral anulus with left upper, right upper PV or anywhere this the roof line depending on the distribution of low voltage areas. Overall success rate of bidirectional conduction block at the roof line was 92% and at the mitral line 94%. After remapping of gaps and re-ablation with conventional 35-40 Watt RF application of unlimited duration, success rate at the roof line improved to 98% and at the mitral line to 97%. No serious complications were associated with creation of these lines, especially, no pericardial tamponade occurred. Limited follow up will presented at the time of presentation. Conclusions CF-controlled creation of ablation lines in the anterior left atrium (roof line and anterior mitral line) by HPSD RF ablation is very efficient and safe in case of areas of low voltage in the course of the linear ablation. In rare cases additional conventional RF application of unlimited duration becomes necessary to complete the lines supported by identification of gaps by high density 3D microelectrode mapping. This approach has the potential to improve efficacy of AF ablation in patients with atrial fibrosis. The hypothesis have to be proven by a prospective controlled study in the near future.

Strategies for repeat ablation for atrial fibrillation: a multicentre comparison of non-pulmonary vein versus pulmonary vein target ablation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Approximately 18% of patients with atrial fibrillation (AF) undergo a repeat ablation within 12 months after their index ablation. Despite the high prevalence, comparative studies on non-pulmonary vein (PV) target strategies in repeat AF ablation are scarce. Purpose: This study aims to describe 12 months efficacy of non-PV and PV target ablations as a repeat ablation strategy. Methods A multicentre retrospective, descriptive study was conducted with data of 280 patients who underwent repeat AF ablation. Ablation strategy for repeat ablation was at the operators’ discretion. Non-PV target ablation (n=140) included posterior wall isolation, mitral line, roofline and/or complex fractionated atrial electrogram ablation. PV target ablation (n=140), included re-isolation and/or wide atrium circumferential ablation. Patients’ demographics and rhythm outcomes during 12-months follow-up were analysed. Results: Overall, the mean age was 63 ± 9 years, 64% were male, and body mass index was 27.1 ± 4.2. Patients undergoing non-PV target ablation had more frequently persistent AF (47.9% vs 14.3%, p < 0.001), and had a higher CHA2DS2 VASc (2.0 vs 1.3, p < 0.001). At 12 months, more atrial tachyarrhythmias were observed in the non-PV target group (48.6%) compared to the PV target group (29.3%, p=0.001). Similarly, a significantly higher AF and atrial tachycardia (AT) recurrence rate was observed after non-PV target ablation compared to PV target ablation (36.4% versus 22.1% and 22.9% versus 10.7%). After adjusting for several associated covariates, a significantly higher AT recurrence risk remained in the non-PV target group (adjusted OR 2.19 95% CI 1.18 – 4.42, p = 0.023) (Figure 1C). Sensitivity analysis was performed with inverse propensity weighting to assess the robustness of the multivariate model and demonstrated comparable outcomes. Both groups significantly de-escalated anti-arrhythmic drug use, de-escalation was more profound after PV target ablation. Patients with isolated PVs during non-PV target ablation had a significantly higher risk for AF recurrence than those with reconnected PVs (Figure 1B). Conclusion: Compared to PV target ablation, non-PV target repeat ablation did not improve outcomes after 12 months and was independently associated with a higher risk for AT recurrences.

Utilising the pericardial CO2 insufflation technique to facilitate endo-epicardial AF ablation, achieving linear radiofrequency lesion sets, for persistent atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Background High rates of persistent atrial fibrillation (PsAF) recurrence have been attributed to conduction gaps, non-transmural linear lesion sets and epicardial substrate. Hybrid thorascopic endo-epicardial AF ablation has been shown to reduce PsAF recurrence when compared to endocardial ablation alone, however with higher complication rates. Aim We propose that the percutaneous pericardial CO2 insufflation technique to access the pericardial space can be safely and effectively used for epicardial mapping and ablation of the left atrium (LA). Methods In a single centre, 15 patients with PsAF (6 with longstanding PsAF) and previous pulmonary vein isolation (PVI), underwent concurrent endo-epicardial AF ablation, using the subxiphoid percutaneous pericardial CO2 insufflation technique, whilst on uninterrupted anticoagulation. Endo-epicardial geometry and bipolar voltage maps were undertaken, and endocardial LA ablation performed comprising a roof, inferior and anterior mitral line (AML) (target LSI 5 for the inferior line and 6 on the roof and AML). If required, additional epicardial ablation was undertaken to establish PVI and linear lesion block. Results Epicardial access was achieved in all patients without acute bleeding complication. Epicardial mapping of the LA, in both transverse and oblique pericardial sinuses, was successful in all patients (Figure 1A, B). Excluding one roof line, all other linear lesions were blocked (44/45). Endocardial ablation alone achieved block in 67% (10 of 15) of roof lines, 87% (13 of 15) of inferior lines and 27% (4 of 15) of AMLs despite extensive endocardial ablation. Of AMLs requiring epicardial ablation, in 91% (10/11) block was achieved with ablation on the upper third of AML via the transverse sinus (Figure 1C). Epicardial ablation directly on the roof line via the transverse sinus was required to achieve block in 3 cases, and block achieved remotely on the upper third of the AML in another. Epicardial ablation on the mid inferior line was required in 2 cases to achieve block. Six patients had arrhythmia recurrence during the blanking period with 5 patients requiring DCCV and 1 patient chemically cardioverting. With a mean follow up time of 225 days, 2 patients have had paroxysmal self-terminating episodes of atrial arrhythmia with all patients off anti-arrhythmic medication. Conclusion Use of the subxiphoid percutaneous pericardial CO2 insufflation technique to achieve epicardial access for LA mapping and ablation is feasible and safe whilst on uninterrupted anticoagulation. Limited success in ablation for PsAF beyond PVI may be due to difficulty in creating trans-mural linear lesions. Epicardial ablation can be safely performed to achieve linear block in the roof, anterior and inferior LA. Epicardial fibrous structures such as the septopulmonary bundle and Bachmann’s bundle likely contribute to difficulty blocking roof lines and AMLs endocardially.

PO-710-04 CONTEMPORARY PREVALENCE AND PREDICTORS OF INTACT PULMONARY VEIN ISOLATION IN PATIENTS UNDERGOING REPEAT ATRIAL FIBRILLATION ABLATION

Pulmonary vein isolation (PVI) is the primary goal of atrial fibrillation (AF) ablation. Prior studies have noted a 50-95% prevalence of pulmonary vein (PV) reconnection at the time of repeat ablation. However, the prevalence of PV reconnection with contemporary AF ablation techniques, including high frequency jet ventilation, is unknown. Furthermore, there is an incomplete understanding of predictors of intact PVI at the time of repeat ablation. To assess the prevalence of PV reconnection in a contemporary cohort utilizing jet ventilation, contact force catheters, and adenosine testing for dormant conduction, and identify patient characteristics and ablation techniques that predict PVI at time of repeat ablation. We reviewed 615 consecutive radiofrequency AF ablations from 2013-2019 at an academic medical center performed by a single operator. There were 121 unique patients who underwent a de novo AF ablation followed by a repeat AF ablation. We evaluated clinical and previous procedural characteristics to identify predictors of PVI at the time of repeat ablation, using logistic regression models. Of the 121 patients, 42.1% were female, average age was 64.5 years, and BMI 31. At the time of repeat ablation, 57% (n=69) had intact prior PVI. Baseline characteristics of patients with intact PVI and reconnected PVI were similar, including age (64 years and 65 years; p=0.75), left atrial diameter (4.13 cm and 4.39 cm; p=0.09), left ventricular ejection fraction (54.5 % and 55.4%; p = 0.38), and time to first atrial fibrillation recurrence (237 days v. 344 days, p=0.28). The only significant clinical predictor of intact PVI was the pre-procedure diagnosis of atypical atrial flutter (20.3 % v. 3.8%, p=0.02) (Figure 1). In multivariate analysis, prior mitral line ablation (OR 8.93, 95%CI [3.65, 21.87]: p <0.01) and first pass isolation of right pulmonary vein during the index AF ablation (OR 2.59, 95% CI [1.09, 6.12]: p = 0.03) strongly predicted intact PVI at the time of repeat AF ablation. With contemporary techniques, PVI reconnection is seen in 43% of patients at the time of repeat AF ablation. History of atypical flutter, prior mitral line ablation, and first pass isolation of the right PVs were significant predictors for intact PVI.

Strategies for repeat ablation for atrial fibrillation: A multicentre comparison of nonpulmonary vein versus pulmonary vein target ablation.

IntroductionApproximately 18% of patients with atrial fibrillation (AF) undergo a repeat ablation within 12 months after their index ablation. Despite the high prevalence, comparative studies on nonpulmonary vein (PV) target strategies in repeat AF ablation are scarce. Here, we describe 12 months efficacy of non‐PV and PV target ablations as a repeat ablation strategy.MethodsA multicentre retrospective, descriptive study was conducted with data of 280 patients who underwent repeat AF ablation. The ablation strategy for repeat ablation was at the operators' discretion. Non‐PV target ablation (n = 140) included PV reisolation, posterior wall isolation, mitral line, roofline, and/or complex fractionated atrial electrogram ablation. PV target ablation (n = 140), included reisolation and/or wide atrium circumferential ablation. Patients' demographics and rhythm outcomes during 12 months follow‐up were analyzed.ResultsAt 12 months, more atrial tachyarrhythmias were observed in the non‐PV target group (48.6%) compared to the PV target group (29.3%, p = .001). Similarly, a significantly higher AF and atrial tachycardia (AT) recurrence rate was observed after non‐PV target ablation compared to PV target ablation (36.4% vs. 22.1% and 22.9% vs. 10.7%). After adjustment, a significantly higher risk of AT recurrence remained in the non‐PV target group. Both groups significantly de‐escalated antiarrhythmic drug use; de‐escalation was more profound after PV target ablation. Patients with isolated PVs during non‐PV target ablation had a significantly higher risk for AF recurrence than those with reconnected PVs.ConclusionCompared to PV target ablation, non‐PV target repeat ablation did not improve outcomes after 12 months and was independently associated with an increased risk for AT recurrences.

Stepwise mapping and ablation algorithm in patients undergoing ablation of unstable, unmappable scar-based atrial tachycardias.

Scar based atrial tachycardia (AT)'s usually presents with a complex electrophysiological substrate. It is not uncommon that multiple instable ATs are present in a single patient. The aim of this study was to analyze clinical and electrophysiological characteristics of patients who had undergone ablation for instable ATs, and report outcomes of the stepwise substrate ablation procedure during the follow-up. Patients scheduled to undergo AT ablation were screened for enrollment to the study. When instable ATs were diagnosed a stepwise mapping and ablation algorithm was applied to all patients. After the procedure, patients were clinically and electrocardiographically followed. Twenty-six patients were enrolled in the study. The mean number of ATs observed during the procedures is 3.1±0.7. At the end of the procedure, 18 (69.2%) patients had isolated posterior wall. Anterior mitral line ablation was successfully performed in 13 (50%), mitral isthmus line in 4 (15.4%), roof line in 4 (15.4%) patients. The mean follow-up was 13.5±5.4 months. During the follow-up period 6(23.1%) patients developed arrhythmia recurrence. A reasonable mid-term success can be expected in patients with instable ATs undergoing ablation according to the stepwise substrate modification algorithm, however due to extensive ablation it should be reserved for patients where conventional activation mapping cannot be performed.

Very long term outcome after linear versus electrogram guided ablation for persistent atrial fibrillation

The optimal ablation strategy for persistent atrial fibrillation (PsAF) remains to be defined. We sought to compare very long-term outcomes between linear ablation and electrogram (EGM)-guided ablation for PsAF. In a retrospective analysis, long-term arrhythmia-free survival compared between two propensity-score matched cohorts, one with pulmonary vein isolation (PVI) and linear ablation including roof/mitral isthmus line (LINE-group, n = 52) and one with PVI and EGM-guided ablation (EGM-group; n = 52). Overall, 99% of patients underwent successful PVI. Complete block following linear ablation was achieved for 94% of roof lines and 81% of mitral lines (both lines blocked in 75%). AF termination by EGM-guided ablation was accomplished in 40% of patients. Non-PV foci were targeted in 7 (13%) in the LINE-group and 5 (10%) patients in the EGM-group (p = 0.76). During 100 ± 28 months of follow-up, linear ablation was associated with superior arrhythmia-free survival after the initial and last procedure (1.8 ± 0.9 procedures) compared with EGM-group (Logrank test: p = 0.0001 and p = 0.045, respectively). In multivariable analysis, longer AF duration and EGM-guided ablation remained as independent predictors of atrial arrhythmia recurrence. Linear ablation might be a more effective complementary technique to PVI than EGM-guided ablation for PsAF ablation.

Single-catheter simplified stepwise approach to persistent atrial fibrillation ablation: A feasibility study

The strategy for atrial fibrillation ablation in persistent atrial fibrillation remains controversial. A single-catheter approach was recently validated for pulmonary vein isolation. To evaluate the feasibility of this approach to performing persistent atrial fibrillation ablation, including pulmonary vein isolation and atrial lines, if needed. We prospectively included 159 consecutive patients referred to our centre for a first persistent atrial fibrillation ablation between January 2018 and December 2018. All patients underwent pulmonary vein isolation. If the patient was still in atrial fibrillation (spontaneously or inducible), we subsequently performed a stepwise approach, including roof line, anterior mitral line, posterior box lesion and cavotricuspid isthmus line. Finally, if patient remained in atrial fibrillation at the end of the procedure, a synchronized direct-current cardioversion was applied to restore sinus rhythm. At baseline, 54 patients were in sinus rhythm and underwent pulmonary vein isolation. For patients in atrial fibrillation, after pulmonary vein isolation and ablation of additional lines, if needed, 18 patients were converted to atrial tachycardia and one directly to sinus rhythm; 96 were still in atrial fibrillation and underwent direct-current cardioversion. After a mean follow-up of 17±6 months, 57 patients (36%) experienced atrial arrhythmia recurrence. No deaths, tamponades or phrenic nerve injuries were observed following the procedure. The main mode of arrhythmia recurrence was atrial fibrillation in 75% of cases and atrial tachycardia in 25% of cases. A single-catheter approach, including pulmonary vein isolation and atrial lines, is feasible and safe in patients undergoing persistent atrial fibrillation ablation, with an acceptable success rate of 64% at mid-term follow-up.

COMPLETENESS OF LINEAR OR FRACTIONATED ELECTROGRAM ABLATION IN ADDITION TO PULMONARY VEIN ISOLATION ABLATION OUTCOME: A SUB-STUDY OF THE STAR AF II

<h3>BACKGROUND</h3> The STAR AF II (Substrate and Trigger Ablation for Reduction of Atrial Fibrillation 2) was a multicenter, randomized trial which randomized patients to pulmonary vein isolation (PVI) alone, PVI plus complex fractionated electrograms (CFE), or PVI plus linear ablation (roof line and mitral line). The study failed to show any additional benefit of additional substrate ablation (CFE or lines) in addition to PVI. However, complete block of linear ablations or total elimination of CFE was not achieved in all patients in the adjuvant ablation arms and this could explain why these additive ablation strategies did not improve outcome. We sought to determine whether completeness of adjuvant linear or CFE ablation affected the outcome of these additive ablation strategies when combined with PVI. <h3>METHODS AND RESULTS</h3> In STAR AF II, 549 patients were randomized 1:4:4 to PVI alone, PVI plus lines, and PVI plus CFE. In this substudy, outcomes of patients with complete linear block and without complete linear block in the PVI + lines group and outcomes for patients with all CFE regions successfully ablated and without all of them ablated in the PVI + CFE are analysed. Of the 243 patients in the PVI plus lines group who received both mitral and roof lines, bidirectional block across both lines was achieved in 179 (74%) but was not achieved in 65 (26%). At 18 months follow-up, AF recurrence occurred in 107 of 179 patients (59.8%) with complete block conduction block across lines and in 40 of 64 patients (62.5%) without complete block (p=0.89) (Figure 1). Even after 2 procedures, AF recurred in 51.9% of patients with complete linear block and 46% of patients without complete block (p=0.09). Of the 207 patients in the PVI plus CFE group who actually underwent CFE ablation, 188 (91%) had elimination of all CFE sites while all CFE were not eliminated in 19 (9%). At 18 months follow-up, AF recurrence occurred in 117 of 188 patients (62.2%) with all the CFE ablated and in 11 of 19 patients (57.9%) without all CFE ablated (p=0.47) (Figure 1). After 2 procedures, AF recurrence occurred in 56.7% of patients with all CFE ablated and 68.0% of patients without all CFE ablated (p=0.29). <h3>CONCLUSION</h3> PVI combined with both linear and CFE ablation did not result in less AF recurrence compared to PVI alone even after more than one procedure regardless of how well empiric linear or CFE ablation is performed.

Time-Averaged Wavefront Analysis Demonstrates Preferential Pathways of Atrial Fibrillation, Predicting Pulmonary Vein Isolation Acute Response.

Electrical activation during atrial fibrillation (AF) appears chaotic and disorganised, which impedes characterisation of the underlying substrate and treatment planning. While globally chaotic, there may be local preferential activation pathways that represent potential ablation targets. This study aimed to identify preferential activation pathways during AF and predict the acute ablation response when these are targeted by pulmonary vein isolation (PVI). In patients with persistent AF (n = 14), simultaneous biatrial contact mapping with basket catheters was performed pre-ablation and following each ablation strategy (PVI, roof, and mitral lines). Unipolar wavefront activation directions were averaged over 10 s to identify preferential activation pathways. Clinical cases were classified as responders or non-responders to PVI during the procedure. Clinical data were augmented with a virtual cohort of 100 models. In AF pre-ablation, pathways originated from the pulmonary vein (PV) antra in PVI responders (7/7) but not in PVI non-responders (6/6). We proposed a novel index that measured activation waves from the PV antra into the atrial body. This index was significantly higher in PVI responders than non-responders (clinical: 16.3 vs. 3.7%, p = 0.04; simulated: 21.1 vs. 14.1%, p = 0.02). Overall, this novel technique and proof of concept study demonstrated that preferential activation pathways exist during AF. Targeting patient-specific activation pathways that flowed from the PV antra to the left atrial body using PVI resulted in AF termination during the procedure. These PV activation flow pathways may correspond to the presence of drivers in the PV regions.

B-PO05-204 LATE ONSET ATYPICAL ATRIAL FLUTTER IN A TRANSPLANTED HEART

Cardiac denervation, allograft rejection and vasculopathy increase the risk of cardiac arrhythmias and pose management challenges in a heart transplant patient. To discuss the management of atrial arrhythmia in a transplanted heart. N/A A 71-year-old Caucasian woman with a history of orthotopic heart transplant in 2001, paroxysmal atrial fibrillation, and transplant vasculopathy status post left circumflex artery stent presented with palpitations. External monitoring revealed supraventricular tachycardia. Twelve lead ECG confirmed an atrial flutter with variable block. Echocardiography showed normal ventricular function. Cardiac biopsy showed focal moderate cellular allograft rejection. Left heart catheterization did not show significant coronary obstruction. The finding of graft rejection prompted commencement of steroids. Following steroid therapy, repeat biopsy was negative for rejection; however, atrial arrhythmia persisted requiring multiple cardioversions. Antiarrhythmic drug therapy caused intolerable side effects. An electrophysiology study revealed atypical mitral flutter in the donor atria. Catheter ablation of the anterior mitral line terminated the flutter. Allograft rejection causes inflammation and fibrosis leading to slowing of conduction in the atria forming the substrate for intra-atrial arrhythmia. Bi-atrial anastomosis might have increased the risk of transmitral flutter in the donor heart. Catheter ablation should be considered for late onset atrial arrhythmia in transplant patients.

Vein of Marshall Ethanol Infusion: Feasibility, Pitfalls, and Complications in Over 700 Patients.

[Figure: see text].

Single procedural outcomes in the setting of percutaneous ablation for persistent atrial fibrillation: a propensity-matched score comparison between different strategies.

Catheter ablation for persistent atrial fibrillation (persAF) is associated with less favorable outcomes than for paroxysmal AF. To improve success rates, left atrial (LA) substrate modification is frequently performed in addition to pulmonary vein isolation (PVI). The purpose of the study was to compare 4 different ablation approaches using radiofrequency catheter ablation (RFCA) or cryoballoon ablation (CB-A) for persAF and to evaluate the respective outcomes on a midterm follow-up of 12 months. We did a propensity score-matched comparison of 30 patients undergoing PVI + LA posterior wall isolation (LAPWI) with CB-A, 30 patients who underwent PVI + linear ablation (roof and mitral lines) using RFCA, 60 patients with PVI alone using CB-A, and 60 patients who had PVI alone using RFCA. The endpoint was recurrence of documented atrial tachyarrhythmias (ATas) > 30 s at 1-year follow-up. After 12 months, freedom from ATas after a single procedure was 83.3% in the PVI + LAPWI group, 46.7% in the PVI + linear ablation group, 58.3% in the PVI-alone CB-A group, and 61.6% PVI-alone RFCA (p = 0.03). Moreover, freedom from ATas was significantly higher comparing the PVI + LAPWI group with each of the other groups. In this propensity-matched comparison of strategies for persAF, LAPW ablation in addition to PVI with CB-A seems to improve 1-year outcome in comparison to PVI + linear ablation using RFCA and to PVI alone using RFCA or CB-A. Randomized comparisons are eagerly awaited.

Abstract 16884: Evaluating the Effectiveness of Atrial Fibrillation Ablation Guided by Spatiotemporal Electrogram Dispersion

Introduction: Catheter ablation of atrial fibrillation (AF) guided by spatiotemporal dispersion (SD) of electrograms has been proposed as an ablation strategy to treat patients with persistent AF. However, external validation of this technique is lacking. Here we report a single center experience using ablation by SD. Hypothesis: Targeting regions with SD is associated with a high rate of termination and favorable freedom from AF among patients with persistent AF. Methods: Patients with persistent AF who underwent SD from November 2018 to January 2020 were included in this study. All patients underwent pulmonary vein isolation (PVI) in addition to targeting areas of SD. Lesions on areas of electrogram dispersion were anchored to the PVI or to mitral or posterior wall lines where appropriate. EKG, Holter, event monitors or device interrogations were obtained at 3 and 6 months to assess for arrhythmia recurrence. Results: 44 patients met the inclusion criteria and were included in the study. The patients had a mean age of 69±8 years and were 68 % male. The prevalence of comorbidities was as follows: hypertension (89%), diabetes (21%), OSA (37%) and CAD (26%). Average CHADSVASC score was 2.9±1.4, LVEF was 53±11% and left atrium (LA) diameter was 5.2±1 cm. The recurrence rate of AF at 6 months was 14% whereas the recurrence of atrial tachycardia was 20%. Acute AF termination was observed in 73% of the patients. Termination to sinus occurred in 38% of the patients and the remaining terminated to atrial tachycardia which was subsequently ablated to sinus. The mean procedure duration was 240±90 minutes. Univariate analysis showed recurrence was associated with LA diameter (r=.52; p&lt;.001). No recurrences were observed among patients with a LA diameter &lt; 5 cm. Termination rates were higher among patients with LA diameter &lt; 5 cm when compared to LA diameter ≥ 5 cm. However, it did not reach statistical significance (80% vs. 60%; p=.21). Conclusions: The target of electrograms with SD during AF ablation added to PVI was associated with a high termination rate and a good freedom from AF recurrence at 6 months. The ideal candidate for this procedure may be those with LA diameter &lt; 5 cm among persistent AF. The long-term efficacy of this technique merits further studies in larger populations.

Electrophysiological findings after bilateral thoracoscopic atrial fibrillation ablation using irrigated bipolar radiofrequency energy

Abstract Background Thoracoscopic atrial fibrillation (AF) ablation (TARAFS) using irrigated bipolar radiofrequency energy should result in posterior left atrial (LA) wall isolation. Purpose To assess the long-term durability of this “box” lesion and the extent of additional ablation needed to achieve AF non-inducibility. Methods 22 patients with AF recurrence after bilateral TARAFS for persistent AF had a radiofrequency catheter ablation (RFA) at least three months after TARAFS. Electroanatomical voltage map was done in all patients prior to any ablation. Results Out of 22 patients, the box lesion was not completed in 15 (68.2%). In these 15 patients, 12 had no signs of any prior ablation in endocardium (voltage &amp;gt;0.5mV), 2 had right pulmonary veins (PVs) isolated and 1 had left PVs isolated. At the end of RFA, box lesion was finished in all 15 patients and AF non-inducibility was achieved in 18 patients. For this endpoint, besides box lesion, mitral line and extensive coronary sinus ablation was necessary in 14, extensive CFAE ablation in 7 patients. Cavotricuspid isthmus line block was done in all patients. Conclusion A minimally invasive thoracoscopic box-lesion ablation is considered to be a safe and effective method of stand-alone AF treatment. However, in a considerable amount of patients no signs of prior ablation are found on electroanatomical voltage map. Gaps thus cannot be found and a completely new complex ablation must be done. In a lot of patients, additional ablation is needed besides box lesion to achieve non-inducibility. Funding Acknowledgement Type of funding source: Public hospital(s). Main funding source(s): University Hospital Olomouc