Epicardial Connections Research Articles

Mechanisms of Mitral Isthmus Reconnection After Ablation With and Without Vein of Marshall Ethanol Infusion.

Reconnection of the mitral isthmus (MI) is common after radiofrequency ablation (RFA). Vein of Marshall ethanol infusion (VOMEI) expedites MI ablation, but long-term results are unclear. This study sought to determine anatomic substrates of failed MI ablation, with and without VOMEI. Consecutive VOMEI procedures were included (n=231; of which 140 were de novo ablations and 91 were prior RFA failures (rescue VOMEI). MI conduction mechanisms were studied with vein of Marshall (VOM) electrograms obtained with a 2-F octapolar catheter, mapping, and differential pacing. In rescue VOMEI, intact VOM electrograms showed epicardial connections, epi-endocardial dissociation, and VOM conduction in pseudo-MI block. After VOMEI, after a follow-up of 725 ± 455days, 78 patients (33.7%) experienced recurrence. Of those, 36 (46%) had evidence of MI reconnection and 42 had other mechanisms. Of the 36 patients with MI reconnection, endocardial radiofrequency (RF) at the annular MI restored block in 16 (45%), and coronary sinus (CS) RF was required in 20 (55%). Post-VOMEI recurrence mechanisms included CS connection-dependent arrhythmias: CS-mediated perimitral flutter, CS-to-left atrium (LA) and CS ostial re-entry, and CS focal activity. Intraprocedural factors associated with MI reconnection included volume of ethanol delivered≥4mL (OR: 0.74; P=NS), CS ablation at VOMEI (OR: 4.05; P=0.003), and age (OR: 1.06; P=0.011). MI reconnections after RFA are due to epicardial connections from VOM. Recurrences after VOMEI are due to incomplete annular MI RFA and CS arrhythmogenesis including CS-mediated perimitral flutter, CS-to-LA re-entry and CS focal activity. Adding complete CS disconnection to VOMEI may prevent recurrences.

Catheter ablation approach targeting epicardial connections to the right pulmonary vein antrum detected before pulmonary vein isolation

BackgroundEpicardial connections from surrounding structures to the right pulmonary vein (PV) antrum impede PV isolation. ObjectiveThis study aimed to evaluate the efficacy of an ablation approach targeting epicardial connections for right PV isolation. MethodsWe prospectively enrolled 124 patients with atrial fibrillation undergoing initial PV isolation. We identified the activation breakthrough into the right PV antrum (BT-RPV) on the activation map created during high right atrial pacing before PV isolation. BT-RPV sites were targeted when right PV isolation was not achieved by wide antral circumferential ablation (WACA). ResultsBT-RPV was observed in 83 patients (67%). PV isolation was achieved by WACA in all 41 patients without BT-RPV. Among patients with BT-RPV, PV isolation was achieved by WACA in 48 patients when all BT-RPV sites were covered by the PV isolation line. Conversely, PV isolation was completed by WACA in only 5 of 35 patients when not all BT-RPV sites were covered. In patients where WACA failed, 35 sites were targeted for BT-RPV ablation. Initial BT-RPV ablation led to PV isolation at 20 sites, while the remaining 15 BT-RPV sites required repeat BT-RPV ablation. The ablated area of successful BT-RPV ablation was 0.9 (0.6–1.2) cm2, corresponding to the area activated within 15 (14–16) ms after BT-RPV emergence. Ablating the area activated within 14 ms of BT-RPV emergence was associated with successful PV isolation (sensitivity 91%; specificity 100%). ConclusionAblation targeting BT-RPV sites is effective for right PV isolation. Extensive ablation is required to eliminate BT-RPV.

A case of biatrial tachycardia involving the intercaval bundle with assumed dual loop reentry.

Epicardial connections provided the anatomical substrate for the biatrial reentry circuit. The connections between the right atrium and right pulmonary vein were called "intercaval bundle," and there are few reports of atrial flutter related to this bundle. We present a case of a biatrial tachycardia, involving the intercaval bundle.

Vein of Marshall Ethanol Infusion for AF Ablation; A Review.

The outcomes of persistent atrial fibrillation (AF) ablation are modest with various adjunctive strategies beyond pulmonary vein isolation (PVI) yielding largely disappointing results in randomised controlled trials. Linear ablation is a commonly employed adjunct strategy but is limited by difficulty in achieving durable bidirectional block, particularly at the mitral isthmus. Epicardial connections play a role in AF initiation and perpetuation. The ligament of Marshall has been implicated as a source of AF triggers and is known to harbour sympathetic and parasympathetic nerve fibres that contribute to AF perpetuation. Ethanol infusion into the Vein of Marshall, a remnant of the superior vena cava and key component of the ligament of Marshall, may eliminate these AF triggers and can facilitate the ease of obtaining durable mitral isthmus block. While early trials have demonstrated the potential of Vein of Marshall 'ethanolisation' to reduce arrhythmia recurrence after persistent AF ablation, further randomised trials are needed to fully determine the potential long-term outcome benefits afforded by this technique.

Identification of epicardial connections can improve the success rate of first-pass right pulmonary vein isolation

BackgroundEpicardial connections between the right pulmonary vein (PV) and the right atrium have been reported. ObjectiveWe evaluated the usefulness of our new PV isolation (PVI) strategy with identification of these epicardial connections. MethodsOverall, 235 patients with atrial fibrillation were included. High-density mapping of the left atrium was performed to identify the earliest activation sites (EASs) before PVI in all patients. With our new strategy, if we identified EASs around the right PV carina, we ablated these sites in addition to performing usual first-pass circumferential PVI. The patients were divided into two groups according to the ablation strategy. One hundred fifteen patients underwent first-pass PVI without information on EASs (non-analyzed group), and 78 patients underwent ablation at EASs around the right PV carina in addition to PVI (analyzed group). After first-pass ablation around the PV antrum, re-mapping was performed. ResultsHigh-density mapping before PVI showed that the prevalence of EASs around the right PV carina was 10.9% in all patients (9.6% in the non-analyzed group and 12.8% in the analyzed group; p = 0.74. The first-pass right PVI success rate was higher in the analyzed group than in the non-analyzed group (93.6% vs. 82.6%; p = 0.04). The radiofrequency application time for PVI was significantly shorter in the analyzed group than in the non-analyzed group (45.6 ± 1.0 min vs. 51.2 ± 0.9 min; p < 0.05). ConclusionIdentification of epicardial connections before ablation could improve the success rate of first-pass right PVI.

Differential Pacing Maneuver From the Vein of Marshall.

Bidirectional mitral isthmus (MI) block is conventionally verified by differential pacing from the coronary sinus (CS) and its sequence change. This study aimed to evaluate the ability of differential pacing from the vein of Marshall (VOM) to detect epicardial MI connections. Radiofrequency and VOM ethanol MI ablation were performed with a VOM electrode catheter inserted to the septal side of the ablation line. MI block was verified using conventional CS pacing. To perform differential VOM pacing analysis, initial pacing was delivered from a distal VOM bipole closer to the block line, and then from a proximal VOM bipole. The intervals from pacing stimulus during different VOM pacing sites to the electrogram recorded through the CS catheter on the opposite side of the line were compared. When the interval during distal VOM pacing was longer than that during proximal VOM pacing, it indicated a VOM connection block; however, if the former interval was shorter, the connection through the VOM was considered persistent. Overall, 50 patients were evaluated. According to CS pacing, MI ablation was incomplete in 9 patients, in whom the analysis indicated persistent VOM connection. Among 41 patients with complete MI block, confirmed by CS finding, in 30 (73%) patients, the interval during distal VOM pacing was longer than that during proximal VOM pacing by 11±5 ms. However, in 11 patients (27%) the former interval was revealed to be shorter than the latter by 16±8 ms, indicating residual VOM connection. Conduction time across the line was significantly shorter in 11 patients than in the other 30 (166±21 versus 197±36 ms; P<0.01). Ten successful reevaluated analyses after VOM ethanol and further radiofrequency ablation of the connection indicated VOM block achievement. Differential VOM pacing maneuver reflects the VOM conduction status. This maneuver can uncover residual epicardial connections that are missing with CS pacing.

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

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

Acute impact of the vein of marshall ethanol infusion on newly-formed lesion and mitral line block in persistent atrial fibrillation ablation

Abstract Catheter ablation in persistent atrial fibrillation (PeAF) has limited success. Strategies beyond pulmonary veins isolation failed to demonstrate improvement of long-term rhythm maintenance. The vein of Marshall (VoM) is a promising therapeutic target because it contains triggers and autonomic parasympathetic and sympathetic activity implicated in arrhythmogenesis of AF. Moreover, as the VoM colocalizes with the trajectory of the "mitral isthmus", alcohol infusion into the vein facilitates bidirectional block across the line eliminating protected epicardial connections (1,2). Purpose We evaluated acute impact on lesion formation post-VOM-ETHO and the mitral line block validation after an approach including VOM-ETHO, pulmonary vein isolation (PVI), roof-line, mitral line (ML) and cavo-tricuspid isthmus line in a population of PeAF patients (Figure 1). We aimed also to report procedural outcomes after a short follow-up period. Methods After a detailed electroanatomical map of the left atrium (LA) (filter at 0.05-0.5 mV if the patient was in sinus rhythm or 0.05-0.3 mV in the case of AF), we thus proceeded with the VoM-ETHO using the technique previously described (3,4). LA map was thus repeated to assess the extension of the newly-formed low voltage area (LVA). According to the newly-formed LVAs, mitral isthmus ablation was completed endocardially. PVI, roof-line and cavo-tricuspid isthmus line were performed to complete the ablation setting. Bidirectional block across line was then validated during pacing from left atrial appendage. In case of persistence of conduction through the mitral line due to epicardial gaps, additional ablations were applied in the "anchored wall" or in the "free-wall" of the great cardiac vein (GCV). Results Twenty-one PeAF patients (67±6 years; 67% male) underwent ablation. The medium value of basal LA-LVAs was 3.1±63.8 cmq and the newly-formed LVAs after the VoM-ETHO procedure was 12.35±67.28 cmq. All patients had bidirectional block validated across the roof-line. Bidirectional block of the ML was achieved in 19/21 patients: in 12/21 patients after endocardial line only and in 9/21 after epicardial gaps ablations into the coronary sinus. The ML procedural time was 11.3±65.9 minutes. No major complications occurred. One patient had mild pericardial effusion due to VoM perforation with a spontaneous resolution. After a short follow-up period (6±63 months), no relapse of AF was observed in 19/21 (90%) patients. 12/21 patients were free from antiarrhythmic drugs (AADs). Interestingly, recurrences happened in patients in whom bidirectional block of the mitral line was not achieved. Conclusions VoM ethanol ablation added to PVI and linear lesions in the context of a methodical and anatomical approach seems to have promising results in PeAF patients. This strategy seems to be safe and reproducible. A favourable outcome depended on the interventional setting completion and the procedural end-points validation is crucial.

Abstract 17174: New Criteria for Block Across Anterior Mitral Line That Includes Bachmann’s Bundle in Patients With Scar Perimitral Flutter

Background: The recurrence rate of scar perimitral flutter (SMF) after anterior mitral line (AML) ablation remains high. Epicardial connections from high right atrium (HRA) to high lateral left atrium (HLA) including the Bachmann bundle (BB) plays a significant role in perimitral flutter recurrence. Hypothesis: We hypothesize that block across BB (BBB) during endocardial anterior line ablation reduces recurrence of atrial tachycardia (AT) and SMF. Methods: Patients undergoing left atrial ablation with SMF that were treated with AML were retrospectively enrolled. Pulmonary veins isolation and bidirectional AML block achieved in all patients. Baseline HRA-HLA, final HRA-HLA, and delta HRA-HLA intervals measured. Changes in HLA activation sequence determined. BBB identified when HRA-HLA interval increased with change in HLA activation sequence and confirmed with differential pacing. (Figure 1). The primary endpoint was recurrence of AT/SMF Results: We identified 101 patients, 51% comprised of women, with a mean age of 69. Patients who had AML without evidence of BBB were 48 compared to 53 patients who had AML with evidence of BBB. The mean baseline, final and delta HRA-LAA were 123 ± 42ms, 219 ± 45 ms and 96± 21 ms respectively in patients with BBB. After median follow up of 48 months, AT/SMF recurred in 43 % of patient without BBB vs 15 % in patient with BBB (p&lt;0.008) (Figure 2). In patients with BBB, delta HRA-HLA &gt;107ms discriminated between recurrence and no recurrence (p&lt;0.023ms and 93% negative predictive value) Conclusion: During endocardial AML ablation for SMF, bidirectional block with evidence of BBB is associated with significant reduction in AT/SMF recurrence.

Unidirectional conduction characterizing epicardial connections in patients with atrial tachyarrhythmias.

Electrophysiological characteristics of epicardial connections (ECs) in atria and pulmonary veins (PVs) are unclear despite their important contributions to atrial fibrillation (AF). Unidirectional conduction associated with source-sink mismatch can occur in ECs due to their fine fibers with abrupt changes in orientation. We detailed the prevalence and electrophysiological characteristics of unidirectional conduction in the atria and investigated its association with the clinical manifestation of AF. This study retrospectively reviewed electrophysiological studies and radiofrequency catheter ablation in 261 consecutive patients with AF. Unidirectional conduction was observed during ablation encircling the PVs in eight (3.1%) patients, and all occurred in the suspected (N = 4) or definitively (N = 4) recognized ECs. These ECs included three intercaval bundles, four septopulmonary bundles, and one Marshall bundle, and were first manifested in a second procedure in 6 (75%) patients. The unidirectional property was from PV to atrium (exit conduction) in all intercaval bundles and three septopulmonary bundles, and from atrium to PV (entrance conduction) in the remaining two bundles. Intercaval bundles acted as a limb of bi-atrial macro-reentrant tachycardia (50%, three of the six including previous cases). Ablation of the exit outside the PVs, including the right atrium, eliminated ECs in three (38%) patients. All patients remain free from arrhythmia recurrence after a mean 13-month follow-up. A unidirectional conduction property was closely associated with the EC, as estimated by histological findings. Recognition of this fact by electrophysiologists may help to clarify mechanisms for AF and atrial tachycardia and guide the creation of efficient and safe ablation lesion sets.

Epicardial connections and bi-atrial tachycardias: From anatomy to clinical practice.

Bi-atrial tachycardia (BiAT) is not rare after extensive atrial ablation or cardiac surgery. The complexity of bi-atrial reentrant circuits poses a great challenge for clinical practice. With recent advances in mapping technologies, we are now able to characterize atrial activation in detail. However, given the involvement of both atria and multiple epicardial conductions, endocardial mapping for BiATs is not easy to understand. Knowledge of the atrial myocardial architecture is the foundation for the clinical management of BiATs; as it is required to understand the possible mechanism of the tachycardia and identify the optimal target of ablation. In this review we summarize current knowledge about the anatomy of interatrial connections as well as other epicardial fibers and discuss the interpretation of electrophysiological findings and ablation strategies for BiATs.

Efficacy of functional substrate map-guide approach for wide circumferential pulmonary vein isolation

Abstract Funding Acknowledgements Type of funding sources: None. Background Pulmonary vein isolation (PVI) with anatomical approach targeting closer interlesion distance (ILD) would be effective, but not efficient. A functional substrate map (FSM) can reveal the unnecessary application site including physiological block and the critical ablation site including direct epicardial connections. Purpose We investigated the efficacy of FSM-guide approach for wide circumferential PVI. Methods We enrolled 55 consecutive patients underwent radiofrequency PVI for atrial fibrillation. In earlier 27 patients were ablated by anatomical approach with closer ILD (&amp;lt;5mm) (control group), in latter 28 patients were by real time PV electrogram and high density electro-anatomical map guide (FSM-guide group). In FSM-guide group, characteristics of electrical conduction including voltage, direction , velocity and barrier between PV and left atrium and epicardial connection were assessed by local activation, coherent and ripple map before ablation. Distributions of the segments required or unnecessary ablation for PVI completion were examined. Results The success rate of first-pass isolation was higher in FSM-guide group than in control (96.4% vs. 74.1%). The number of required ablation tags for PVI were significantly lesser in FSM-guide group than control group (left-sided PV (LPV); 23.2±1.6 vs. 29.2±1.6, p=0.0112, right-sided PV (RPV); 22.6±1.7 vs. 32.4±1.8, p=0.0124, respectively). The time for PVI completion was significantly shorter in FSM-guide group than control group (RPV; 17.0±2.2 min vs. 25.2±2.8 min, p=0.0124, LPV; 18.7±1.5 min vs. 20.5±1.5 min, p=0.042, respectively). In FSM-guide group, unnecessary application sites were frequently located at posterior of RIPV (46%), anterior of LIPV (43%) and anterior of RSPV (35.7%). Frequently required segments for PVI completion were roof and carina of LPV and roof and posterior of RPV. In most cases of control group, full circumferential ablation was required (LPV 22/27(81%) and RPV 24/27(89%)). Acute reconnections during procedure were similar in FSM-guide group and control group (LPV; 6/28 (21.4%) vs. 4/27 (14.8%), p=0.7287, RPV; 9/28 (32.1%) vs. 4/27 (14.8%), p=0.2047, respectively). All of reconnection sites in FSM-guide group were ablated site. Conclusions FSM-guide approach for extensive PVI could reveal unnecessary application sites and result in shorter procedure with comparable ablation quality.

PO-02-089 EMPIRIC VEIN OF MARSHALL ETHANOL INFUSION IN PATIENTS UNDERGOING REPEAT CATHETER ABLATION WITH DURABLY ISOLATED PULMONARY VEINS

The procedural strategy for patients with recurrent atrial fibrillation (AF) despite isolated pulmonary veins is unknown. Ablative strategies beyond pulmonary vein isolation (PVI) have not consistently shown benefit. Vein of Marshall (VoM) ethanol ablation has a proven benefit in patients with persistent AF undergoing index procedure, however its role in patients with durably isolated pulmonary veins is unknown. To evaluate the benefit of empiric VoM ethanol ablation in addition to posterior wall isolation (PWI) during the repeat procedure in patients with durable pulmonary vein isolation from index procedure. Twenty-three patients (age 67.1 +/- 7.4, 74% males) who received empiric VoM ethanol infusion in addition to PWI (study group) were matched for age, gender, EF and LA size with thirty-four historic patients receiving empiric PWI alone (control group). All patients in the study group underwent endocardial ablation on the mitral isthmus to complete a lateral mitral isthmus line. Additional ablation was based on program and trigger stimulation. Primary outcome was freedom from AF or AT after a blanking period of 3 months using either qualification of symptoms, routine office EKG, wearable or implantable monitor or device (pacemaker or defibrillator). Significant baseline characteristic differences between study vs control group included BMI (35.07 +/- 8.98 vs. 30.85 +/- 5.65, p = 0.033) and incidence of persistent AF (83% vs. 55%, p=0.029). The 1 year AF-free survival for the study and control groups were 20 (86.96%) and 21 (61.76%) patients respectively (p=0.038). Cox proportional hazard regression analysis showed significant reduction in AF or AT recurrence in the study group (HR 0.26, 95% CI 0.074-0.919, p=0.037). Among patients undergoing repeat catheter ablation for recurrent AF with durably isolated pulmonary veins, addition of VoM ethanol infusion increased the likelihood of remaining free from AF or AT at 12 months. The mechanism for increased long-term procedural success with VoM ethanol infusion is unclear. It may be due to ablation of non-pulmonary vein triggers originating from the ligament of Marshall, left atrial parasympathetic denervation, or transmural block across the lateral mitral isthmus with ablation of epicardial connections.

PO-02-003 IDENTIFICATION OF AREAS OF ANISOTROPIC CONDUCTION USING OMNIPOLAR TECHNOLOGY TO PREDICT FIRST-PASS ISOLATION AND RECONNECTION OF THE POSTERIOR WALL

Posterior wall isolation (PWI) can be a useful adjunct to pulmonary vein isolation (PVI) for the management of persistent atrial fibrillation (AF). Successful isolation of the posterior wall is challenging, with first-pass isolation rates under 40%. Difficulties in achieving block may be due to inability to create transmural lesions due to complex posterior wall architecture from septopulmonary (SPB) and septoatrial (SAB) bundle insertion. Activation mapping using omnipolar technology (OT) may allow identification of areas of anisotropic conduction that represent atrial fiber and bundle insertion points to target for additional ablation. Correlate areas of anisotropy to first-pass isolation of the posterior wall and determine whether anisotropy can predict sites requiring additional ablation to achieve bidirectional block We retrospectively analyzed patients with persistent AF who underwent first-time PVI with PWI from November 2020 to December 2022 at a single tertiary referral center with using the EnSite X mapping system with OT (Abbott, IL). Demographic and procedural information was collected. The posterior wall was divided into 6 regions and areas of anisotropy, defined as an abrupt pivot or collision in OT vectors, along with mean and maximum bipolar voltage were recorded. Areas requiring additional ablation to achieve bidirectional block were recorded. 17 patients were included in our cohort, of which 5 had first-pass isolation (29%). Final isolation of the posterior wall was achieved in all cases. There were no significant differences in patient demographics. Total ablation times were significantly less in the first-pass group (2174 versus 1721 seconds, p = 0.035). Anisotropic areas were present in 80% of first-pass cases versus 75% of cases without first-pass. While overall PW voltage was similar in both groups, voltage at sites of anisotropy was significantly higher in patients without first-pass (6.8 vs 2.6, p = 0.024). In patients without first-pass, reconnection was at site of anisotropy in 50% of cases with mean bipolar voltage 7.4mV. Activation mapping using OT may help identify areas of anisotropic conduction that are common sites of epicardial connections. Targeting these areas with additional ablation may improve rates of first-pass isolation and reduce rates of chronic reconnection. Further investigation and a larger cohort is needed to validate the predictive utility of OT.

Growing thrombus adhesion on the left atrial wall after catheter ablation of atrial fibrillation.

Growing thrombus adhesion on the left atrial wall after catheter ablation of atrial fibrillation.

All that is "red" is not "dead": role of epicardial connections in atrial fibrillation ablation.

All that is "red" is not "dead": role of epicardial connections in atrial fibrillation ablation.

Vein of Marshall ethanol infusion: First-step or adjunctive choice for perimitral atrial tachycardia?

Perimitral atrial tachycardia (PMAT) is the most frequent type of iatrogenic atrial tachycardia (AT) after atrial fibrillation (AF) ablation. Vein of Marshall ethanol infusion (EIVOM) is a promising technique in mitral isthmus (MI) ablation. A total of 165 patients with PMAT were divided into three groups according to ablation strategies, including RF only group (n=89), RF-EIVOM group (initial RF ablation with adjunctive EIVOM, n=28), and EIVOM-RF group (first-step EIVOM with touch-up RF ablation, n=48). Acute and follow-up procedure outcomes were evaluated. PMAT terminated in 89.9%, 89.3%, and 93.7% of patients in RF only, RF-EIVOM and EIVOM-RF groups, respectively (p=.715), with complete MI block achieved in 80.9%, 89.3%, and 95.8% of patients (EIVOM-RF vs. RF only, p=.012). First-step utilization of EIVOM was associated with a significant shortening of RF ablation time at MI (EIVOM-RF 2.1±1.3min, RF only 7.9±5.9min, RF-EIVOM 6.8±5.8min; p<.001) and a decrease in the proportion of patients need ablation within coronary sinus (CS, EIVOM-RF 14.6%, RF only 61.8%, RF-EIVOM 64.3%; p<.001). After a mean follow-up of 12.1±6.2 months, AF/AT recurred in 39 (43.8%), 6 (21.4%), and 12 (25.0%) patients in RF only, RF-EIVOM, and EIVOM-RF group (RF-EIVOM vs. RF only, p=.026; EIVOM-RF vs. RF only, p=.022). EIVOM was associated with an enhanced acute MI block rate as well as reduced AF/AT recurrence. First-step utilization of EIVOM promises to significantly simplify the RF ablation process. PMAT is the most common type of iatrogenic AT after AF ablation procedures. EIVOM contributed to a higher acute MI block rate and lower arrhythmia recurrence risk during follow-up. First-step utilization of EIVOM significantly reduced the need for radiofrequency ablation at MI and inside CS with the advantage of creating a homogenous, transmural lesion and eliminating epicardial connections.

Abstract 11726: Atrial Arrythmia Recurrence in Patients After Left Atrial Ablation is Associated With Epicardial Connections and Directly Correlated to Reduced Left Ventricular Ejection Fraction

Introduction: Heart Failure with Reduced Ejection Fraction has a positive association with atrial arrhythmia incidence and recurrence. However, this has not been studied in atrial fibrillation (AF) and atrial tachycardia (AT) patients who underwent left atrial radiofrequency ablation(RFA) and were subsequently found to have epicardial connections(EC). Hypothesis: Heart Failure with Reduced Ejection Fraction was associated with an increased recurrence of atrial tachyarrythmias in patients with epicardial connections. Methods: We studied 40 consecutive patients with persistent atrial arrhythmias who underwent RFA for AF and AT at our center. Epicardial connections were determined by high density mapping, missing isochrones and activation patterns. Clinical, echocardiographic and activation mapping pattern characteristics were collected. Results: Forty patients were found to have EC (Table 1). The association of EC and echocardiographic parameters were assessed. Reduced Left Ventricular Ejection Fraction was associated with an increased recurrence of atrial tachyarrhythmias in patients due to epicardial connections((HR:1.25(1.05-1.48)) (Table 2). Conclusions: Reduced Left Ventricular Ejection Fraction is positively correlated with atrial tachyarrythmia recurrence in patients due to epicardial connections.

Abstract 11738: Epicardial Connections as an Etiology in Recalcitrant Tachyarrhythmias After Left Atrial Ablations in Patients With Persistent Atrial Fibrillation

Introduction: Left atrial radio frequency ablation(RFA) for persistent atrial fibrillation(AF) and left atrial tachycardias(LAT) are often challenging due to the presence of epicardial connections(EC). Hypothesis: Mapping and subsequent ablation of epicardial connections using high density(HD) mapping and activation patterns leads to successful termination of persistent AF and LAT. Methods: We studied 40 patients who were found to have epicardial connections as determined by HD mapping, missing isochrones and activation patterns. All patients underwent antral ablation for pulmonary vein isolation (PVI). LAT were remapped using Advisor HD Grid catheter. Results: At baseline, the mean age and BMI was 74±6.4 and 33.5±5.8 respectively. Out of 40 patients with EC, 21 were associated with the Vein of Marshall (Figure 1), 4 were associated with Septo-pulmonary bundles(figure 2), 6 were associated with the Bachman Bundle(Figure 3) and 9 were associated with Septo-atrial bundles. Acutely, endocardial ablation opposite to the epicardial connection sites achieved success with PVI, Posterior Wall Isolation(PWI) and termination of LAT. Conclusions: EC significantly contributes to the failure of PVI, PWI and the reorganization of LAT. Rigorous mapping of the connecting bundles using HD mapping helps target the ablation sites for successful outcomes.

Epicardial Connections After a Conventional Pulmonary Vein Antrum Isolation in Patients With Atrial Fibrillation.

The existence of epicardial connection(s) (ECs) between the pulmonary veins (PVs) and atrium may hinder establishing a complete PV antrum isolation (AI) (PVAI) in patients with atrial fibrillation (AF). Thus, the purpose of this study was to determine the prevalence and location of ECs inside the conventional PVAI lines. Three-hundred consecutive patients with non-valvular AF were evaluated. This study revealed that: (1) the prevalence of patients with ECs and the number of ECs per patient between the PVs and atrium became significantly greater, respectively, in accordance with the progression of paroxysmal to long-lasting AF and left atrial enlargement; (2) some ECs were located at sites far distal to the PVAI lines; (3) 25% of ECs could be detected only by high-density mapping catheters, but not by conventional circular mapping catheters; (4) a B-type natriuretic peptide (BNP) level of 176.6pg/mL and left atrial volume (LAV) of 129.0 mL may be important predictors of the presence of ECs; and (5) the rate of conduction of ECs from the right PVs was dominantly to the atrium and His-bundle, and that from the left PVs to the coronary sinus was most dominant. The PVAI may not be completed by using only a conventional PVAI method, and additional EC ablation inside the PVAI lines detected using high-density mapping may be able to achieve a more complete PVAI.