Superior Vena Cava Isolation Research Articles

Electrophysiological characteristics and catheter ablation of symptomatic focal premature atrial contractions originating from pulmonary veins and non-pulmonary veins.

We aimed to explore electrophysiological characteristics of premature atrial contractions (PACs) originating from pulmonary veins (PVs) and non-PVs and to evaluate the effectiveness and safety of catheter ablation for PACs. Symptomatic PACs originated from different positions and whether could be ablated. Symptomatic, frequent, and drug-refractory PAC patients were enrolled in this study. All patients underwent electrophysiological study and catheter ablation. A total of 81 patients were enrolled: 45 patients with PACs originating from PVs (group A), 24 patients with PACs originating from non-PVs (group B), and 12 patients with PACs arising from both PVs and non-PVs (group C). Twenty (44.4%) patients in group A, 6 (50.0%) patients in group C, and 3 (12.5%) patients in group B presented paroxysmal atrial fibrillation (P < 0.05). PV isolation was performed in groups A and C. Focal ablation or superior vena cava isolation was performed in groups B and C, depending on patient condition. PACs were abolished in all patients except one patient in group B. During a median follow-up period of 21.3 ± 14.3 months, 40 (88.9%) patients in group A, 10 (83.3%) patients in group C, and 21 (87.5%) patients in group B were free of recurrence after initial ablation. Frequent PACs originating from PVs were associated with increased incidence of atrial fibrillation compared with PACs originating from non-PVs. Catheter ablation yields a satisfactory success rate and could be a good choice for eliminating symptomatic, frequent, and drug-refractory PACs.

Spiral activation of the superior vena cava: The utility of ultra-high-resolution mapping for caval isolation

Little is known about the manner in which the superior vena cava (SVC) is activated during sinus rhythm. The purpose of this study was to assess the manner of caval activation with an ultra-high-density mapping system (Rhythmia, Boston Scientific, Marlborough, MA) and its utility for SVC isolation. Forty patients with atrial fibrillation (mean age 55 ± 12 years; paroxysmal atrial fibrillation in 23[58%]) who underwent SVC mapping with Rhythmia were studied. The location of the sinus node (SN), phrenic nerve (PN), and the manner of caval activation during sinus rhythm were analyzed. The SVC was isolated by radiofrequency applications at electrical connections, shown as breakthroughs on the Rhythmia map. The SN location varied widely (lateral/posterior/anterior 60%/8%/32%), while the PN was mostly located in the lateral segment (lateral/anterior 82%/18%). In 36 patients who underwent SVC isolation, the mean number of breakthroughs was 2.5±0.8. The first breakthrough predominantly located in the anterior aspect (anterior/septal/posterior/lateral 78%/14%/5%/3%), and atrial activation was conducted superiorly and clockwise from the SN (referred to as spiral activation) in 32 patients (89%). The mean rotation angle from the SN to the first breakthrough was 79° ± 41°. In addition, 10 patients (25%) showed the SN within the SVC. Although radiofrequency applications were needed at the PN capture site in 11 patients (31%) the SVC was successfully isolated without any complications in all patients. The SN location showed great heterogeneity; however, atrial activation predominantly showed a clockwise spiral form. This is the first report to use ultra-high-resolution mapping to demonstrate the manner of spiral activation, which is useful for the safe and efficient isolation of the SVC.

Isolation of the superior vena cava from the right atrial posterior wall: a novel ablation approach.

Superior vena cava (SVC) isolation might be difficult to achieve because of the vicinity of the phrenic nerve (PN) and sinus node. Based on its embryogenesis, we hypothesized the presence of preferential conduction from the right atrial (RA) posterior wall, making it possible to isolate the SVC antrally, sparing its anterior and lateral aspect. This is a descriptive cohort study of 105 consecutive patients in which SVC isolation was obtained with radiofrequency ablation, starting in the septal aspect of the SVC-RA junction and continued posteriorly and inferiorly targeting sites of early activation until electrical isolation was obtained. Acute SVC isolation was achieved in 103 (98%) patients; the mean distance between the site of SVC isolation and the SVC-RA junction was 19.9 ± 5.3 (range 9.7-33.7) mm. During follow-up, 2 (2%) patients developed symptomatic diaphragmatic paralysis due to transient right PN injury; 13 patients underwent a repeat ablation: SVC reconnection was observed in 5 patients, and re-isolation was easily achieved by targeting the corresponding sites of early activation. Superior vena cava isolation can be completed by targeting its septal segment and sites of early activation in the posterior SVC-RA junction and RA posterior wall; this is a feasible alternative ablation strategy in patients in which SVC isolation cannot be completed with the standard approach. The risk of sinus node injury or SVC stenosis are eliminated; PN injury is still possible but can easily be prevented with high-output pacing to exclude a true posterior course of the PN.

P1441The characteristics of superior vena cava isolation, which is useful to avoid procedural complications: the findings obtained from high- resolution substrate mapping

P1441The characteristics of superior vena cava isolation, which is useful to avoid procedural complications: the findings obtained from high- resolution substrate mapping

The Role of Superior Vena Cava Isolation in the Management of Atrial Fibrillation.

The superior vena cava (SVC) has been identified as one of the most common sources of non-pulmonary vein triggers for atrial fibrillation (AF). SVC isolation has been shown to improve long-term maintenance of normal sinus rhythm in patients with paroxysmal AF. However, ablation at the SVC is associated with risks of phrenic nerve injury, sinus node dysfunction, and SVC stenosis. The use of electroanatomical mapping, intracardiac echocardiography, compound motor action potentials, and segmental (rather than circumferential) ablation are all strategies to reduce complications. Given these risks, SVC isolation is most effective as an adjunct to pulmonary vein isolation for patients with paroxysmal AF who have been found to have an arrhythmogenic SVC.

Electrical superior vena cava isolation using a novel pace-and-ablate technique under diaphragmatic electromyography monitoring

Diaphragmatic compound motor action potential (CMAP) amplitude monitoring is a standard technique to anticipate phrenic nerve injury during cryoballoon ablation. The purpose of this study was to evaluate the feasibility of a novel superior vena cava isolation (SVCI) technique using simultaneous pacing and ablation through the tip of a single mapping/ablation catheter. Fifty-four patients with atrial fibrillation were included. Radiofrequency energy was delivered point by point uniformly for 20 seconds with a power of 20 W until achieving SVCI. Diaphragmatic CMAPs were obtained from modified surface electrodes by high-output pacing from the mapping/ablation catheter throughout the procedure (pace-and-ablate group). Applications were interrupted if CMAP amplitudes significantly decreased without fluoroscopy. The data were compared with those of the 54 patients undergoing conventional SVCI (conventional group). Successful SVCI procedures were achieved in all with a mean of 10.3 ± 2.9 applications. In total, among 559 ablation sites, CMAPs were recorded at 95 (17.0%) with baseline amplitudes of 0.45 ± 0.23 mV. In 10 patients (18.5%), isolation was achieved without any radiofrequency deliveries at CMAP-recorded sites. Among the 95 applications, 6 (6.3%) were interrupted because of CMAP amplitude reductions. At the remaining 88 sites, 20-second radiofrequency applications were delivered without any amplitude decrease (from 0.45 ± 0.21 to 0.46 ± 0.23 mV; P = .885). Phrenic nerve injury occurred in 1 patient in the pace-and-ablate group, which recovered 3 months later, and in 3 conventional group patients, of whom 1 recovered 1 month later (P = .308). The total procedure time tended to be shorter (14.5 ± 6.3 minutes vs 16.7 ± 9.2 minutes; P = .153) and fluoroscopy time significantly shorter (3.9 ± 3.0 minutes vs 6.7 ± 5.7 minutes, P = .002) in the pace-and-ablate group than in the conventional group. A novel and simple pace-and-ablate technique under diaphragmatic electromyography monitoring might be feasible for an electrical SVCI.

Comparison of Empiric Isolation and Conventional Isolation of Superior Vena Cava in Addition to Pulmonary Vein Isolation on the Outcome of Paroxysmal Atrial Fibrillation Ablation.

Radiofrequency catheter ablation (RFCA) in the treatment of AF is currently based on pulmonary vein isolation (PVI). Some studies have investigated the efficacy of empiric SVC isolation (SVCI) in addition to conventional PVI in order to improve success rates and reduce recurrence rates. However, the results of the studies have given conflicting data.We performed a meta-analysis to evaluate the efficacy and safety of the empiric SVCI compared with conventional SVCI for paroxysmal atrial fibrillation (PAF) ablation.We searched MEDLINE, EMBASE, the Web of Science, and the Cochrane Database from the period January 1986 to August 2016 and identified qualified studies. The primary clinical outcome was the recurrence rate of atrial tachyarrhythmias, and the secondary clinical outcomes were procedure time, fluoroscopy time, and complications.We identified 3 randomized controlled trials (RCTs) and one nonrandomized, observational study (nROS) involving 245 patients with empiric SVCI and 269 patients with conventional SVCI. The empiric SVCI group had a lower recurrence rate of atrial tachyarrhythmia after a single procedure compared with the conventional SVCI group (16.7% versus 29.4%, OR: 0.48, 95%CI: 0.31 to 0.74, P = 0.0009). There was no significant difference in fluoroscopic time (P = 0.22), procedure time (P = 0.32), or clinical complications (P = 0.33) between the two groups.Empiric SVCI is more effective than conventional SVCI in terms of the long-term outcomes of PAF patients after a single PVI procedure, with the same fluoroscopic time, procedure time, and clinical complications.

Abstract 13447: Superior Vena Cava Isolation From the Right Atrial Posterior Wall: A Case Series

Introduction: Superior vena cava (SVC) isolation is a common ablation strategy to address non-pulmonary vein triggers in patients with paroxysmal and non-paroxysmal AF. SVC isolation with circumferential ablation might be difficult to achieve because of the phrenic nerve (PN) location in its anterolateral aspect. Hypothesis: It is possible to isolate the SVC sparing its anterolateral aspect given the presence of preferential conduction from the posterior wall of the right atrium (RA) to the SVC. Methods: Consecutive patients in which SVC isolation ablating in the RA posterior wall. RF ablation was started in the septal aspect of the SVC-RA junction and it was continued posteriorly-inferiorly in sites of early activation (relative to the SVC) until electrical isolation was obtained. The distance between the SVC-RA junction and the site of SVC isolation was measured with 3D electro-anatomical mapping. Results: 85 patients were included in the analysis. 27% were females, with a mean age of 66 ± 10 years, 21% had paroxysmal AF, 42% persistent AF, 36% longstanding persistent AF. The procedure was a repeat ablation in 58% of the cases, with a mean procedure time of 124 ± 38 minutes. Acute SVC isolation was achieved in 98%. Mean distance of isolation from the SVC-RA junction was 19.9 ± 5.1 mm (range 10.2-32.1 mm). At follow-up, we observed 2 (2%) transient PN injuries. After this, we began performing PN mapping in the PW, which precluded complete SVC isolation in 1 case (see Figure 2). Conclusions: SVC isolation can be achieved without circumferential ablation by targeting sites with early activation (relative to the SVC) in the RA posterior wall.

Long-term outcome after catheter ablation of paroxysmal atrial fibrillation: Impact of different atrial fibrillation foci

BackgroundWe aimed to determine whether differing foci in paroxysmal atrial fibrillation (PAF) affected the long-term outcome of catheter ablation (CA). MethodsA total of 865 consecutive PAF patients (age, 61±10years; 670 male) undergoing initial AF ablation were included. After pulmonary vein (PV) isolation, superior vena cava (SVC) isolation was performed for SVC foci; other non-PV foci were focally ablated. Long-term outcomes were compared among patients with SVC foci (Group SVC), other non-PV foci (Group Non-PV), and those without these foci (Group PV). ResultsGroups PV, SVC, and Non-PV contained 740 (85.8%), 57 (6.6%), and 68 (7.6%) patients, respectively. Structural heart disease (P=0.01) and duration of AF history (P=0.04) were significantly associated with Group Non-PV, and female sex (P=0.0002) was significantly associated with Group SVC. AF recurrence-free rates at 5years in Group PV, SVC, and Non-PV were 62.0%, 66.3%, and 49.3%, respectively (P=0.03), after the initial CA, and 84.7%, 83.9%, and 77.0%, respectively (P=0.02), after the final CA. The duration of AF history (HR, 1.04, P<0.0001) and left atrial dimension (HR, 1.37 per 10mm increase, P=0.0003) were significant predictors of AF recurrence after the initial CA. Although Group Non-PV was weakly associated (HR 1.38, P=0.08) with AF recurrence, Group SVC was not associated with AF recurrence. ConclusionsLong-term outcome of CA of PAF was significantly worse in patients with non-PV foci other than SVC foci. These foci may affect the outcome not independently but as an aspect of atrial remodeling.

Impact of Catheter Contact Force on Superior Vena Cava Mapping and Localization of the Right Phrenic Nerve by High Output Pacing.

Right phrenic nerve injury (PNI) is a major concern during superior vena cava (SVC) isolation. Phrenic nerve (PN) localization by high-output pacing is a standard technique for anticipating PNI. This study evaluated the impact of catheter contact force (CF) on SVC mapping and PN localization. Twenty-one atrial fibrillation patients undergoing cardiac enhanced computed tomography (CT) were prospectively enrolled. SVC geometries were created at the SVC-right atrium junction level with low (<10 × g) and high (>10 × g) CFs. The PN was localized by high-output pacing (10 V, 2 milliseconds) at the SVC and anterior right superior pulmonary vein (RSPV) with different CFs. The SVC cross-sectional area was significantly greater when created with high (22.1 ± 4.9 × g) compared with low CFs (4.2 ± 1.3 × g) (5.3 ± 1.4 cm2 vs. 2.3 ± 0.7 cm2 , P < 0.0001). High CFs distorted the SVC and anterior RSPV by a mean of 4.8 ± 2.5 and 4.4 ± 1.7 mm, with minimal distortion at the anteroseptal SVC. The PN was more frequently captured with a high compared with low CF at the SVC (95.2% vs. 71.4%, P = 0.038) and RSPV (66.7% vs. 14.3%, P = 0.0005). The PN capture area was also wider with a high compared with low CF at the SVC (9.0 ± 4.1 mm vs. 4.5 ± 2.8 mm, P = 0.001). The PN location was at the anterolateral, lateral, and posterolateral SVC in 3 (14.3%), 13 (61.9%), and 5 (23.8%) patients, respectively, which was identical to that identified on CT. No PNs located >1.98 mm from the RSPV were captured by RSPV pacing. CF impacted the SVC mapping and PN localization. Cardiac CT identified the PN location, and the distance from the pacing site influenced PN capture.

Pericardial adhesions as a consequence of cryoballoon ablation detected during the hybrid AF ablation procedure

Pericardial adhesions as a consequence of cryoballoon ablation detected during the hybrid AF ablation procedure

Impact of Pulmonary Vein Isolation on Superior Vena Cava Potentials With a Second-Generation Cryoballoon.

Radiofrequency ablation of the right superior pulmonary vein (RSPV) can lead to inadvertent superior vena cava (SVC) isolation due to the close anatomical proximity. This study aimed to evaluate the impact of PV isolation on SVC potentials with a second-generation cryoballoon. Thirty-one consecutive paroxysmal atrial fibrillation patients who underwent PV isolation exclusively with a 28 mm second-generation cryoballoon and single 3-minute freeze technique were prospectively enrolled. The produced SVC potential conduction delay during the RSPV isolation was prospectively evaluated using circular mapping catheters placed in the SVC throughout the cryoballoon procedure. Stable SVC potentials were recorded in 28 (90.3%) patients. The produced SVC potential conduction delay during the RSPV isolation was a median of 6.0 (0.5-7.6) milliseconds, and >5.0 milliseconds in 16 (57.1%) patients. Among them, the delay had shortened by >5.0 milliseconds in 7 (43.8%) patients within 5 minutes after the RSPV application. The distance between the RSPV ostium and SVC was the sole parameter correlated with the produced delay (R = 0.77, P < 0.0001). For the association between the distance and a produced delay of >5 milliseconds, the area under the curve was 0.896 (95% confidential interval = 0.775-1.000). The optimal cutoff point for the distance predicting the occurrence of the conduction delay (>5 milliseconds) was 2.5 mm (sensitivity 83.3%, specificity 81.2%). RSPV isolation with a second-generation cryoballoon could produce an SVC potential conduction delay. The anatomical distance between the RSPV and SVC significantly correlated with the impact.

Impact of an Empiric Isolation of the Superior Vena Cava in Addition to Circumferential Pulmonary Vein Isolation on the Outcome of Paroxysmal Atrial Fibrillation Ablation

The safety and efficacy of an empiric superior vena cava isolation (SVCI) in addition to circumferential pulmonary vein isolation (CPVI) in patients with paroxysmal atrial fibrillation (PAF) have not been clarified. A total of 186 consecutive patients who underwent catheter ablation of PAF were included. All patients underwent a CPVI. Patients in the first half underwent an additional SVCI only if SVC-triggered AF or rapid SVC activity was observed during the procedure (n = 93, as-needed SVCI, group I), and those in the second half underwent an empirical SVCI after the CPVI (n = 93, empiric SVCI, group II). The CPVI was successfully performed in all patients. An SVCI was performed in 8 of 93 patients (9%) in group I and 81 of the 93 patients (87%) in group II. In the remaining 12 patients in group II, an SVCI was not performed because of the lack of SVC potentials. During a mean follow-up of 27 ± 12 months, the atrial tachyarrhythmia recurrence rate after a single ablation procedure in the patients in group II was lower than that in group I (44% vs 23%, p = 0.035). A Cox regression multivariate analysis demonstrated that an empiric SVCI was an independent predictor of an atrial tachyarrhythmia recurrence after a single ablation procedure (odds ratio: 0.57, 95% confidence interval 0.31 to 0.999; p = 0.049). Neither sinus node injury nor any injury to the phrenic nerve was observed. In conclusion, an empiric SVCI in addition to the CPVI improved the outcome of AF ablation in patients with PAF without any additional adverse effects.

Remote-controlled magnetic pulmonary vein isolation combined with superior vena cava isolation for paroxysmal atrial fibrillation: A prospective randomized study

Radiofrequency ablation (RFA) of paroxysmal atrial fibrillation (PAF) has focused on pulmonary vein isolation (PVI). However, despite initial positive results, significant recurrences have occurred, partly because of pulmonary vein (PV) reconnection or non-PV ectopic foci, including the superior vena cava (SVC). This prospective, randomized study sought to investigate the efficacy of additional SVCI combined with PVI in symptomatic PAF patients referred for ablation. From November 2011 to May 2013, RFA was performed remotely using a CARTO(®) 3 System in patients randomized to undergo PVI for symptomatic drug-refractory PAF, with (PVI+SVCI group) or without (PVI alone group) SVCI. PVI and SVCI were confirmed by spiral catheter recording during ablation. Procedural data, complications and freedom from atrial tachycardia (AT) and atrial fibrillation (AF) were assessed. Over an 18-month period, 100 consecutive patients (56±9years; 17 women) with symptomatic PAF were included in the study (PVI+SVCI, n=51; PVI, n=49); the CHA2DS2-VASc score was 0.9±1. Median duration of procedure (±interquartile), 2.5±1hours; total X-ray exposure, 13.3±8minutes; transseptal puncture and catheter positioning, 8±5minutes; left atrium electroanatomical reconstruction, 3±2minutes; and catheter ablation, 3.7±3minutes. After a median follow-up of 15±8months, and having undergone a single procedure, 84% of patients were symptom free, while 86% remained asymptomatic after undergoing two procedures. The cumulative risks of atrial arrhythmias (AT or AF) were interpreted using Kaplan-Meier curves and compared using the log-rank test. Long-term follow-up revealed no significant difference between groups, with atrial arrhythmias occurring in six (12%) patients in the PVI+SVCI group and nine (18%) patients in the PVI alone group (P=0.6). One transient phrenic nerve palsy and one phrenic nerve injury with partial recovery occurred in the PVI+SVCI group. SVCI combined with PVI did not reduce the risk of subsequent AF recurrence, and was responsible for two phrenic nerve injuries. Accordingly, the benefit-to-risk ratio argues against systematic SVCI.

High Atrial Defibrillation Threshold With Internal Cardioversion Indicates Arrhythmogenicity of Superior Vena Cava in Non-Long-Standing Persistent Atrial Fibrillation.

The purpose of this study was to clarify the relation between atrial defibrillation threshold (ADFT) for internal cardioversion (IC) and arrhythmogenicity of the superior vena cava (SVC). A total of 159 consecutive patients (139 male, age 59.9±10.3 years) who underwent radiofrequency catheter ablation of atrial fibrillation (AF) were assessed. IC was performed in 50 patients with non-long-standing persistent AF (non-LSAF) with a purpose-built cardioversion catheter in which direct current is delivered between the right atrium and the coronary sinus. SVC arrhythmogenicity was defined as SVC firing initiating AF, SVC associated with maintenance of AF, or frequent ectopy in the SVC. In all 50 non-LSAF patients, AF termination was obtained on IC during the procedure except in 1 patient with SVC AF. In the patients with ADFT >10 J (n=10), SVC arrhythmogenicity was observed more often than in those with ADFT ≤10 J (n=40; 60% vs. 13%; P=0.004). There were no significant differences between the 2 groups in left atrial diameter (40.8±7.6 vs. 40.6±6.3 mm; P=0.92), persistent AF (33% vs. 50%; P=0.46), or other clinical parameters. The patients who underwent SVC isolation, however, had higher ADFT before SVC isolation than those who did not (15.5±8.8 vs. 9.2±4.4 J; P=0.01). High IC ADFT is associated with SVC arrhythmogenicity in non-LSAF patients.

Abstract 17189: Superior Vena Cava as the Substrate of Various Forms of Atrial Tachycarrhythmias: Consideration into the Mechanism and Tachycardia Circuit

Background: The superior vena cava (SVC) is known to possess the myocardial sleeves extending from the right atrium which has been shown to be a substrate for various atrial tachyarrhythmias. However, the precise mechanisms and electrophysiologic feature of these atrial tachyarrhythmias, originating from the SVC has not been elucidated well. Objective: The purpose of this study was to define the mechanisms and electrophysiologic characteristics of atrial tachyarrhythmias originating from the SVC. Methods: In 21 patients with atrail tachycarrhythmias originating from the SVC, the mechanism and tachycardia circuit were examined by the contact or non-contact mapping system (EnSite NavX or 3000). Results: There were 5 reentrant atrial tachycardia (AT), 4 focal ATs and 12 atrial fibrillation (AF). Three reentrant ATs showed a macro-reentrant activation around the SVC sleeve with critical slow conduction zone (SCZ) in the SVC and the remaining 2 showed a localized reentry within the SVC. Four focal AT showed a focal discharge source in the SVC. In 8 of 9 ATs, SCZ or focal discharge source was observed at the area extending from the anterior to lateral portions of the SVC. All 12 AF were initiated by the repetitive discharge from SVC and was maintained by the meandering reentrant activation within the SVC involving the junction between the SVC and right atrium during AF. All 9 ATs were terminated by the radiofrequency energy delivery to the SCZ (n=4) and the focal discharge source (n=3) or isolation of SVC (n=2). All 12 AF were terminated by the circular application of radiofrequency energy delivery around the junction between SVC and right atrium, resulting in the SVC isolation in 9 patients. Conclusions: SVC provides the focal discharge source and the substrate of SCZ of AT. These critical area for maintaining AT mostly located at the antero-lateral portions of the SVC. Focal discharge source and substrate for meandering reentry within the SVC also maintained the SVC origin AF. These unique electrophysiologic characteristics of SVC provide the substrate of various forms of atrial tachycarrhythmias.

Abstract 15957: A Simple Ablation Strategy Targeting Exclusively AF Triggers is Equally Effective for Paroxysmal and Persistent Atrial Fibrillation: Single Center Large Series

Backgrounds: Recent studies reported that the ablation strategies including ganglionated plexi ablation, linear ablation and ablation of complex and fractionated electrograms and atrial fibrillation (AF) rotors in conjunction with pulmonary vein isolation (PVI) were superior to the conventional ablation strategy aimed to eliminate AF triggers in terms of post-ablation clinical outcomes. It is controversial whether addition of above-mentioned supplementary ablation to PVI improves post-ablation clinical outcomes in persistent AF (PeAF). Purposes: To test the post-ablation clinical outcomes of our ablation strategy exclusively targeting AF triggers in paroxysmal (PAF) and PeAF, and to compare the post-ablation clinical outcomes between PAF and PeAF in a single center large series. Methods: Consecutive 1183 patients (pts) (age: 64±11 years, LA diameter: 40±6mm) with PAF (988 pts (84%)) or PeAF (195 pts (16%), AF duration: 5±3 months (range: 1-11)) who received ablation procedures in our institution were included. Irrespective of AF types, the procedure consisted of encircling PVI (EPVI) and SVC isolation (SVCI) in all pts, and additional ablation targeting non-PV, non-SVC AF triggers if spontaneous AF initiation was observed by high dose (100-400μg/hr) isoproterenol (ISP) infusion and bolus administration of 40mg of adenosine triphosphate (ATP) during ISP infusion. Procedure end point was complete elimination of spontaneous AF initiation on by ISP infusion and ATP boluses. Results: Total of 1949 procedures were performed in all 1183 pts (1.3±0.5/pt, range: 1-4). EPVI and SVCI were successful in all pts. Non-PV, non-SVC AF triggers were identified in 50 pts (4%) and eliminated by focal ablation in 42 (84%). Kaplan-Meier analysis revealed similarly favorable recurrence-free survivals after the last ablation procedure without antiarrhythmic drugs (blanking period of 1 month) in both PAF and PeAF groups (945 (96%)/988 vs. 190 (97%)/195; p&gt;0.05, follow-up period: 414±245 days (median: 395)). Conclusions: This study exhibited that post-ablation recurrence-free survivals were similar between PAF and PeAF, even if only AF triggers were targeted. An ablation strategy targeting only AF triggers may be sufficient in both PAF and PeAF.

Abstract 15975: Atrial Fibrillation Triggers From Non-PV, Non-SVC Foci: Assessment of Incidence, Characteristics and Efficacy of Catheter Ablation in a Single Center, High Volume Series

Backgrounds: The electrical isolation of the thoracic veins to eliminate triggers of atrial fibrillation (AF) is the mainstay of catheter ablation (CA) for AF. AF is sometimes triggered by repetitive firings from the non-PV, non-SVC (nPVnSVC) foci, and their characteristics have not been fully elucidated. Purposes: To elucidate the incidence, characteristics and efficacy of CA of the nPVnSVC foci in AF patients (pts). Methods: Consecutive 1491 pts who received CA for AF (1080 males, age: 64±10 years, paroxysmal: 995, non-paroxysmal: 496) were included in this study. In index procedures, PV and SVC isolation were performed in all pts without subsequent provocation of nPVnSVC triggers. In repeat procedures, high dose isoproterenol (up to 400μg/hr) and boluses of adenosine triphosphate were given to provoke AF initiation by nPVnSVC triggers and focal ablation of all AF triggers was performed. Results: Among 2097 procedures in all 1491 pts, 58 AF triggers from nPVnSVC foci were provoked in 55 pts (3.7%; 30 paroxysmal and 25 non-paroxysmal AF pts) during 57 procedures (12 index and 45 repeat procedures). The pts with nPVnSVC triggers were significantly more likely to be females (42 vs 28%; P=0.03). The trigger foci were localized in the RA (20 foci; CS os in 8, crista terminalis in 7, IVC os in 3 and tricuspid annulus in 2), LA (24 foci; anterior (6), inferior (3) and posterior wall (3), roof in 3, mitral annulus in 3, Marshall vein in 5 and appendage in 1) and septum (14 foci; left (7) and right side (2) of fossa ovalis, high right septum in 4 and non-coronary cusp of the aortic sinus in 1). All AF triggers were eliminated in 46 pts (84%), while in the others they were not. During follow-up after the last procedure (284±218 days), recurrence-free survival was similar in those with and without nPVnSVC triggers (91 vs 95%; P=0.05), although mean procedure number was significantly larger in those with nPVnSVC triggers than in those without (2.1±0.6 vs 1.4±0.6 times/pt; P&lt;0.0001). Conclusions: The nPVnSVC triggers were observed in 3.7% of all AF pts. The location of the triggers could be clustered to the several anatomical regions. Successful elimination of nPVnSVC triggers contributed to high post-ablation recurrence-free survival that was similar to that in those without nPVnSVC triggers.

Prevalence and clinical outcome of phrenic nerve injury during superior vena cava isolation and circumferential pulmonary vein antrum isolation using radiofrequency energy

Phrenic nerve injury (PNI) is recognized as an important complication during atrial fibrillation ablation. This study aimed to investigate the incidence and outcome of PNI during superior vena cava isolation (SVCI) and circumferential pulmonary vein isolation (CPVI) using radiofrequency (RF) energy and the factors associated with its occurrence. Five hundred sixty-seven consecutive patients who underwent SVCI after CPVI without substrate modification who completed a 12-month follow-up were retrospectively analyzed. Point-by-point RF applications were applied with maximum energy settings of 35 W and 30 seconds for the SVCI. In the former 210 patients, sites where pacing captured the PN were avoided whenever possible; however, the maximum power was 35 W. In the latter 357 patients, RF energy was delivered regardless of PN capture; however, the power at PN capture sites was limited to 10 W during continuous diaphragmatic movement monitoring on fluoroscopy. Circumferential pulmonary vein isolation and SVCI were successfully achieved in all. Twelve patients (2.1%) had PNI during SVCI but not during CPVI. Phrenic nerve injury completely recovered in all patients a median of 8.0 months after the procedure. The prevalence was higher in the former period (3.8% vs 1.1%; P = .03). A multivariate logistic regression analysis revealed that the study period (odds ratio 3.546; 95% CI 1.051-11.965; P = .041) was the sole independent predictor for identifying patients with PNI during SVCI. Phrenic nerve injury occurred in 2.1% of the patients. All occurred during SVCI but not during contemporary CPVI. Energy titration and continuous diaphragmatic movement monitoring significantly decreased the incidence during SVCI.

Discrimination of Thoracic Vein Potentials Facilitated by Atrial Pacing during the Isolation

Although electrical thoracic vein (TV) isolation is an established strategy during atrial fibrillation (AF) ablation, discriminating TV potentials from far-field signals is critical for the achievement. One hundred consecutive drug-refractory symptomatic paroxysmal AF patients who underwent AF catheter ablation were included. All patients underwent circumferential pulmonary vein (PV) isolation during distal coronary sinus (CS) pacing with a cycle length of 600 ms. A superior vena cava (SVC) isolation was added during high right atrial (HRA) pacing with the same cycle length in 79 patients in whom SVC potentials were identified. The interval between the near-field PV potentials and far-field atrial signals significantly prolonged more during distal CS pacing than sinus rhythm (SR) in the left superior (26.0 [18.5-32.8] ms to 36.0 [24.3-55.5] ms, P < 0.01) and left inferior PVs (21.0 [14.0-30.0] ms to 40.0 [23.0-56.0] ms, P < 0.01), but not in the right superior (34.0 [20.0-40.0] ms to 23.0 [18.0-36.0] ms, P = 0.13) and right inferior PVs (22.0 [16.0-28.0] ms to 25.0 [18.0-38.0] ms, P = 0.05). The interval between the SVC potentials and far-field atrial signals significantly prolonged more during HRA pacing than SR (20.0 [0-32.0] ms to 34.0 [24.0-46.0] ms, P < 0.01). Electrical isolation was successfully achieved in all TVs without any complications except for transient right phrenic nerve palsy in two patients. Discrimination of ipsilateral left PVs and SVC potentials is facilitated by pacing from the distal CS and HRA, respectively. Better recognition of TV potentials would help to achieve electrical isolation.