Pulmonary Vein Antrum Research Articles

RETRACTED: Impact of Rotor Ablation in Nonparoxysmal Atrial Fibrillation Patients Results From the Randomized OASIS Trial [J Am Coll Cardiol 2016;68:274–82

Nonrandomized studies have reported focal impulse and rotor modulation (FIRM)-guided ablation to be superior to pulmonary vein antrum isolation (PVAI) for persistent atrial fibrillation and long-standing persistent atrial fibrillation. This study sought to compare efficacy of FIRM ablation with or without PVAI versus PVAI plus non-PV trigger ablation in randomized persistent atrial fibrillation and long-standing persistent atrial fibrillation patients. Nonparoxysmal atrial fibrillation (AF) patients undergoing first ablation were randomized to FIRM only (group 1), FIRM+ PVAI (group 2) or PVAI+ posterior wall+ non-PV trigger ablation (group 3). Primary endpoint was freedom from atrial tachycardia/AF. The secondary endpoint was acute procedural success, defined as AF termination,≥10% slowing, or organization into atrial tachycardia. A total of 113 patients were enrolled at 3 centers; 29 in group 1 and 42 each in groups 2 and 3. Group 1 enrollment was terminated early for futility. Focal drivers or rotors were detected in all group 1 and 2 patients. Procedure time was significantly shorter in group 3 versus groups 1 and 2 (p< 0.001). In groups 1 and 2, acute success after rotor-only ablation was achieved in 12 patients (41%) and 11 (26%), respectively. After 12 ± 7 months' follow-up, 4 patients (14%), 22 (52.4%), and 32 (76%) in groups 1, 2, and 3, respectively, were AF/atrial tachycardia-free while off antiarrhythmic drugs (log-rankp<0.0001). Group 3 patients experienced higher success compared with groups 1 (p< 0.001) and 2 (p= 0.02). Outcomes were poor with rotor-only ablation. PVAI+ rotor ablation had significantly longer procedure time and lower efficacy than PVAI+ posterior wall+ non-PV trigger-ablation. (Outcome of Different Ablation Strategies in Persistent and Long-Standing Persistent Atrial Fibrillation [OASIS]; NCT02533843).

Pulmonary Vein Antrum Isolation in Patients With Paroxysmal Atrial Fibrillation: More Than a Decade of Follow-Up.

We report the outcome of pulmonary vein (PV) antrum isolation in paroxysmal atrial fibrillation (AF) patients over more than a decade of follow-up. A total of 513 paroxysmal AF patients (age 54±11 years, 73% males) undergoing catheter ablation at our institutions were included in this analysis. PV antrum isolation extended to the posterior wall between PVs plus empirical isolation of the superior vena cava was performed in all. Non-PV triggers were targeted during repeat procedure(s). Follow-up was performed quarterly for the first year and every 6 to 9 months thereafter. The outcome of this study was freedom from recurrent AF/atrial tachycardia. At 12 years, single-procedure arrhythmia-free survival was achieved in 58.7% of patients. Overall, the rate of recurrent arrhythmia (AF/atrial tachycardia) was 21% at 1 year, 11% between 1 and 3 years, 4% between 3 and 6 years, and 5.3% between 6 and 12 years. Repeat procedure was performed in 74% of patients. Reconnection in the PV antrum was found in 31% of patients after a single procedure and in no patients after 2 procedures. Non-PV triggers were found and targeted in all patients presenting with recurrent arrhythmia after ≥2 procedures. At 12 years, after multiple procedures, freedom from recurrent AF/atrial tachycardia was achieved in 87%. In patients with paroxysmal AF undergoing extended PV antrum isolation, the rate of late recurrence is lower than what previously reported with segmental or less extensive antral isolation. However, over more than a decade of follow-up, nearly 14% of patients developed recurrence because of new non-PV triggers.

Quantitative Analysis of the Isolation Area During the Chronic Phase After a 28-mm Second-Generation Cryoballoon Ablation Demarcated by High-Resolution Electroanatomic Mapping.

The post-second-generation cryoballoon (CB) ablation isolation area during the chronic phase has not been described. The aim of this study was to quantitatively evaluate the chronic-phase isolation area after 28-mm second-generation CB ablation and compare it to the estimated conventional radiofrequency circumferential pulmonary vein isolation (CPVI) line. Thirty-two patients with paroxysmal atrial fibrillation underwent pulmonary vein (PV) isolation using second-generation CB. After a median of 6.0 (4.0-9.0) months, the PV isolation area was evaluated using high-resolution mapping (1-mm electrode, 2-mm interelectrode spacing; 527±99 points per map) and pacing techniques in all patients (17 with and 15 without arrhythmia recurrence beyond blanking period) and compared with estimated conventional radiofrequency CPVI area. PV reconnections were observed in 34 of 126 PVs (27.0%) among 21 of 32 patients (65.6%), which were eliminated by a median of 1.0 (1.0-3.0) focal radiofrequency application. The left- and right-sided PV antrum isolation area and nonablated posterior wall areas were 9.8±1.7, 8.1±2.3, and 17.0±6.1 cm(2), respectively. The cryoablated areas were significantly smaller than the estimated conventional radiofrequency CPVI areas in all but the right inferior PV. The difference was highest in the left superior PV. In 2 patients (6.3%), recurrent atrial fibrillation originated from the foci identified at the left superior PV antrum outside the CB isolation area but inside the estimated conventional radiofrequency CPVI line. Although the PV isolation areas during the chronic phase after the second-generation CB ablation were generally wide, they were significantly smaller than the area encircled by the CPVI line except at the right inferior PV antrum. Recurrent atrial fibrillation could originate from the left superior PV antrum and could be isolated by a CPVI but not by a CB.

Local Heterogeneous Electrical Restitution Properties of Rabbit Atria.

This study aims to characterize the regional variability in rate-adaptation in the atria. Action potential (AP) responses to pulses with uniform as well as pseudo-random non-uniform pacing intervals were recorded from rabbit sino-atrial node, right and left atrial pectinate as well as pulmonary vein antrum tissue preparations using conventional intracellular glass microelectrodes. Steady-state restitution curves were reconstructed for various AP waveform metrics. We observed significant variability between the four regions under basal pacing representing the rabbit resting heart rate as well as regional variability in rate-adaptation to increased pacing frequencies. Right-left atrial restitution differences were further confirmed using the non-uniform pacing protocol, with significant differences in AP amplitude, duration (APD) as well as maximum phase 0 depolarization rate restitution curves in response to an identical sequence of non-uniform pacing intervals. In addition, we report regional differences in alternans of AP waveform metrics, over a wide range of pacing frequencies and not simply prior to 1:1 entrainment being lost. We also observed an increase in APD90 along the conduction pathway from the left atrium to pulmonary vein junction. Our results identified significant regional differences in electrical restitution in the rabbit atria and suggest their dependency on both baseline AP morphology and local intrinsic differences in rate-adaptation. We propose that the atrial heterogeneity in rate-adaptation could contribute to arrhythmogenesis and the greater susceptibility of pulmonary vein myocardial sleeves to ectopic foci and reentrant activity.

Vagal response during pulmonary vein isolation: Re-recognized its characteristics and implications in lone paroxysmal atrial fibrillation

BackgroundThe role of autonomic innervation around the pulmonary vein (PV) antrum in the genesis of atrial fibrillation (AF) has been demonstrated but the characteristics of radiofrequency induced vagal response (VR) in the PV antrum and its clinical impact on pulmonary vein isolation (PVI) for paroxysmal AF need to be further elucidated. MethodOf 995 consecutive patients with symptomatic paroxysmal AF undergoing PVI at a single center over a 2-year period, 516 met exclusion criteria and the remaining 479 patients, 156 positive VR (PVR) and 323 negative VR (NVR), underwent 12-month follow-up. The primary endpoint was freedom from AF or other sustained atrial tachycardia (AT), verified by monthly visits and electrocardiographic monitoring. The frequency-domain analysis was performed to evaluate the autonomic activity before and after the procedure. ResultsVR was most commonly elicited during PVI at the LSPV roof (65.4%) and anterior RSPV (44.9%, with a >5s sinus pause in 37/70 [52.8%] cases). Compared with the NVR group, ablation was associated with reduced AF recurrence at 12months in the PVR (hazard ratio: 0.53, 95% confidence interval: 0.22–0.89). Furthermore, the PVR group showed a significantly abbreviated AF cycle length at the left PV, and significantly lower HF and LF parameters with stable LF/HF ratio during follow-up. ConclusionComplete elimination of vagal response, most commonly elicited by radiofrequency application around the roof of LSPV and anterior RSPV, appeared associated with reduced 12-month recurrence of AF and with marked heart rate variability changes consistent with autonomic nervous withdrawal.

Spatial Relationship of Focal Impulses, Rotors and Low Voltage Zones in Patients With Persistent Atrial Fibrillation.

Focal impulses (FI) and rotors are sources associated with the initiation and maintenance of atrial fibrillation (AF). Their ablation results in a lower recurrence rate. The aim of this study was to characterize for the first time the spatial relationship between such sources and atrial low voltage zones (LVZ) representing fibrosis. Twenty-five consecutive patients undergoing their first ablation for persistent AF were included. Voltage mapping of both atria was done during AF. Endocardial mapping of FI and rotors (sources) was performed using a basket catheter and displayed using RhythmView(TM) (Topera Inc.) before ablation. Spatial relationship of LVZ and sources was analyzed. LVZs covered 13 ± 12% of right atrial (RA) endocardial surface and 33 ± 25% of left atrial (LA) endocardial surface. The median number of sources was 1 [1-3] in RA and 3 [1-4] in LA. Of LA sources, 18 (30%) were definitely not associated with LVZs or pulmonary vein (PV) antra. Of RA sources, 32 (84%) were remote from LVZ. During ablation of such sources substantial cycle length (CL) prolongation or AF conversion occurred in 11/23 patients (48%). Altogether, 8/11 (73%) of these pertinent sources were located remotely from LVZ and PV antra. There is a wide discrepancy in distribution of LVZ areas and sites of identified rotors. Site and incidence of FIRM sources appear to be unpredictable with atrial substrate mapping. Further prospective, randomized studies are necessary to elucidate the impact of additional ablation of such sources in patients with persistent or longstanding persistent AF.

Spatial Relation Between Left Atrial Anatomical Contact Areas and Circular Activation in Persistent Atrial Fibrillation.

Atrial low-voltage zones (LVZs) may be related to maintenance of atrial fibrillation (AF). The influence of left atrial (LA) contact areas (CoAs) on reentrant or rotor-like sources maintaining AF has not been investigated. Forty patients with persistent AF (PsAF) were analyzed. Three representative CoA regions in the LA (ascending aorta: anterior wall; descending aorta: left inferior pulmonary vein; and vertebrae: posterior wall) were visualized by enhanced CT. Using circular catheters, the LVZs (<0.5 mV) were assessed after restoration of SR, and local activation mapping and frequency domain analyses were performed after induction of AF. Circular activation during AF was visually defined as sites with ≥2 rotations by serial electrograms encompassing >80% of the mean AF cycle length. A pivot was defined as the core of the localized circular activation. Anterior (39/40 patients, 98%), left pulmonary vein antrum (27/40, 68%), and posterior (19/40, 48%) CoAs were identified, and 80% (68/85) of those sites were overlapped by or close (<3 mm) to LVZs. Thirty-six (90%) patients demonstrated circular activation (3.1±1.7 sites/patients) along with significantly higher organized dominant frequencies (6.3 ± 0.5 Hz, regularity-index: 0.26 [0.23-0.41]) within the LA, and the average electrogram amplitude of those pivots was 0.30 mV (0.18-0.52). Of those sites, 55% (66/120) were located at or close to CoA regions. Catheter ablation including of LVZs neighboring CoAs terminated AF in 9 (23%) patients. External anatomical structures contacting the LA may be related to unique conduction properties in diseased myocardium necessary for PsAF maintenance.

Five-year efficacy of pulmonary vein antrum isolation as a primary ablation strategy for atrial fibrillation: a single-centre cohort study.

Pulmonary vein antrum isolation (PVAI) is the cornerstone of atrial fibrillation (AF) ablation. There is an ongoing discussion on whether and when to add substrate modification to PVAI. This study evaluates (1) long-term efficacy of PVAI as a primary ablation strategy in all patients independently from AF type and (2) predictors of arrhythmia recurrence. A total of 509 consecutive patients (mean age 57 years, 38.9% non-paroxysmal AF) with AF underwent PVAI. In redo procedures, ablation was restricted to re-pulmonary vein (PV) isolation in case of PV reconnection. If the PVs were found to be isolated, substrate modification was performed. In total, 774 procedures were performed. Mean follow-up duration after the first and last ablation was, respectively, 66 ± 23 and 55 ± 25 months. A single PVAI was sufficient in restoring and maintaining long-term sinus rhythm in 41.3% (n = 210) of patients. Multiple procedures (mean 1.5) with re-PV isolation increased long-term success to 58.3% (n = 297). Additional substrate modification (n = 70) increased success to 62.5% (n = 318). After the last ablation, 87.5% of patients experienced success or significant clinical improvement on or off antiarrhythmic drugs. The incidence of left-sided atrial flutter or atrial tachycardia was 5% after PVAI and increased to 32% after additional substrate modification. Independent predictors for arrhythmia recurrence after the last ablation were non-paroxysmal AF, female sex, body mass index, hypertension, and AF duration. Five-year freedom of atrial tachyarrhythmia could be achieved by PVAI as primary ablation strategy in 58.3% of patients. Additional substrate modification only moderately increased overall success.

Pharmacological Tests in Atrial Fibrillation Ablation.

The invasive management of atrial fibrillation (AF) has been considerably changed by the identification of major sites of AF initiation and/or maintenance within the pulmonary vein antra. Percutaneous catheter ablation of these targets has become the standard of care for sustained maintenance of sinus rhythm. Long-term failure of ablation is related to an inability to create a durable transmural lesion or to identify all of the non-pulmonary vein arrhythmia triggers. Pharmacological challenges during catheter ablation have been suggested to improve outcomes in both paroxysmal and persistent AF. Herein we review the mechanism and evidence for the use of pharmacological adjuncts during the catheter ablation of AF.

Paradoxical Response of Giant Left Atrial Appendage Aneurysm after Catheter Ablation of Atrial Fibrillation

A giant left atrial appendage (LAA) aneurysm is a very rare cardiac anomaly, and associated with the supraventricular arrhythmia including atrial fibrillation (AF) (1-3). Furthermore, the giant LAA aneurysm may be the main source of thrombosis in patients with AF (1-3). With technical developments of catheter ablation, the percutaneous electrical isolation of cardiac arrhythmogenic substrates has been considered as the effective strategy for management of drug-refractory AF (4). Additionally, Hof et al. (5) reported that a patient with AF and giant LAA aneurysm could be successfully treated by percutaneous pulmonary vein antrum isolation. Echocardiography is the first line imaging technique to detect the giant LAA aneurysm (2). Especially transesophageal echocardiography (TEE) allows clear visualization of the LAA, and can be effective for the diagnosis of giant LAA aneurysm and thrombi. However, TEE may provide a relatively narrow field of view in the delineation of entire parts of giant LAA aneurysm (2). The role of cardiac magnetic resonance (CMR) has been emphasized in the comprehensive evaluation of cardiac anatomy, function, and This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Received: May 9, 2016 Revised: June 13, 2016 Accepted: June 14, 2016

Usefulness of filtered unipolar electrogram morphology for evaluating transmurality of ablated lesions during pulmonary vein isolation

BackgroundAlthough alteration of the amplitude and morphology of bipolar electrograms is used widely as a guide of the ablation effect, there is little information concerning unipolar electrograms. The amplitude and morphology of filtered bipolar (BP) and filtered unipolar (UP) electrograms were compared during pulmonary vein isolation in patients with atrial fibrillation. MethodsBP (30–250Hz) and UP (30–100Hz) signals from the ablation catheter were recorded before and after each ablation point at the pulmonary vein antrum in 6 patients with atrial fibrillation. ResultsIn the electrogram group with low-voltage amplitude in BP electrograms before ablation (<0.5mV), the reduction in amplitude after ablation was significantly greater in the UP than in the BP electrograms, whereas the reduction was similar between the two recording methods in the electrogram group with high-voltage amplitude in BP electrograms (≥0.5mV). Furthermore, the S wave in the UP electrograms disappeared at the sites of no pace capture after ablation, whereas no characteristic morphologic changes were observed in the BP electrograms. ConclusionFiltered UP electrograms may be useful in assessing the effectiveness of lesion formation.

Lack of regional association between atrial late gadolinium enhancement on cardiac magnetic resonance and atrial fibrillation rotors

The extent of left atrial (LA) late gadolinium enhancement (LGE), as a surrogate for fibrosis, has been associated with atrial fibrillation (AF) recurrence after catheter ablation. Furthermore, there is ex vivo evidence that islands of fibrosis may anchor fibrillatory rotors. The purpose of this study was to examine the anatomical association of AF rotors with LA and right atrial (RA) LGE on cardiac magnetic resonance. The cohort included 9 patients with persistent AF (mean age 61.1 ± 9.7 years) who underwent LGE cardiac magnetic resonance before AF ablation using the focal impulse and rotor modulation system. The extent of LA and RA LGE was quantified globally and in each of the 7 sectors: LA posterior/inferior wall, anterior wall, roof, left and right pulmonary vein antra, and RA lateral and septal regions. The multivariable association of rotor incidence with global and per sector LGE extent was examined using multivariable Bernoulli logistic regression estimated by generalized estimating equations. The mean RA and LA volumes were 113.2 ± 37.31 and 143.03 ± 58.25 mL, respectively. The mean RA and LA LGE burden was 17.2% ± 11.0% and 17.4% ± 14.4%, respectively. A total of 18 LA rotors and 9 RA rotors were identified in all patients. No univariable or multivariable association was observed between global or per sector LGE extent and focal impulse and rotor modulation rotor incidence. In this cohort of patients, there was no association between AF rotor incidence and the global or regional extent of RA and LA LGE.

Abstract 18637: Recurrence Quantification Analysis to Distinguish Active From Passive Mechanisms of CFAEs During Catheter Ablation of Atrial Fibrillation

Background: Ablation of complex fractionated atrial electrograms (CFAEs) is controversial, primarily because of difficulty in visually distinguishing CFAEs representing an active site of driver activity from a passive site of double potentials, wave break, and/or slow conduction. We hypothesized that CFAEs within rotors in atrial fibrillation (AF) would exhibit highly recurrent behavior compared with CFAEs remote from these driver regions. Methods: Active and passive mechanisms of CFAE formation were simulated in several 2D 7.5 x 7.5 cm modified Luo-Rudy 1 models. CFAEs within areas of rotors were considered active, while those caused by wave break, slow conduction or double potentials remote from rotors were considered passive. Clinical signals were also collected during catheter ablation of paroxysmal AF (n=8 patients). An active driver CFAE site was defined by termination of AF with ablation followed by non-inducibility. A passive site was defined as CFAE occurring remotely. Detection of CFAEs was based on mean cycle length (MCL) calculated from 4 second windows using -dV/dt for detection (40ms refractory period/10ms maximum EGM width for simulations; 45ms/15ms respectively for clinical signals). Recurrence quantification analysis (RQA) was performed on discrete time series of simulated and clinical CFAE activations. Results: RQA was performed on 20 simulated EGMs. MCL was similar in both active and passive CFAEs (74±11ms and 78±6ms respectively, p=NS), but recurrence was significantly higher in active compared to passive sites (%recurrence: 61±22% active, 4±6% passive, p&lt;0.01). In patients with AF, the driver sites were all located within the pulmonary vein antra while passive CFAEs were remote. The MCL of CFAEs at active driver sites was similar to that of passive sites (100±13ms active, 98±17ms passive, p=NS), but recurrence was significantly higher in the active driver sites (%recurrence: 18±15% active, 2±1% passive, p=0.02). Conclusion: CFAEs may occur due to either active or passive mechanisms. Sites within rotors or focal drivers of AF are more likely to exhibit recurrent patterns. RQA may be a powerful tool to differentiate driver from bystander CFAEs enabling more efficient targeting for ablation.

Abstract 15733: Long-Term Follow-Up of Patients With Paroxysmal Atrial Fibrillation and Severe Left Atrial Scarring: Comparison Between Pulmonary Vein Antrum Isolation Only or PVAI Combined With Either Scar Homogenization or Trigger Ablation

Background: Left atrial (LA) scarring, a consequence of cardiac fibrosis is a powerful predictor of procedure-outcome in atrial fibrillation (AF) patients undergoing catheter ablation. We sought to compare the long-term outcome in patients with paroxysmal AF and severe LA scarring/fibrosis identified by 3D mapping undergoing ablation of the pulmonary veins (PVAI) only or PVAI and the entire scar areas (scar homogenization) or PVAI plus ablation of the non-PV triggers. Methods: One-hundred seventy seven consecutive patients with paroxysmal atrial fibrillation and severe left atrial scarring were included in this study. LA scarring was diagnosed by 3D voltage mapping. The degree of scar was described as severe when &gt;60% of the LA area was involved. Non-PV triggers were defined as ectopic triggers originating from sites other than pulmonary veins such as interatrial septum, superior vena cava, left atrial appendage, ligament of Marshall, crista terminalis and coronary sinus. Patients underwent ablation of the pulmonary vein antrum (PVAI) only (n=45, group 1), PVAI extended to the entire scar areas (scar homogenization [n=66, group 2]) or PVAI plus ablation of non-PV triggers (n=66, group 3). Choice of ablation strategy was determined by the operator. Patients were followed up for arrhythmia recurrence with event recorders, ECG and Holter monitoring. Results: Baseline characteristics were not different between the groups (age 63±9 vs 58±10 vs. 60±11 years, p=0.23; male 71%, vs. 72% vs. 73% p= 0.91). After a single procedure, all patients were followed-up for a minimum of two years. The long-term success rate at the end of the follow up was 19% (12 pts) in group 1, 21% (14 pts) in group 2, and 61% (40 pts) in group 3. Kaplan-Meier log-rank test indicated that the cumulative probability of AF-free survival was significantly higher in group 3 (overall log-rank p &lt;0.001, pairwise comparison 1 vs. 3 and 2 vs. 3 was significant at p&lt;0.01). Conclusions: In patients with paroxysmal atrial fibrillation and severe left atrial scarring, PVAI plus ablation of non-PV triggers is associated with significantly better long-term outcome than PVAI alone or when PVAI is combined with scar homogenization.

Abstract 20107: Randomized Comparison of Personalized versus Standardized Substrate Modification During Catheter Ablation for Symptomatic Atrial Fibrillation

Introduction: Pulmonary vein (PV) isolation forms the cornerstone of any ablation procedure for atrial fibrillation (AF). There is, however, no uniform strategy how to detect and target left atrial (LA) arrhythmogenic substrate outside the PV antra. Fibrosis that corresponds well to LA low-voltage areas (LVAs) seems to play a key role in AF arrhythmogenesis and might therefore be a suitable target for additional substrate modification (SM). Objective: The purpose of this prospective randomized study was to compare a novel technique for SM based on ablation of potentially arrhythmogenic LA LVAs with a standard approach consisting of empiric LA linear ablation. Methods: Patients (pts) with symptomatic paroxysmal or persistent AF were randomized to standard (group 1) or personalized (group 2) SM. Circumferential PV isolation was the primary step in both groups. In group 1, pre-defined linear lesions were applied at the LA roof and bottom, respectively, and at the mitral isthmus only in pts with persistent AF. In group 2, targets for SM (i.e. LVAs) were identified by detailed bipolar voltage mapping (BVM) during sinus rhythm irrespective of AF type. Peak-to-peak electrogram amplitudes were defined as “normal” (&gt; 0.5 mV), as “low voltages” (0.2 to 0.5 mV), or as “scar” (&lt; 0.2 mV). LVAs were targeted by tissue homogenization and / or strategic linear lesions. The primary endpoint was freedom from any atrial arrhythmia (i.e. AF, atrial flutter, or atrial tachycardia) &gt; 30 seconds off antiarrhythmic drugs on serial 7-d-Holter ECG recordings after a follow-up period of 12 months. Results: In total, 124 ablation-naïve pts (mean age 63 ± 9 years, 62 % male, 49 % with persistent AF) were enrolled in this study. LVAs were present in 18 % of pts with paroxysmal and in 41 % of pts with persistent AF (p&lt;0.05). At the end of the follow-up period, 25 out of 59 pts (42 %) in the conventional group were free from arrhythmia recurrence as compared to 40 out of 59 pts (68 %) in the BVM-guided group (unadjusted log rank p = 0.003). Conclusion: Personalized SM guided by endocardial BVM is associated with a higher success rate compared to a conventional approach applying empirical SM based on AF phenotype.

Abstract 15628: Prevalence of Non-Pulmonary Vein Triggers in Patients With Previous History Of Coronary Artery Bypass Grafting Undergoing Catheter Ablation for Atrial Fibrillation

Introduction: Post-operative atrial fibrillation (AF) is reported in up to 5-40% of patients following coronary artery bypass graft (CABG) surgery. Age-related atrial dilatation and fibrosis, electrical remodeling, autonomic imbalance and post-operative inflammation are few of the many pathophysiological factors that play an important role in the genesis and persistence of post-CABG AF. Recent data on fibroblast-myocyte interaction indicates the central role of cardiac fibrosis in the origin of non-pulmonary vein (non-PV) drivers that serve as a source for maintenance of AF. Therefore, we sought to examine the prevalence of non-PV triggers and their impact on ablation outcome in post-CABG AF patients. Methods: Two-hundred sixty seven patients with history of CABG undergoing catheter ablation for atrial fibrillation were included in this analysis (61±11 years, 69% male, LVEF 50±10%, LA size 41.0±6.8mm, non-PAF 72%). All patients underwent pulmonary vein antrum (PVAI) and posterior wall isolation. Non-PV triggers were defined as ectopic triggers originating from sites other than pulmonary veins such as interatrial septum, superior vena cava, left atrial appendage, coronary sinus, ligament of Marshall, crista terminalis. Those were identified by isoproterenol challenge and were ablated based on operator choice. Results: During ablation, non-PV triggers were detected in 243 (91%) patients. The triggers were most commonly mapped to CS (62%) and LAA (70%). Additional sites of non-PV triggers were LA septum, superior vena cave, crista terminalis and mitral valve annulus. Based on operator choice, non-PV triggers were ablated in 118 of the 243 patients and not targeted in 125 patients. At the end of 32±7 month follow-up after a single procedure, overall success rate was 130 (53.5%). Of the 118 patients undergoing non-PV trigger ablation, 81(68.6%) patients remained arrhythmia-free off anti-arrhythmic drugs compared to 49 of 125 (39.2%) where non-PV ablation was not performed (log rank p &lt;0.001, hazard ratio 3.76 [95% CI 2-6.43]). Conclusion: Our results for the first time demonstrate that non-PV foci are highly prevalent in post-CABG AF patients and ablation of those triggers results in significantly better long-term outcome.

Abstract 16285: Routine Use of 3D Mapping and Irrigated Ablation Improves Outcomes of Pulmonary Vein Antral Isolation Among Patients With Persistent AF

Bckground: Pulmonary Vein Antrum Isolation (PVAI) is a widely accepted treatment option in Atrial Fibrillation (AF). However, despite procedural advancements, post-PVAI AF recurrences remain a common challenge. We thought to investigate whether the addition of routine 3D electroanatomical mapping and routine use of irrigated ablation catheters (IC) vs 8 mm tip catheters made an impact on the outcomes of PVAI guided by intracardiac echocardiography (ICE) and a decapolar circular mapping catheter (CMC) alone. Methods: Patient and procedural data were collected for 884 AF consecutive patients undergoing PVI at a single Canadian center during 2004 - 2014 (469 patients in 2004-2009, Group 1vs. 415 patients in 2010-2014, Group 2). Group 1 patients received PVAI guided by ICE and CMC. All Group 2 patients had PVAI guided by ICE, CMC and 3D mapping with the use of irrigated tip ablation catheters. Mean ages for Groups 1 and 2 were = 58.6 ± 10.0 and 61.0 ± 10.7 years respectively (p= 0.001). Mean follow up time was 17.1 ± 18.8 months for Group 1 and 14.1± 9.7 months for Group 2 (p=0.003). ECG and ambulatory monitoring was performed at 1, 3, 6, and 12 months. Recurrences ≤ 3 months post-PVI were considered Early (ER), while recurrences after 3 months post-PVI were considered Late (LR). Using survival analysis, rates of LR stratified by AF type [Paroxysmal AF (PAF) vs. Non-PAF (NPAF)] were compared between the two cohorts Results: ER rate was lower in Group 2 vs. Group 1 (36.8% vs. 44.7%, P=0.05) in patients with PAF and for those with NPAF (54.8% vs. 66.9%, P=0.03). LR rates did not differ between the Groups among PAF patients (62.5% in Group 1 vs. 57.3% in Group 2, P=0.16), but improved significantly for the NPAF patients (55.6% in Group 1 vs. 37.9% in Group 2 , P=0.002). Conclusion: Late recurrence of AF post-PVI has dramatically improved since 2010 for patients with persistent AF following routine addition of 3D mapping to ICE and CMC, while substituting an irrigated for an 8mm ablation catheter.

Pulmonary Vein Stenosis After Ablation: The Difference Between Clinical Symptoms and Imaging Findings, and the Importance of Definitions in This Context

Pulmonary vein (PV) stenosis is a well-known complication of invasive therapy for atrial fibrillation, informally known as ‘‘PV ablation’’. This complication was detected in the early years after the introduction of the technique. Pulmonary vein ablation was developed from the pathophysiological finding in some patients with paroxysmal atrial fibrillation that paroxysmal arrhythmias are triggered by high frequency electrical discharges. This focal activity originates in striated muscle bands or sleeves in the last few centimeters before the PVs open into the left atrium and are connected to the latter through electrical excitation. Originally, cardiologists tried to ablate this electrical activity at the originating foci inside the PV. This procedure resulted in a high incidence of PV stenosis, probably secondary to tissue retraction from the ablation site lesion. In view of this common complication, together with the finding that arrhythmia mechanisms may also originate in the PV antrum, beyond the tubular portion of the PV, the ablation approach was then changed with the aim of achieving electrical isolation of the PV by performing antral ablation, thus isolating the PV from a distance. The wide diameter of the antrum prevents PV stenosis, even in the presence of scar retraction at the ablation sites. The adoption of this new ablation approach has drastically decreased symptomatic PV stenosis. However, there are still several lingering reasons for concern: a) the lack of controlled studies comparing different ablation approaches; b) some areas of the PV, such as the raphe that separates the left PVs from the left atrial appendage, make it impossible to perform PV ablation from a distance; c) the esophagus sometimes lies in close proximity to PVs on one side, and ablation has to be performed on the PV itself to avoid damaging the esophagus, and d) PV stenosis initially appeared to be confined to radiofrequency energy but has since been described with other forms of energy, suggesting that this complication can also occur with other ablation techniques.

Balloon-based pulmonary vein isolation for the treatment of paroxysmal atrial fibrillation (cryoballoon and laserballoon).

Electrical isolation of the pulmonary veins still remains one of the major objectives during catheter ablation of atrial fibrillation. In patients with paroxysmal atrial fibrillation, balloon-based technologies hold great promise to simplify the approach to successful pulmonary vein isolation. While the cryoballoon represents the only true 'single-shot' technology, the laserballoon allows real-time endoscopic visualization of the pulmonary vein antrum during energy delivery. Either technology aims at complete electrical isolation, requiring continuous transmural lesion sets encircling the pulmonary veins. Strategies to confirm and to improve upon the efficacy of pulmonary vein isolation are the key to acute and long-term clinical success and will be reviewed in this article.

CoolLoop® First: A First In Man Study To Test A Novel Circular Cryoablation System In Paroxysmal Atrial Fibrillation.

Pulmonary vein (PV) isolation is the mainstay of catheter treatment of paroxysmal atrial fibrillation (AF). The CoolLoop® cryoablation catheter (AFreeze® GmbH; Innsbruck, Austria) was developed to create wide and complete circular lesions around the PVs. In this study we evaluated feasibility and safety of this novel ablation system in humans. 10 patients (6M/4F; 57.6±7.6y) with paroxysmal AF were included in 2 referral centers. The CoolLoop® catheter was positioned at each PV antrum using a steerable transseptal sheath. Subsequently, 2-6 double-freezes over 5min were performed at each vein and PV-isolation was assessed thereafter using a circular mapping catheter. During cryoablation of the right PVs, pacing was used to monitor phrenic nerve function. The CoolLoop® catheter could be successfully positioned at each PV. A mean of 5.6±1.8 cryoablations were performed in the LSPV, 5.2±1.6 in the LIPV, 6.3±2.5 in the RSPV and 5.4±1.6 in the RIPV, respectively. Mean procedure time was 251±60min and mean fluoroscopy time was 44.0±13.2min. 6 / 10 LSPV, 6 / 10 LIPV, 5 / 10 RSPV and 6 / 10 RIPV could be isolated exclusively using the novel cryoablation system. One patient developed groin hematoma and a brief episode of ST-elevation due to air embolism was observed in another subject. No other clinical complications occurred during 3 months of follow up. PV-isolation for paroxysmal atrial fibrillation using the CoolLoop® catheter is feasible and appears safe. Clinical long term efficacy still needs to be evaluated and will be compared with established catheters used for AF ablation.