Paroxysmal Atrial Fibrillation Maintained by Nonpulmonary Vein Sources Can Be Predicted by Dominant Frequency Analysis of Atriopulmonary Electrograms

Introduction: Increasing evidence suggests that high-frequency excitation in the pulmonary vein (PV) plays a dominant role in the maintenance of paroxysmal atrial fibrillation (AF). However, in a certain population of patients, AF remains inducible after PV isolation (PVI). We sought to clarify whether dominant frequency (DF) analysis of atriopulmonary electrograms can predict paroxysmal AF maintained by non-PV sources.
Methods and Results: Sixty-one patients with paroxysmal AF (aged 59 ± 12 years) were studied. Before PVI, bipolar electrograms during AF were recorded simultaneously from three PV ostia, the coronary sinus (CS), and the septum and free wall of the right atrium (RA). DF was obtained by fast Fourier transform (FFT) analysis. AF was rendered noninducible after PVI in 39 of the 61 patients (noninducible group), but was still inducible in the remaining 22 (inducible group). Among the six recording sites, the highest DF was documented in the PV in all of the patients in the noninducible group; the maximum DF among the three PVs (PV-DF_max) was higher than that among the CS and two RA sites (atrial DF_max; 7.2 ± 1.0 Hz vs 5.8 ± 0.7 Hz, P < 0.0001). In contrast, the highest DF was documented in the CS or RA in 45.5% of the patients in the inducible group; PV-DF_max was comparable with atrial DF_max (6.6 ± 0.8 Hz vs 6.6 ± 0.6 Hz). AF inducibility after PVI was predicted by a PV-to-atrial DF_max gradient of <0.5 Hz, with a sensitivity of 90.9% and a specificity of 89.7%.
Conclusion: Paroxysmal AF maintained by non-PV sources can be predicted by the PV-to-atrial DF gradient.     

Pulmonary Vein Antral Isolation for Paroxysmal Atrial Fibrillation: Results from Long‐Term Follow‐Up

Long‐Term Follow‐Up After Atrial Fibrillation Ablation . Introduction: Pulmonary veins play an important role in triggering atrial fibrillation (AF). Pulmonary vein isolation (PVI) is an effective treatment for patients with paroxysmal AF. However, the late AF recurrence rate in long‐term follow‐up of circumferential PV antral isolation (PVAI) is not well documented. We sought to determine the time to recurrence of arrhythmia after PVAI, and long‐term rates of sinus rhythm after circumferential PVAI. Methods: One hundred consecutive patients with a mean age of 54 ± 10 years, with paroxysmal AF who underwent PVAI procedure were analyzed. Isolation of pulmonary veins was based on an electrophysiological and anatomical approach, with a nonfluoroscopic navigation mapping system to guide antral PVI. Ablation endpoint was vein isolation confirmed with a circular mapping catheter at first and subsequent procedures. Clinical, ECG, and Holter follow‐up was undertaken every 3 months in the first year postablation, every 6 months thereafter, with additional prolonged monitoring if symptoms were reported. Time to arrhythmia recurrence, and representing arrhythmias, were documented. Results: Isolation of all 4 veins was successful in 97% patients with 3.9 ± 0.3 veins isolated/patient. Follow‐up after the last RF procedure was at a mean of 39 ± 10 months (range 21–66 months). After a single procedure, sinus rhythm was maintained at long‐term follow‐up in 49% patients without use of antiarrhythmic drugs (AADs). After repeat procedure, sinus rhythm was maintained in 57% patients without the use of AADs, and in 82% patients including patients with AADs. A total of 18 of 100 patients had 2 procedures and 4 of 100 patients had 3 procedures for recurrent AF/AT. Most (86%) AF/AT recurrences occurred ≤1 year after the first procedure. Mean time to recurrence was 6 ± 10 months. Kaplan–Meier analysis on antiarrhythmics showed AF free rate of 87% at 1 year and 80% at 4 years. There were no major complications. Conclusion: PVAI is an effective strategy for the prevention of AF in the majority of patients with PAF. Maintenance of SR requires repeat procedure or continuation of AADs in a significant proportion of patients. After maintenance of sinus rhythm 1‐year post‐PVAI, a minority of patients will subsequently develop late recurrence of AF. (J Cardiovasc Electrophysiol, Vol. 22, pp. 137‐141, February 2011)     

Cryoballoon Pulmonary Vein Isolation Supported by Intracardiac Echocardiography: Integration of a Nonfluoroscopic Imaging Technique in Atrial Fibrillation Ablation

Intracardiac Echo Supported Cryoballoon Ablation . Introduction: Cryoballoon ablation has been adopted for pulmonary vein (PV) isolation (PVI) in many centers. Complete occlusion of PV by an adequately sized balloon is crucial for effectiveness of cryoenergy delivery. The aim of this study was to evaluate intracardiac echocardiography (ICE) as an alternative imaging technique compared to angiographic imaging in cryoballoon PVI. Methods and Results: A total of 75 PVs were treated in 22 patients (61 ± 13 years, 17 male) undergoing PV cryoballoon ablation for drug refractory paroxysmal atrial fibrillation. Decision for an adequate balloon size was based on diameters of the PV antra assessed by ICE and PV angiography. Per PV 2.4 ± 0.4 cryoenergy pulses were applied. Decision for the balloon size was similar either based upon angiography or on ICE. A single 23 or 28 mm balloon was chosen in 10 and 3 patients, respectively. Two different sized balloons were used in 9 patients. PVI was evaluated after 2 cryoenergy applications. Total occlusion of the PV confirmed by ICE color flow Doppler (CFD) during ablation predicted successful PVI in 70 of 75 (93%) and unsuccessful PVI in 8 of 8 (100%). PV flow registered by pulsed wave Doppler at the PV ostium pre‐ and postablation was 0.48 ± 0.10 and 0.51 ± 0.12 m/s, respectively (n.s.). PVI was finally confirmed by entrance block in all PVs. No procedural complications occurred. Conclusions: ICE is a feasible novel imaging technique in cryoballoon ablation procedures. It allows decision for adequate balloon size, exact balloon placement, prediction of acute ablation success, and excludes acute narrowing of PV ostia. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1325‐1330, December 2010)     

Acute and Long‐Term Clinical Outcome After Endoscopic Pulmonary Vein Isolation: Results from the First Prospective,Multicenter Study

Clinical Outcome After Endoscopic PVI. Introduction: The acute and long‐term outcome of pulmonary vein isolation (PVI) using an endoscopic ablation system (EAS) has only been reported in single‐center studies. The current prospective, multicenter study assessed the acute and 1‐year outcome following PVI using the EAS. Methods and Results: Seventy‐two patients (34 female, mean age 58 ± 10 years) with a history (5 ± 6 years) of drug‐refractory paroxysmal atrial fibrillation (AF) were included. Endoscopic PVI was performed in all patients. Follow‐up was based on regular telephone interviews, Holter ECG, and transtelephonic ECG recordings. Recurrence was defined as a symptomatic and/or documented AF episode >30 seconds following a blanking period of 3 months. In 72 patients, a total of 281 pulmonary veins (PVs) were targeted and 277/281 (98.6%) PVs were isolated successfully using only the EAS. PV stenosis, thrombembolic events, pericardial effusion, pericardial tamponade, and phrenic nerve palsy occurred in 0 of 72, 0 of 72, 3 of 72 (4.2%), 4 of 72 (5.6%), and in 1 of 72 (1.4%) patients, respectively. Sixty‐seven of 72 (93.1%) patients completed a follow‐up of 365 days and 42 of 67 (62.7%) patients remained in stable sinus rhythm after a single procedure. A total of 13 of 25 (52%) patients suffering from AF recurrence consented to repeat PVI using conventional radiofrequency energy 221 ± 121 days after the index procedure. LA to PV reconduction was found in 30 of 45 (67%) previously isolated PVs. Conclusions: A very high rate of acute electrical PVI is achieved using exclusively the EAS. The 1‐year single‐procedure success rate in patients with paroxysmal AF is comparable to conventional PVI. PV reconduction is the major determinant for AF recurrence. (J Cardiovasc Electrophysiol, Vol. 24, pp. 7‐13, January 2013)     

Persistence of Pulmonary Vein Isolation After Robotic Remote‐Navigated Ablation for Atrial Fibrillation and its Relation to Clinical Outcome

Robotic Remote Ablation for AF . Aims: A robotic navigation system (RNS, Hansen?) has been developed as an alternative method of performing ablation for atrial fibrillation (AF). Despite the growing application of RNS‐guided pulmonary vein isolation (PVI), its consequences and mechanisms of subsequent AF recurrences are unknown. We investigated the acute procedural success and persistence of PVI over time after robotic PVI and its relation to clinical outcome. Methods and Results: Sixty‐four patients (60.7 ± 9.8 years, 53 male) with paroxysmal AF underwent robotic circumferential PVI with 3‐dimensional left atrial reconstruction (NavX?). A voluntary repeat invasive electrophysiological study was performed 3 months after ablation irrespective of clinical course. Robotic PVI was successful in all patients without complication (fluoroscopy time: 23.5 [12–34], procedure time: 180 [150–225] minutes). Fluoroscopy time demonstrated a gradual decline but was significantly reduced after the 30th patient following the introduction of additional navigation software (34 [29–45] vs 12 [9–17] minutes; P < 0.001). A repeat study at 3 months was performed in 63% of patients and revealed electrical conduction recovery in 43% of all PVs. Restudied patients without AF recurrence (n = 28) showed a significantly lower number of recovered PVs (1 (0–2) vs 2 (2–3); P = 0.006) and a longer LA‐PV conduction delay than patients with AF recurrences (n = 12). Persistent block of all PVs was associated with freedom from AF in all patients. At 3 months, 67% of patients were free of AF, while reablation of recovered PVs led to an overall freedom from AF in 81% of patients after 1 year. Conclusion: Robotic PVI for PAF is safe, effective, and requires limited fluoroscopy while yielding comparable success rates to conventional ablation approaches with PV reconduction as a common phenomenon associated with AF recurrences. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1079‐1084)     

Incidence and Electrophysiologic Properties of Dissociated Pulmonary Vein Activity Following Pulmonary Vein Isolation During Catheter Ablation of Atrial Fibrillation

Dissociated PV Activity During AF Ablation. Introduction: Pulmonary veins (PV) play an important role in the arrhythmogenesis of atrial fibrillation (AF). Catheter‐based PV isolation is one of the primary treatments for symptomatic drug refractory AF. Following electrical isolation, isolated rhythms in the PV are encountered. The aim of this study was to assess the frequency of postisolation PV activity and classify the different rhythms observed. Methods and Results: This single center prospective study sought to assess the dissociated activity in the PVs following their isolation during AF ablation. In 100 consecutive patients (60 paroxysmal, 40 persistent) undergoing AF ablation, dissociated PV activity was recorded using a multielectrode mapping catheter following antral PV isolation. The dissociated PV activity was classified as (1) silent, (2) isolated ectopic beats, (3) ectopic rhythm, and (4) PV fibrillation. All the PVs were successfully isolated in all the patients. In 91 of 100 patients, there was dissociated activity in at least 1 isolated ipsilateral PV group. There was no significant difference in spontaneous PV activity between patients with paroxysmal and persistent AF (91.7% vs 90%, P = 1.0). Among the 200 isolated ipsilateral PV groups, 64 of 200 (32%) were silent, 86 of 200 (43%) demonstrated isolated ectopic beats, 41 of 200 (20.5%) had ectopic rhythms and 9 of 200 (4.5%) had PV fibrillation. The average cycle length of the PV ectopic rhythm was 2594 ± 966 ms (range 1193–4750 ms). Conclusions: Following PV isolation, a majority of patients demonstrate dissociated activity in at least 1 PV. This finding was evident in patients with both paroxysmal and persistent AF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1338‐1343, December 2010)     

Pulmonary Vein Isolation Alone in Patients with Persistent Atrial Fibrillation: An Ablation Strategy Facilitated by Antiarrhythmic Drug Induced Reverse Remodeling

PVI Alone in Patients with Persistent AF . Introduction: Pulmonary vein isolation (PVI) alone has been thought to be insufficient in patients with persistent atrial fibrillation (PersAF). We hypothesized that preablation treatment of PersAF with a potent antiarrhythmic drug (AAD) would facilitate reverse atrial remodeling and result in high procedural efficacy after PVI alone. Methods and Results: Seventy‐one consecutive patients (59.4 ± 9.8 years) with PersAF and prior AAD failure were treated with oral dofetilide (768 ± 291 mcg/day) for a median of 85 days pre‐PVI. P‐wave duration (Pdur) on ECG was used to assess reverse atrial remodeling. Thirty‐five patients with paroxysmal (P) AF not treated with an AAD served as controls. All patients underwent PVI alone; dofetilide was discontinued 1–3 mos postablation. In the PersAF patients, the Pdur decreased from 136.3 ± 21.7 ms (assessed postcardioversion on dofetilide) to 118.6 ± 20.4 ms (assessed immediately prior to PVI) (P < 0.001). In contrast, no change in Pdur (122.6 ± 11.5 ms vs. 121.3 ± 13.7 ms, P = NS) was observed in PAF patients. The 6 and 12 mos AAD‐free response to ablation was 76% and 70%, respectively, in PersAF patients, similar to the 80% and 75%, response in PAF patients (P = NS). A decline in Pdur in response to dofetilide was the only predictor of long‐term clinical response to PVI in patients with PersAF. Conclusions: Pre‐treatment with AAD resulted in a decrease in Pdur suggesting reverse atrial electrical remodeling in PersAF patients. This may explain the excellent clinical outcomes using PVI alone, and may suggest an alternative ablation strategy for PersAF. (J Cardiovasc Electrophysiol, Vol. 22, pp. 142‐148, February 2011)     

ATP‐Induced Dormant Pulmonary Veins Originating from the Carina Region After Circumferential Pulmonary Vein Isolation of Atrial Fibrillation

Dormant Pulmonary Veins from the Carina Region . Introduction: Elimination of transient pulmonary vein recurrences (dormant PVs) induced by an ATP injection and ablation at the PV carina region is an effective strategy for atrial fibrillation (AF) ablation. The relationship between dormant PVs and the PV carina region has not been evaluated. Methods: A total of 212 consecutive symptomatic AF patients underwent circumferential PV electrical isolation (CPVEI) with a double lasso technique. They were divided into 2 groups in a retrospective review; Group 1: those given an ATP injection during an intravenous isoproterenol infusion after the CPVEI (n = 106), and Group 2: those in which it was not given after the CPVEI (n = 106). Radiofrequency energy was applied at the earliest dormant PV activation site identified using a Lasso catheter on the CPVEI line and then PV carina region if it was ineffective. Results: After a successful PVEI, 54 patients (51%) in Group 1 had PV reconnections during an ATP injection. Acute PVEI sites were observed on the carina region within the CPVEI line in the right PVs (16%) and left PVs (10%). Dormant PVs were reisolated at the carina region in the right PVs (23%) and left PVs (26%). The distribution of the dormant PV sites, except for the RIPV, significantly differed from that of the acute PVEI sites (P < 0.05). Further, AF recurred significantly in the Group 2 patients as compared to those in Group 1 during 16 ± 6.1 months of follow‐up (P < 0.05). Conclusion: PV carina region origins may partly be responsible for an acute PVEI and potential recurrences. (J Cardiovasc Electrophysiol, Vol. 21, pp. 494‐500, May 2010)     

Cryoballoon Versus Radiofrequency for Pulmonary Vein Re‐Isolation After a Failed Initial Ablation Procedure in Patients with Paroxysmal Atrial Fibrillation

Cryoballoon versus Radiofrequency Ablation . Aim: Catheter ablation of paroxysmal atrial fibrillation (PAF) is associated with an important risk of early and late recurrence, necessitating repeat ablation procedures. The aim of this prospective randomized patient‐blind study was to compare the efficacy and safety of cryoballoon (Cryo) versus radiofrequency (RF) ablation of PAF after failed initial RF ablation procedure. Methods: Patients with a history of symptomatic PAF after a previous failed first RF ablation procedure were eligible for this study. Patients were randomized to Cryo or RF redo ablation. The primary endpoint of the study was recurrence of atrial tachyarrhythmia, including AF and left atrial flutter/tachycardia, after a second ablation procedure at 1 year of follow‐up. All patients were implanted with a cardiac monitor (Reveal XT, Medtronic) to continuously track the cardiac rhythm. Patients with an AF burden (AF%) ≤ 0.5% were considered AF‐free (Responders), while those with an AF% > 0.5% were classified as patients with AF recurrences (non‐Responders). Results: Eighty patients with AF recurrences after a first RF pulmonary vein isolation (PVI) were randomized to Cryo (N = 40) or to RF (N = 40). Electrical potentials were recorded in 77 mapped PVs (1.9 ± 0.8 per patient) in Cryo Group and 72 PVs (1.7 ± 0.8 per patient) in RF Group (P = 0.62), all of which were targeted. In Cryo group, 68 (88%) of the 77 PVs were re‐isolated using only Cryo technique; the remaining 9 PVs were re‐isolated using RF. In RF group, all 72 PVs were successfully re‐isolated (P = 0.003 vs Cryo). By intention‐to‐treat, 23 (58%) RF patients were AF‐free vs 17 (43%) Cryo patients on no antiarrhythmic drugs at 1 year (P = 0.06). Three patients had temporary phrenic nerve paralysis in the Cryo group; the RF group had no complications. Of the 29 patients who had only Cryo PVI without any RF ablation, 11 (38%) were AF‐free vs 20 (59%) of the 34 patients who had RF only (P = 0.021). Conclusion: When patients require a redo pulmonary vein isolation ablation procedure for recurrent PAF, RF appears to be the preferred energy source relative to Cryo. (J Cardiovasc Electrophysiol, Vol. 24, pp. 274‐279, March 2013)     

Clinical Experience with a Single Catheter for Mapping and Ablation of Pulmonary Vein Ostium

Introduction: The aim of this single center study is to evaluate the safety and the efficacy of performing pulmonary vein isolation (PVI) using a single high-density mesh ablator (HDMA) catheter.
Methods: A total of 17 consecutive patients with paroxysmal (10 patients) or persistent atrial fibrillation (7 patients) and no heart disease were enrolled. A single transseptal puncture was performed and the HDMA was placed at each PV ostium identified with anatomic and electrophysiological mapping. Pulsed radiofrequency (RF) energy was delivered at the targeted temperature of 58°C with maximum power of 80 watts. No other ablation system was utilized. The primary objective of the study was acute isolation of the targeted PV, and the secondary objective was clinical efficacy and safety of PVI with HDMA for atrial fibrillation (AF) prevention. Patients were followed at intervals of 1, 3, 6, and 12 months.
Results: PVI was attempted with HDMA in 67/67 PVs. [Correction made after online publication October 27, 2008: PVs changed from 6/67 to 67/67] Acute success rate were: 100% (16/16) for left superior PV, 100% (16/16) for left inferior PV, 100% (17/17) for right superior PV, 100% (1/1) for left common trunk and 47% (8/17) for right inferior PV. Total procedure time was 200 ± 36 minutes (range 130–240 minutes) and total fluoroscopy time was 42 ± 18 minutes (range 23–75 minutes). During a mean follow-up of 11 ± 4 months, 64% of patients remained in sinus rhythm (8/10 paroxysmal AF and 3/7 for persistent AF). No complications occurred either acutely or at follow-up.
Conclusions: PV isolation with HDMA is feasible and safe. The midterm efficacy in maintaining sinus rhythm is higher in paroxysmal than in persistent patients.     

Relationship between arrhythmogenic pulmonary veins and the surrounding atrial substrate in patients with paroxysmal atrial fibrillation

Arrhythmogenic PVs and the Fibrillatory Activities . Introduction: The relationship between pulmonary veins (PVs) with atrial fibrillation (AF) initiating triggers and their surrounding atrial substrate has not been elucidated. We aimed to clarify the atrial substrate properties around the PVs. Methods and Results: Twenty‐three paroxysmal AF patients were studied with the identification of PV initiating triggers. High‐density mapping of the dominant frequency (DF, 1200 Hz) and the mean degree of the complex fractionated electrograms (CFE mean interval over 6 seconds) was evaluated in 2 zones (zone 1: < 5 mm, zone 2: 5–15 mm from the PVs) and the left atrial (LA) using a NavX system prior to the PV isolation. High‐DFs (>8 Hz) and continuous CFEs (<50 ms) were identified in 1.5 ± 0.9 and 2.3 ± 1.1 regions per patient, respectively. Most of the high‐DF regions (86%) and continuous CFE regions (77%) were located within 15 mm of the PV ostia. Of those, 75% of the high‐DF regions and 54% of the continuous CFE regions were related to arrhythmogenic PVs. There was a significant DF gradient from arrhythmogenic PV zone 1 to zone 2, while the mean CFE exhibited a significant gradient between arrhythmogenic PV zone 2 and the rest of the LA. Additionally, 69% of the procedural AF termination sites were at arrhythmogenic PV zone 2. Conclusion: Evaluation of the atrial substrate properties may be useful for locating arrhythmogenic PVs during AF and defining the extent of the circumferential PV isolation. (J Cardiovasc Electrophysiol, Vol. 22, pp. 405‐410)     

Pulmonary Vein Antral Isolation and Nonpulmonary Vein Trigger Ablation without Additional Substrate Modification for Treating Longstanding Persistent Atrial Fibrillation

PV Ablation for Persistent Atrial Fibrillation. Introduction: Effectiveness of antral pulmonary vein isolation (PVAI) and ablation of non‐PV triggers (non‐PVTA) in controlling longstanding persistent atrial fibrillation (AF) has not been reported. We sought to describe clinical outcomes with this ablation strategy in patients (pts) followed for at least 1 year. Methods: Two hundred pts underwent PVAI for longstanding persistent AF and were followed for recurrence. Thirty‐three pts with <1‐year follow‐up and 37 pts with additional RF atrial ablation were excluded, leaving 130 pts for analysis. Results: All 130 pts (108 men, mean LA 4.7 ± 0.6 cm, mean AF duration of 38 ± 44 months) underwent PVAI with entrance/exit block. In addition, 24 pts (15 pts during the initial procedure and 9 additional pts at repeat ablations) had 40 non‐PVTA, including 3 with AVNRT. During follow‐up, atrial flutter (AFL) was noted in 7 (5%) pts. The AF‐free survival after single procedure without antiarrhythmic drugs (AAD) was 38%. Repeat AF or AFL ablation was performed in 37 pts (28%) with PV reconnection uniformly identified (3.7 ± 0.5 veins/pt). During mean follow‐up of 41.1 ± 23.8 months (range 12–103 months), 85/130 pts (65%) were in sinus rhythm with 65 pts (50%) off AAD, 20 pts (15%) on AAD. Additionally, 9 pts (7%) have had rare episodes of AF such that 72% of pts have had good long‐term clinical outcome. Of the 36 pts with recurrent AF, 20 pts have not had a repeat procedure. Conclusions: PVAI with non‐PVTA for longstanding persistent AF provides good long‐term AF control in over 70% of patients with infrequent (5%) AFL. AAD therapy and repeat PVAI may be required for this optimal outcome. (J Cardiovasc Electrophysiol, Vol. 23, pp. 806‐813, August 2012)     

Role of Residual Potentials Inside Circumferential Pulmonary Veins Ablation Lines in the Recurrence of Paroxysmal Atrial Fibrillation

Residual Potentials After Pulmonary Vein Isolation. Background: Residual gaps due to incomplete ablation lines are known to be the most common cause of recurrent atrial fibrillation (AF) after catheter ablation. We hypothesized that any residual potentials at the junction of the left atrium and pulmonary vein (PV), inside the circumferential PV ablation (CPVA) lines, would contribute to the recurrence of AF or post‐AF ablation atrial flutter (AFL); therefore, the elimination of these potentials increases AF‐/AFL‐free survival rates. Methods and Results: One hundred and two patients with paroxysmal AF (PAF) were enrolled and prospectively randomized to a group with ablation of residual potentials as add‐on therapy to CPVA + PV electrical isolation (PVI) (group 1, n = 49), or a group without ablation of the residual potentials (group 2, n = 53). Post‐CPVA residual potentials, inside the ablation lines, were identified by contact bipolar electrode mapping catheter and a detailed 3‐dimensional voltage map. Twenty‐three patients in group 1 and 18 patients in group 2 had post‐CPVA residual potentials (46.9% vs 34.0%, P = 0.182). The AF‐/AFL‐free survival rate during follow‐up of 23.3 ± 7.9 months was not different in comparisons between the 2 groups (P = 0.818), and 79.6% and 81.1% of the patients in groups 1 and 2 maintained a sinus rhythm (P = 0.845), respectively. Conclusions: Residual potentials inside CPVA were commonly found in the patients with PAF after CPVA + PVI. Further ablation of residual potentials did not increase the efficacy of catheter ablation in patients with PAF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 959‐965, September 2010)     

Pulmonary vein isolation under direct visual identification of the left atrium—pulmonary vein junction using intra-cardiac echography

Introduction: Intra-cardiac echocardiography (ICE) which has some benefits, can be used to obtain detailed anatomy of the heart chambers or large vessels, and the catheter positions, and it has been considered useful for improving the outcome of the ablation. In the present study, we performed pulmonary vein isolation (PVI) under real time monitoring of ICE imaging utilizing an ICE catheter placed at the junction of the left atrium (LA) and PVs (LA-PV junction). Methods: PVI for atrial fibrillation (AF) was performed in 30 cases with drug-resistant AF (mean age: 66-years-old; including 22 males). An ICE catheter utilizing a 9 MHz frequency was inserted into the LA via the atrial septum, and placed at the LA-PV junction. Circumferential ablation was performed in the LA outside of the PV ostium, encircling both the superior and inferior ostia together under ICE imaging. Results: The anatomy of the LA to the PVs and catheter sites were clearly identified by the ICE during the procedure, which enabled a precise and safe catheter manipulation with minimal fluoroscopy. Further, the wall thickness of the PV and LA, and position of the esophagus could be obtained by ICE, facilitating care in adjusting the power and/or duration of the current delivery. Conclusion: ICE imaging of the LA-PV junction permitted real time monitoring of the target sites for PVI during the ablation procedure, and was considered a useful technique for performing PVI.     

Feasibility of Electroporation for the Creation of Pulmonary Vein Ostial Lesions

Feasibility of Electroporation . Introduction: There is an obvious need for a better energy source for pulmonary vein (PV) antrum isolation. Objective: We investigated the feasibility and safety of electroporation for the creation of PV ostial lesions. Methods: After transseptal puncture, a custom 7F decapolar 20 mm circular ablation catheter was placed in the PV ostia of 10 pigs. Ablation was performed with a nonarcing, 200 J application delivered between the catheter and an indifferent patch electrode on the lower back. A single pulse was applied for each catheter position, with a maximum of 4 per ostium. Local PV electrogram amplitude and stimulation threshold were measured at multiple locations in both ostia before and directly after ablation, and after 3 weeks survival, using a regular 4 mm mapping catheter. All PV ostia were sectioned, stained, and histologically investigated. Results: The 3‐week survival period was uneventful. PV ostial electrogram amplitude decreased and stimulation threshold increased significantly in most ostia. PV angiograms did not show any stenosis during this short follow‐up. Histologically, up to 3.5‐mm‐deep lesions were found. Conclusion: Data suggest that electroporation can safely be used to create lesions in a sensitive environment like PV ostia. (J Cardiovasc Electrophysiol, Vol. 22, pp. 302‐309, March 2011)     

Catheter Ablation of Long‐Standing Persistent Atrial Fibrillation: A Lesson from Circumferential Pulmonary Vein Isolation

Catheter Ablation of Long‐Standing Persistent AF. Introduction: Circumferential pulmonary vein isolation (CPVI) is associated with a high success rate in patients with paroxysmal and persistent atrial fibrillation (AF). However, in patients with long‐standing persistent AF, the ideal ablation strategy still remains a matter of debate. Methods and Results: Two‐hundred and five patients underwent catheter ablation for long‐standing persistent AF defined as continuous AF of more than 1‐year duration. In a first step, all patients underwent CPVI. If direct‐current cardioversion failed following CPVI, ablation of complex fractionated atrial electrograms (CFAEs) was performed. The goal was conversion into sinus rhythm (SR) or, alternatively, atrial tachycardia (AT) with subsequent ablation. A total of 340 procedures were performed. CPVI alone was performed during 165 procedures in 124 of 205 (60.5%) patients. In the remaining 81 patients, additional CFAE ablation was performed in 45, left linear lesions for recurrent ATs in 44 and SVC isolation in 15 patients, respectively, resulting in inadvertent left atrial appendage isolation in 9 (4.4%) patients. After the initial ablation procedure, 67 of 199 patients remained in SR during a mean follow‐up of 19 ± 11 months. Six patients were lost to follow‐up. After a mean of 1.7 ± 0.8 procedures, 135 of 199 patients (67.8%) remained in SR. Eighty‐six patients (43.2%) remained in SR following CPVI performed as the sole ablative strategy. Conclusions: CPVI alone is sufficient to restore SR in 43.2% of patients with long‐standing persistent AF. Multiple procedures and additional ablation strategies with a significant risk of inadvertent left atrial appendage isolation are often required to maintain stable SR. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1085‐1093)     

Pulmonary Vein Contraction Before and After Radiofrequency Ablation for Atrial Fibrillation

Pulmonary Vein Contraction After Ablation. Introduction: Cardiovascular magnetic resonance imaging (cMRI) may provide a noninvasive method to test for pulmonary vein (PV) isolation after ablation for atrial fibrillation (AF) by detecting changes in PV contraction. Methods: PV contraction (the maximal percentage change in PV cross‐sectional area [CSA] during the cardiac cycle) measured 1 month before and 2 months after PV isolation was compared in 63 PVs from 16 patients with medically refractory AF. Repeat cMRI imaging and invasive catheter mapping was performed prior to repeat PV ablation in 50 PVs from 14 additional patients with recurrent AF. Contraction in PVs with sustained isolation after the initial ablation was compared to contraction in PVs with electrical reconnection to adjacent atrium. Receiver operating characteristic (ROC) curve analysis was performed to determine the optimal cutoff PV contraction value for prediction of PV‐atrial reconnection after ablation. The cutoff value was then prospectively tested in 40 PVs from 12 additional patients. Results: PV contraction decreased after AF ablation (22.4 ± 10% variation in CSA before ablation vs 10.1 ± 8% variation in CSA after ablation, P < 0.00001). PVs with sustained isolation on invasive mapping contracted less than PVs with electrical reconnection to adjacent atrium (13.7 ± 10.6% vs 21.4 ± 9.3%, P = 0.021). PV contraction produced a c‐index of 0.74 for prediction of PV‐atrial reconnection after ablation and >17% variation in PV CSA predicted reconnection with a sensitivity of 84.6% and specificity of 66.7%. Conclusion: PV contraction is reduced by ablation. PV contraction measurement may provide a noninvasive method to test for PV isolation after ablation procedures. (J Cardiovasc Electrophysiol, Vol. 22, pp. 169‐174, February 2011)     

Triggering Pulmonary Veins: A Paradoxical Predictor for Atrial Fibrillation Recurrence After PV Isolation

Triggering Pulmonary Veins and Recurrence After Ablation . Purpose: To identify procedural parameters predicting recurrence of atrial fibrillation (AF) after a first circumferential pulmonary vein isolation (CPVI). Methods: One hundred seventy‐one patients undergoing CARTO‐guided CPVI for recurrent AF with a left atrial (LA) diameter <45 mm were studied. Follow‐up (symptoms and 7‐day Holter) was performed at 1 and 3 months and every 3 months thereafter. Clinical and procedural characteristics between successful patients and patients undergoing repeat ablation were compared. In addition, procedural parameters of the first procedure were compared with parameters during repeat ablation. Results: After first CPVI, 80% of patients were free of AF without antiarrhythmic drugs after a follow‐up (FU) of 28 ± 11 months (N = 136). Thirty‐five patients (20%) had recurrence of AF of which 25 underwent repeat ablation (N = 25). Clinical characteristics did not differ between the successful and repeat group. A triggering vein during the index procedure was significantly more observed in the repeat group (56% vs 11%, P < 0.001). At repeat ablation, 2.6 ± 1.2 veins per patient were reconnected. Whereas there was no preferential reconnecting PV, all PVs triggering at index were reconnected (100%). Conclusions: (1) In patients with symptomatic recurrent AF, the presence of a triggering pulmonary vein during ablation is a paradoxical predictor for AF recurrence after PV isolation. (2) The consistent finding of reconnection of the triggering PV at repeat ablation, suggests that, in these patients, the triggering PV is the culprit vein and that reconnection invariably results in clinical AF recurrence. (3) The present study advocates a strategy of even more stringent PV isolation in case of a triggering PV. (J Cardiovasc Electrophysiol, Vol. 21, pp. 381–388, April 2010)     

Heat‐Stress Responses Modulate Beta‐Adrenergic Agonist and Angiotensin II Effects on the Arrhythmogenesis of Pulmonary Vein Cardiomyocytes

Effect of Heat Stress on Pulmonary Vein Cardiomyocytes. Introduction: Heat stress‐induced responses reduce the occurrence of atrial fibrillation (AF). Pulmonary vein (PV) cardiomyocytes with pacemaker activity play a critical role in the pathophysiology of AF. In this study, we examined whether heat‐stress responses alter the electrophysiological characteristics of PV cardiomyocytes and protect the PV against angiotensin II‐ or isoproterenol‐induced arrhythmogenesis. Methods and Results: We used whole‐cell patch clamp techniques to investigate the spontaneous activity and ionic currents in single isolated rabbit PV pacemaker cardiomyocytes with or without (control) exposure to heat stress (43°C, 15 minutes) 5 ± 1 hours before the experiments. Compared to control cardiomyocytes, heat‐stressed PV cardiomyocytes had slower beating rates. Heat‐stressed PV cardiomyocytes had larger L‐type calcium currents, transient outward currents, smaller inward rectifier potassium currents, but similar sodium‐calcium exchanger currents_. Additionally, heat‐stressed PV cardiomyocytes had a lower incidence of pacemaker currents than control PV cardiomyocytes. Moreover, isoproterenol increased the beating rate of control cardiomyocytes but not heat‐stressed PV cardiomyocytes. Similarly, angiotensin II also increased the beating rate of control cardiomyocytes, but not heat‐stressed PV cardiomyocytes, in association with decreased expression of the angiotensin II type 1 receptor. Conclusion: Heat‐stress responses altered the electrophysiological characteristics of PV cardiomyocytes and attenuated the effects of isoproterenol and angiotensin II on PV arrhythmogenesis, which may play a role in the protective potential of heat‐stress responses. (J Cardiovasc Electrophysiol, Vol. 22, pp. 183‐190, February 2011)     

Two Versus One Repeat Freeze-Thaw Cycle(s) After Cryoballoon Pulmonary Vein Isolation: The ALSTER EXTRA Pilot Study

Two versus One Repeat Freeze–Thaw Cycle(s) . Background: Repeated freezing (bonus applications) during cryoballoon pulmonary vein isolation (PVI) has been suggested to improve lesion durability. However, the long‐term clinical effects of repeated freezing have not been investigated. Methods and Results: A total of 51 patients (pts) with paroxysmal atrial fibrillation (AF) underwent PVI using the single big (28 mm) cryoballoon technique. One (27 pts, group I) or 2 bonus applications (24 pts, group II) were performed at all PVs subsequent to PVI. Clinical follow‐up consisted of continuous rhythm monitoring by an implantable cardiac monitor (ICM, 24 pts) and serial 7‐day Holter‐ECG recording (7DH, 27 pts). The primary endpoint was defined as recurrent AF or atrial tachycardia. Acute PVI of all PVs was obtained in 50/51 pts (98%). The median (Q1;Q3) follow‐up duration in this study was 384 (213;638) days. The primary endpoint occurred in 48% (group I, 15 pts ICM, 12 pts 7DH) and 46% (group II, 9 pts ICM, 15 pts 7DH), P = 0.84. Procedure‐ and fluoroscopy‐time for group I versus group II was 193 ± 56 minutes versus 207 ± 27 and 33 ± 13 minutes versus 34 ± 11 minutes, respectively. Right phrenic nerve palsy (PNP) occurred in 3 pts (all group II, time to resolution: 128 ± 112 days). In 2 of these pts, PNP occurred during the second bonus application. Conclusion: Application of 2 when compared to 1 freeze–thaw cycle(s) following cryoballoon PVI did not result in improved clinical success but was associated with a higher complication rate. (J Cardiovasc Electrophysiol, Vol. 23, pp. 814‐819, August 2012)