Arrhythmogenic Pulmonary Veins Research Articles

Long-Term Follow-Up In Paroxysmal Atrial Fibrillation Patients With Documented Isolated Trigger.

Supraventricular tachycardias may trigger atrial fibrillation (AF). The aim of the study was to evaluate the prevalence of supraventricular tachycardia (SVT) inducibility in patients referred for AF ablation and to evaluate the effects of SVT ablation on AF recurrences. 249 patients (mean age: 54 ± 14 years) referred for paroxysmal AF ablation were studied. In all patients, only AF relapses had been documented in the clinical history. 47 patients (19%; mean age: 42 ± 11 years) had inducible SVT during the electrophysiological study and underwent an ablation targeted only at SVT suppression. Ablation was successful in all 47 patients. The ablative procedures were: 11 slow-pathway ablations for atrioventricular nodal re-entrant tachycardia; 6 concealed accessory pathway ablations for atrioventricular re-entrant tachycardia; 17 focal ectopic atrial tachycardia ablations; 13 with only one arrhythmogenic pulmonary vein. No recurrences of SVT were observed during the follow-up (32 ± 18 months). 4 patients (8.5%) showed recurrence of at least one episode of AF. Patients with inducible SVT had less structural heart disease and were younger than those without inducible SVT. A significant proportion of candidates for AF ablation are inducible for an SVT. SVT ablation showed a preventive effect on AF recurrences. Those patients should be selected for simpler ablation procedures tailored only to the triggering arrhythmia suppression.

Abstract 13614: Why the Pulmonary Veins: Linking Atrial 4D Flow MRI Derived Biomechanics and Pulmonary Vein Electrical Remodeling

Introduction: Pulmonary veins (PV) often trigger atrial fibrillation (AF). However, the underlying mechanism is not completely understood and predicting who benefits from PV isolation (PVI) is imprecise. We propose that arrhythmogenic PV remodeling may be related to myocardial mechanical function. Flow-encoded cardiac magnetic resonance imaging (4D Flow MRI) based computational modeling enables assessment of left atrial (LA) hemodynamics and biomechanics. In this pilot study, 4D Flow MRI derived parameters were compared to invasive electroanatomic mapping (EAM) and hemodynamics to explore potential non-invasive evaluation of PV remodeling and arrhythmogenicity. Methods: Patients (5 female, 4 male, age 64±6.7 years) with paroxysmal or early persistent AF scheduled for PVI were enrolled. All patients underwent 4D Flow MRI prior to ablation (in sinus rhythm) and intraprocedural EAM (Carto) with atrial pacing under baseline conditions and after increasing LA pressure with a fluid bolus. Non-invasive measures included peak and average velocity (m/s) and net flow (ml/cycle) in each vein (n=36) and averaged for each patient. Apparent conduction velocities in the proximal, mid and distal portions of each vein were calculated under baseline and stretch conditions from EAM. Change in LA pressure per volume bolus, a measure of atrial stiffness, was compared to non-invasive parameters. Results: In patients with LA stiffness greater than median, peak velocities (0.77±0.12 vs. 0.62±0.24 m/s, p=0.26) and net flows were higher (17±2.0 vs. 14.0±2.4 ml/cycle, p=0.06). Patients with paroxysms of spontaneous arrhythmias during mapping had higher LA stiffness (11.5±5.7 vs. 7.6±5.3 mmHg/L, p=0.30). There was a significant correlation between non-invasive average velocity and apparent conduction velocity in the proximal portion of the vein (R=-0.36, p=0.03) and the suggestion of a correlation between increasing peak flow velocity and decreased apparent conduction velocity under stretch conditions compared to baseline (R=-0.24, p=0.16). Conclusions: Our findings may indicate a link between atrial hemodynamics, electrical remodeling and PV arrhythmogenicity. Additional studies are warranted to confirm and better define these findings.

Pulmonary vein volume and myocardial sleeve extension estimated by 3D computed tomography and voltage mapping predict arrhythmogenic triggers of paroxysmal atrial fibrillation

Relationship between pulmonary vein (PV) anatomy and the pathophysiology of paroxysmal atrial fibrillation (PAF) remains incompletely studied. The aim of this study was to determine whether PV anatomy predicts arrhythmogenic PVs. Twenty-six consecutive PAF patients with spontaneous PAF or consistently frequent ectopic beats during electrophysiological study were enrolled. Computed tomography (CT) images for PVs were reconstructed into 3D images. The PV diameter and volume were measured based on the 3D images. The PV myocardial sleeve area was measured based on the 3D voltage mapping results. The PV myocardial sleeve area index was calculated by dividing the sleeve area of each PV by the average sleeve area of all PVs in each patient. The diameter and volume of the arrhythmogenic PVs were larger than those of the non-arrhythmogenic PVs (21.08 ± 4.57mm vs. 16.47 ± 3.31mm, P < 0.001 and 7.70 ± 3.28cm3 vs. 4.09 ± 1.99cm3, P < 0.001, respectively). The myocardial sleeve area and sleeve area index of the arrhythmogenic PVs were also larger than those of the non-arrhythmogenic PVs (8.62 ± 5.33cm2 vs. 4.77 ± 3.84cm2, P < 0.001 and 1.59 ± 0.35 vs. 0.81 ± 0.38, P < 0.001, respectively). Multivariate analysis showed the PV myocardial sleeve area index was the independent predictor for arrhythmogenic PVs (P < 0.001). PV size plays an important role in triggering PAF. A large myocardial sleeve extension is a powerful and independent predictor for arrhythmogenic PV, which may be useful anatomical markers to facilitate PAF ablation.

Clinical recurrence and electrical pulmonary vein reconnections after second-generation cryoballoon ablation

Electrical reconnections after pulmonary vein isolation (PVI) are less common after second-generation cryoballoon than radiofrequency ablation. The purpose of this study was to investigate the incidence and characteristics of pulmonary vein (PV) reconnections after second-generation cryoballoon ablation in patients with and those without clinical recurrences. Forty patients with paroxysmal atrial fibrillation undergoing second procedures after cryoballoon ablation were enrolled. Twenty-five patients experienced clinical recurrences, and the remaining 15 did not. All 158 PVs were reevaluated a median [25th, 75th percentiles] of 6.0 [4.0-9.0] months after the initial procedure. In total, reconnections were detected in 39 PVs (24.7%) among 25 patients (62.5%). Reconnected PVs included 6 left superior (LS) (15.8%), 7 left inferior (LI) (18.4%), 5 right superior (RS) (12.5%), 20 right inferior (RI) (50.0%), and 1 left common (LC) (50.0%) PV. Reconnected PV potential conduction delays were a median of 112 [76-130], 103 [82-133], 84 [66-96], 68 [49-73], and 204 ms in the LS, LI, RS, RI, and LC PV, respectively. There was no significant difference between those with and those without clinical recurrences with regard to clinical characteristics, procedural results, incidence of reconnections (25/98 vs 14/60, P = .758), and PV conduction delays in each PV. The most common gap location was the RI PV bottom in both groups. Among 5 patients with reconnections of arrhythmogenic PVs (with atrial fibrillation initiation), 2 experienced clinical recurrences, whereas 3 did not. Non-PV foci (with atrial fibrillation initiation) were identified in a second procedures in 10 of 25 patients with clinical recurrences. The incidence and characteristics of PV reconnections after second-generation cryoballoon ablation were similar between patients with and those without clinical recurrences. The results should be considered when discussing the optimal dose of cryoballoon applications.

Efficacy of selective arrhythmogenic pulmonary veins isolation versus empirical all pulmonary veins isolation for atrial fibrillation: a meta-analysis of randomized and observational studies

Several clinical trials showed inconsistent results of the effect of isolating all versus arrhythmogenic pulmonary veins (PVs) on long-term control of atrial fibrillation (AF). We hypothesized that isolation of arrhythmogenic veins had a comparable success rate to the empiric isolation of all PVs. PUBMED, EMBASE, and the Cochrane Library were searched for randomized controlled trials and nonrandomized, observational studies. The efficacy and adverse events of isolating all versus arrhythmogenic PVs were presented as risk ratio (RR) with 95 % confidence intervals (CIs), and weighted mean differences and 95 % CIs were calculated to compare the procedure time and fluoroscopic time between the isolation all PVs and arrhythmogenic PVs. Six trials with 658 patients were included in the analysis. Isolation of arrhythmogenic PVs was as efficacious as empiric isolation of all PVs in achieving long-term AF control (RR, 0.96; 95 % CI, 0.87-1.05; p = 0.36). Isolation of arrhythmogenic PVs group had shorter procedure time, fluoroscopic time and fewer adverse events than the isolation of all PVs group. The present analysis suggests that isolation of arrhythmogenic veins had a comparable long-term success rate, shorter procedure time, fluoroscopic time, and fewer adverse events than the empiric isolation of all PVs.

A Prospective Randomized Study Comparing Isolation of the Arrhythmogenic Vein Versus All Veins in Paroxysmal Atrial Fibrillation

Ablation procedures in patients with paroxysmal atrial fibrillation (PAF) includes isolation of all pulmonary veins (PVs). We hypothesized that an approach using an algorithm to detect arrhythmogenic PVs (aPVs) might lead to shorter procedure duration (PD) and fewer proarrhythmic effects (PE). Isolation of the aPVs only leads to a reduced PD, reduced PEs, and fewer adverse events, with a success rate comparable to the standard all-PV approach. In this prospective trial, 207 patients with PAF were randomized to undergo isolation of the aPV (AG group, n = 105) or isolation of all PVs (VG group, n = 102). The aPV was identified by atrial fibrillation (AF) induction, focal discharge, or short local PV decremental conduction during PV pacing. Patients were followed with repetitive 7-day Holter electrocardiograms (ECGs) after 3, 6, and 12 months in our arrhythmia clinic. In 97% of patients, at least 1 aPV was identified (mean, 2.1). PD did not differ significantly (152.3 ± 57.1 minutes vs 162 ± 68 minutes, P = 0.27) between the groups, but the number of radiofrequency (RF) applications and fluoroscopy time (FT) and dose were significantly lower in the AG group than in the VG group. The occurrence of PE (new-onset atrial tachycardia) and adverse events (AE) did not differ between the 2 groups (P = 0.1). Sinus rhythm off antiarrhythmic medication (documented on 7-day Holter ECGs) 12 months after a single procedure was achieved in 53% in the AG group and 59% in the VG group (P = 0.51). Isolation of the aPVs detected by a straightforward algorithm leads to similar success rates compared to a standard all-PV approach with regard to PD, AE, or PE and is associated with less RF and a shorter FT.

Thromboembolic risk of the hot- and cold-catheter ablation for atrial fibrillation

In the last decade, catheter ablation procedures aimed at the electrical isolation of arrhythmogenic pulmonary veins (PVs) and/or modification of left atrial substrate have evolved as an important therapeutic option for patients with atrial fibrillation (AF). 1 Lip G.Y. Tse H.F. Management of atrial fibrillation. Lancet. 2007; 370: 604-618 Abstract Full Text Full Text PDF PubMed Scopus (186) Google Scholar , 2 Camm A.J. Kirchhof P. Lip G.Y. et al. Guidelines for the management of atrial fibrillation: the Task Force for the Management of Atrial Fibrillation of the European Society of Cardiology (ESC). Eur Heart J. 2010; 31: 2369-2429 Crossref PubMed Scopus (4116) Google Scholar While conceptually attractive and technical feasible with promising clinical efficacy, these catheter ablation procedures, mainly with radiofrequency energy, are limited by the risk of major complications, including PV stenosis, atrioesophageal fistula, and thromboembolism. 3 Cappato R. Calkins H. Chen S.A. et al. Prevalence and causes of fatal outcome in catheter ablation of atrial fibrillation. J Am Coll Cardiol. 2009; 53: 1798-1803 Abstract Full Text Full Text PDF PubMed Scopus (469) Google Scholar , 4 Cappato R. Calkins H. Chen S.A. et al. Updated worldwide survey on the methods, efficacy, and safety of catheter ablation for human atrial fibrillation. Circ Arrhythm Electrophysiol. 2010; 3: 32-38 Crossref PubMed Scopus (1536) Google Scholar Tissue heating with radiofrequency energy can potentially lead to endocardial disruption, charring, PV stenosis, platelet activation, and thrombus formation. As a result, other alternative energy sources such as cryoablation, microwave, and laser 5 Tse H.F. Reek S. Timmermans C. et al. Pulmonary vein isolation using transvenous catheter cryoablation for treatment of atrial fibrillation without risk of pulmonary vein stenosis. J Am Coll Cardiol. 2003; 42: 752-758 Abstract Full Text Full Text PDF PubMed Scopus (181) Google Scholar , 6 Yiu K.H. Siu C.W. Lau C.P. et al. Transvenous catheter-based microwave ablation for atrial flutter. Heart Rhythm. 2007; 4: 221-223 Abstract Full Text Full Text PDF PubMed Scopus (10) Google Scholar have been developed with the aim to reduce these complications. Among these alternative energy sources, cryoablation appears to have the best safety profile. Prior experimental studies have demonstrated that cryoablation creates minimal endocardial disruption with the reservation of underlying tissue architecture, reduce platelet and clotting activation, 7 Khairy P. Chauvet P. Lehmann J. et al. Lower incidence of thrombus formation with cryoenergy versus radiofrequency catheter ablation. Circulation. 2003; 107: 2045-2050 Crossref PubMed Scopus (420) Google Scholar and is associated with a lower risk of thrombus formation 8 van Oeveren W. Crijns H.J. Korteling B.J. et al. Blood damage, platelet and clotting activation during application of radiofrequency or cryoablation catheters: a comparative in vitro study. J Med Eng Technol. 1999; 23: 20-25 Crossref PubMed Scopus (38) Google Scholar as well as atrioesophageal fistula 9 Ripley K.L. Gage A.A. Olsen D.B. et al. Time course of esophageal lesions after catheter ablation with cryothermal and radiofrequency ablation: implication for atrio-esophageal fistula formation after catheter ablation for atrial fibrillation. J Cardiovasc Electrophysiol. 2007; 18: 642-646 Crossref PubMed Scopus (80) Google Scholar compared with radiofrequency energy. Cellular damage, platelet activation, and inflammatory response after pulmonary vein isolation: A randomized study comparing radiofrequency ablation with cryoablationHeart RhythmVol. 9Issue 2PreviewExperimental data suggest that use of cryoablation in pulmonary vein isolation (PVI) is associated with less cell damage and less thrombus formation compared to radiofrequency (RF) energy. Full-Text PDF

Relationship Between Arrhythmogenic Pulmonary Veins and the Surrounding Atrial Substrate in Patients with Paroxysmal Atrial Fibrillation

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. 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. Evaluation of the atrial substrate properties may be useful for locating arrhythmogenic PVs during AF and defining the extent of the circumferential PV isolation.

The Novel Electrophysiology of Complex Fractionated Atrial Electrograms: Insight from Noncontact Unipolar Electrograms

The noncontact mapping (NCM) system possesses the merit of global endocardial recording for unipolar and activation mapping. We aimed to evaluate the unipolar electrogram characteristics and activation pattern over the bipolar complex fractionated atrial electrogram (CFAE) sites during atrial fibrillation (AF). Twenty patients (age 55 +/- 11 years old, 15 males) who underwent NCM and ablation of AF (paroxysmal/persistent = 13/7) were included. Both contact bipolar (32-300 Hz) and NCM virtual unipolar electrograms (0.5-300 Hz) were simultaneously recorded along with the activation pattern (total 223 sites, 11 +/- 4 sites/patient). A CFAE was defined as a mean bipolar cycle length of <or= 120 ms with an intervening isoelectric interval of more than 50 ms (Group 1A, n = 63, rapid repetitive CFAEs) or continuous fractionated activity (Group 1B, n = 59, continuous fractionated CFAEs), measured over a 7.2-second duration. Group 2 consisted of those with a bipolar cycle length of more than 120 ms (n = 101). The Group 1A CFAE sites exhibited a shorter unipolar electrogram cycle length (129 +/- 11 vs 164 +/- 20 ms, P < 0.001), and higher percentage of an S-wave predominant pattern (QS or rS wave, 63 +/- 13% vs 35 +/- 13%, P < 0.001) than the Group 2 non-CFAE sites. There was a linear correlation between the bipolar and unipolar cycle lengths (P < 0.001, R = 0.87). Most of the Group 1A CFAEs were located over arrhythmogenic pulmonary vein ostia or nonpulmonary vein ectopy with repetitive activations from those ectopies (62%) or the pivot points of the turning wavefronts (21%), whereas the Group 1B CFAEs exhibited a passive activation (44%) or slow conduction (31%). The bipolar repetitive and continuous fractionated CFAEs represented different activation patterns. The former was associated with an S wave predominant unipolar morphology which may represent an important focus for maintaining AF.

Is Isolation of Arrhythmogenic Pulmonary Veins Sufficient for the Long-term Efficacy of Atrial Fibrillation Ablation?

Atrial fibrillation (AF) is the commonest cardiac rhythm disorder, affecting about 5% of elderly patients.1 Despite the wide spread prevalence of AF, treatment options for the condition up until recently, were limited. Antiarrhythmic drug therapy which for a long time had been and to some extent still is the cornerstone for treating these patients, has shown a disappointing (≤ 40%) efficacy for long-term maintenance of sinus rhythm.2 The seminal observations by Haissaguerre and colleagues demonstrating AF initiation from electrical depolarizations in the pulmonary veins (PV) and cure of AF in these patients by radiofrequency ablation (RFA) of the PV focus, has led to the emergence of percutaneous catheter based AF ablation.3 Since its original description in 1998, the AF ablation procedure has evolved considerably.4-7 This evolution was the result of several short comings of the original technique (focal ablation) including the inability to expeditiously target multiple evanescent PV foci effectively and the long term consequences of delivering RF energy within the PVs i.e., occurrence of vein stenosis.8-12 Thus an alternative approach was developed where instead of ablating individual foci within the veins, RF lesions are delivered around the circumference of the PV ostium in order to interrupt PV-left atrial (LA) electrical connections and thus achieve PV isolation (PVI).8 Compared with focal AF ablation, PVI has shown a significant enhancement in long term arrhythmia control while dramatically reducing the occurrence of PV stenosis.11, 13 both of which are welcome developments. A potential reason for the enhanced success of PVI may be that the triggers of AF are clustered in close proximity to the vein ostia. However, an alternative explanation for the enhanced success of PVI is that the procedure inadvertently targets LA tissue (around PV os) and so results in modification of the underlying substrate. This hypothesis has been supported by the observation that anatomically guided circumferential PV ostial ablation without necessarily achieving true PVI (entry / exit block) is equally efficacious in achieving long term AF control.5,6 In fact, this observation has led to the development of an anatomically guided incremental ablation strategy which attempts to substantially modify the AF substrate by extensive LA ablation.14-16 However, such an approach has not consistently demonstrated a significant improvement in long term AF control rates as compared with PVI alone, which would suggest that PVs may be critical to the initiation and / or maintenance of AF.18,19 The purpose of this editorial is to provide the readers with a concise overview on the arrhythmogenic potential of PVs and to discuss how best we can identify and target such veins and whether that translates into long term control of AF.

Is Isolation of Arrhythmogenic Pulmonary Veins sufficient for The Long-term Efficacy of Atrial Fibrillation Ablation?

Is Isolation of Arrhythmogenic Pulmonary Veins sufficient for The Long-term Efficacy of Atrial Fibrillation Ablation?

Morphological characteristics of the Holter P-waves associated with pulmonary vein pacing

Identification of arrhythmogenic pulmonary veins (PVs) initiating atrial fibrillation is helpful for catheter ablation. The aim of this study was to examine the possibility to recognize the arrhythmogenic PV using Holter ECG. In 20 patients, P-wave characteristics were studied during pacing from four PVs. Holter ECG was recorded using two leads: the modified CC5 (Lead 1) and NASA (Lead 2), and the P-wave amplitude and duration were evaluated. In Lead 1, P-waves produced by left PV pacing were significantly lower in amplitude than right PV pacing (-3 +/- 75 vs. 86 +/- 43 microV, P < 0.001). In Lead 2, pacing in superior PVs produced P-waves with higher amplitude than inferior PVs (210 +/- 74 vs. 125 +/- 66 muV, P < 0.001). The criteria proposed by the morphological characteristics of P-waves identified putative arrhythmogenic PVs with an accuracy of 78%. It might be possible to identify putative arrhythmogenic PVs by modified Holter ECG recording.

Catheter ablation of atrial fibrillation via superior approach in patients with interruption of the inferior vena cava

Percutaneous transcatheter ablation of atrial fibrillation (AF) in patients with interruption of inferior vena cava (IVC) has not been reported in the literature. The purpose of this article was to demonstrate the safety and feasibility of the superior approach via the right internal jugular vein in performing catheter ablation of AF. We performed AF ablation in 3 patients (mean age: 51.7 +/- 18.5 years, 2 paroxysmal AF and 1 persistent AF) with complete interruption of IVC. Transseptal puncture was performed via the right internal jugular vein with a long sheath and manually curved Brockenbrough needle to facilitate the tip downward to the FO. Three-dimensional (3D) mapping was performed in 2 patients. Electrical isolation of each pulmonary vein (PV) was confirmed by a circular mapping catheter. Bidirectional block at the RA isthmus was achieved in 1 patient with clinically documented typical atrial flutter. In all patients, AF ablation after transseptal puncture via the superior approach was successfully performed without complications. Selective PV isolation of arrhythmogenic PV was done in 1 patient, and circumferential bilateral antral ablations were done in 2 patients. In 1 patient with persistent AF, linear ablations of left atrial roof and perimitral and RA isthmus were done after electrical isolation of all PVs. At a mean follow-up of 18.7 +/- 15.5 months, arrhythmias were free without any antiarrhythmic drugs in all patients. AF ablation via the superior approach is a safe and feasible alternative technique when a femoral venous approach is not available.

Is Empirical Four Pulmonary Vein Isolation Necessary for Focally Triggered Paroxysmal Atrial Fibrillation? Comparison of Selective Pulmonary Vein Isolation Versus Empirical Four Pulmonary Vein Isolation

We questioned whether the empirical four pulmonary vein (PV) isolation (EmPVI) was necessary in patients with paroxysmal atrial fibrillation (PAF) triggered from clearly and reproducibly defined arrhythmogenic PVs. We compared the selective or ipsilateral isolation of the PVs triggering AF (SePVI: n = 42) and EmPVI (n = 35) in 77 patients (males 80.5%, mean age 53.0 +/- 13.4 years) with PAF who underwent radiofrequency catheter ablation (RFCA). Arrhythmogenic PVs were identified by the immediate recurrence of AF three consecutive times after cardioverting AF. (1) The duration of the RF energy deliveries (P < 0.01) and total procedure time (P < 0.01) were shorter for the SePVI than the EmPVI. (2) During a mean follow-up of 38.6 +/- 23.1 months, the AF recurrence rate was 38.1% in the SePVI group and 25.7% in the EmPVI group (P = NS). (3) A redo-ablation was performed in 25 patients, and 81.0% of the recurrent arrhythmogenic foci were found at a previously ablated PV or ipsilateral PV. (4) In 15.4% of the SePVI and 20.0% of the EmPVI procedures, AF recurred after 32.5 +/- 15.2 months of the redo-ablation. Subsequently, the AF-free rate for each group was 88.1% (37/42) in the SePVI group and 91.4% (32/35) in the EmPVI group (P = NS). In patients with clearly documented arrhythmogenic PVs, the SePVI of the PV triggering the AF or an ipsilateral PV had a comparable long-term success rate and shorter RF energy delivery and procedure times than the EmPVI.

Long-Term Follow-Up After Cryothermic Ostial Pulmonary Vein Isolation in Paroxysmal Atrial Fibrillation

This study was designed to evaluate the long-term effect of segmental pulmonary vein (PV) cryoablation in patients with recent-onset paroxysmal atrial fibrillation (PAF). Patients with PAF have more triggers to initiate and less substrate to sustain atrial fibrillation (AF). Elimination of the potential initiators alone may be sufficient to abolish the arrhythmia. Patients with PAF were prospectively recruited from July 2001 to July 2005. If the triggers for AF were identified, PV cryoisolation of the arrhythmogenic vein(s) was performed. Otherwise, all PVs were isolated. Seventy patients with minimal or no heart disease (54 men; age 40 +/- 10 years) were enrolled. The duration of AF was 4 +/- 1 year. The left ventricular ejection fraction and left atrial size were 59 +/- 8% and 41 +/- 5 mm, respectively. An arrhythmogenic PV was found in 10 patients (14%). Complications occurred in 3 patients (4%). No PV stenosis or esophageal injury was detected during a mean follow-up of 33 +/- 15 months. Thirty-four patients (49%) achieved complete success (no AF and no antiarrhythmic drugs [AAD]); 15 patients (22%) had no recurrences with AAD; and 8 patients (11%), still with sporadic bursts of AF, improved >50% with AAD. Overall, 82% of the patients benefited from the procedure. Patients in whom the arrhythmogenic PV was identified and isolated had no recurrences. Pulmonary vein cryoisolation is effective in 82% of patients with recent-onset PAF during a mean follow-up of 33 +/- 15 (range 15 to 60) months. If the arrhythmogenic PV is identified and isolated, the long-term outcome is excellent, indicating no need to isolate all PVs.

Single procedure efficacy of isolating all versus arrhythmogenic pulmonary veins on long-term control of atrial fibrillation: A prospective randomized study

Current atrial fibrillation (AF) ablation involves isolation of all pulmonary veins (PVs) with or without additional linear lesions. However, whether such extensive ablation is necessary is unclear. The purpose of this study was to assess the efficacy of different ablation strategies on long-term AF control. We prospectively randomized patients to undergo isolation of all versus arrhythmogenic PVs (identified by standardized stimulation protocol). PV isolation was guided by circular mapping catheter. The endpoint was entry/exit block persisting for > or = 20 minutes. Patients were evaluated at three clinic visits (at 6 weeks, 6 months, and 1 year) and multiple transtelephonic monitoring periods. Antiarrhythmic drugs were discontinued at 6 weeks. Primary study endpoint was long-term AF control (freedom or >90% reduction in AF burden off or on previously ineffective antiarrhythmic drugs at 1 year after a single ablation procedure). Over a 20-month period, 105 patients (76 men and 29 women, age 57 +/- 9 years; paroxysmal AF = 77) were randomized, and 103 patients completed 1-year follow-up (51 patients in all-PV arm, 52 patients in arrhythmogenic PV arm). The primary endpoint was achieved in 75 (73%) patients and was similar in patients randomized to all-PV arm versus arrhythmogenic PV arm [38 (75%) patients vs 37 (71%) patients, respectively; odds ratio 1.18, 95% confidence interval 0.50, 2.83, P = .70]. Secondary study endpoints, including freedom from AF off antiarrhythmic drugs, total procedure/fluoroscopy times, and occurrence of serious adverse events, were not different between the two groups. In a randomized comparison, isolation of arrhythmogenic veins was as efficacious as empiric isolation of all veins in achieving long-term AF control.

Reversal of Left Ventricular Dysfunction Following Ablation of Atrial Fibrillation

Evaluation of ventricular rate control in atrial fibrillation (AF) can be difficult, and the presence of an AF-induced ventricular cardiomyopathy due to intermittent poor rate control or other causes may be underestimated. The outcome with AF ablation in patients with a decreased left ventricular ejection fraction (LVEF) may provide insight into this important clinical issue. To determine the effect of pulmonary vein isolation on LVEF in patients with AF and decreased LVEF (< or = 50%). Ablation consisted of proximal isolation of arrhythmogenic pulmonary veins (PVs) and elimination of non-PV triggers. LVEF was determined within 24 hours after ablation and again at up to 6 months follow-up. Transtelephonic monitoring was performed routinely for 2-3 weeks prior to ablation, at 6 weeks, and 6 months post and with symptoms following ablation. AF control was defined as freedom from AF or marked (>90%) reduction in AF burden on or off previously ineffective antiarrhythmic medication. AF ablation was performed in 366 patients and 67 (18%) patients had decreased LV function with a mean LVEF of 42 +/- 9%. An average of 3.4 +/- 0.9 PVs were isolated. AF control in the depressed LVEF group compared favorably with the normal EF group (86% vs. 87% P = NS), although more redo procedures were required (1.6 +/- 0.8 vs 1.3 +/- 0.6 procedures; P < or = 0.05). Only 15 of 67 patients (22%) with decreased LVEF had shown tachycardia (>100 bpm) on repeated preablation ECG recordings during AF. In the decreased LVEF group, the LVEF increased from 42 +/- 9% to 56 +/- 8% (P < 0.001) after ablation. Patients with AF and decreased LVEF undergoing AF ablation have similar success to patients with normal LVEF and have improvement in LVEF after ablation. These results suggest the presence of a reversible AF-induced ventricular cardiomyopathy in many patients with AF and depressed LV function. The presence of under-recognized and reversible cardiomyopathy even when tachycardia is not persistent is important to recognize.

Clinical predictors and outcomes associated with acute return of pulmonary vein conduction during pulmonary vein isolation for treatment of atrial fibrillation

Pulmonary vein electrical isolation (PVI) is an effective treatment for atrial fibrillation (AF). However, recurrence of pulmonary vein (PV) conduction after ablation may limit long-term success. We sought to determine the clinical predictors of acute PV reconnection during PVI and assess the long-term clinical outcomes associated with this phenomenon. We studied all patients with AF referred for PVI between November 2000 and August 2004. Over the course of the study period, PVI of arrhythmogenic PVs was performed segmentally using a 4-mm tip (52 degrees , 40 W, up to 90 seconds) or 8-mm tip catheter (50 degrees , 70 W, up to 60 seconds). PVI was defined as entry and exit block using a multipolar Lasso catheter. All veins were resampled to confirm isolation after 20-60 minutes. AF control was defined as no AF on or off a previously ineffective antiarrhythmic drug. Follow-up data included transtelephonic monitoring and clinical data collection from patient interviews. There were 424 patients who underwent isolation of 1,347 PVs during the study period. Acute reconnection of at least one PV occurred in 211 (50%) of the 424 patients and 326 (24%) of 1,347 of the PVs targeted. The left superior PV was most likely to acutely recover conduction compared with the other veins (left superior 31%, right superior 26%, right inferior 22%, left inferior 24%; P = .03). Patients with acute reconnection were more likely to be older, have a larger left atrium, have a history of hypertension or obstructive sleep apnea, and demonstrate persistent AF. After a single procedure, AF control was achieved in 153 (70%) of the 213 patients who demonstrated acute PV reconnection compared with 148 (73%) of 211 patients without acute PV reconnection observed (P = .52). Acute return of PV conduction is common after successful PVI and is more likely to occur in older patients with nonparoxysmal AF, hypertension, a large left atrium, and sleep apnea. There was no significant difference in acute PV reconnection between the 4-mm and 8-mm tip RF catheter despite differences in power and duration of energy delivery. Furthermore, there was no effect of PV reconnection on long-term AF control after repeated disconnection was performed.

A Tailored Approach to Catheter Ablation of Paroxysmal Atrial Fibrillation

Because the genesis of atrial fibrillation (AF) is multifactorial and variable, an ablation strategy that involves pulmonary vein isolation and/or a particular set of ablation lines may not be equally effective or efficient in all patients with AF. A tailored strategy that targets initiators and drivers of AF is a possible alternative to a standardized lesion set. Catheter ablation was performed in 153 consecutive patients (mean age, 56+/-11 years) with symptomatic paroxysmal AF with the use of an 8-mm tip radiofrequency ablation catheter. The esophagus was visualized with barium. The pulmonary veins and left atrium were mapped during spontaneous or induced AF. Arrhythmogenic pulmonary veins were isolated or encircled. If AF was still present or inducible, complex electrograms in the left atrium, coronary sinus, and superior vena cava were targeted for ablation. The end point of ablation was absence of frequent atrial ectopy and spontaneous AF during isoproterenol infusion and noninducibility of AF. Routine energy applications near the esophagus were avoided. During follow-up, left atrial flutter developed in 19% of patients and was still present in 10% at >12 weeks of follow-up. A repeat ablation procedure was performed in 18% of patients. During a mean follow-up of 11+/-4 months, 77% of patients were free from AF and/or atrial flutter without antiarrhythmic drug therapy. Pericardial tamponade or transient neurological events occurred in 2% of procedures. A tailored ablation strategy that only targets triggers and drivers of AF is feasible and eliminates paroxysmal AF in approximately 80% of patients.

Frequency Analysis in Different Types of Paroxysmal Atrial Fibrillation

This study sought to investigate the regional frequency distribution from multiple bi-atrial sites in different types of paroxysmal atrial fibrillation (AF). A previous study showed a left atrium (LA) to right atrium (RA) frequency gradient in patients with paroxysmal AF. Forty-four patients (age = 60 +/- 16, male patients = 27) with paroxysmal AF originating from the pulmonary veins (PVs) (n = 31) or superior vena cava (SVC) (n = 13) were included. Frequency analysis was performed on the intracardiac electrograms (7 s, 1 kHz/channel) recorded from PV, posterior LA, coronary sinus (CS), posterolateral RA, and SVC. The largest peak frequency was identified as the dominant frequency (DF). In the PV-AF patients, there was a frequency gradient from the PV ostium to the LA, RA, and SVC (8.5 +/- 3.3 Hz vs. 5.9 +/- 1.1 Hz vs. 5.2 +/- 0.85 Hz vs. 5.5 +/- 0.48 Hz, respectively, p < 0.001). The highest DFs were mostly located at the arrhythmogenic PV ostium (58%). The DFs of the arrhythmogenic PV and PV ostium were significantly higher than those of the non-arrhythmogenic PVs and PV ostia (p < 0.05). In the SVC-AF patients, there was a frequency gradient from the SVC to the RA, LA, and PV (8.0 +/- 2.4 Hz vs. 5.9 +/- 1.1 Hz vs. 5.9 +/- 0.7 Hz vs. 5.8 +/- 0.7 Hz, respectively, p = 0.001). The highest DFs were mostly located inside the SVC (77%) instead of the SVC ostium (as compared with PV-AF patients, p = 0.035). The location of the highest DF depended on the arrhythmogenic PV or SVC. A frequency gradient was present between the arrhythmogenic thoracic vein and atrium in all patients.