Anatomical Ablation Research Articles

Impacts of Left Atrium Size and AF Duration upon Predictive Value of Procedural AF Elimination for Freedom from Post-Ablation Recurrences in Persistent AF Ablation

Introduction: There are controversies regarding predictors of freedom from post-ablation recurrences in persistent AF with different degrees of progression of anatomical atrial remodeling. Methods and Results: Consecutive 254 patients with persistent AF (AF duration (AFD): 68±77 months, LA diameter (LAD): 46±5 mm) underwent initial ablation session for anatomical linear ablation in LA and RA after circumferential PV isolation with procedural endpoint of AF elimination. AF termination (n=23) or conversion to AT (n=63) or flutter (n=22) was achieved in 108 patients (42.5%), while AF persisted after completion of ablation protocol in the remaining 146 patients (57.5%). One hundred ninety-eight patients were followed beyond blanking period (2 months) for 289±226 days after initial procedure and 104 patients (53%) were free from AF/AT recurrences. Kaplan-Meier analysis showed recurrence-free survival rate after initial procedure was significantly higher in those with procedural AF elimination than in those without [54/85 (64%) vs. 50/113 (44%); P=0.01]. Multivariate analysis showed that AF duration and procedural AF elimination were independent predictors of freedom from post-ablation recurrence (P 51 mm or AFD =/> 5 years, while it remained significant among those with LAD 5 years and/or LAD =/> 51 mm.

Clinical Importance of the Inferiorly Dislocated Fast Pathway in the Patients with Atrioventricular Nodal Reentrant Tachycardia

Backgrounds: In the catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT), the patients with the inferiorly dislocated fast pathway (IDF) were high risk of the inadvertent atrioventricular block. Objective: The purpose of this study is to show the effects of the IDF on the results of the catheter ablation. Methods: 43 consecutive patients with AVNRT were entered this study. Using the electroanatomical mapping system, the antegrade fast pathway entrance (AF) was detected and divided into 4 groups; outside and posterior to the triangle of Koch (TOK) (group F: n=17) and inside and the upper (group S: n=7), the middle (group M: n=5), and the lower (group I: n=14) third of the TOK. Group M and I were defined as the IDF. In all patients, anatomical slow pathway ablation was performed. Results: The dimension of the TOK was not different in all groups. The success rate of the slow pathway ablation was 100% in group F and S, but 80% in group M and 71% in Group I. During follow-up, no patient in group F, S, and M, but 2 patients in group I had a recurrence of the tachycardia. Conclusion: The patients with the IDF were not only refractory to the conventional slow pathway ablation, but also showed high rate of recurrence.

Optimized Length of Blanking Period after Catheter Ablation of Persistent Atrial Fibrillation

Background: Mechanisms and implications of early recurrence (ER) within a blanking period are not clear, and the theoretically optimal length of a blanking period has been still debatable.Methods: Consecutive 206 patients (age: 62±9 years) with persistent AF [AF duration: 70±75 months, LA diameter: 47±5 mm] underwent the initial ablation procedure for the anatomical bi-atrial linear ablation after the encircling PV isolation. Early and late recurrences (LR) were defined as a documented episode of AF or atrial tachycardia (AT) within and more than two months after the initial ablation procedure, respectively.Results: ER occurred in 115 patients (56%) at a mean of 9±1 days after the initial procedure. During follow-up of 426±223 days after the initial procedure, 98 patients (48%) experienced late recurrences at mean of 169±156 days after the initial procedure. Of the 98 patients with LR, 72 patients had ER. ROC curve analysis revealed an optimal cut-off value for the length of a blanking period was 36 days after the initial procedure (sensitivity: 94% and specificity: 62%).Conclusions: The results of this study suggested that the optimal length of the post-ablation blanking period was 36 days after the initial ablation session in persistent AF. A 36-day-long blanking period could best pick out ER not related with LR and exclude ER related with LR as much as possible.

Systematic Comparison of P-Wave Morphology of Intermediary Atrial Tachycardia during AF Ablation Procedure and Post-Ablation Recurrent Atrial Tachycardia

Background: In longstanding, persistent AF, AF often converts into intermediary atrial tachycardia (iAT) before restoration of sinus rhythm during ablation procedure and recurrent ATs (rATs) are commonly observed during post-ablation follow-up. Whether iAT and rAT documented in the same patient are identical or not is, however, unknown.Methods: This study included consecutive 48 patients (40 males, age: 66±8 years) in whom AF converted into an iAT during anatomical linear ablation and subsequently a rAT was documented during post-ablation follow-up. The P-wave polarity in 12-lead ECGs of iAT and rAT was evaluated in leads I, II, III, aVF, V1 and V6, and it was categorized into one of positive, negative, biphasic (positive/negative or negative/positive) and isoelectric. The P-wave matching score (0–6) was calculated by adding each one point when the P-wave polarity was identical between the ECGs of iAT and rAT in each ECG lead.Results: Mean P-wave matching score was 5.6±0.9, and it was 6 in 40 (84%), 5 in 2 (4%), 4 in 2 (4%), and 3 in 4 (8%) patients.Conclusions: In more than 80% of the patients with both documented iAT and rAT, P-wave morphology of iAT and rAT was quite similar. This suggested that complete abolition of iAT during AF ablation procedure would be mandatory in terms of reduction of AT recurrence during post-ablation follow-up.

Efficacy of bundle ablation for cavotricuspid isthmus-dependent atrial flutter: combination of the maximum voltage-guided ablation technique and high-density electro-anatomical mapping

Pathological studies have demonstrated that the cavotricuspid isthmus (CTI) is often composed of discrete muscle bundles, which are thought to be represented electrically as high-amplitude electrograms. Based on this observation, we visualized the bundles using an electro-anatomical mapping system (EAMS) and investigate the efficacy of bundle ablation which is an ablation method for selectively targeting high-voltage sites obtained by high-density electro-anatomical mapping along the CTI. Sixty patients with atrial flutter were randomly assigned to cavotricuspid isthmus ablation using a conventional anatomical approach (Group 1) or bundle ablation approach (Group 2). In Group 2, CTI was mapped in detail with EAMS, and we visualized the bundles that were 1.5 mV or more on a bipolar voltage map. Radiofrequency (RF) ablation was delivered sequentially from the maximum voltage site at the shortest distance of the bundle until bidirectional block was achieved. Bidirectional block was achieved in all patients. Mean ablation times (Group 1, 1,392 + or - 960 s; Group 2, 638 + or - 342 s, p < 0.01), the mean number of RF applications (Group 1, 31.7 + or - 23.6; Group 2, 13.0 + or - 7.0, p < 0.01), and fluoroscopy times (Group 1, 50.4 + or - 28.3 min; Group 2, 42.3 + or - 21.3 min, p < 0.01) were significantly shorter in Group 2 than those in Group 1. Bundle ablation at CTI is highly effective for achieving a bidirectional block requiring shorter ablation times, shorter fluoroscopy times, and fewer RF applications.

Ganglionated plexi ablation for longstanding persistent atrial fibrillation

To study the potential efficacy of ganglionated plexi (GP) ablation in the setting of longstanding persistent atrial fibrillation (AF). Anatomic ablation at the areas of GP in the left atrium was performed in 89 patients with symptomatic, drug-refractory, persistent AF (71 men, 56 +/- 7 years of age). In 29 patients, a second procedure by means of circumferential pulmonary vein (PV) isolation was performed, and 5 of them were subjected to a third circumferential ablation. At 16 +/- 7 months after the final ablation procedure, 53 (59.6%) of the 89 patients were in sinus rhythm in the absence of antiarrhythmic drug therapy, 5 (5.6%) patients had permanent AF, and 31 (34.8%) patients had paroxysmal AF. The long-term success rate for patients who underwent a single ablation procedure with only GP ablation was 38.2% over a follow-up of 24 +/- 3 months. Independent predictors of later arrhythmia recurrences were left atrial diameter [HR 1.039 (1.00-1.07), P = 0.028] and duration of AF prior to ablation [HR 1.116 (1.02-1.22), P = 0.008]. Ganglionated plexi ablation in chronic AF results in long-term maintenance of sinus rhythm in 38.2% of cases. Repeat procedures with circumferential isolation of all PV offer a success rate of 59.6% over a follow-up of 16 +/- 7 months.

Mapping of dominant frequency and complex fractionated electrograms in atrial fibrillation patients: Caveat medicus

While percutaneous radiofrequency catheter ablation has become an accepted treatment for atrial fibrillation (AF), success rates are not yet optimal.1 Therefore, different strategies exist for clinical mapping and ablation in AF patients. Many studies have attempted to understand the mechanisms involved in the initiation and maintenance of AF, and much attention has focused not only on an anatomical ablation approach that involves isolating the pulmonary veins but also on electrophysiologic approaches that target additional intracardiac areas that are thought to be initiating and/or maintaining AF.

Pulmonary vein isolation and left atrial catheter ablation using a three-dimensional navigation system for the treatment of atrial fibrillation

Atrial fibrillation (AF) is often triggered by ectopic foci originating from pulmonary veins (PVs), with the posterior left atrium (LA) comprising part of the substrate for maintenance. Catheter ablation strategies targeting PVs and the posterior LA may be further refined by incorporating technology beyond standard fluoroscopy. To prospectively assess the usefulness of a navigation sys-tem to guide a radiofrequency catheter ablation strategy, combining PV isolation (PVI) with anatomical LA ablation. Sixty-four patients (51 men; mean [+/- SD] age 52+/-8 years) who were referred for catheter ablation of paroxysmal (n=49) or persistent (n=15) AF underwent this ablation strategy using the NavX system (Endocardial Solutions Inc, USA). Electrical PVI was guided by a circular mapping catheter. Anatomical ablation consisted of lines drawn along the posterior aspect of the LA from the superior PVs to the inferior PVs. NavX was used for the construction of three-dimensional LA and PV maps with projection of mapping and ablation catheters on the image in real time and for tracking of lesions during posterior LA ablation. Electrical PVI was achieved in 100% of procedures and all patients underwent the linear posterior LA ablation described above. Procedural and fluoroscopy times were 188+/-41 min and 60+/-12 min, respectively. Repeat procedures for AF recurrence were required in 38(59%) patients. After a mean follow-up period of 16+/-10 months, 59(92%) patients remained arrhythmia-free, including 52 (81%) without antiarrhythmic drugs. An AF ablation strategy that combines nonfluoroscopic visualization of catheters with electrical PVI and anatomical LA ablation is feasible, safe and effective, but often requires repeat procedures.

Selective ganglionated plexi ablation for paroxysmal atrial fibrillation

Selective ganglionated plexi (GP) ablation guided by high-frequency stimulation has been proposed for the treatment of paroxysmal atrial fibrillation (AF), but the efficacy of the method is not established. This study sought to compare selective ablation of GP identified by high-frequency stimulation with extensive regional ablation targeting the anatomic areas of GP in patients with paroxysmal AF. Eighty patients with paroxysmal AF (age 53 +/- 9 years) were randomized to undergo selective GP ablation or regional left atrial ablation at the anatomic sites of GP. For selective GP ablation (n = 40), ablation targets were the sites where vagal reflexes were evoked by high-frequency stimulation. Vagal reflexes were defined as prolongation of the R-R interval by >50% and a concomitant decrease in blood pressure (>20 mm Hg) during AF. The end point of the procedure was failure to reproduce vagal reflexes with repeated high-frequency stimulation. For anatomic ablation, lesions were delivered at the sites of GP clustering. At 13.1 +/- 1.9 months, 42.5% of patients with selective GP and 77.5% of patients with anatomic ablation were free of symptomatic paroxysmal AF (PAF) (P = .02). Parasympathetic denervation was more prominent in patients with anatomic than selective GP ablation, and in patients free of AF compared to these with AF recurrence immediately after ablation, but this trend was abolished at 6 months. Selective GP ablation directed by high-frequency stimulation does not eliminate paroxysmal AF in the majority of patients. An anatomic approach for regional ablation at the sites of GP confers better results.

Atrial tachycardias adjacent to the phrenic nerve: Recognition, potential problems, and solutions

Ablation of atrial tachycardias (AT) arising from the crista terminalis region (CT) can be complicated by phrenic nerve (PN) injury. This study sought to describe epicardial protection techniques to prevent PN injury from endocardial ablation of AT. Ablation was attempted in 4 patients with focal AT arising from the CT in whom conventional endocardial ablation was limited by PN proximity identified by capture during pacing. Four women ages 20, 28, 30, and 31 years with structurally normal hearts presented with symptomatic ATs failing medical therapy. In the first patient, endocardial cryoablation was performed during superior vena cava (SVC) PN pacing. After acute success, AT recurred. Open surgical ablation was then performed, but AT was noninducible under anesthesia, and an anatomic ablation was performed. AT was abolished, but sinus node dysfunction required pacemaker implantation. In the subsequent 3 patients with AT adjacent to the right PN, protection of the PN was attempted by inserting a peripheral angioplasty balloon (2 patients) or steerable ablation catheter and sheath into the epicardial space between the PN and atrium. Endocardial radiofrequency ablation was successful in all 3 patients without PN injury. Epicardial protection of the PN allowing for safe endocardial ablation of CT ATs is a feasible method of managing these challenging cases and seems to be preferable to surgery.

Anatomical ablation during sinus rhythm for noninducible idiopathic left ventricular tachycardia

Anatomical ablation during sinus rhythm for noninducible idiopathic left ventricular tachycardia

Integration of Three‐Dimensional Left Atrial Magnetic Resonance Images into a Real‐Time Electroanatomic Mapping System: Validation of a Registration Method

The alignment of three-dimensional (3D) left atrial images acquired by magnetic resonance (MR) with the anatomical information yielded by 3D mapping systems is one of the most critical issues in image integration techniques for catheter ablation of atrial fibrillation (AF). We assessed the accuracy of a simplified method of superimposing 3D MR left atrial images on real-time left atrial electroanatomic maps (registration). MR data on the left atrium in 40 patients with drug-refractory AF were imported into the CartoMerge (Biosense Webster, Inc., Diamond Bar, CA, USA) electroanatomic mapping system. Registration was obtained by combining "visual alignment" of one endocardial point and "surface registration" of a limited number of points sampled on the posterior wall of the left atrium. The accuracy of the registration process was assessed through a statistical algorithm incorporated into the CartoMerge system, and through the percentage of pulmonary veins (PVs) in which electrical isolation was achieved after anatomical ablation. The mean registration surface-to-point distance and ablation surface-to-point distance were 1.33 +/- 0.96 mm and 1.47 +/- 1.15 mm, respectively. Upon completion of the circumferential anatomical ablation around the PVs, electrical PV isolation was confirmed by a multipolar circular mapping catheter in 129 of 146 PVs (89%). Our registration method, which is mainly based on the surface registration of the posterior wall of the left atrium, enables almost 90% of PVs to be isolated by means of an anatomically based catheter ablation approach.

Robotic and magnetic navigation for atrial fibrillation ablation. How and why?

Catheter ablation techniques for atrial fibrillation are evolving with targets for radiofrequency ablation of atrial fibrillation increasingly being selected based on anatomic considerations. Such anatomic ablation techniques require precise catheter localization and stable contact during ablation. Even experienced electrophysiologists occasionally encounter difficulties in maintaining stable catheter contact, especially in some regions of complex anatomy where catheter stability is crucial. Limitations of manually deflected conventional ablation catheters in performing complex catheter maneuvers may also contribute to these challenges. The CARTO RMT version 8 has been recently released to guide left atrial mapping and ablation in conjunction with the Stereotaxis system for remote control of the ablation catheter. We aim to describe how this system works and why it is needed in the field of catheter ablation.

Assessment of the maximum voltage-guided technique for cavotricuspid isthmus ablation during ongoing atrial flutter

We aimed to test the maximum voltage-guided cavotricuspid isthmus (CTI) ablation technique during ongoing atrial flutter. Former pathological and electrophysiological studies clarified that the cavotricuspid isthmus is composed of distinct muscular bundles, which are responsible for the conduction of electrical activation. Based on this observation, a maximum voltage-guided ablation technique (MVGT) was developed. This technique was assessed during pacing from the coronary sinus and was reported to be a feasible method to reach bidirectional isthmus block without the need for a complete anatomic ablation line. This was a prospective, randomized single center study. Twenty patients underwent CTI ablation during atrial flutter. In group I (10 pts) CTI ablation was performed with complete anatomical ablation line. In group II (10 pts) ablation was guided by the highest amplitude potentials on the CTI sequentially until bidirectional isthmus block was reached. The following parameters were compared: acute success rate, procedure time, fluoroscopy time, number of radiofrequency (RF) applications and total RF duration. In all patients, atrial flutter terminated during ablation. Bidirectional isthmus block could be achieved in all pts. Procedure time was shorter in group II (107 +/- 40 vs 68 +/- 19 min, p < 0.01). Significantly less fluoroscopy was used in group II (22.6 +/- 10.6 vs 12.1 +/- 3.8 min, p < 0.01). There were less RF applications in group II (27.1 +/- 21.5 vs 5.9 +/- 2.4, p < 0.001). (1) The major finding of this study is that MVGT is a feasible method even during ongoing atrial flutter. (2) Our data confirm that MVGT is an effective technique for CTI ablation with considerable decrease in procedure and fluoroscopy times.

Anatomical and electrophysiological approach to atrial fibrillation ablation: technical limitations

Pulmonary vein (PV) disconnection by radiofrequency (RF) catheter ablation has been reported to cure atrial fibrillation (AF). Different techniques have been proposed. The aim of this study was to evaluate the technical limitations of both anatomical and electrophysiological approaches. A total of 110 PVs were ablated in 26 consecutive patients (23 male, 3 female, mean age 51 +/- 9.5 years) with paroxysmal (n = 19, 73%), persistent (n = 3, 12%) or permanent (n = 4, 15%) AF. Accurate reconstructions of the PV ostia were obtained using fluoroscopy, electrophysiology, and the CARTO mapping system. Electrophysiological mapping was attempted in all PVs by means of a decapolar circular catheter. RF ablation was performed in a single-blind fashion in order to anatomically create circumferential lines around each PV. Completeness of anatomically-guided, circumferential RF lesions around the PVs was established by the physician using the CARTO system, who was unaware of the decapolar circular catheter electrophysiological recordings of the PVs. If PV potentials persisted, RF delivery was targeted to the electrophysiological breakthroughs. All PV ostia were anatomically ablated by performing circumferential RF lesions. Among 110 PVs, 73 (66%) were fully mapped by use of circular catheters. After anatomical ablation, electrical disconnection was achieved in 44/73 PVs (60%). In the remaining 29 PVs (40%), a median of one RF pulse (mean 1.8 +/- 1.4) was necessary to achieve complete PV disconnection. Total procedure duration, fluoroscopy time, and RF delivery time were 232 +/- 29, 50 +/- 16 and 39 +/- 11 min, respectively. Pericardial effusion occurred in one patient after the procedure. After 10.5 +/- 6.4 months, 21 patients (81%) were in stable sinus rhythm and 13 of them (62%) discontinued all drugs after 6 months. Only 4 patients (15%) required two procedures. Electrical PV disconnection cannot be achieved in many PVs by means of a pure anatomical approach. On the other hand, electrophysiological mapping cannot be performed in many PVs owing to anatomical variations. An integrated approach might overcome these limitations.

Incidence and Predictors of Pulmonary Vein Stenosis Following Catheter Ablation of Atrial Fibrillation Using the Anatomic Pulmonary Vein Ablation Approach: Results From Paired Magnetic Resonance Imaging

Incidence and Predictors of Pulmonary Vein Stenosis Following Catheter Ablation of Atrial Fibrillation Using the Anatomic Pulmonary Vein Ablation Approach: Results From Paired Magnetic Resonance Imaging

Towards a unified strategy for atrial fibrillation ablation?: reply

I thank Drs Pappone and Santinelli for their interest in my editorial titled ‘Towards more effective techniques for catheter ablation of atrial fibrillation: to aim for electrical disconnection of pulmonary veins or not’?1 The authors observe that adding ablation lines at the left posterior wall and the mitral isthmus to the anatomical circumferential ablation (ACA) catheter technique for the treatment of paroxysmal or persistent atrial fibrillation is associated with a significantly lower incidence (from 10.0 to 3.9%) of iatrogenic left atrial flutter during long-term …

Predictive Value of Early Atrial Tachyarrhythmias Recurrence After Circumferential Anatomical Pulmonary Vein Ablation

Radiofrequency (RF) ablation at the ostia of the pulmonary veins (PVs) to cure atrial fibrillation (AF) is often followed by early AF recurrence. The aims of this study were to determine the rate of early atrial tachyarrhythmia as recurrence after circumferential anatomical PV ablation; to evaluate whether the early recurrence of atrial tachyarrhythmias correlates with the long-term outcome of ablation; and to identify the predictors of early atrial tachyarrhythmias relapse. We studied 143 consecutive patients who underwent circumferential anatomical PV ablation. We defined early atrial tachyarrhythmias relapse as the recurrence of atrial tachyarrhythmias during the first 3 months after RF ablation. After a mean follow-up of 18.7 +/- 7.2 months, 102/143 patients (71%) were deemed responders to ablation. Atrial tachyarrhythmias relapsed during the first 3 months of follow-up in 65/143 (46%) patients. Patients without early atrial tachyarrhythmias relapse had a higher probability of long-term clinical success than patients with early atrial tachyarrhythmias relapse (95% vs 43%, P < 0.0001). However, patients who relapsed within the first month had 45.5% probability of long-term clinical success. On multivariate analysis, the presence of structural heart disease and the lack of a successful anatomical ablation of all targeted PV were significantly and independently correlated with early atrial tachyarrhythmias relapse. A delayed cure may be expected in almost 50% of patients in whom atrial tachyarrhythmias relapses within the first month after circumferential anatomical PV ablation. The presence of structural heart disease and the lack of a successful anatomical ablation of all targeted PV predict early atrial tachyarrhythmias recurrence.

Towards more effective techniques for catheter ablation of atrial fibrillation: to aim for electrical disconnection of pulmonary veins or not?

This editorial refers to ‘Prevalence of pulmonary vein disconnection after anatomical ablation for atrial fibrillation: consequences of wide atrial encircling of the pulmonary veins’† by M. Hocini et al. , on page 696 The recent discovery of a dominant role played by excitable tissues within the pulmonary veins (PVs) and at the left atrium–PV junction in the initiation and possibly also the maintenance of atrial fibrillation (AF) has led investigators to develop several catheter-based strategies aimed at limiting the electrophysiological interactions between these areas and the remaining atria. Among these, two have emerged as dominant strategies in current clinical practice: one aiming at ostial segmental disconnection (OSD) of all PVs from the adjacent atrial tissue and another aiming at anatomical circumferential ablation (ACA) away from the orifice of the PVs. OSD is best accomplished with the help of a pre-shaped circumferential multi-electrode mapping catheter advanced to the orifice of the target PV while an ablation catheter is used for radiofrequency (RF) pulse delivery at the orifice of the same PV. Using this approach, RF pulses are delivered under the guidance of the circumferential electrical activation recorded from the multi-electrode mapping catheter until no propagation of atrial impulses to the PV is observed ( Figure 1A ). Ablation is repeated in each remaining PV until electrical disconnection of all PVs is achieved. OSD is commonly achieved through segmental rather than circumferential ablation at the orifice of the PVs.1 Figure 1. Schematics of the ablation designs aimed for using OSD ( A ) or ACA ( B ). The symbols (straight arrow and wavy arrow) indicate, respectively, conduction block and delayed conduction of the electrical impulses across ablation lines obtained at the end of the two ablation strategies. Note that after segmental disconnection at the ostium of each PV, electrical impulses are inhibited from entering into or … *Tel: +39 02 5277 4337; fax: +39 02 5560 3125. E-mail address : rcappato{at}libero.it

Prevalence of pulmonary vein disconnection after anatomical ablation for atrial fibrillation: consequences of wide atrial encircling of the pulmonary veins

Anatomical and wide atrial encircling of the pulmonary veins (PVs) has been proposed as a cure of atrial fibrillation (AF). We evaluated the acute achievement of electrical PV isolation using this approach. In addition, the consequences of wide encircling of the PVs with isolation were assessed. Twenty patients with paroxysmal AF were studied. Anatomically guided ablation was performed utilizing the CARTO system to deliver coalescent lesions circumferentially around each PV to produce a voltage reduction to <0.1 mV, with the operator blinded to recordings of circumferential PV mapping. After achieving the anatomical endpoint, the incidence of residual conduction and the amplitude and conduction delay of residual PV potentials were determined. Electrical isolation of the PV was then performed and the residual far-field potentials evaluated. Individual PV ablation was performed in all PVs. Anatomically guided PV ablation was performed for 47.3+/-11 min, after which 44 (55%) PVs were electrically isolated. In the remaining 45%, despite abolition of the local potential at the ablation site, PV potentials [amplitude 0.2 mV (range 0.09-0.75) and delay of 50.3+/-12.6 ms] were identified by circumferential mapping. After electrical isolation (12.2+/-11.7 min ablation), 55 (69%) PVs demonstrated far-field potentials; with a greater incidence (P=0.015) and amplitude (P=0.021) on the left compared with the right PVs. At 13.2+/-8.3 months follow-up, 13 patients (65%) remained arrhythmia-free without anti-arrhythmics. In four patients (20%), spontaneous sustained left atrial macrore-entry required re-mapping and ablation. Macrore-entry was observed to utilize regions around or bordering the previous ablation as its substrate. Anatomically guided circumferential PV ablation results in apparently coalescent but electrically incomplete lesions with residual conduction in 45% of PVs. Wide encircling of the PVs was associated with left atrial macrore-entry in 20% of patients.