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Introduction: Early restoration of sinus rhythm following ablation of atrial fibrillation (AF) facilitates reverse atrial remodeling and improves the long-term outcome. The purpose of this study was to determine the predictors and outcome in patients with very early AF recurrences (< 2 days)., Methods and Results: Ablation was performed in 339 consecutive AF patients (paroxysmal AF = 262). Biatrial voltage was mapped during sinus rhythm. If recurrent AF occurred within 2 days following the ablation, electrical cardioversion was performed to restore sinus rhythm. Very early recurrences of AF occurred in 39 (15%) patients with paroxysmal AF and 26 (34%) with nonparoxysmal AF. Patients with very early recurrence had a higher incidence of nonparoxysmal AF (40% vs 18.6%, P< 0.001), requirement of electrical cardioversion during procedure, larger left atrial (LA) diameter (43 ± 7 vs 39 ± 6 mm, P< 0.001), lower left ventricular ejection fraction (54 ± 10% vs 59 ± 7, P< 0.001), longer procedural time, and lower LA voltage (1.5 ± 0.7 vs 1.9 ± 0.8 mV, P< 0.001). A multivariate analysis revealed that the independent predictors of a very early recurrence were a longer procedural time and lower LA voltage. During a follow-up of 13 ± 5 months, a very early recurrence did not predict the long-term outcome of a single procedure recurrence in the patients with paroxysmal AF, but was associated with a late recurrence in the nonparoxysmal AF patients., Conclusion: Very early recurrence occurred in patients with paroxysmal AF is not associated with long-term recurrence. Nonparoxysmal AF is an independent predictor of late recurrence of AF in patients with very early recurrence., (© 2011 Wiley Periodicals, Inc.)

Background: Atrial tachycardias (ATs) are commonly observed following catheter ablation of atrial fibrillation (AF). The aim of this study was to identify ECG characteristics that differentiate focal from macroreentrant ATs after circumferential pulmonary vein isolation (CPVI)., Methods and Results: One hundred and twenty ATs that occurred after CPVI were mapped using a 3-dimensional mapping system in 87 patients with AF. Further ablation was performed to eliminate the ATs. The surface ECGs of 68 ATs in 41 consecutive patients (Group 1) were analyzed retrospectively to create diagnostic algorithms. The algorithms were tested in the second 46 consecutive patients (Group 2). Patients with macroreentrant AT had lower left atrial (LA) voltage than those with focal AT (1.3 ± 0.3 vs 1.5 ± 0.2 mV, P = 0.01). Focal AT had a higher incidence of a positive polarity in V6 compared with macroreentrant AT (88% vs 55%, P = 0.03). The positive amplitude of the flutter/P waves in V6 was higher for focal AT than macroreentrant AT. The cycle lengths of the focal ATs were longer than those for macroreentrant AT (296 ± 107 vs 244 ± 25 ms, P < 0.001). Right atrial macroreentrant AT had a higher incidence of a negative polarity in at least 1 precordial lead compared with LA macroreentry. The positive flutter waves in V1 could differentiate roof/mitral isthmus dependent from non-roof/mitral isthmus dependent macroreentry. This algorithm correctly differentiated the focal from macroreentrant ATs with a sensitivity of 94%, specificity of 91%, and predictive accuracy of 92% in Group 2., Conclusion: Different electrophysiological properties may facilitate the differentiation between macroreentrant and focal ATs after CPVI., (© 2011 Wiley Periodicals, Inc.)

Background: Multiple remodeling patterns have been observed after catheter ablation of atrial fibrillation (AF)., Objective: We aimed to clarify the electrical/structural properties associated with recurrences after ablation of chronic AF., Methods: After a stepwise ablation procedure in 120 consecutive patients with persistent/long-lasting persistent AF, 36 had a recurrence of AF (Group 1/Group 2: recurrence with paroxysmal/persistent AF, n = 16/20)., Results: During the first procedure, the left atrial (LA) bipolar voltage did not differ between the 2 groups, and the LA volume was smaller in Group 1 than in Group 2 and it was the only factor predicting the recurrent types (P = 0.009, OR = 1.04). In the second procedure, the bipolar voltage of the global left atrium increased (1.33 ± 0.11 mV vs 1.76 ± 0.16 mV, P = 0.001) in Group 1 and decreased (1.31 ± 0.14 mV vs 0.90 ± 0.12 mV, P = 0.01) in Group 2, when compared with that of the first procedure. The LA low-voltage area (<0.5 mV) decreased in Group 1, and increased in Group 2. The LA volume (90 ± 8 cm(3) vs 72 ± 8 cm(3), P = 0.002) decreased in the second procedure in Group 1. It remained the same in Group 2. The right atrial substrates did not change between the procedures. After a follow-up of 27 ± 3 months, all patients in Group 1 and 14 patients in Group 2 remained in sinus rhythm (P = 0.02)., Conclusion: A better outcome with reverse electrical and structural remodeling occurred after the ablation of chronic AF when the recurrence was paroxysmal AF. Progressive electrical remodeling without any structural remodeling developed in those with a recurrence involving persistent AF., (© 2010 Wiley Periodicals, Inc.)

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., (© 2010 Wiley Periodicals, Inc.)

Introduction: Information about the impact of age on the electrophysiological characteristics of accessory pathways (APs) in patients with Wolff-Parkinson-White (WPW) syndrome remains limited., Methods and Results: A total of 1,885 consecutive patients (mean age 43 ± 17 years, male 61.5%) with WPW syndrome who were referred to the tertiary center for an electrophysiological study and radiofrequency catheter ablation were investigated. The patients were divided into 4 groups based on their age (Group 1: <20; Group 2: 20-39; Group 3: 40-59; Group 4: ≧60 years old). With age, more left-sided APs (53.2%, 67.7%, 71.7%, 75.7%, P < 0.001) and a longer duration of the arrhythmia (4.3 ± 2.8 years, 10.1 ± 7.0 years, 12.4 ± 10.9 years, 14.0 ± 12.4 years, P < 0.001) were noted. The incidence of concealed APs (53.5%, 53.0%, 57.8%, 60.9%, P = 0.01), and orthodromic atrioventricular (AV) reentrant tachycardia (92.4%, 94.2%, 96.5%, 96.3%, P = 0.023) increased with age. The tachycardia cycle length, antegrade (275.5 ± 42.2 ms, 286.7 ± 62.7 ms, 302.5 ± 66.5 ms, 315.2 ± 80.2 ms, P < 0.001) and retrograde AP effective refractory periods (APERPs) (254.0 ± 42.5 ms, 263.3 ± 51.8 ms, 274.5 ± 100.5 ms, 292.7 ± 57.0 ms, P < 0.001), atrial ERP, antegrade AV node effective refractory period (AVNERP), and ventricular effective refractory period (VERP) lengthened as the age increased. The incidence of decremental APs, multiple APs, and a catecholamine response were similar. The duration of the catheter ablation, total fluoroscopy time, acute success rate, complication rate, and incidence of a secondary procedure were similar between the different age groups., Conclusion: The electrophysiological characteristics and pattern of the arrhythmic attack associated with the AP changed with age., (© 2010 Wiley Periodicals, Inc.)

Introduction: The detailed electrophysiological characteristics of the gender differences associated with atrioventricular nodal reentrant tachycardia (AVNRT) have not been clarified. This study investigated the gender-related electrophysiological differences in a large series of patients undergoing radiofrequency catheter ablation., Methods and Results: A total of 2,088 consecutive AVNRT patients (men/women 869/1,219) who underwent catheter ablation were enrolled in this study. We evaluated the gender differences in their electrophysiological characteristics. Women had a significantly younger age of onset, higher incidence of multiple jumps, shorter AH interval, atrial effective refractory period (ERP), anterograde fast pathway ERP, anterograde slow pathway ERP, and retrograde slow pathway ERP, and longer ventricular ERP than men. The incidence of baseline ventriculoatrial dissociation was lower in women than in men. Women needed less isoproterenol/atropine to induce AVNRT. No gender differences in the radiation exposure time, procedure time, complication rate, acute success rate, or second procedure rate were noted. Both typical and atypical AVNRT were more predominant in women. In the patients with atypical AVNRT, there was no significant gender difference in incidence of baseline ventriculoatrial dissociation; however, the retrograde slow pathway ERP was significantly shorter in women than in men. Women of premenopausal age (≤50 years old) had a significantly higher incidence of anterograde multiple jumps and a retrograde jump phenomenon, and a shorter anterograde slow pathway ERP and retrograde slow pathway ERP than those of women over 50 years old., Conclusion: Gender differences in the anterograde and retrograde AV nodal electrophysiology were noted in the patients with AVNRT., (© 2010 Wiley Periodicals, Inc.)

Background: Previous studies have indicated that atrial fibrillation (AF) in patients over the age of 60 at diagnosis is a risk factor for a substantial increase in cardiovascular events. However, information about the impact of age on the atrial substrate and clinical outcome after catheter ablation of AF is limited., Methods: This study included 350 patients (53 ± 12 years, 254 males) who underwent circumferential pulmonary vein isolation (CPVI) of AF, guided by a NavX mapping system. The subjects were divided into three groups according to their age, as follows: Group I: age ≤50 (n = 141), Group II: age = 51-64 (n = 149) and Group III: age ≥65 years old (n = 60). The mean voltage and total activation time of the individual atria were obtained by using a NavX mapping system before ablation. Several parameters, including the gender, AF duration, and left atrial (LA) diameter were analyzed., Results: The younger age group had a significantly smaller LA diameter (Group I vs Group II vs Group III, 36.89 ± 7.11 vs 39.16 ± 5.65 vs 40.77 ± 4.95 mm, P = 0.002) and higher LA bipolar voltage (2.09 ± 0.83 vs 1.73 ± 0.73 vs 1.86 ± 0.67 mV, respectively, P = 0.024), compared with the older AF patients. The LA bipolar voltage exhibited a significant reduction when the patients became older, however, that did not occur in the right atrium. The incidence of an AF recurrence was higher in the older age group than in the younger age groups. A subgroup of patients with lone AF was analyzed and age was found to be an independent predictor of the AF recurrence after receiving the first CPVI in the multivariable model (P < 0.05)., Conclusions: Age has a significant impact on the LA substrate properties and outcome of the catheter ablation of AF., (© 2010 Wiley Periodicals, Inc.)

Background: The noncontact mapping (NCM) system possesses the merit of global endocardial recording for unipolar and activation mapping., Objective: We aimed to evaluate the unipolar electrogram characteristics and activation pattern over the bipolar complex fractionated atrial electrogram (CFAE) sites during atrial fibrillation (AF)., Methods: 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

Introduction: Elucidating the functional properties and remodeling process of the entire left atrium (LA) is important not only for offering the mechanistic insight into atrial fibrillation (AF) but also for assessing the effectiveness of catheter ablation., Methods: We included 65 patients with paroxysmal AF and 29 controls. Baseline multidetector computed tomography (MDCT) was acquired in all subjects and a follow-up MDCT was available in 48 patients after pulmonary vein and LA ablation. The 3-dimensional images at atrial end-diastole (ED) and end-systole (ES) were analyzed., Results: The LA volume (ED: 61.11 +/- 15.94 vs 54.12 +/- 8.94 mL/m(2), P = 0.03; ES: 45.29 +/- 17.64 vs 33.38 +/- 7.78 mL/m(2), P < 0.001) was increased, and ejection fraction (EF) (26.93 +/- 13.40 vs 38.09 +/- 11.62%, P < 0.001) decreased in AF patients as compared to controls. After ablation, the ES LA volume (44.73 +/- 14.93 vs 38.04 +/- 11.51 mL/m(2), P = 0.04) decreased and the LA EF (25.04 +/- 13.13 vs 30.82 +/- 7.85%, P = 0.03) increased in patients without any AF recurrence. The wall motion (WM) analysis of the 18 segments of LA revealed increased motional magnitudes of entire LA except for the anterior roof. In contrast, the volume, EF, and WM of LA remained similar in patients with recurrence., Conclusion: Dilated LA with global hypokinesia was noted in AF patients. Improved LA transport function was demonstrated in patients without any recurrence after ablation. However, the anatomic and functional reverse remodeling was not significant in patients with AF recurrence.

Background: Nonpulmonary vein (PV) ectopy initiating atrial fibrillation (AF)/atrial tachycardia (AT) is not uncommon in patients with AF. The relationship of complex fractionated atrial electrograms (CFAEs) and non-PV ectopy initiating AF/AT has not been assessed. We aimed to characterize the CFAEs in the non-PV ectopy initiating AF/AT., Methods: Twenty-three patients (age 53 +/- 11 y/o, 19 males) who underwent a stepwise AF ablation with coexisting PV and non-PV ectopy initiating AF or AT were included. CFAE mapping was applied before and after the PV isolation in both atria by using a real-time NavX electroanatomic mapping system. A CFAE was defined as a fractionation interval (FI) of less than 120 ms over 8-second duration. A continuous CFAE (mostly, an FI < 50 ms) was defined as electrogram fractionation or repetitive rapid activity lasting for more than 8 seconds., Results: All patients (100%) with non-PV ectopy initiating AF or AT demonstrated corresponding continuous CFAEs at the firing foci. There was no significant difference in the FI among the PV ostial or non-PV atrial ectopy or other atrial CFAEs (54.1 +/- 5.6, 58.3 +/- 11.3, 52.8 +/- 5.8 ms, P = 0.12). Ablation targeting those continuous CFAEs terminated the AF and AT and eliminated the non-PV ectopy in all patients (100%). During a follow-up of 7 months, 22% of the patients had an AF recurrence with PV reconnections. There was no recurrence of any ablated non-PV ectopy during the follow-up., Conclusion: The sites of the origin of the non-PV ectopies were at the same location as those of the atrial continuous CFAEs. Those non-PV foci were able to initiate and sustain AF/AT. By limited ablation targeting all atrial continuous CFAEs, the AF could be effectively eliminated.

Background: The left atrial (LA) size is an important predictor of atrial fibrillation (AF) procedural termination and the long-term outcome. We sought to evaluate the long-term outcome in regard to the LA size and procedural termination., Methods: Eighty-seven consecutive chronic AF patients (72 males, 53 +/- 10 years) underwent 3D mapping (NavX) and ablation. A stepwise approach including circumferential pulmonary vein (PV) isolation, linear ablation, and continuous complex-fractionated electrogram (CFE) ablation (targeting fractionation intervals of < 50 ms). Electrical cardioversion was applied to those without any procedural termination. The freedom from AF was defined as the maintenance of sinus rhythm without the use of any class I or III antiarrhythmic drugs after the blanking period., Results: Among the 87 patients, all received a circumferential PV isolation, 93% a linear ablation, and 59% a continuous CFE ablation. Those with AF procedural termination (n = 30) had a better long-term outcome when compared with those without termination during a follow-up of 21 +/- 12 months. Moreover, a Kaplan-Meier analysis showed that in those with an LA diameter of less than 45 mm (n = 49), the freedom from AF rate was higher when procedural termination was achieved (P = 0.004). On the contrary, the outcome was comparable in those with an LA diameter of >or= 45 mm (n = 38), whether AF procedural termination occurred or not (P = 0.658)., Conclusions: AF procedural termination was related to the long-term success during chronic AF ablation, especially in those with an LA diameter of less than 45 mm. The favorable effect of termination decreased when the LA diameter was >or= 45 mm.

Introduction: Although several studies have reported the benefits of cooled-tip ablation for circumferential pulmonary veins isolation (CPVI), the acute change of substrate property and acute PV reconnection have not been well demonstrated. The aim of this study was to compare the cooled-tip with regular 4-mm-tip catheter in acute substrate change after CPVI and long-term efficacy., Methods and Results: One hundred and fifty-six patients (115 males, age 53 +/- 12 years) who underwent CPVI for treatment of atrial fibrillation (AF) were included. Group A consisted of 52 patients with cooled-tip ablation, and group B consisted of 104 patients with 4-mm-tip catheter ablation. The bipolar voltage of circumferential lesions was obtained using a 3-dimensional (3D) mapping system (NavX) before and after CPVI. The electrical reconnections of 4 PVs were evaluated 30 minutes after CPVI using a circular catheter. Cooled-tip catheter caused more reduction of the electrical voltage in PV antrum, lower incidence of acute PV reconnection, inducibility of AF, and gap-related atrial tachyarrhythmia (AT). Less number of left atrial (LA) ablation line and ablation applications and less procedure time were found in cooled-tip group compared to 4-mm-tip group. No significant difference in the incidence of pain sensation and complication was observed between the 2 groups. At a 14-month follow-up, the recurrence rate in the cooled-tip group was lower than in the 4-mm group (13.5% vs 33.7%, P = 0.009)., Conclusion: Cooled-tip catheter has a superior long-term outcome than the 4-mm-tip catheter in CPVI, which may be associated with the efficacy of transmural block and electrical isolation in PV antrum.

Introduction: The left atrial (LA) substrate plays an important role in the maintenance of atrial fibrillation (AF). However, little is known about the acute effect of circumferential pulmonary vein isolation (CPVI). This study was to investigate the acute change of LA activation, voltage and P wave in surface electrocardiogram (ECG) after CPVI., Methods and Results: Electroanatomic mapping (NavX) was performed in 50 patients with AF (mean age = 54 +/- 10 years, 36 males) who underwent only CPVI. The mean peak-to-peak bipolar voltage and total activation time of LA were obtained during sinus rhythm before and immediately after CPVI. The average duration and amplitude of P waves in 12-lead ECG were also analyzed before and after CPVI. Change in the earliest LA breakthrough sites could cause decreased LA total activation time. Downward shift in the breakthrough site was inversely proportional to the proximity of the breakthrough site to the radiofrequency lesions. A shortening of P-wave duration and decrease in voltage after CPVI were observed after CPVI. Patients with recurrent AF had less voltage reduction in the atrial wall 1 cm from the circumferential PV lesions compared with those without recurrent AF (60.1 +/- 11.7% vs 74.1 +/- 6.6%, P = 0.002). Reduction of voltage < or = 64.4% in this area after CPVI is related with recurrent AF., Conclusion: CPVI could result in acute change of LA substrate, involving LA activation and voltage. Less reduction of voltage in the atrial wall adjacent to the circumferential PV lesions after CPVI may be associated to the recurrence of AF.

Background: The efficacy of ablation of complex fractionated atrial electrograms (CFEs) in the single ablation procedure for nonparoxysmal atrial fibrillation (AF) patients is not well demonstrated. The aim of this study was to compare the ablation strategies of pulmonary vein isolation (PVI) plus linear ablation with and without additional ablation ofCFEs in these patients., Methods: Consecutive 60 patients (49 +/- 11 years old, 50 male, 10 female) with nonparoxysmal AF underwent catheter ablation guided by a NavX mapping system. A stepwise approach included a circumferential PVI and left atrial (LA) linear ablation followed by either the additional ablation of continuous CFEs in the LA/coronary sinus (the first 30 patients) or not (the second 30 patients), detected by an automatic algorithm., Results: There was no difference in the baseline characteristics between the two groups. Complete PVI eliminated some continuous CFEs and altered the distribution of CFEs. Following PVI and linear ablation,the remaining continuous CFEs were identified in 7.9 +/-10% mapping sites of the LA and CS, and were ablated successfully with a procedural AF termination rate of 53%. With a follow-up of 19 +/-11 months, a Kaplan-Meier analysis showed that the patients with additional ablation of the CFEs had a higher rate of sinus rhythm maintenance. Multivariate analysis showed the single procedure success could be predicted by the procedural AF termination and the additional ablation of continuous CFEs in the LA/CS., Conclusions: Ablation of continuous CFEs after PVI and LA linear ablation had a better long-term efficacy based on the results of single-ablation procedure.

Introduction: Atrial tachycardia (AT), including focal and reentrant AT, can occur after circumferential pulmonary vein isolation (CPVI). The aim of this study was to investigate the electrophysiological characteristics of induced AT and its clinical outcome., Methods and Results: In our series of 160 patients with paroxysmal atrial fibrillation (AF), 45 ATs were induced by high-current burst pacing after CPVI in 26 patients. All induced ATs were mapped using a three-dimensional (3D) mapping system. Noninducibility was the endpoint of the ablation of the AT. Gap-related AT was considered if the AT was related to the CPVI lesions. A 16-slice multidetector computed tomography scan was performed in all patients to correlate the anatomical structure with electroanatomical mapping. Thirty-five (78%) reentrant ATs and 10 (22%) focal ATs were identified. Of those, 34 were gap-related ATs (24 reentrant and 10 focal ATs). Reentrant AT had more gaps in the left atrial appendage ridge than did focal AT (39.6% vs 0%, P = 0.02). Focal AT had a higher incidence of gap in the PV carina compared with reentrant AT (80% vs 10%, P < 0.001). Reentrant ATs were mostly terminated during the ablation creating the mitral and roof lines with crossing of the gaps. During a mean follow-up of 21 +/- 8 months, only one patient (0.6%) with induced mitral reentry had a recurrent AT., Conclusion: The location of the AT gap may be related with the complex anatomy of the LA. The induced ATs after CPVI can be eliminated by catheter ablation.

Background: The characteristics of cavotricuspid isthmus (CTI) in patients with atrial fibrillation (AF) and flutter that may predict recurrence of flutter is not known. We aimed to investigate the CTI characteristics in patients who underwent a second ablation procedure for recurrent AF after previous combined pulmonary vein (PV) and CTI ablation., Methods: Among 196 consecutive patients with drug-refractory symptomatic AF who underwent PV isolation and CTI ablation with bidirectional isthmus block, 49 patients (age 50 +/- 12 years, 43 males) had recurrent AF and received a second procedure 291 +/- 241 days after the first procedure. Right atrial angiography for the evaluation of the CTI morphology, and the biatrial contact bipolar electrograms were obtained before both procedures., Results: In the second procedure, 11 (group 1) of the 49 patients demonstrated recovered CTI conduction. Compared with the patients without CTI conduction (group 2, n = 38), group 1 patients had a higher frequency of a pouch-type anatomy (82% vs 13%, P < 0.001), longer CTI (34.0 +/- 8.6 vs 25.5 +/- 7.5 mm, P = 0.01), longer ablation time, and larger number of radiofrequency applications; furthermore, the preablation bipolar voltage decreased along both the CTI and ablation line in group 2, whereas it remained similar in group 1 in the second procedure., Conclusions: A high (22%) percentage of CTIs exhibited recurrent conduction in the long-term follow-up. The CTIs with recurrent conduction had a higher incidence of a pouch and longer length compared with those without recurrent conduction.

The noncontact mapping system is a new tool for electrophysiologic study and radiofrequency ablation. The mode of operation includes single beat, three-dimensional, high-density mapping. Careful analysis of unipolar electrograms and isopotential maps are essential to understand the mechanism of the arrhythmia. Radiofrequency catheter ablation guided by this system is effective in curing patients of their tachycardias.

Objectives and Background: The success rate of achieving electrical isolation by circumferential pulmonary vein ablation (CPVA) varies from 32% to 88%. We carried out ablation at the pulmonary vein carina to evaluate the elimination rates of the pulmonary vein potentials (PVPs) after one round of CPVA had failed to eliminate all the PVPs in the patients with atrial fibrillation (AF)., Methods: Ninety-seven patients (75 males; mean age: 50 +/- 12 years; 15 with persistent AF and 82 with paroxysmal AF) who underwent catheter ablation were analyzed. All patients underwent one round of CPVA with PVP elimination as the endpoint. The electrophysiology tracings were then analyzed to look for the presence of any gaps that were subsequently targeted by radiofrequency ablation. The patients in whom the PVPs still persisted underwent ablation at the pulmonary vein carina and the success rate of the PVP elimination was studied. The patients were followed up for a mean duration of 12.9 +/- 8.2 months., Results: One hundred ninety-four ipsilateral pulmonary veins in 97 patients were subjected to CPVA with successful elimination of the PVPs in 110 ipsilateral pulmonary veins (success rate of 56.7%). A carina ablation was carried out in the remaining 84 ipsilateral pulmonary vein pairs harboring PVPs. Elimination of the PVPs was achieved in all the remaining ipsilateral pulmonary veins after the carina ablation., Conclusion: Considering the limited efficacy of CPVA in eliminating the PVPs, pulmonary vein carina ablation is advisable to substantially increase the PVP elimination rate.

Introduction: Paroxysmal supraventricular tachycardia (PSVT) is often associated with paroxysmal atrial fibrillation (AF). However, the relationship between PSVT and AF is still unclear. The aim of this study was to investigate the clinical and electrophysiological characteristics in patients with PSVT and AF, and to demonstrate the origin of the AF before the radiofrequency (RF) ablation of AF., Methods and Results: Four hundred and two consecutive patients with paroxysmal AF (338 had a pure PV foci and 64 had a non-PV foci) that underwent RF ablation were included. Twenty-one patients (10 females; mean age 47 +/- 18 years) with both PSVT and AF were divided into two groups. Group 1 consisted of 14 patients with inducible atrioventricular nodal reentrant tachycardia (AVNRT) and AF. Group 2 consisted of seven patients with Wolff-Parkinson-White (WPW) syndrome and AF. Patients with non-PV foci of AF had a higher incidence of AVNRT than those with PV foci (11% vs. 2%, P = 0.003). Patients with AF and atypical AVNRT had a higher incidence of AF ectopy from the superior vena cava (SVC) than those with AF and typical AVNRT (86% vs. 14%, P = 0.03). Group 1 patients had smaller left atrial (LA) diameter (36 +/- 3 vs. 41 +/- 3 mm, P = 0.004) and higher incidence of an SVC origin of AF (50% vs. 0%, P = 0.047) than did those in Group 2., Conclusion: The SVC AF has a close relationship with AVNRT. The effect of atrial vulnerability and remodeling may differ between AVNRT and WPW syndrome.

Background: Smoking is a major risk factor for cardiovascular disease. The impact of smoking on the right and left atrial substrates is unknown., Methods: This study included 88 patients (age 50 +/- 13 years, M/F = 71/17) who underwent four pulmonary veins isolation (PVI) for paroxysmal atrial fibrillation (AF). The mean voltage and total activation time of the individual atria were obtained by using a NavX mapping system, and were compared between the patients with and without a previous smoking history. The dose effect was evaluated by the smoking intensity-duration, defined as the number of packs per day plus how many years they had been smoking., Results: The right atrial (RA) mean voltage was lower in the patients with a previous history of smoking than in those without a history of smoking (1.92 +/- 0.49 vs 2.17 +/- 0.56 mV, P < 0.05). The left atrial (LA) mean voltage was similar between the two groups (1.73 +/- 0.67 vs 1.82 +/- 0.48 mV, P = 0.488). Further, the total activation time of the RA was longer in the patients with a previous history of smoking than in those without a history of smoking, but not so for the LA. Furthermore, the voltage reduction in the RA was related to the smoking intensity-duration (Pearson's correlation, r = 0.650, P < 0.001)., Conclusions: In patients with atrial fibrillation, the RA mean voltage and total activation time were significantly correlated to smoking and had a dose-dependent effect.

Background: The features of multiple catheter ablation procedures for paroxysmal atrial fibrillation (AF) are unknown. We aimed to investigate the electrophysiologic characteristics and the clinical outcomes in the patients with AF who received more than two ablation procedures., Methods: The study consisted of 15 consecutive patients (age 48 +/- 14 years, 10 males) who had undergone three to five (3.3 +/- 0.6) catheter ablation procedures for recurrent paroxysmal AF., Results: Ten patients had pulmonary vein (PV)-AF and one had AF originating from both PVs and the superior vena cava (SVC) in the first ablation procedure. All of them exhibited PV reconnection during the recurrent episodes. Four of the 15 patients had AF originating from non-PV foci (three from the SVC, one from the crista terminalis) in the first procedure, and two had AF recurrences due to recovered conduction from the SVC. In all patients with PV-AF recurrences, repeated PV isolation procedures could effectively eliminate the AF. The incidence of the need for additional LA linear ablation lesions was higher comparing between the first procedure and in the following ablation procedures (18% vs. 71%, P = 0.02). During a follow-up of 1.7 +/- 1.1 years, 73% of the patients remained in sinus rhythm without any antiarrhythmic drugs after the final procedure., Conclusions: Recovered PV connection was the major cause of the AF recurrences despite undergoing multiple catheter ablation procedures. It is advisable to inspect all PVs during the AF recurrence. Repeated PV isolation plus left atrial linear ablations could effectively eliminate the AF with satisfactory outcomes.

Background: The atrial substrate is the determinant of occurrence and maintenance of atrial fibrillation (AF), which can induce remodeling of atrial function and structure. This study investigated the relationship between the left atrial (LA) substrate properties and LA mechanical function., Methods: Forty-four consecutive patients (50.3 +/- 10.7 years old, 33 men) who presented with sinus rhythm during echocardiographic study before receiving catheter ablation for AF were enrolled. The LA diameter, LA volume, ratio of early and late transmitral filling flow velocities (E/A), LA appendage flow velocity, and transmitral velocity-time integral (VTI) were measured by the echocardiography. The LA empty fraction (LAEF), which was obtained via dividing the difference between maximal and minimal LA volume by maximal LA volume, was calculated as a parameter of the global LA contractile function. The LA global contact voltage mapping (NavX system) was performed before pulmonary vein isolation., Results: Mean LA voltage and LA low voltage zone index (LVZ index, area with voltage < 0.5 mV, divided by total LA surface area) showed significant correlation with LA diameter and volume, but only the LA LVZ index showed significant correlation with A-wave velocity, transmitral A-wave VTI, and LAEF (r =-0.340, -0.411, -0.426; P = 0.024, 0.006, 0.005, respectively). We divided the LA LVZ index into three groups (< 10%, 10-20%, > 20%). The LAEF got worse and the transmitral A-wave VTI percentage (divided by transmitral VTI) decreased as LA LVZ index increased., Conclusions: The LA substrate properties showed close correlation with LA size, but only the LA LVZ index correlated with the LA mechanical function.

Introduction: The atrial substrate plays an important role in the maintenance of atrial fibrillation (AF). Further investigation of the biatrial substrate may be helpful for understanding the mechanism of AF. The aim of this study was to investigate the properties of right and left atrial (RA and LA) substrate in AF patients and their impact on the catheter ablation., Methods: Biatrial electroanatomic mapping using a three-dimensional mapping system (NavX) was performed in 117 consecutive patients with paroxysmal (n = 99) and persistent (n = 18) AF. The biatrial voltage and total activation time (TAT) were obtained during sinus rhythm., Results: The LA had a lower voltage (1.6 +/- 0.5 vs 2.0 +/- 0.6 mV, P < 0.001) than the RA. The TAT correlated with the voltage (r = -0.65, P < 0.001). The patients with persistent AF had a lower atrial voltage, higher coefficient of variance for the LA voltage, longer LA TAT, and more extensive scar than those with paroxysmal. The patients with recurrent AF after catheter ablation had a lower LA voltage and higher incidence of LA scarring than those without recurrence. A scar located in the low anteroseptal or low posterior wall of LA was related to recurrence of AF. LA scarring was the independent predictor of AF recurrence after catheter ablation., Conclusion: The LA voltage was lower than the RA, and the atrial voltage correlated with the TAT. Electroanatomical remodeling of the atria could be crucial to the maintenance of AF. The LA substrate properties may play an important role in the recurrence of AF after catheter ablation of AF.

Introduction: Noncontact mapping (NCM) can record virtual unipolar electrograms (Egs) from multiple sites simultaneously; therefore, it has the potential to perform simultaneous frequency mapping during atrial fibrillation (AF). The aim of this study was to validate the frequency spectra of the noncontact unipolar Egs in both atria., Methods: This study enrolled 12 patients (age = 61 +/- 16 years) with paroxysmal or persistent AF who underwent catheter ablation guided by NCM. Noncontact and contact unipolar Egs were recorded simultaneously. The cross-correlation of the Eg morphology, activation time difference of the time-domain signals, and resultant frequency spectra were compared via dominant frequency (DF) and magnitude-squared coherence (MSC)., Results: A total of 159 sites were analyzed during AF. The variables that independently predicted a higher correlation between the contact and noncontact electrogram morphology were a smaller activation timing difference P < 0.01), smaller distance of the mapping sites to the array center (P = 0.01), and higher atrial voltage (P = 0.03). However, the average MSC of the frequency band within the physiologic range of AF (2 to 15 Hz) was only affected by the activation timing difference (P = 0.002). The DF value between the contact and noncontact unipolar signals correlated well with each other throughout the right atria and left atria in 94% of the mapping sites (r = 0.87, P < 0.001)., Conclusion: The accuracy of the noncontact unipolar Eg morphology decreased when the mapping sites harbored a smaller atrial voltage and longer distance to the array center. The DF difference between the contact and noncontact unipolar Eg was not affected by the distance to the array center.

Introduction: Atrio-bronchial fistula (ABF) can be a rare but potentially lethal complication following the catheter ablation of atrial fibrillation (AF). Understanding the extent of the contact between the bronchial tree and pulmonary veins (PVs) is critical to avoid this complication. We investigated the anatomic relationship between the four PVs and bronchial tree using multi-detector computed tomography (MDCT) images., Methods and Results: Seventy patients with drug refractory AF were included. They underwent 16-slice MDCT before the ablation. The spatial relationship between the bronchus and PVs was demonstrated by the multi-planar images. The bronchus was in direct contact with four PVs in the vast majority of patients. The mean distances between the bronchus and the ostia of right superior, left superior, right inferior, and left inferior PV were 7.1 +/- 5.5, 3.5 +/- 4.8, 12.3 +/- 5.6, and 17.9 +/- 6.8 mm, respectively. Patients were categorized into two groups: Group I: proximal contact (<5 mm from the PV ostium) and Group II: distal contact (>5 mm from the PV ostium). For the right superior pulmonary vein (RSPV), the Group I patients were associated with thinner connective tissue between them (P = 0.001), a larger RSPV (17.2 +/- 2.2 vs 15.5 +/- 2.1 mm, P < 0.001), and right inferior pulmonary vein (RIPV) diameter (15.9 +/- 1.9 vs 14.6 +/- 1.6 mm, P < 0.01). For the left superior pulmonary vein (LSPV), the Group I patients were associated with an older age (P = 0.02)., Conclusion: Isolation of the superior PVs may carry the potential risk of bronchial damage. The clinical or anatomic characteristics associated with the proximal contact between the bronchi and superior PVs can provide useful information to prevent this complication.

Background: Electrical isolation of pulmonary veins (PVs) is an effective therapy for atrial fibrillation (AF). Both segmental ostial PV ablation and circumferential ablation with PV-left atrial (LA) block have been implicated to eliminate AF. However, the mechanism of the recurrent AF after undergoing either strategy remains unclear., Methods and Results: Of the 73 consecutive patients with symptomatic AF that underwent PV isolation and had recurrences of AF, Group 1 consisted of 46 patients (age 56 +/- 13 years old, 35 males) who underwent PV isolation by segmental ostial PV ablation and Group 2 consisted of 27 patients (age 51 +/- 11 years old, 24 males) who underwent circumferential ablation with PV-LA block. In Group 1, the earliest ectopic beat or ostial PV potentials were targeted. In Group 2, circumferential ablation with PV-LA block was performed by encircling the extraostial regions around the left and right PVs. During the first procedure, all patients had PV-AF. There was no difference in the non-PV ectopy between Group 1 and Group 2. During the second procedure, the incidence of an LA posterior wall ectopy initiating AF was significantly lower (20% vs. 0%, P = 0.01) in Group 2. There was no difference in the PV ectopy initiating AF during the second procedure., Conclusion: Circumferential ablation of AF with PV-LA block may eliminate the LA posterior wall ectopy and decrease the incidence of LA posterior wall ectopy initiating AF during the second procedure.

Background: The optimal recording technique of the electrogram voltage for detecting abnormal atrial tissue remains unclear. The aim of this study was to compare the impact of various recording techniques on the electrogram voltage after the delivery of ablation therapy in the human right atrium (RA)., Material and Methods: Noncontact mapping was performed in 27 patients with typical atrial flutter (mean age = 63 +/- 16, males = 20). Noncontact unipolar and bipolar electrograms were obtained before and after cavotricuspid isthmus (CTI) linear ablation. All unipolar electrograms were acquired with both wide-band filtering (0.5-300 Hz) and narrow-band filtering (32-300 Hz). The unipolar voltage measurements included both the peak-to-peak voltage and peak-negative voltage (PNV) for both filter settings., Results: A comparison of the electrogram voltage along the ablation line before and after the ablation demonstrated a greater reduction in the unipolar PNV with wide-band filtering (70 +/- 24%) than in any of the other recording modalities (P = 0.03). It was the most sensitive and specific recording technique to predict conduction block (cut-off Value 0.35 mV; sensitivity = 94.4% and specificity = 80%). A comparison of the electrogram voltage between the ablated atrial myocardium and nearby nonablated myocardium showed that the unipolar PNV with the wide-band filtering remained the most sensitive method to detect the acute ablative tissue injury, whereas the peak-to-peak bipolar voltage was the most specific method., Conclusion: The noncontact unipolar electrogram using the PNV with wide-band filter settings (0.5-300 Hz) provided the most sensitive recording technique for detecting acute ablative tissue injury.

Introduction: Some conflicting results of the efficacy of the inducibility test used in the catheter ablation of atrial fibrillation (AF) have been reported. The aim of this study was to investigate the inducibility and efficacy of circumferential ablation with pulmonary vein isolation (PVI) in patients with paroxysmal AF and its relationship to the atrial substrate., Methods and Results: This study consisted of 88 patients with paroxysmal AF who underwent catheter ablation. Electroanatomic mapping using a NavX system was performed and the biatrial voltage was obtained during sinus rhythm. After successful circumferential ablation with PVI, an inducibility test was performed to determine the requirement for creating left atrial (LA) ablation line. After procedure, patients with inducible AF had a higher recurrence rate than did those with noninducibility of AF (55% vs 18%, P = 0.02). The patients with inducible AF after the PVI had a lower biatrial voltage than did those with negative inducibility. The patients with inducible AF after the final procedure who had a recurrence had a lower LA voltage (1.3 +/- 0.4 vs 1.8 +/- 0.4 mV, P = 0.02) and longer LA total activation time (99 +/- 18 vs 88 +/- 13 msec, P = 0.02) than did those with noninducible AF and no recurrence. None of the patients had occurrence of LA flutter during the follow-up., Conclusion: After a single procedure of circumferential ablation with PVI and noninducibility, 82% patients did not have recurrence of AF. The inducibility of AF was related to the recurrence of AF. The atrial substrate affected the outcome of the inducibility.

Background: Atrial substrate properties have been demonstrated to be related to atrial arrhythmias. This study investigated whether the atrial substrate exhibits progressive remodeling in patients with recurrence of atrial fibrillation (AF) after catheter ablation., Methods and Results: Fifteen consecutive AF patients (52 +/- 12 years old, 12 males) underwent the same mapping technique (NavX, St. Jude Medical, Minnetonka, MN, USA) and same ablation technique for primary AF and recurrence of AF (170 +/- 66 days after the first procedure). The bipolar mean peak-to-peak voltage (PPV) of the global left atrium during sinus rhythm significantly decreased in the second procedure (2.25 +/- 0.62 vs. 1.79 +/- 0.60 mV, P = 0.008). Also, the percentage of the surface area of the low voltage zone (LVZ; less than 0.5 mV) in the left atrium increased from 6 +/- 4% to 13 +/- 6% (P = 0.001) in the second procedure. There was no significant change in the right atrial bipolar mean PPV or surface area of the LVZ in the second procedure., Conclusion: Atrial substrate remodeling with a progressive decrease in the left atrial voltage was demonstrated in patients with recurrent AF.

Introduction: Radiofrequency ablation (RFA) of typical AFL is sometimes difficult because of the poor electroanatomic approach to the cavotricuspid isthmus (CTI). The aim of this study was to correlate the anatomy of the CTI between contact mapping (NavX) and right atrial angiography (RAG), and to investigate the impact of the electroanatomic characteristics of the CTI on the RFA of typical atrial flutter (AFL)., Methods: One hundred patients with typical AFL undergoing RFA were studied. The image-guided group consisted of 50 consecutive patients with the guidance of NavX. NavX geometry and RAG were performed to investigate the morphology of the CTI. The bipolar voltages of the CTI were collected during sinus rhythm by a NavX. The control group consisted of 50 consecutive patients with the guidance of conventional fluoroscopy., Results: There was a good correlation between the angiography and NavX for the anatomy of the CTI. The pouch type had a longer length of CTI than the flat type (33.4 +/- 5.0 vs 22.6 +/- 8.4 mm, P < 0.0001) and deeper depth than the concave type (6.5 +/- 2.2 vs 3.7 +/- 0.8 mm, P < 0.0001) on the angiography. The pouch-type CTI had a longer ablation time and larger pulses of RFA than the other two types. The control group had a longer ablation time, fluoroscopy time, and larger pulses of RFA than image-guided group., Conclusions: The 3-D mapping system provided a good reconstruction of CTI, which may help in the RFA in patients with a complex anatomy of the CTI.

Introduction: The left atrial appendage (LAA) has been proven to be the most important site of thrombus formation in patients with atrial fibrillation (AF). However, the information regarding the morphometric alteration of the LAA related to the outcome of AF ablation is still lacking. Thus, we evaluated the long-term changes of the LAA morphology in patients undergoing catheter ablation of AF using magnetic resonance angiography (MRA)., Methods and Results: Group 1 included 15 controls without any AF history. Group 2 included 40 patients with drug-refractory paroxysmal AF. They were divided into two subgroups: group 2a included 30 patients without AF recurrence after pulmonary vein (PV) ablation. Group 2b included 10 patients with late recurrence of AF. The LAA morphology before and after (20 +/- 11 months) ablation was evaluated by three-dimensional MRA. The group 2 patients had a larger baseline LAA size (including the LAA orifice, neck, and length) and less eccentric LAA orifice and neck. After the AF ablation, there was a significant reduction in the LAA size in the group 2a patients, and the morphology of the LAA neck became more eccentric during the follow-up period. In group 2b, the LAA size increased and no significant change in the eccentricity of the orifice and neck could be noted., Conclusions: The morphometric remodeling of the LAA in the AF patients could be reversed after a successful ablation of the AF. Progressive dilation of the LAA was noted in the patients with AF recurrence. These structural changes in the LAA may play a role in reducing the potential risk of cerebrovascular accidents.

Introduction: Left atrial (LA) isthmus ablation was reported to improve the success rate of catheter ablation of paroxysmal atrial fibrillation (AF). LA isthmus ablation could also cure a subset of LA flutter. Therefore, understanding the anatomy of the LA isthmus is important for performing the ablation effectively., Methods and Results: Group I included 45 patients (40 male, mean age = 50 +/- 13 years) with paroxysmal AF who underwent catheter ablation. Group II included 45 patients (37 male, mean age = 54 +/- 10 years) without a history of AF. They underwent a 16-slice multidetector computed tomography (MDCT) scan to delineate the LA structures before the ablation procedure. The average length of the LA isthmus was longer in group I than in group II (lateral isthmus: 3.30 +/- 0.68 vs 2.71 +/- 0.60 cm, P < 0.001; medial isthmus: 5.12 +/- 0.94 vs 4.45 +/- 0.63 cm, P < 0.001), and morphological patterns of lateral and medial isthmus were similar between groups. In addition, the average depth of lateral isthmus was similar between groups (0.62 +/- 0.32 vs 0.55 +/- 0.33 cm, P = 0.41), but the average depth of medial isthmus was larger in group I than in group II (0.60 +/- 0.32 vs 0.44 +/- 0.25 cm, P = 0.01). The medial isthmus had more ridges, as compared to the lateral isthmus (13% vs 0%, P = 0.026). Furthermore, the distances between esophagus and lateral isthmus were longer in group I than in group II (at the middle of isthmus and mitral annulus level: 21.0 +/- 4.8 vs 18.4 +/- 6.0 mm, P < 0.001; and 37.1 +/- 5.7 vs 29.6 +/- 8.1 mm, P < 0.001, respectively)., Conclusion: The LA isthmus was longer in the AF patients. The morphology of the isthmus was variable. Compared with the lateral isthmus, the medial isthmus was longer and had more ridges. A peculiar configuration of the isthmus provided by CT images could influence the ablation strategy.

Background: Although the reentrant circuit of typical atrial flutter (AFL) has been well recognized, the activation around the Eustachian ridge (ER) has not been fully characterized. The aim of this study was to delineate the activation patterns around the ER during typical AFL using high-resolution noncontact mapping., Methods: Fifty-three patients (M/F = 43/10, 62 +/- 14 years) with typical AFL were included. The high-resolution mapping of the right atrium using a noncontact mapping system during AFL and pacing from the coronary sinus (CS) was performed to evaluate the conduction through the ER., Results: Three types of activation patterns around the ER could be classified according to the ER conduction during AFL and CS pacing. Type I (n = 21, M/F = 16/5, 61 +/- 13 years) exhibited conduction block at the ER during AFL and CS pacing. The local unipolar electrograms at the ER exhibited long double potentials (DPs) (109 +/- 12 ms, range 77-153 ms) during AFL and CS pacing (84 +/- 18 ms, range 48-129 ms). Type II (n = 8, M/F = 7/1, 61 +/- 15 years) exhibited conduction block at the ER during AFL, but conduction through the ER during CS pacing. The unipolar electrograms exhibited long DPs (119 +/- 12 ms, range 97-141 ms) at the ER during the tachycardia and an rS pattern during CS pacing. Type III (n = 24, M/F = 20/4, 61 +/- 16 years) exhibited an activation wavefront that passed along the ER, with the sinus venosa as the posterior barrier during AFL. During CS pacing, all cases exhibited conduction through the ER with an rS pattern., Conclusions: This study is the first to demonstrate the three patterns of activation along the ER during AFL and CS pacing. This finding suggested that the ER is an anatomic and functional barrier during typical AFL.

Introduction: The left atrium (LA) ablation in different regions, including LA appendage (LAA), LA roof, and LA septum, has recently been proposed to improve the success rate of treating patients with atrial fibrillation (AF). The purpose of this study was to investigate the anatomy of LAA, LA roof, and LA septum, using computed tomography (CT)., Methods and Results: Multidetector CT scan was used to depict the LA in 47 patients with drug-refractory paroxysmal AF (39 males, age = 50 +/- 12 years) and 49 control subjects (34 males, age = 54 +/- 11 years). The area of LAA orifice, neck, and the length of roof line were greater in AF group than in control subjects. Three types of LAA locations and two types of LAA ridges were observed. Higher incidence of inferior LAA was noted in AF patients. The different morphologies of LA roof were described. Roof pouches were revealed in 15% of AF and 14% of controls. Moreover, we found septal ridge in 32% of AF and 23% of controls., Conclusions: Considerable variations of LAA and LA roof morphologies were demonstrated. Peculiar structures, including roof pouches and septal ridges, were delineated by CT imaging. These findings were important for determining the strategy of AF ablation and avoiding the procedure-related complications.

Introduction: Acquired pulmonary vein (PV) stenosis is a well-known complication following catheter ablation of atrial fibrillation (AF). However, the details of congenital PV stenosis have not been reported in patients who underwent catheter ablation of AF., Methods and Results: A total of 178 patients (110 men, age: 54 +/- 11 years) with drug-refractory AF received MRA or multidetector CT (MDCT) before ablation for delineation of PV morphologies. Five PVs in 5 patients (2.8%) showed at least 50% stenosis before ablation. We demonstrated two types of preexisting PV stenosis. Type I is the external compression of PV by the descending aorta, observed in LIPV of the three patients. Type II is the focal narrowing of PV, observed in RSPV of the two patients., Conclusion: Preexisting stenosis of PV may be a consequence of congenital focal narrowing or external compression by the adjacent structures. Detection of this condition by 3D CT or MRA before catheter ablation can provide information for planning of ablation strategy and prevent misdiagnosis of ablation-related PV stenosis.

Introduction: The anatomic proximity between the esophagus and the coronary sinus (CS) might render the esophagus vulnerable to thermal injury during ablation. Therefore, we investigated the anatomic relationship between the esophagus and the CS in patients with atrial fibrillation (AF)., Methods and Results: Thirty patients (25 males, mean age = 54 +/- 11 years) with drug-refractory paroxysmal AF were included. Sixteen-slice multidetector computed tomography was performed to depict the course of the esophagus and relationship to the CS. The esophagus was in direct contact with the CS in 57% (17/30) of patients (group 1). The mean length of the contact was 6.1 +/- 3.4 mm. In the remaining 13 patients, the esophagus did not come in direct contact with the CS (group 2). The shortest distance between the esophagus and the CS was 4.0 +/- 2.6 mm. The CS diameter (9.4 +/- 1.8 vs 8.5 +/- 2.4 mm, P = 0.15), esophagus width (18.6 +/- 1.6 vs 18.6 +/- 1.7 mm, P = 0.87), anteroposterior diameter of the left atrium (35.9 +/- 3.8 vs 35.0 +/- 3.3 mm, P = 0.58), thickness of the anterior wall of the esophagus (2.9 +/- 0.6 vs 2.9 +/- 0.6 mm, P = 0.97), and shortest distance from the esophagus to the CS ostium (19.3 +/- 5.4 vs 25.0 +/- 6.2 mm, P = 0.02) and to the great cardiac vein (8.5 +/- 5.3 vs 12.1 +/- 6.9 mm, P = 0.10) were compared between the two groups., Conclusions: In 57% of our patients, the esophagus was in direct contact with the CS, and a significantly shorter distance between the esophagus and the CS ostium was noted in these patients. It is important to prevent esophageal damage when applying energy within the CS.

Introduction: The mechanisms of late (<1 year after the ablation) and very late (>1 year after the ablation) recurrences of paroxysmal atrial fibrillation (AF) after catheter ablation have not been reported., Methods and Results: Fifty consecutive patients undergoing a repeated electrophysiologic study to investigate the recurrence of paroxysmal AF after the first ablation were included. Group 1 consisted of 12 patients with very late (26 +/- 13 months) and group 2 consisted of 38 patients with late (3 +/- 3 months) recurrence of paroxysmal AF. In the baseline study, group 1 had a lower incidence of AF foci from the pulmonary veins (PVs) (67% vs 92%, P = 0.048) and a higher incidence of AF foci from the right atrium (50% vs 13%, P = 0.014) than group 2. In the repeated study, group 1 had a higher incidence of AF foci from the right atrium (67% vs 3%, P < 0.001) and a lower incidence of AF foci from the left atrium (50% vs 97%, P < 0.001), including a lower incidence of AF foci from the PVs (50% vs 79%, P = 0.07) and from the left atrial free wall (0% vs 29%, P = 0.046) than group 2. Furthermore, most of these AF foci (64% of group 1, 65% of group 2) were from the previously targeted foci., Conclusion: The right atrial foci played an important role in the very late recurrence of AF, whereas the left atrial foci (the majority were PVs) were the major origin of the late recurrence of AF after the catheter ablation of paroxysmal AF.

Background: Previous studies have shown that the highest dominant frequency (DF) is located in the left atrium (LA) during atrial fibrillation (AF) in pacing-induced AF. However, there have been few studies on the mechanisms of the increased DF of AF during acute atrial dilatation. The purpose of this study was to investigate the mechanisms of the increased maximal DF (max DF) in pacing-induced AF during acute atrial dilatation., Methods: In eight Langendorff-perfused canine hearts (26 +/- 2 kg), noncontact balloon catheters were placed into the right atrium (RA) and LA, respectively. AF was induced by extrastimulation pre- and postdilatation in the atrium (0 and 15 cm H(2)O, respectively). Fast Fourier transformation analysis was performed to analyze the max DF and harmonic index (HI) from the bi-atrial unipolar virtual electrograms during AF. The fibrillation cycle lengths were obtained from different atrial sites. The number of wavefronts was analyzed during AF. The frequency of regional splitting was defined as the number of wavefront splits per second in different atrial regions during AF. The percentage of the low-voltage zones (<0.5 mV) was defined as the ratio of the area of the low-voltage zones to the total atrial surface area., Results: The DF was measured during AF. The shortest fibrillation cycle length was located in the LA posterior wall and became shorter during acute atrial dilatation. The max DF was located in the LA posterior wall and increased during acute atrial dilatation (7.1 +/- 0.8 vs 8.8 +/- 2.1, P = 0.02). The max DF of the LA correlated with the wavefront number (r = 0.797, P < 0.001 predilatation; r = 0.860, P < 0.001 postdilatation). The splitting of wavefronts facilitated the formation of new wavefronts. During acute atrial dilatation, the frequency of regional splitting was closely correlated with the percentage of the low-voltage zones (r = 0.876, P < 0.001). Furthermore, the LA posterior wall had a higher percentage of the low-voltage zones than the other sites., Conclusion: In acute atrial dilatation, the percentage of the low-voltage zones increased, especially in the LA posterior wall, which correlated with the regional splitting of the AF wavefronts. The increase in the splitting facilitated the formation of new wavefronts and resulted in a higher max DF during acute atrial dilatation.

We report a case with SVC ectopy initiating AF; the origin and breakout point of the sinus node was inside the SVC, and the SVC ectopy was conducted through the same path as the sinus node activation to depolarize the right atrium. Injury to the sinus node happened after successful isolation of SVC.

Background: Catheter ablation of atrial fibrillation (AF) has become another nonpharmacologic therapeutic option for medically refractory paroxysmal AF. Whether this method is better than atrioventricular (AV) junction ablation plus pacing therapy is unknown. The purpose of this study was to compare the very long-term (longer than 4 years) clinical outcomes of the 2 methods in elderly patients (>65 years old) with medically refractory paroxysmal AF., Methods: From January 1995 to December 2001, 71 elderly patients with medically refractory paroxysmal AF were included; group 1 included 32 patients with successful AV junction ablation plus pacing therapy and group 2, 37 patients with successful catheter ablation of AF., Results: After a mean follow-up of more than 52 months, the AF was better controlled in the group 1 patients than group 2 (100% vs 81%, P = 0.013), however, they had a significantly higher incidence of persistent AF (69% vs 8%, P < 0.001) and heart failure (53% vs 24%, P = 0.001). Furthermore, the incidence of ischemic stroke and cardiac death was similar between the 2 groups. Compared with the preablation values, a significant increase in the NYHA functional class (1.7 +/- 0.9 vs 1.4 +/- 0.7, P = 0.01) and significant decrease in the left ventricular ejection fraction (44 +/- 8% vs 51 +/- 10%, P = 0.01) were noted in the group 1 patients, but not in the group 2 patients., Conclusions: Although AV junction ablation plus pacing therapy better controlled the AF in elderly patients with medically refractory paroxysmal AF, that method was associated with a higher incidence of persistent AF and heart failure than catheter ablation of AF in the very long-term follow-up.

Introduction: The structural changes of the superior caval vein, pulmonary veins, and left atrium in atrial fibrillation initiated by superior caval vein ectopy have not been reported., Methods and Results: Nine patients with atrial fibrillation initiated by superior caval vein ectopic beats (male = 5, 54 +/- 10 years) and 15 control (n = 15, male = 10, 52 +/- 8 years) without any cardiac arrhythmias were included in this study. Using gadolinium-enhanced magnetic resonant angiography with three-dimensional reconstruction, the parameters of the superior caval vein morphology (length, various diameters, area, eccentricity, and volume) were measured. The morphological parameters of the four pulmonary veins (diameter, ostial area, and eccentricity) were also measured at the pulmonary vein-left atrial junction in an oblique sagittal section from the multiple-plane reconstruction images. The left atrial diameters and volume were measured. The different morphological parameters were compared between the two groups. The patients with atrial fibrillation initiated by superior caval vein ectopic beats exhibited a more eccentric structure of the second part of the superior caval vein as compared to the control group. All the ectopic beats initiating atrial fibrillation were located in the second part of the superior caval vein. Furthermore, the patients with atrial fibrillation initiated by superior caval vein ectopic beats had a larger superior caval vein volume, left atrial volume, and pulmonary vein size, and more eccentric pulmonary vein ostia than the controls., Conclusion: Structural changes of the superior caval vein were demonstrated in the patients with atrial fibrillation initiated by superior caval vein ectopic beats. These findings might explain the arrhythmogenic mechanism of atrial fibrillation initiated by superior caval vein ectopy.

Background: The purpose of the present study was to investigate the electrocardiographic and electrophysiologic characteristics of right midseptal (RMS) and left midseptal (LMS) accessory pathways (APs), and to develop a stepwise algorithm to differentiate RMS from LMS APs., Methods and Results: From May 1989 to February 2004, 1591 patients with AP-mediated tachyarrhythmia underwent RF catheter ablation in this institution, and 38 (2.4%) patients had MS APs. The delta wave and precordial QRS transition during sinus rhythm, retrograde P wave during orthodromic tachycardia, and electrophysiologic characteristic and catheter ablation in 30 patients with RMS APs and 8 patients with LMS APs were analyzed. There was no significant difference in electrophysiologic characteristics and catheter ablation between RMS and LMS APs. The polarity of retrograde P wave during orthodromic tachycardia also showed no statistical difference between patients with RMS and LMS APs. The delta wave polarity was positive in leads I, aVL, and V3 to V6 in patients with RMS and LMS APs. Patients with LMS APs had a higher incidence of biphasic delta wave in lead V1 than patients with RMS APs (80% vs. 15%, P=0.012). The distributions of precordial QRS transition were different between RMS APs (leads V2; n = 10, V3; n = 7 and V4; n = 3) and LMS APs (leads V1; n = 1 and V2; n = 4) (P = 0.03). The combination of a delta negative wave in lead V1 or precordial QRS transition in lead V3 or V4 had a sensitivity of 90%, specificity of 80%, positive predictive value of 95%, and negative predictive value of 66% in predicting an RMS AP., Conclusions: Delta wave polarity in lead V1 and precordial QRS transition may differentiate RMS and LMS APs.

Unlabelled: Right atrial substrate of supraventricular tachyarrhythmias., Background: Voltage mapping has been used to detect diseased myocardium. However, accurate determination of the local atrial voltage at the same site, and simultaneous recordings from multiple mapping sites were limited. The purpose of this study was to investigate the right atrial (RA) substrate properties in patients with supraventricular tachyarrhythmias (SVT)., Methods and Results: Forty patients (aged 55+/-20 years) undergoing noncontact mapping and ablation of SVT constituted the study population. There were eight patients with atrioventricular node reentrant tachycardia (AVNRT), eight patients with focal atrial tachycardia (AT), 14 patients with atrial flutter (AFL), and 10 patients with atrial fibrillation (AF). The mean peak negative voltage (PNV) was analyzed in virtual unipolar electrograms, which were obtained from 256 equally distributed RA endocardial sites during sinus rhythm (SR), atrial pacing, and tachycardia. The mean PNV of global RA during SR (-1.34+/-0.22 vs. -0.90+/-0.40 vs. -1.00+/-0.36 vs. -0.85+/-0.35 mV, P=0.04), atrial pacing at cycle lengths of 500 ms (-1.30+/-0.29 vs. -0.70+/-0.35 vs. -0.76+/-0.25 vs. -0.64+/-0.26 mV, P=0.02), and 300 ms (-1.54+/-0.47 vs. -0.94+/-0.21 vs. -0.75+/-0.27 vs. -0.57+/-0.22 mV, P<0.01) were significantly greater in patients with AVNRT compared to AT, AFL, and AF. Furthermore, the mean PNV decreased during atrial pacing with shorter pacing cycle length was demonstrated only in patients with AFL and AF., Conclusion: Negative unipolar voltage analysis of global RA showed different RA substrate characteristics during various SVT. The substrate property of activation and cycle length-dependent voltage reduction may be related to the development of AFL and AF.

Introduction: Understanding the structural remodeling and reverse remodeling of the left atrium (LA) and pulmonary vein (PV) after radiofrequency ablation of atrial fibrillation (AF) may provide important insights into the mechanism and management of AF. This study used magnetic resonance angiographic (MRA) images to investigate changes in PV and LA morphologies before and more than 1 year after ablation., Method and Results: Forty-five patients (36 men and 9 women, mean age 60 +/- 13 years) who underwent MRA before and more than 12 months (mean 21 +/- 11) after ablation of paroxysmal AF were included in the study. The patients were divided into two groups: group I included 35 patients without AF recurrence, and group II included 10 patients with late (>1 month postablation) recurrence of AF. The sizes of the LA and nonablated PV were compared before and after ablation. In group I, significant reduction of ostial area of both superior PVs was noted (left superior PV: from 2.85 +/- 0.67 to 2.59 +/- 0.73 cm2; right superior PV: from 2.89 +/- 0.85 to 2.60 +/- 0.73 cm2, both P <0.001). Geometric alteration toward a round shape was noted in the ostia of superior PVs during follow-up (eccentricity of right superior PV and left superior PV decreased from 0.31 +/- 0.10 to 0.22 +/- 0.13 and from 0.27 +/- 0.11 to 0.19 +/- 0.13, respectively, both P <0.01). However, LA volume showed only borderline reduction (from 61.52 +/- 19.06 to 56.64 +/- 17.13 mL, P=0.05). In group II, significant dilation of the LA (from 61.14 +/- 17.54 to 78.73 +/- 25.27 mL, P=0.004) and right superior PV (from 3.41 +/- 1.12 to 4.08 +/- 1.31 cm2, P=0.016) was noted during follow-up. Ostial area and eccentricity of the left superior, left inferior, and right inferior PVs and LA were similar before and after ablation., Conclusion: Structural remodeling of the superior PVs and LA can be reversible after successful ablation without AF recurrence; however, late recurrence of AF is associated with progressive LA dilation.