Stepwise Catheter Ablation Research Articles

A novel stepwise catheter ablation method of the mitral isthmus for persistent atrial fibrillation: efficacy and reproducibility

BackgroundEthanol infusion of the vein of Marshall (EI-VOM) has been widely used to facilitate mitral isthmus (MI) ablation. According to the literature, the success rate of achieving a bidirectional conduction block across the MI ranges from 51 to 96%, with no standardized strategy or method available for cardiac electrophysiologists.ObjectivesThis study aimed to introduce and evaluate a novel ablation method of MI.MethodsConsecutive patients with persistent atrial fibrillation (PeAF) that underwent catheter ablation were included. The MI ablation procedure followed a stepwise approach. In step 1, ethanol infusion of the vein of Marshall (EI-VOM) was performed. In step 2, a “V-shape” endocardial linear ablation connecting the left inferior pulmonary vein (LIPV) to mitral annulus (MA) was performed. In step 3, earliest activation sites(EASs) near the ablation line were identified using activation mapping followed by reinforced ablation. In step 4, precise epicardial ablation was performed, with the catheter introduced into the coronary sinus(CS) to target key ablation targets (KATs).Results135 patients with PeAF underwent catheter ablation with the stepwise ablation method adopted in 119 cases. Bidirectional conduction blocks were achieved in 117 patients (98.3%). The block rates of every step were 0%, 58.0%, 44.0%, and 92.9%, and the cumulative block rates for the four steps were 0%, 58.0%, 76.5%, and 98.3%, respectively. No patient experienced fatal complications.ConclusionsOur novel stepwise catheter ablation method for MI yielded a high bidirectional block rate with high reproducibility.

Dynamics of Intraprocedural Dominant Frequency Identifies Ablation Outcome in Persistent Atrial Fibrillation.

Background: The role of dominant frequency (DF) in tracking the efficiency of a stepwise catheter ablation (step-CA) in persistent atrial fibrillation (peAF) remains poorly studied. We hypothesized that the DF time-course during step-CA displays divergent patterns between patients in whom a step-CA successfully restores long-term sinus rhythm (SR) and those with recurrence.Methods: This study involved 40 consecutive patients who underwent a step-CA for peAF (sustained duration 19 ± 11 months). Dominant frequency was computed on electrograms recorded from the right and left atrial appendages (RAA; LAA) and the coronary sinus before and during the step-CA synchronously to the 12-lead ECG. Dominant frequency was defined as the highest peak within the power spectrum.Results: Persistent atrial fibrillation was terminated by a step-CA in 28 patients [left-terminated (LT)], whereas 12 patients remaining in AF after ablation [not left-terminated (NLT)] were cardioverted. Over a mean follow-up of 34 ± 14 months, all NLT patients had a recurrence. Among the 28 LT patients, 20 had a recurrence, while 8 remained in SR throughout follow-up. The RAA and V1 DF had the best predictive values of the procedural failure to terminate AF (area under the curve; AUC 0.84, p < 0.05). A decision tree model including a decrease in LAA DF ≥ 6.61% during the first 20 min following pulmonary vein isolation (PVI) and a baseline RAA DF <5.6 Hz predicted long-term SR restoration with a sensitivity of 83% and a specificity of 93% (p < 0.05).Conclusion: This study found that high baseline DF values are predictive of unfavorable ablation outcomes. The reduction of the LAA DF at early ablation steps following PVI is associated with procedural AF termination and long-term SR maintenance.

ECG-Based Indices to Characterize Persistent Atrial Fibrillation Before and During Stepwise Catheter Ablation.

Background: Consistently successful patient outcomes following catheter ablation (CA) for treatment of persistent atrial fibrillation (pers-AF) remain elusive. We propose an electrocardiogram (ECG) analysis designed to (1) refine selection of patients most likely to benefit from ablation, and (2) examine the temporal evolution of AF organization indices that could act as clinical indicators of ongoing ablation effectiveness and completeness.Method: Twelve-lead ECG was continuously recorded in 40 patients (61 ± 8 years) during stepwise CA (step-CA) procedures for treatment of pers-AF (sustained duration 19 ± 11 months). Following standard pre-processing, ECG signals were divided into 10-s epochs and labeled according to their temporal placement: pre-PVI (baseline), dur-PVI (during pulmonary vein isolation), and post-PVI (during complex-fractionated atrial electrograms and linear ablation). Instantaneous frequency (IF), adaptive organization index (AOI), sample entropy (SampEn) and f-wave amplitude (FWA) measures were calculated and analyzed during each of the three temporal steps. Temporal evolution of these measures was assessed using a statistical test for mean value transitions, as an indicator of changes in AF organization. Results were then compared between: (i) patients grouped according to step-CA outcome; (ii) patients grouped according to type of arrhythmia recurrence following the procedure, if applicable; (iii) within the same patient group during the three different temporal steps.Results: Stepwise CA patient outcomes were as follows: (1) left-atrium (LA) terminated, not recurring (LTN, n = 8), (2) LA terminated, recurring (LTR, n = 20), and (3) not LA terminated, all recurring at follow-up (NLT, n = 12). Among the LTR and NLT patients, recurrence occurred as AF in seven patients and atrial tachycardia or atrial flutter (AT/AFL) in the remaining 25 patients. The ECG measures indicated the lowest level of organization in the NLT group for all ablation steps. The highest organization was observed in the LTN group, while the LTR group displayed an intermediate level of organization. Regarding time evolution of ECG measures in dur-PVI and post-PVI recordings, stepwise ablation led to increases in AF organization in most patients, with no significant differences between the LTN, LTR, and NLT groups. The median decrease in IF and increase in AOI were significantly greater in AT/AFL recurring patients than in AF recurring patients; however, changes in the SampEn and FWA parameters were not significantly different between types of recurrence.Conclusion: Noninvasive ECG measures, though unable to predict arrhythmia recurrence following ablation, show the lowest levels of AF organization in patients that do not respond well to step-CA. Increasing AF organization in post-PVI may be associated with organized arrhythmia recurrence after a single ablation procedure.

P979Persistent atrial fibrillation terminated within the left atrium without recurrence at follow-up demonstrates a gradual intracardiac organization during stepwise ablation

Abstract Introduction We previously reported that patients (pts) with recurrence (Rec) after stepwise catheter ablation (step-CA) of persistent atrial fibrillation (pAF) exhibit high bi-atrial intracardiac dominant frequencies (DF) values before ablation, indicative of a severe bi-atrial electro-anatomical remodeling. Purpose Herein, we hypothesized that a gradual decrease in DF values during step-CA is associated with pAF termination and maintenance of sinus rhythm (SR) on the long term. Method In 40 consecutive pts (61±8 yo, sustained AF duration 19±11 months), pulmonary vein isolation (PVI) and left atrium (LA) ablation were performed until pAF termination or cardioversion. 10-sec intracardiac electrograms (EGMs) epochs were recorded before ablation (BL), during PVI and during complex fractionated atrial electrograms (CFAEs) and linear ablation (post_PVI) in the right atrial (RAA) and left atrial (LAA) appendages and in the coronary sinus (CS). DF was defined as the highest peak within the [3–15] Hz EGM spectrum. Rec was defined as any atrial arrhythmia lasting &gt;30 sec during follow-up (FU). Results pAF was terminated within the LA in 70% (28/40, LT) of the pts, while 30% (12/40, NLT) were not. After a mean FU of 34±14 months, all NLT pts had a Rec, while LT pts presented a Rec in 71% (20/28, LT_rec) and remained in SR in 29% (8/28, LT_norec). Figure 1 shows: 1) a gradient in DF values measured in the LAA (panel A), RAA (panel B) and CS (panel C) with the highest values in NLT pts (red), intermediate values in LT_rec pts (yellow) and lowest DF values in LT_norec pts (green); 2) all three groups displayed a gradual intracardiac organization during LA ablation as shown by decreasing DF values (p&lt;0.05, BL vs post_PVI), but the LT_norec pts (green) exhibited the highest relative changes in DF from BL (p&lt;0.05, LT_norec vs NLT, Δ range: −5.31 to −9.69%). Figure 1. Effect of ablation on DF Conclusion Low DF values before ablation and gradual intracardiac organization until pAF termination are associated with maintenance of SR on the long term.

Use of Intraprocedural Ibutilide During Stepwise Ablation of Long-Standing Persistent Atrial Fibrillation.

Catheter ablation is an effective therapy for symptomatic atrial fibrillation (AF). The aim of this study was to assess the effect of ibutilide administration in patients with long standing persistent AF undergoing catheter ablation. We included 25 patients undergoing stepwise catheter ablation with ibutilide 1.0 mg infused prior to mapping and ablation as first step. Procedural and long-term outcomes were compared to a matched cohort of 25 patients in which ibutilide was not used but all other steps remained the same. Mean age of the cohort was 65.6±8.2 years, and duration of persistent AF 71.7±96.8 months. Termination to sinus rhythm (SR) directly or through an atrial tachycardia (AT) was achieved in 88% of patients administered ibutilide (32% SR/68% AT) vs. 64% in the control group. Ibutilide was associated with increased AF mean cycle-length (mCL) (208.3±31.6 vs. 156.0±23.7 ms; p<0.001) and decreased CFE mean surface area (29.2±20.2% vs. 47.3±13.7%; p=0.002). Procedure and radiofrequency (RF) times were less in the ibutilide group (288.8±49.6 vs. 335.3±47.4 min and 66.0±16.0 vs. 78.0±18.2 min; p=0.002 and 0.029 respectively). The 1-year recurrence was 44% in the ibutilide group and 60% in the control groups (p=0.29). Ibutilide patients had significantly reduced ShEn (6.1±0.14 vs. 7.09±0.14; p<0.001) and ShEn was higher in patients that recurred (6.47±0.24 vs. 5.73±0.15; p<0.001). In long-standing persistent AF the use of ibutilide in the context of a stepwise ablation results in increased AF mCL, reduction of fractionation and ShEn and higher rates of AF termination, more often through an intermediate AT. Procedure and RF times are also decreased, without compromising long-term outcomes.

A High Baseline Electrographic Organization Level Is Predictive of Successful Termination of Persistent AtrialFibrillation by Catheter Ablation.

This study sought to investigate whether the level of organization of electrocardiographic (ECG) signals based on novel indexes is predictive of persistent atrial fibrillation (pAF) termination by catheter ablation (CA). Whether the level of ECG organization in pAF is correlated with the restoration of sinus rhythm by CA remains unknown. Thirty consecutive patients who underwent stepwise CA for pAF (sustained duration 19 ± 11 months) were included in the study (derivation cohort). ECG lead V6 was placed on the patients' back (V6b) to improve left atrial (LA) recording. Two novel ECG indexes were computed using an adaptive harmonic frequency tracking scheme: 1) the adaptive organization index (AOI), which quantifies the cyclicity of AF harmonic oscillations; and 2) the adaptive phase index (API), which quantifies the phase coupling between the harmonic components. Index cutoff values predictive of procedural AF termination were then tested on a validation cohort of 8 consecutive patients. In the derivation cohort, CA terminated AF in 21 patients within the LA (70%; left-terminated [LT] group), whereas CA did not terminate AF in 9 patients (30%; non-left-terminated [NLT] group). LT patients displayed a higher ECG organization level at baseline than the NLT patients, with the best separation achieved by AOI and API computed on lead V1 (area under the curve [AUC]= 0.94 and AUC= 0.88, respectively; p< 0.05) and API on lead V6b (AUC= 0.83; p< 0.05). Similar results were obtained for both AOI and API in the validation cohort. Patients in whom pAF terminated within the LA exhibited a higher level of atrial ECG organization, which was suggestive of a limited number of LA drivers than that of patients in whom the pAF could not be terminated by CA.

96-10: Low prevalence of pulmonary vein reconnection and active arrhythmogenic sources at first repeat procedure after stepwise catheter ablation for long-standing persistent atrial fibrillation

96-10: Low prevalence of pulmonary vein reconnection and active arrhythmogenic sources at first repeat procedure after stepwise catheter ablation for long-standing persistent atrial fibrillation

Difference in the maintenance mechanism of atrial fibrillation perpetuated after pulmonary vein isolation between paroxysmal and persistent atrial fibrillation: Effects of subsequent stepwise ablation

BackgroundNeither the atrial fibrillation (AF) maintenance mechanism after pulmonary vein isolation (PVI) nor the mechanism of AF termination via stepwise ablation is clearly understood. MethodsAmong 226 consecutive AF patients (154 paroxysmal (P-AF) and 72 persistent AF (Per-AF) patients), left atrial endocardial non-contact mapping was performed after PVI in the initial 10 P-AF and 16 Per-AF patients to define the AF maintenance mechanism. Subsequently, effect of stepwise catheter ablation (linear roof lesion and complex fractionated atrial electrogram (CFAE) following PVI) was evaluated in all patients. ResultsAfter PVI, AF was maintained by the activation around isolated PV/mitral annulus, focal discharge and disorganized activations mostly observed over residual CFAE region (pivoting activation, wave break and fusion). CFAE region in P-AF was smaller than Per-AF after PVI (1.6±2.1 vs. 7.7±2.5cm2, p<0.0001). The frequency of pivoting activation, wave break and fusion in P-AF were lower than those in Per-AF (1.9±2.0 vs. 11.8±5.0 times/s; p<0.0001, 0.1±0.3 vs. 3.6±2.5 times/s; p<0.001, 5.8±3.6 vs. 9.8±3.2 times/s; p<0.01). AF termination was more frequent in P-AF than Per-AF (94.8% vs 81.9%, p=0.0019). AF termination by PVI alone was more frequent in P-AF than Per-AF (85.6% vs. 18.6%, p<0.0001). However, AF termination via roof line and/or CFAE ablation was less frequent in P-AF than Per-AF (14.4 vs. 81.4%, p<0.0001). ConclusionsDisorganized activations after PVI, more prominent in Per-AF, were associated with residual CFAE region. Most P-AF was terminated by PVI alone, however additional roof line lesion and CFAE ablation were necessary to terminate Per-AF, consistent with mapping results.

Nonlinear analysis of right atrial electrograms predicts termination of persistent atrial fibrillation within the left atrium by catheter ablation

The termination of long-standing persistent atrial fibrillation (LS-pAF) can be achieved by stepwise catheter ablation (step-CA) within the left atrium (LA). Our study aims to applying complexity measures derived from nonlinear time series analysis in order to characterize LS-pAF in terms of organization and to identify patients in whom AF can be terminated from those in whom AF cannot be terminated by step-CA within the LA. A total of 33 consecutive patients (age 61 ± 7 years, sustained AF duration 19 ± 11 months) with LS-pAF underwent step-CA. The organization of right bipolar electrograms before and during the ablation procedure was assessed using the coarse-grained correlation dimension. LS-pAF was terminated into sinus rhythm or atrial tachycardia in 22 patients during step-CA within the LA (left terminated patients—LT). In 11 patients the ablation procedure failed to terminate AF within LA (not left terminated patients—NLT). The statistical analysis of the estimated coarse-grained correlation dimension revealed that a higher right atrial (RA) organization before step-CA was associated to AF termination within the LA. During the ablation procedure, the level of RA organization displayed distinctive evolution between LT and NLT patients with a significant organization increase before AF termination for the LT patients.

Atrial Fibrillation Complexity Parameters Derived From Surface ECGs Predict Procedural Outcome and Long-Term Follow-Up of Stepwise Catheter Ablation for Atrial Fibrillation.

The success rate of catheter ablation for persistent atrial fibrillation (AF) is still far from satisfactory. Identification of patients who will benefit from ablation is highly desirable. We investigated the predictive value of noninvasive AF complexity parameters derived from standard 12-lead ECGs for AF termination and long-term success of catheter ablation and compared them with clinical predictors. The study included a training (93 patients) and a validation set (81 patients) of patients with persistent AF undergoing stepwise radiofrequency ablation. In the training set AF terminated in 81% during catheter ablation, 77% were in sinus rhythm after 6 years and multiple ablations. ECG-derived complexity parameters were determined from a baseline 10-s 12-lead ECG. Prediction of AF termination was similar using only ECG (cross-validated mean area under the curve [AUC], 0.76±0.15) or only clinical parameters (mean AUC, 0.75±0.16). The combination improved prediction to a mean AUC of 0.79±0.13. Using a combined model of ECG and clinical parameters, sinus rhythm at long-term follow-up could be predicted with a mean AUC of 0.71±0.12. In the validation set AF terminated in 57%, 61% were in sinus rhythm after 4.6 years. The combined models predicted termination with an AUC of 0.70 and sinus rhythm at long-term follow-up with an AUC of 0.61. Overall, fibrillation-wave amplitude provided the best rhythm prediction. The predictive performance of ECG-derived AF complexity parameters for AF termination and long-term success of catheter ablation in patients with persistent AF is at least as good as known clinical predictive parameters, with fibrillation-wave amplitude as the best predictor.

Sinus rhythm restoration and arrhythmia noninducibility are major predictors of arrhythmia-free outcome after ablation for long-standing persistent atrial fibrillation: a prospective study.

The impact of restoring sinus rhythm (SR) by initial ablation in patients with long-standing persistent atrial fibrillation (LSPAF) is not fully established. The purpose of this study was to investigate the prognostic value of SR restoration at the initial procedure and arrhythmia noninducibility at the final repeat procedure for long-term outcome. A total of 203 patients (22% female; age 59 ± 9 years) underwent stepwise catheter ablation for LSPAF. The procedural end-point of SR restoration was achieved in 50% of patients. During follow-up (median 48 months) and after 1.7 procedures per patient, 72% of patients were free from arrhythmia off antiarrhythmic drugs. Failure to restore SR was independently predicted by left atrial (LA) long-axis diameter ≥68 mm (relative risk [RR] 1.55, P = .03], proportion of high-voltage LA sites <20% (RR 1.62, P = .02), and left atrial appendage (LAA) atrial fibrillation cycle length (AFCL) <155 ms (RR 1.5, P = .05). Arrhythmia recurrence after the initial procedure was predicted by SR nonrestoration (RR 2.99, P <.000001) and LAA AFCL ≥155 ms (RR 1.90, P = .0002). Arrhythmia recurrence after the final procedure was predicted by SR nonrestoration at the initial procedure (RR 2.83, P = .0007), persistent AF duration ≥24 months (RR 2.74, P = .002), LAA outflow velocity <40 cm/s (RR 2.21, P = .006), and LAA AFCL ≥155 ms (RR 1.92, P = .02). In 115 patients with repeat procedure(s), failure to achieve arrhythmia noninducibility at the final procedure (19% of patients) was associated with arrhythmia recurrence (RR 8.9, P < .000001). SR restoration at the initial procedure and arrhythmia noninducibility at the last repeat procedure were major predictors of arrhythmia-free outcome after ablation for LSPAF.

0170: Long-term success with magnetic navigation catheter ablation in patients with persistent and longstanding persistent atrial fibrillation

Different techniques in catheter ablation (CA) of persistent (Pers) and longstanding (LS) Pers AF have been described with variable outcomes. We report long-term results in a series of Pers AF patients who underwent CA with magnetic navigation (MN). We prospectively included 50 patients (pts; 43 males; 61±10 y) referred for CA of Pers AF. Pers and LS Pers AF were defined according to published guidelines. Freedom from AF is defined as the absence of symptomatic or ECG/Holter documented AF after ablation. All pts underwent stepwise CA using MN: circumferential pulmonary veins isolation, bi-atrial complex fragmented electrograms ablation, roof ± left isthmus ± cavo-tricuspid isthmus lines. Atrial tachycardia (AT) occurring during CA were also targeted. Total duration of AF history was 56±42m (range 4 m-12 y, median 48m). Mean duration of continuous AF was 8±12m (range 1-84m, median 5.5m; 18% LS and 82% Pers AF). AF was lone in 50%. LA size was 30±5cm 2 , CT-scan volume 139±51ml. Procedures’ duration was 256±56 minutes with a fluoroscopy time of 13±5 min. RF time was 47±27 min. AF stopped without electrical cardioversion in 17 pts (34%; sinus rhythm in 8 and AT in 9). A redo CA for recurring AF was performed in 6 pts (12%). Complications (4 pts) resolved w/o sequellae: acute coronary syndrome (1), pericardial effusion (1), AV fistula (1) and intraalveolar haemorrhage (1). After 19.9±9.5m (range 6-40, median 17.5m), with 1.1 procedures/pt, 40 pts (80%) had no AF recurrence, of which 28 were off AAD and 12 remained on AAD. Incidence of postablation AT was 12% (6/50). Magnetic navigation for Pers AF ablation yields excellent (80%) long-term (20m) prevention of AF recurrence (figure next page). Abstract 0170 – Figure: AF-free survival

Adaptive frequency tracking of the baseline ECG identifies the site of atrial fibrillation termination by catheter ablation

Multiple organization indices have been used to predict the outcome of stepwise catheter ablation in long-standing persistent atrial fibrillation (AF), however with limited success. Our study aims at developing innovative organization indices from baseline ECG (i.e. during the procedure, before ablation) in order to identify the site of AF termination by catheter ablation. Seventeen consecutive male patients (age 60±5 years, AF duration 7±5 years) underwent a stepwise catheter ablation. Chest lead V6 was placed in the back (V6b). QRST cancelation was performed from chest leads V1 to V6b. Using an innovative adaptive harmonic frequency tracking, two measures of AF organization were computed to quantify the harmonics components of ECG activity: (1) the adaptive phase difference variance (APD) between the AF harmonic components as a measure of AF regularity, and (2) and adaptive organization index (AOI) evaluating the cyclicity of the AF oscillations. Both adaptive indices were compared to indices computed using a time-invariant approach: (1) ECG AF cycle length (AFCL), (2) the spectrum based organization index (OI), and (3) the time-invariant phase difference TIPD. Long-standing persistent AF was terminated into sinus rhythm or atrial tachycardia in 13/17 patients during stepwise ablation, 11 during left atrium ablation (left terminated patients – LT), 2 during the right atrium ablation (right terminated patients – RT), and 4 were non terminated (NT) and required electrical cardioversion. Our findings showed that LT patients were best separated from RT/NT before ablation by the duration of sustained AF and by AOI on chest lead V1 and APD from the dorsal lead V6b as compared to ECG AFCL, OI and TIPD, respectively. Our results suggest that adaptive measures of AF organization computed before ablation perform better than time-invariant based indices for identifying patients whose AF will terminate during ablation within the left atrium. These findings are indicative of a higher baseline organization in these patients that could be used to select candidates for the termination of AF by stepwise catheter ablation.

Clinical Outcome of Catheter Ablation in Patients With Nonparoxysmal Atrial Fibrillation

Background— Catheter ablation of atrial fibrillation (AF) became an effective therapy for patients with drug-refractory AF, and the indications have broadened to include nonparoxysmal AF patients. However, data about the long-term effectiveness of ablation in patients with nonparoxysmal AF are lacking. The aim of the present study was to investigate the long-term outcomes of catheter ablation in patients with nonparoxysmal AF. Methods and Results— A total of 88 nonparoxysmal AF patients who received a stepwise catheter ablation (isolation of the pulmonary veins plus substrate modification) from 2006 to 2008 were enrolled. Freedom of recurrence was defined as the absence of atrial arrhythmias without using any antiarrhythmic agents after the catheter ablation. There were 63 patients (71.6%) with recurrences (47 patients with AF and 16 patients with atrial flutter/atrial tachycardia) after the initial procedure during a median follow-up period of 36.8 months. A CHADS 2 score of ≥3 and the left atrial (LA) diameter were significant predictors of recurrences in the multivariable analysis. Of the patients with CHADS 2 scores of ≥3 and an LA dimension ≥44 mm, all had recurrences within 1 year after the initial procedure. The overall recurrence-free rate could increase to 47.7% after the second procedure and 51.1% after the third procedure. Conclusions— The long-term recurrence-free rate of ablation in nonparoxysmal AF was only 28.4% after a single procedure, and multiple procedures were necessary to raise the recurrence-free rate. The CHADS 2 score and LA dimension may help us to identify patients who will have recurrences after catheter ablations of nonparoxysmal AF.

Improved outcome following restoration of sinus rhythm prior to catheter ablation of persistent atrial fibrillation: A comparative multicenter study

Catheter ablation of persistent atrial fibrillation (AF) is associated with longer procedure times and lower long-term success rates than that of paroxysmal AF. To test the hypothesis that restoration/maintenance of sinus rhythm (SR) preablation would facilitate AF termination and improve outcomes in patients with persistent AF. We conducted a 2-group cohort study of consecutive patients with persistent AF and SR restored for at least 1 month prior to ablation (SR group; n = 40) and controls matched by age, sex, and AF duration (control group; n = 40). Radiofrequency stepwise catheter ablation was performed in AF for both groups (induced and spontaneous, respectively). Success was defined as freedom from atrial tachyarrhythmia without antiarrhythmic drugs beyond 1 year of follow-up. During the index ablation procedure, AF cycle length was longer in the SR group than in the control group (183 ± 32 ms vs 166 ± 20 ms; P = .06), suggestive of reverse remodeling. In the SR group, AF more frequently terminated during ablation (95.0% vs 77.5%; P <.05) and required less extensive ablation of complex fractionated electrograms (40.0% vs 87.5%; P <.001) and linear lesions (42.5% vs 82.5%; P <.001). Mean procedural (199.8 ± 69.8 minutes vs 283.5 ± 72.3 minutes; P <.001), fluoroscopy (51.0 ± 24.9 minutes vs 96.3 ± 32.1 minutes; P <.001), and radiofrequency energy delivery (47.5 ± 18.9 minutes vs 97.0 ± 30.6 minutes; P <.001) times were shorter in the SR group. Clinical success rates were similar between groups for first (55.0% vs 45.0%; P = .28) and last (80.0% vs 70.0%; P = .28) procedures, during similar follow-up periods (21.1 ± 9.7 months). Restoration of SR prior to catheter ablation for persistent AF whenever possible decreases the extent of ablation with the same high clinical efficacy.

Effects of Stepwise Ablation of Chronic Atrial Fibrillation on Atrial Electrical and Mechanical Properties

This study sought to evaluate the effects of stepwise catheter ablation of chronic atrial fibrillation (AF) on atrial electrical and mechanical properties. Although stepwise catheter ablation of chronic AF is associated with acute arrhythmia termination and a favorable clinical outcome, atrial tissue damage following the procedure has not been evaluated. Forty patients who had previously undergone catheter ablation of chronic AF were studied. In the index procedure, termination of AF was achieved by catheter ablation alone in 36 of 40 patients (90%). Electroanatomical mapping was performed in sinus rhythm > or =1 month after the index procedure, during which the surface area of scar (bipolar voltage of <0.05 mV), low-voltage tissue (<0.5 mV), and atrial propagation were evaluated. Left atrial (LA) mechanical function was assessed by transthoracic echocardiography. Electroanatomical mapping showed areas of scar and low-voltage accounting for 31% +/- 12% and 32% +/- 17% of the total LA surface area respectively, with the ablated pulmonary vein region accounting for 20% +/- 4% of the LA surface area. The area of scar outside the pulmonary vein region represented 14% +/- 12% of the LA surface area using the initial randomized ablation strategy, and 6% +/- 8% (p = 0.02) using a specific ablation strategy. Atrial conduction was diversely affected by ablation with a wide range of LA conduction times observed (range 100 to 360 ms). The LA contraction was shown in all patients by the presence of late diastolic mitral flow (37 +/- 15 cm/s) and a mean LA active emptying fraction of 18 +/- 11%. At 9 +/- 5 months of follow-up, 39 patients (98%) were in sinus rhythm. Stepwise ablation achieving sinus rhythm in patients with chronic AF has a significant impact on LA electrical activity but is associated with recovery of LA function.

Stepwise Catheter Ablation of Chronic Atrial Fibrillation:Importance of Discrete Anatomic Sites for Termination

Background: Chronic atrial fibrillation (CAF) can be acutely terminated using a combination of approaches targeting thoracic veins, left atrial areas showing rapid/heterogeneous electrical activity, and by linear ablation. This observational study emphasizes the crucial role for conventional endocardial mapping to identify discrete anatomical sites, ablation of which is indispensable for the achievement of atrial fibrillation (AF) termination. Methods: Eighty consecutive patients with CAF underwent catheter ablation using the stepwise approach. Pulmonary vein isolation and roof‐line ablation were performed as the initial two steps in all patients. In the presence of locally rapid or heterogeneous activity, ablation was then performed at all sites within the left atrium and coronary sinus (CS) region with the endpoint of local organization or slowing. If AF persisted, the mitral isthmus was targeted. Patients in whom AF terminated during one of these five ablation steps were differentiated from those in whom AF was terminated by radiofrequency ablation at a single discrete anatomic site within 1 minute. Electrograms at discrete anatomic sites of termination were classified according to morphology. Results: Termination of AF was achieved in 69 (86%) patients by ablation alone. In 50 patients (72%), this occurred while following the predetermined ablation schema. In the remaining 19 patients (28%), ablation targeting a discrete site (preferentially located at the CS, the base of left atrial appendage, and the interatrial septum) terminated AF. Such sites were identified by (1) continuous electrical activity and fractionation and (2) bursts of short cycle activity (130–160 msec), centrifugal activation or local activation gradients, indicating sources perpetuating AF. Conclusion: In 28% of patients with termination of CAF, the final successful ablation site is anatomically discrete and displays electrophysiological characteristics that can be effectively identified by point and activation mapping. Failure to identify these sites may significantly reduce the likelihood of termination of CAF by catheter ablation.

Radiofrequency Catheter Ablation of the Anterosuperior and Posteroinferior Atrial Approaches to the AV Node for Treatment of AV Nodal Reentrant Tachycardia

Radiofrequency catheter ablation has been established as a first-line curative treatment modality in patients with symptomatic AV nodal reentrant tachycardia (AVNRT). The successful sites of stepwise catheter ablation approaches of the so-called fast and slow pathways strongly suggest that AVNRT involves the atrial approaches to the AV node. The typical fast pathway ablation sites are located anterosuperior toward the apex of the triangle of Koch, which also contains the compact AV node, whereas the usual slow pathway ablation sites are located posteroinferior toward the base of the triangle of Koch at a greater distance to the compact AV node and bundle of His. Accordingly, ablation studies with large patient cohorts have demonstrated that fast pathway ablation carries a higher risk of inadvertent complete AV block. Thus, the slow pathway is clearly the primary target site, and fast pathway ablation is rarely necessary. Different approaches for slow pathway ablation have been elaborated: anatomically oriented stepwise techniques, ablation guided by double potentials recorded within the area of the slow pathway insertion, and combined techniques. The modern concept of AVNRT suggests that this arrhythmia involves the highly complex three-dimensional nonuniform anisotropic AV junctional area. Accordingly, mapping and ablation studies demonstrated that the anterior approach is not identical with fast pathway ablation, and the posterior approach is not identical with slow pathway ablation. Therefore, it is essential for interventional electrophysiologists to familiarize themselves with the anatomic and electrophysiologic details of this complex and variable specialized AV junctional region. In this review, the anatomic and pathophysiologic aspects of the AV junctional area as they relate to interventional therapy are summarized briefly, and the catheter techniques for ablation of the so-called fast and slow AV nodal pathways for the treatment of AVNRT are described.