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Introduction: Carina breakthrough (CB) at the right pulmonary vein (RPV) can occur after circumferential pulmonary vein isolation (PVI) due to epicardial bridging or transient tissue edema. High-power short-duration (HPSD) ablation may increase the incidence of RPV CB. Currently, the surrogate of ablation parameters to predict RPV CB is not well established. This study investigated predictors of RPV CB in patients undergoing ablation index (AI)-guided PVI with HPSD., Methods: The study included 62 patients with symptomatic atrial fibrillation (AF) who underwent AI-guided PVI using HPSD. Patients were categorized into two groups based on the presence or absence of RPV CB. Lesions adjacent to the RPV carina were assessed, and CB was confirmed through residual voltage, low voltage along the ablation lesions, and activation wavefront propagation., Results: Out of the 62 patients, 21 (33.87%) experienced RPV CB (Group 1), while 41 (66.13%) achieved first-pass RPV isolation (Group 2). Despite similar AI and HPSD, patients with RPV CB had lower contact force (CF) at lesions adjacent to the RPV carina. Receiver operating characteristic (ROC) curve analysis identified CF < 10.5 g as a predictor of RPV CB, with 75.7% sensitivity and 56.2% specificity (area under the curve: 0.714)., Conclusion: In patients undergoing AI-guided PVI with HPSD, lower CF adjacent to the carina was associated with a higher risk of RPV CB. These findings suggest that maintaining higher CF during ablation in this region may reduce the occurrence of RPV CB., (© 2023 Wiley Periodicals LLC.)

Introduction: Despite undergoing an index ablation, some patients progress from paroxysmal atrial fibrillation (PAF) to persistent AF (PersAF), and the mechanism behind this is unclear. The aim of this study was to investigate the predictors of progression to PersAF after catheter ablation in patients with PAF., Methods: This study included 400 PAF patients who underwent an index ablation between 2015 and 2019. The patients were classified into three groups based on their outcomes: Group 1 (PAF to sinus rhythm, n = 226), Group 2 (PAF to PAF, n = 146), and Group 3 (PAF to PersAF, n = 28). Baseline and procedural characteristics were collected, and predictors for AF recurrence and progression were evaluated., Results: The mean age of the patients was 58.4 ± 11.1 years, with 272 males. After 3 years of follow-up, 7% of the PAF cases recurred and progressed to PersAF despite undergoing an index catheter ablation. In the multivariable analysis, a larger left atrial (LA) diameter and the presence of non-pulmonary vein (PV) triggers during the index procedure independently predicted recurrence. Moreover, a larger LA diameter, the presence of non-PV triggers, and a history of thyroid disease independently predicted AF progression., Conclusion: The progression from PAF to PersAF after catheter ablation is associated with a larger LA diameter, history of thyroid disease, and the presence of non-PV triggers. Meticulous preprocedural evaluation, patient selection, and comprehensive provocation tests during catheter ablation are recommended., (© 2023 Wiley Periodicals LLC.)

Introduction: Ventricular arrhythmia (VA) commonly originate from the left ventricular summit (LVS) and results in left ventricular (LV) dysfunction in some patients; however, factors related to LV cardiomyopathy have not been well elucidated. Therefore, this study aimed to investigate the risk factors for LV cardiomyopathy and the outcomes of patients with LVS VA., Methods: Between 2013 and 2018, a total of 139 patients (60.7% men; mean age 53.2 ± 13.9 years old) underwent catheter ablation for LVS VA in two centers. Detailed patient demographics, electrocardiograms, electrophysiological characteristics, and clinical outcomes were analyzed. LV cardiomyopathy was defined as left ventricular ejection fraction (LVEF) <50%., Results: Acute procedural success was achieved in 92.8% of patients. There were 40 patients (28.8%) with LV cardiomyopathy, and the mean LVEF improved from 37.5 ± 9.3% to 48.5 ± 10.2% after ablation (p < .001). After multivariate analysis, the independent factors of LV dysfunction were wider QRS duration (QRSd) of the VA (odds ratio [OR] 1.02; 95% confidence interval [CI]: 1.00-1.04; p = .046) and the absolute earliest activation time discrepancy (AEAD) between epicardium and endocardium (OR 1.05; 95% CI: 1.00-1.09; p = .048). After ablation, the LV function was completely recovered in 20 patients (50%). The factors for LV dysfunction without recovery included wider premature ventricular complex (PVC) QRSd (OR 1.09; 95% CI: 1.02-1.17; p = .012) and poorer LVEF (OR 0.85; 95% CI: 0.74-0.97; p = .020)., Conclusion: In patients with VA from the LVS, PVC QRSd and AEAD are factors associated with deteriorating LV systolic function. Catheter ablation can reverse LV remodeling. Narrower QRSd and better LVEF are associated with better recovery of LV function after ablation., (© 2023 Wiley Periodicals LLC.)

Instruction: We hypothesized that real-time simultaneous amplitude frequency electrogram transform (SAFE-T) during sinus rhythm (SR) is able to identify and characterize the drivers of atrial fibrillation (AF) in nonparoxysmal (NP) AF., Methods: Twenty-one NPAF patients (85.71% males, mean age 52 years old) underwent substrate mapping during SR (SAFE-T and voltage) and during AF (complex fractionated atrial electrograms [CFAE] and similarity index [SI]). After pulmonary veins isolation, extensive substrate ablation was performed with the endpoint of procedural termination or elimination of all SI sites (>63% similarities). Sites with procedural termination and non-termination sites were tagged for postablation SR analysis using SAFE-T., Results: In 74 CFAE sites identified (average of 3 ± 2 sites per person), 28 (37.84%) were identified as termination sites demonstrating a high SI compared with the non-termination sites (80.11 ± 9.57% vs. 45.96 ± 13.38%, p < .001) during AF. During SR, these termination sites have high SAFE-T values and harbor a highly resonant, localized, repetitive high frequency components superimposed in the low frequency components compared with non-termination sites (5.70 ± 3.04 vs. 1.49 ± 1.66 Hz·mV, p < .001). In the multivariate analysis, the termination sites have higher SAFE-T and SI value (p < .001)., Conclusion: AF procedural termination sites harbored signal characteristics of repetitive, high frequency component of individualized electrogram during SR, which can be masked by the low frequency fractionated electrogram and are difficult to see from the bipolar electrogram. Thus, SAFE-T mapping is feasible in identifying and characterizing sites of AF drivers., (© 2023 Wiley Periodicals LLC.)

Introduction: Dynamic display of real-time wavefront activation pattern may facilitate the recognition of reentrant circuits, particularly the diastolic path of ventricular tachycardia (VT)., Objective: We aimed to evaluate the feasibility of LiveView Dynamic Display for mapping the critical isthmus of scar-related reentrant VT., Methods: Patients with mappable scar-related reentrant VT were selected. The characteristics of the underlying substrates and VT circuits were assessed using HD grid multielectrode catheter. The VT isthmuses were identified based on the activation map, entrainment, and ablation results. The accuracy of the LiveView findings in detecting potential VT isthmus was assessed., Results: We studied 18 scar-related reentrant VTs in 10 patients (median age: 59.5 years, 100% male) including 6 and 4 patients with ischemic and nonischemic cardiomyopathy, respectively. The median VT cycle length was 426 ms (interquartile range: 386-466 ms). Among 590 regional mapping displays, 92.0% of the VT isthmus sites were identified by LiveView Dynamic Display. The accuracy of LiveView for isthmus identification was 84%, with positive and negative predictive values of 54.8% and 97.8%, respectively. The area with abnormal electrograms was negatively correlated with the accuracy of LiveView Dynamic Display (r = -.506, p = .027). The median time interval to identify a VT isthmus using LiveView was significantly shorter than that using conventional activation maps (50.5 [29.8-120] vs. 219 [157.5-400.8] s, p = .015)., Conclusion: This study demonstrated the feasibility of LiveView Dynamic Display in identifying the critical isthmus of scar-related VT with modest accuracy., (© 2022 Wiley Periodicals LLC.)

Introduction: Identifying the critical isthmus (CI) in scar-related macroreentrant atrial tachycardia (AT) is challenging, especially for patients with cardiac surgery. We aimed to investigate the electrophysiological characteristics of scar-related macroreentrant ATs in patients with and without cardiac surgery., Methods: A prospective study of 31 patients (mean age 59.4 ± 9.81 years old) with scar-related macroreentrant ATs were enrolled for investigation of substrate properties. Patients were categorized into the nonsurgery (n = 18) and surgery group (n = 13). The CIs were defined by concealed entrainment, conduction velocity less than 0.3 m/s, and the presence of local fractionated electrograms., Results: Among the 31 patients, a total of 65 reentrant circuits and 76 CIs were identified on the coherent map. The scar in the surgical group is larger than the nonsurgical group (18.81 ± 9.22 vs. 10.23 ± 5.34%, p = .016). The CIs in surgical group have longer CI length (15.27 ± 4.89 vs. 11.20 ± 2.96 mm, p = .004), slower conduction velocity (0.46 ± 0.19 vs. 0.69 ± 0.14 m/s, p < .001), and longer total activation time (45.34 ± 9.04 vs. 38.24 ± 8.41%, p = .016) than those in the nonsurgical group. After ablation, 93.54% of patients remained in sinus rhythm during a follow-up of 182 ± 19 days., Conclusion: The characteristics of the isthmus in macroreentrant AT are diverse, especially for surgical scar-related AT. The identification of CIs can facilitate the successful ablation of scar-related ATs., (© 2021 Wiley Periodicals LLC.)

Objectives: This study aimed to assess the comparative efficacy of four ablation strategies on the incidence rates of freedom from atrial fibrillation (AF) or atrial tachycardia (AT) through a 3-year follow-up in patients with persistent AF., Background: The optimal substrate modification strategies using catheter ablation for patients with persistent AF remain unclear., Methods: Patients with persistent AF were enrolled consecutively to undergo each of four ablation strategies: (a) Group 1 (Gp 1, n = 69), pulmonary vein isolation (PVI) plus rotor ablation assisted by similarity index and phase mapping; (b) Gp 2 (n = 75), PVI plus linear ablations at the left atrium; (c) Gp 3 (n = 42), PVI plus the elimination of complex fractionated atrial electrograms; (d) Gp 4 (n = 67), PVI only. Potential confounders were adjusted via a multivariate survival parametric model., Results: Baseline characteristics were similar across the four groups. At a follow-up period of 34.9 ± 38.6 months, patients in Gp 1 showed the highest rate of freedom from AF compared with the other three groups (p = .002), while patients in Gp 3 and 4 showed lower rates of freedom from AT than those of the other two groups (p = .006). Independent predictors of recurrence of AF were the ablation strategy (p = .002) and left atrial diameter (LAD) (p = .01)., Conclusion: In patients with persistent AF, a substrate modification strategy using rotor ablation assisted by similarity index and phase mapping provided a benefit for maintaining sinus rhythm compared with the other strategies. Both ablation strategy and baseline LAD predicted the 3-year outcomes of freedom from AT/AF., (© 2021 The Authors. Journal of Cardiovascular Electrophysiology Published by Wiley Periodicals LLC.)

Introduction: A drug provocation test (DPT) is important for the diagnosis of Brugada syndrome (BrS). The link, however, between dynamic changes of electrocardiography (ECG) features after DPT and unstable ventricular arrhythmia (VA) in BrS remains unknown., Methods: Between 2014 and 2019, we assessed 27 patients with BrS (median age: 37.0 [interquartile range, IQR: 22.0-51.0] years; 25 men), including 9 (33.3%) with a history of unstable VA and 18 (66.7%) without. All patients in the study presented with Brugada-like ECG features before DPT. The ECG parameters and dynamic changes (∆) in 12-lead ECGs recorded from the second, third, and fourth intercostal spaces (ICS) before and at 1, 6, 12, 18, and 24 h after DPT (oral flecainide 400 mg) were analyzed., Results: The total amplitude of V 1 at the third ICS 18 and 24 h after DPT was significantly lower in patients with a history of unstable VA than in those without. Patients with BrS and unstable VAs had a significantly larger ∆ amplitude of V 1 at the second ICS 12 h after DPT than in those without unstable VAs (0.28 [0.18-0.41] mV vs. 0.08 [0.01-0.15] mV, p = .01). A multivariate analysis revealed that the amplitude of V 1 at the third ICS 18 and 24 h after DPT and the ∆ amplitude of V 1 at the second ICS 12 h after DPT were associated with a history of unstable VA., Conclusion: Nonuniform changes and spatiotemporal differences in precordial ECG features after DPT were observed in patients with BrS and these may be surrogate markers for risk stratification., (© 2021 Wiley Periodicals LLC.)

Introduction: Accurate identification of slow conducting regions in patients with scar-related atrial tachycardia (AT) is difficult using conventional electrogram annotation for cardiac electroanatomic mapping (EAM). Estimating delays between neighboring mapping sites is a potential option for activation map computation. We describe our initial experience with CARTO 3 Coherent Mapping (Biosense Webster Inc,) in the ablation of complex ATs., Methods: Twenty patients (58 ± 10 y/o, 15 males) with complex ATs were included. We created three-dimensional EAMs using CARTO 3 system with CONFIDENSE and a high-resolution mapping catheter (Biosense Webster Inc). Local activation time and coherent maps were used to aid in the identification of conduction isthmus (CI) and focal origin sites. System-defined slow or nonconducting zones and CI, defined by concealed entrainment (postpacing interval < 20 ms), CV < 0.3 m/s and local fractionated electrograms were evaluated., Results: Twenty-six complex ATs were mapped (mean: 1.3 ± 0.7 maps/pt; 4 focal, 22 isthmus-dependent). Coherent mapping was better in identifying CI/breakout sites where ablation terminated the tachycardia (96.2% vs 69.2%; P = .010) and identified significantly more CI (mean/chamber 2.0 ± 1.1 vs 1.0 ± 0.7; P < .001) with narrower width (19.8 ± 10.5 vs 43.0 ± 23.9 mm; P < .001) than conventional mapping. Ablation at origin and CI sites was successful in 25 (96.2%) with long-term recurrence in 25%., Conclusions: Coherent mapping with conduction velocity vectors derived from adjacent mapping sites significantly improved the identification of CI sites in scar-related ATs with isthmus-dependent re-entry better than conventional mapping. It may be used in conjunction with conventional mapping strategies to facilitate recognition of slow conduction areas and critical sites that are important targets of ablation., (© 2020 The Authors. Journal of Cardiovascular Electrophysiology Published by Wiley Periodicals, Inc.)

Background: The management of refractory electrical storm (ES) requiring mechanical circulation support (MCS) remains a clinical challenge in structural heart disease (SHD)., Objective: The study sought to explore the 30-day and 1-year outcome of rescue ablation for refractory ES requiring MCS in SHD., Methods: A total of 81 patients (mean age: 55.3 ± 18.9, 73 men [90.1%]) undergoing ablation were investigated, including 26 patients with ES requiring MCS (group 1) and 55 patients without (group 2). The 30-day and 1-year outcome, including mortality and recurrent ventricular tachyarrhythmias (VAs) receiving appropriate implantable cardioverter defibrillators therapies, were assessed., Results: The patients in group 1 were characterized by older age, more ischemic cardiomyopathies, worse left ventricular ejection fraction, and more comorbidities. Thirty days after ablation, overall events were seen in 15 patients (mortality in 10 and recurrent VA in 7), including pumping failure-related mortality in 6 (60%). During a 30-day follow-up, higher mortality was noted in group 1. After a 1-year follow-up, in spite of the higher mortality in group 1 (P < .001), the overall events and VA recurrences were similar between these two groups (P = .154 and P = .466, respectively). There was a significant reduction of VA burden in both groups and two patients had recurrent ES., Conclusion: Higher 30-day mortality was observed in patients undergoing rescue ablation for refractory ES requiring MCS, and pumping failure was the major cause of periprocedural death. Rescue ablation successfully prevented VA recurrences and resulted in a comparable 1-year prognosis between ES with and without MCS., (© 2019 Wiley Periodicals, Inc.)

Background: The relationship between gastroesophageal reflux disease (GERD) and atrial fibrillation (AF) has been previously reported. However, the detailed mechanism remains unknown. In this study, we investigated the effects of acid reflux on the intrinsic cardiac autonomic nervous system, atrial/ventricular electrophysiology, and AF inducibility., Methods: Eighteen rabbits were randomized into three groups: acid reflux (group 1, n = 6), control (group 2, n = 6), and acid reflux with periesophageal vagal blockade (group 3, n = 6). Atrial and ventricular effective refractory periods (ERPs) and AF inducibility were checked at baseline and then hourly until 5 hours after the experiment., Results: Three hours after the experiment, atrial ERP prolongation was noted in groups 2 and 3 (P < .05), whereas shortening of the atrial ERPs was observed in group 1, compared with the baseline. However, no changes were observed in ventricular ERPs in the three groups. The AF inducibility was higher in group 1 than in groups 2 and 3. Pathological examination showed clear esophageal mucosal breaks in groups 1 and 3., Conclusions: In this study, we found that the antimuscarinic blockade prevents GERD induced changes to atrial electrophysiology and susceptibility to AF-making it highly likely that autonomic activity is important in mediating this effect., (© 2019 Wiley Periodicals, Inc.)

Background: Acute failure of radiofrequency ablation (RFA) of ventricular arrhythmias (VAs) occur in 10%-20% of patients and is partly attributed to inadequate lesion depth acquired with standard ablation protocols. Half-normal saline (HNS)-irrigation is a promising strategy to improve the success rate of VA ablation., Objective: This study investigated the efficacy of HNS-irrigated ablation after a failed standard plain normal saline solution (PNSS)-irrigated ablation on idiopathic outflow tract ventricular arrhythmia (OT-VA)., Method: This is a prospective observational study of consecutive patients undergoing RFA of idiopathic OT-VA comparing the efficacy of additional HNS-irrigated ablation for failed standard PNSS-irrigated ablation. Acute failure was defined as persistence of spontaneous VA or persistent inducibility of the clinical VA., Results: Out of 160 OT-VA cases (51 ± 15-year-old, 62 males), 31 underwent HNS irrigation after a failed standard PNSS-irrigated ablation. The HNS group had a significantly longer procedure time (60.06 ± 43.83 vs 37.51 ± 33.40 minutes; P = .013) and higher radiation exposure (31.45 ± 20.24 vs 17.22 ± 15.25 minutes; P = .001) than the PNSS group but provided an additional acute success in 21 of 31 (67.7%) patients. Over a follow-up duration of 7.8 ± 4.6 months, 24 recurrences were identified, including 8 (25.8%) in the HNS and 16 (12.4%) in the PNSS group, with lower freedom from recurrence in the HNS group (log rank P = .009). No major complication was observed., Conclusion: HNS-irrigated ablation after failed standard PNSS-irrigated ablation is safe and additionally improves acute ablation success by 67.7% for idiopathic OT-VA but with a higher rate of recurrence on follow-up. Whether the application of HNS as initial irrigant could result in better outcome requires further investigation., (© 2019 Wiley Periodicals, Inc.)

Introduction: We aimed to clarify the effect of vein of Marshall (VOM) ethanol infusion for treating VOM triggers and/or mitral flutter after first-attempt endocardial ablation in patients with nonparoxysmal atrial fibrillation (AF)., Methods and Results: Of the 254 consecutive patients (age, 56 ± 10 years; 221 male) undergoing catheter ablation for drug-refractory nonparoxysmal AF, 32 (12.6%) received VOM ethanol infusion. The patients were stratified into group 1 (pulmonary vein isolation [PVI], substrate modification, VOM ethanol infusion), group 2 (PVI, substrate modification), and group 3 (PVI alone). Propensity-matched analysis (N = 128) of long-term outcomes (3.9 ± 0.5 years) revealed a higher AF recurrence risk in group 2 (hazard ratio [HR], 4.17; 95% confidence interval [95% CI], 1.63-10.69; P = .003) and group 3 (HR, 1.82; 95% CI, 1.09-3.04; P = .021) than in group 1, as well as a higher atrial arrhythmia recurrence risk in group 2 than in group 1 (HR, 2.42; 95% CI, 1.16-5.03; P = .018). A higher procedural termination rate was observed in group 1 than groups 2 and 3 (41.7% vs 17.2% vs 18.8%; P = .042). On multivariate analysis, VOM ethanol injection was an independent predictor of freedom from recurrence of AF (HR, 0.20; 95% CI, 0.08-0.52; P = .001) and atrial arrhythmia (HR, 0.35; 95% CI, 0.17-0.74; P = .005), whereas a left atrial diameter >45 mm and hypertension were independent risk factors for recurrence. Periprocedural complications rates were comparable among the groups., Conclusion: Adjunctive VOM ethanol infusion is effective and safe for treating nonparoxysmal AF in patients with VOM triggers and/or refractory mitral flutter, providing good long-term freedom from AF and atrial arrhythmia., (© 2019 Wiley Periodicals, Inc.)

Aims: Most left atrial tachycardia (LAT) is associated with atrial fibrillation (AF). The clinical and electrophysiological characteristics and outcomes of LAT without AF have not been investigated. This study sought to determine the long-term ablation outcomes and predictors of recurrence of isolated LAT., Methods: This is a single-center study of consecutive patients with isolated LAT. Atrial arrhythmia recurrence was determined from follow-up records of patients who underwent LAT ablation from 2008 to 2017. Clinical and electrophysiologic characteristics associated with atrial arrhythmia recurrence were identified., Results: A total of 50 patients (53 ± 19 years, 46% male) with 59 LAT (1.16 ± 0.47 per patient) were enrolled. Over a mean follow-up of 37 ± 33 months, atrial arrhythmia recurrence occurred in 22 (44%) patients, 11 with atrial tachycardia (AT) only, five with AF only, and six with concurrent AT and AF. The incidence of pulmonary vein (PV) origins increased significantly in the repeat procedure (P = 0.036). Multivariate analysis identified left ventricular ejection fraction (LVEF) as the only predictor of any atrial arrhythmia recurrence and LAT recurrence, while smoking and identified macroreentrant LAT in the index procedure predicted AF recurrence., Conclusion: This study demonstrated a higher rate of atrial arrhythmia recurrence, including AF, among patients with initially isolated LAT. A lower LVEF predicted any atrial arrhythmia and LAT recurrence, whereas smoking and index macroreentrant AT mechanism predicted long-term AF. PV ATs were frequently observed in recurrent patients irrespective of index procedure origin., (© 2019 Wiley Periodicals, Inc.)

Introduction: Phase singularity (PS) mapping provides additional insight into the AF mechanism and is accurate in identifying rotors. The study aimed to evaluate the feasibility of PS mapping in identifying AF rotors using data obtained from an automatic ultra-rapid high-resolution mapping system with a high-density mini-basket catheter., Methods: Twenty-three pigs underwent rapid right atrial (RA) pacing (RAP 480 bpm) for 5 weeks before the experiment. During AF, RA endocardial automatic continuous mappings with a mini-basket catheter were generated using an automatic ultra-rapid mapping system. Both fractionation mapping and waveform similarity measurements using a PS mapping algorithm were applied on the same recording signals to localize substrates maintaining AF., Results: Seventeen (74%) pigs developed sustained AF after RAP. Three were excluded because of periprocedural ventricular arrhythmia and corrupted digital data. RA fractionation maps were acquired with 6.17 ± 4.29 minutes mean acquisition time, 13768 ± 12698 acquisition points mapped during AF from 581 ± 387 beats. Fractionation mapping identified extensively distributed (66.7%) RA complex fractionated atrial electrogram (CFAE), whereas the nonlinear analysis identified high similarity index (SI > 0.7) parts in limited areas (23.7%). There was an average of 1.67 ± 0.87 SI sites with 0.43 ± 0.76 rotor/focal source/chamber. AF termination occurred in 11/16 (68.75%) AF events in 14 pigs during ablation targeting max CFAE. There was a higher incidence of rotor/focal source at AF termination sites compared with non-AF termination sites (54.5% vs 0%, P = 0.011)., Conclusions: The data obtained from ultra-rapid high-density automatic mapping is feasible and effective in identifying AF rotors/focal sources using PS technique, and those critical substrates were closely related to AF procedural termination., (© 2019 Wiley Periodicals, Inc.)

Background: The reason for recurrence of ventricular arrhythmia (VA) after catheter ablation in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) is not clear., Methods: In this study, 91 ARVC patients (age, 47 ± 13 years; 47 men) who underwent catheter ablation for drug-refractory ventricular arrhythmia (VA) were enrolled. The patients were categorized into single or multiple procedures (n = 28). The baseline characteristics and electrophysiological features of the patients were examined to elucidate the reason of the VA recurrences., Results: A total of 186 VAs were induced during the index procedure and 176 (94.6%) were eliminated. Successful, partially successful, and failed ablations were achieved in 89.0%, 8.8%, and 2.2% of the patients, respectively. During a mean follow-up period of 32 ± 26 months, 35 patients had VA recurrences. Forty-two repeat procedures were performed for 81 induced VAs in 28 patients. Of the 42 repeat procedures, successful, partially successful, and failed ablations were achieved in 37, 4, and 1 of the procedures, respectively. Most of the recurrent VAs (70 [72.9%]) originated from the newly-developed circuits owing to the scar progression. The patients with repeat procedure had worsening right ventricular remodeling. The multivariate analysis revealed that history as endurance athlete significantly predicted the need of a repeat procedure in spite of the initially successful endocardial/epicardial ablation and negative inducibility (hazard ratio: 3.014, 95% confidence interval: 1.493-6.084, P = 0.002)., Conclusions: In spite of the initial complete VA elimination, history as an athlete was associated with scar progression, RV remodeling, and VA recurrences from the newly developed arrhythmogenic substrates/circuit in ARVC., (© 2019 Wiley Periodicals, Inc.)

Background: Epidemiological evidence has shown an association between ambient fine particulate matter (PM2.5) exposure and cardiovascular mortality. Increased ventricular premature complex (VPC) burden can cause left ventricular dilatation and dysfunction. We aimed to investigate the relationship between acute PM2.5 exposure and VPC burden in patients without structural heart disease., Methods: We reviewed 26 820 patients who underwent 24-hour Holter electrocardiogram (ECG) recordings between 1 Jan 2013 and 1 Dec 2016. We enrolled patients with significant idiopathic (structurally normal heart) VPC burden defined as ≥30 VPCs/h (Lown grade 2) who had at least two Holter ECG recordings. The VPC burden between the studies on high and low PM2.5 exposure dates was compared in 24 and 12 hours time periods., Result: Sixty-seven patients (31 men, 56.49 ± 18.35 years) were enrolled. Patients were exposed to 25.63 ± 11.47 and 14.66 ± 7.51 μg/m 3 of PM2.5 during the high and low study dates, respectively. The overall VPC counts (10,490.69 ± 10,681.63/day) and burden (10.22% ± 10.17%) were significantly higher on the days with higher PM2.5 exposure compared with low PM2.5 exposure dates (8293.31 ± 9009.09; P = 0.014% and 9.14% ± 12.73%, P = 0.012, respectively). Compared with low PM2.5 exposure dates, the VPC burden on high exposure dates was significantly higher from 9 am to 9 pm (5.85% ± 6.41% vs 4.84% ± 6.97%; P = 0.025) but not at nocturnal periods., Conclusion: Our study demonstrated a significantly higher VPC burden on high PM2.5 exposure date. The burden was increased in the daytime but not at nighttime. This result suggests that daytime PM2.5 exposure may be associated with ventricular arrhythmia burden in the healthy population., (© 2018 Wiley Periodicals, Inc.)

Introduction: It has not been previously investigated whether the recurrence mechanism after cryoballoon ablation (CBA) of paroxysmal atrial fibrillation (AF) is similar to that of radiofrequency catheter ablation (RFCA). We aimed to evaluate the differences of recurrence characteristics between RFCA and CBA after the index procedure., Methods: A total of 210 patients were enrolled in the study, and 69 patients underwent pulmonary vein (PV) isolation using a 28-mm second-generation CBA. The control group comprising 140 patients underwent PV isolation using an open-irrigated radiofrequency ablation catheter. A total of 69 patients in the CBA group and 69 patients in the RFCA group were investigated after propensity score matching. Recurrence patterns of AF were studied in the repeated procedure., Results: During the index procedure, there was no difference in PV or non-PV triggers between the two groups. Nineteen (27.5%) patients in the CBA group and 19 (27.5%) patients in the RFCA group had recurrence after a follow-up of 11.3 ± 7 months. The Kaplan-Meier curve did not reveal significant difference in recurrence (log-rank, P = 0.364) between the two groups. In the second procedure, the CBA group had more non-PV triggers (63.6%, P = 0.009) and left atrial (LA) flutters (54.5%, P = 0.027) compared with the RFCA group (12.5% and 12.5%, respectively). The PV reconnection rates were similar between both groups., Conclusions: There was no difference in AF recurrence after catheter ablation between CBA and RFCA, but significant increases of non-PV triggers and LA flutter during the second procedure suggest the importance of the atrial substrate in maintaining AF during the second procedure after previous CBA., (© 2018 Wiley Periodicals, Inc.)

Background: Coexistence of idiopathic left fascicular ventricular tachycardia (ILFVT) and atrioventricular nodal reentrant tachycardia (AVNRT) has been rarely reported., Objectives: The study aimed at elucidating the prevalence of coexisted AVNRT in patients with ILFVT during longitudinal follow-up. The electrophysiological properties and clinical predictors of coexisted ILFVT and AVNRT were investigated., Methods: From 1999 to 2017, a total of 108 patients (age: 33.7 ± 14.3, 84 male) with ILFVT from one tertiary center were consecutively enrolled. The prevalence of coexisted arrhythmias was explored during a longitudinal follow-up and the electrophysiological parameters from the index procedure were compared., Results: During a mean follow-up period of 106.8 ± 69.5 months, 21 of 108 patients (19.4%) had coexisted AVNRT. The electrophysiological study demonstrated patients with coexisted ILFVT and AVNRT were characterized by more antegrade dual AV node conduction (52.4% vs. 19.5%, P = 0.002; 9.5%), shorter antegrade slow pathway effective refractory period (285.1 ± 34.1 ms vs. 329.2 ± 69.2 ms, P = 0.034), longer retrograde fast pathway effective refractory period (368.9 ± 56.7 ms vs. 312.5 ± 95.2, P = 0.036), and less VA dissociation (19.0% vs. 60.9%, P = 0.001) than those without a coexisted AVNRT. Multivariate logistic analysis showed that presence of antegrade dual AV nodal physiology and retrograde VA conduction could predict a coexisted AVNRT in patients with ILFVT (P = 0.005, OR: 4.80, 95% CI: 1.65-14.37 and P = 0.002, OR: 0.14, 95% CI: 0.04-0.49, respectively)., Conclusion: There was a high prevalence of coexisted AVNRT in patients with ILFVT during longitudinal follow-up. The presence of antegrade dual AV nodal physiology and retrograde VA conduction can predict the coexisted AVNRT in patients with ILFVT., (© 2018 Wiley Periodicals, Inc.)

Introduction: Cigarette smoking contributes to the development of atrial fibrosis via nicotine. The impact of smoking on ablation results in persistent atrial fibrillation (AF) is unknown. We aimed to investigate the triggers and long-term outcome between smokers and nonsmokers in the patients with persistent AF after catheter ablation., Methods: This study included 201 (177 males, 53 ± 10 years old) patients who received index catheter ablation, including pulmonary vein isolation (PVI) and complex fractionated atrial electrograms (CFAEs) ablation for persistent AF, retrospectively. Electrophysiological characteristics at the index procedure and long-term outcome were investigated to determine the differences between smokers and nonsmokers., Results: Baseline characteristics were similar between two groups. Pulmonary vein (PV) triggers were found in all patients in the two groups. There was a higher incidence of nonpulmonary vein (NPV) triggers in smokers than in nonsmokers (61% vs. 31%, P < 0.05). There were no differences of the long-term ablation outcomes between smokers and nonsmokers in Kaplan-Meier analysis. Smokers with PV plus right atrial NPV (RA-NPV) triggers had a higher incidence of recurrence (log-rank P < 0.05) than those without RA-NPV triggers, but not in nonsmokers, after a mean follow-up of 31 ± 25 months., Conclusions: Smoking increases the incidence of NPV triggers in patients with persistent AF. Smokers who have RA-NPV triggers during index procedure do have a worse outcome after catheter ablation, indicating the harmful effects of nicotine to right atrium., (© 2018 Wiley Periodicals, Inc.)

Background: Septal ventricular outflow tract ventricular arrhythmias (OT-VAs) are defined as septal origin VAs from the right ventricular or left ventricular OT. Patients with septal OT-VAs may require a sequential bilateral OT ablation. This study aimed to evaluate the electrophysiological characteristics and ablation outcome in patients with septal OT-VAs., Methods: We retrospectively analyzed the electrocardiography and electrophysiological parameters in 96 patients (mean age 49 ± 15 years, 49 male) undergoing bilateral activation mapping before catheter ablation of idiopathic septal OT-VAs. The patients were categorized into three groups based on the successful ablation sites, including the right ventricular outflow tract (RVOT), RVOT/left ventricular outflow tract (LVOT), and LVOT., Results: Mapping in the three groups demonstrated a gradually decreasing and increasing trend in the earliest activation time obtained from the RVOT and LVOT, respectively. The absolute earliest activation time discrepancy (AEAD) of ≤18 milliseconds could predict the requirement for a sequential bilateral ablation with a sensitivity and specificity of 100.0% and 93.7%, respectively. The small AEAD (≤21 milliseconds) was associated with a higher recurrence rate in patients receiving a successful unilateral ablation, while patients with a longer distance between the bilateral OT earliest activation sites (DEA > 26 mm) increased future recurrences after an initially successful sequential bilateral ablation., Conclusions: The application of bilateral OT-VA activation mapping and the measurement of the AEAD and DEA provided not only pivotal information for the ablation strategy, but also prognostic implications for recurrences in patients with septal OT-VAs., (© 2017 Wiley Periodicals, Inc.)

Introduction: Various ECG algorithms have been proposed to identify the origin of idiopathic outflow tract (OT)-ventricular arrhythmia (VA). However, electrocardiographic features of failed and recurrent right ventricular outflow tract (RVOT) ablation of idiopathic OT-VAs have not been clearly elucidated., Methods and Results: A total of 264 consecutive patients (mean age: 44.0 ± 13.0 years, 96 male) undergoing RVOT ablation for OT-VAs with a transition ≥V 3 , including 241 patients (91.6%) with initially successful procedures and 23 patients (8.4%) with failed ablation. Detailed clinical characteristics and ECG features were analyzed and compared between the two groups. VAs with failed RVOT ablation had larger peak deflection index (PDI), longer V 2 R wave duration (V 2 Rd), smaller V 2 S wave amplitude, higher R/S ratio in V 2 , higher V 3 R wave amplitude, and larger V 2 transition ratio than those with successful ablation. Multivariate analysis demonstrated that PDI, V 2 Rd, V 2 transition ratio, and pacemapping score acquired during mapping independently predicted failed ablation (P  =  0.01, P  =  0.01, P  =  0.01, and P < 0.001, respectively). In 31 recurrent cases (12.8%) after initially successful ablation, multivariate Cox regression analysis showed that only the earliest activation time acquired during mapping predicted the recurrences after successful ablation (P  =  0.001). The recurrent cases displayed different ECG features comparing with those with failed ablation., Conclusion: The electrocardiographic features of failed RVOT ablation of idiopathic OT-VAs with a transition ≥V 3 were characterized by PDI, V 2 Rd, V 2 transition ratio, and pacemapping score acquired during mapping, unlike the recurrent RVOT ablation., (© 2017 Wiley Periodicals, Inc.)

Introduction: Although rare, some paroxysmal atrial fibrillations (AF) still progress despite radiofrequency (RF) ablation. In the study, we evaluated the long-term efficacy of RF ablation and the predictors of AF progression., Methods: A total of 589 paroxysmal AF patients (404 men and 185 women; aged 54 ± 12 years) who received 3-dimensional mapping and ablation were enrolled. Their clinical parameters and electrophysiological characteristics were collected. They were divided into Group 1 (N = 13, with AF progression) and Group 2 (N = 576, no AF progression). AF progression was defined as recurrence of persistent AF., Results: Group 1 patients had larger left atrial (LA) diameter, larger left ventricle (LV) end-systolic and end-diastolic diameters, poorer LV systolic function, and more amiodarone use at baseline. After 1.2 ± 0.5 procedures, 123 (21%) patients experienced recurrence during 56 ± 29 months' follow-up. In the multivariate analysis, LA diameter (P = 0.018, HR = 1.12, 95% CI = 1.02-1.24) and LV end-systolic diameter (P = 0.005, HR = 1.10, 95% CI = 1.03-1.17) independently predicted AF progression. LA diameter >43 mm and LV end-systolic diameter >31 mm were the best cut-off values for predicting AF progression by ROC analysis. AF progression rate achieved 19% if they had both larger LA diameter (>43 mm) and LV end-systolic diameter (>31 mm)., Conclusion: RF ablation prevents the progression of paroxysmal AF effectively, except in patients with increased LA diameter and LV end-systolic diameter on echocardiogram, suggesting more aggressive rhythm control therapies should be considered in these patients., (© 2016 Wiley Periodicals, Inc.)

Background: The recurrence of atrial fibrillation (AF) is not uncommon in the era of catheter ablation. This study aimed to evaluate the characteristics of AF patients who underwent multiple (>2) ablation procedures., Methods and Results: Of 666 consecutive patients (53 ± 11 y/o, 484 men) who underwent catheter ablation of AF (paroxysmal AF, n = 530), 144 (22%) underwent 2 procedures and 52 (8%) underwent more than 2 procedures due to symptomatic recurrences refractory to medication during 48 ± 23 months of follow-up. Baseline and procedural characteristics at the index procedure were investigated to determine their impact on the necessity of multiple procedures. After 2 procedures, 48 (92%) of 52 patients had pulmonary vein (PV) ectopic beats initiating AF. Coexisting PV and non-PV triggers were found in 23 of 48 patients. In a multivariate analysis, the presence of non-PV triggers (P = 0.004; odds ratio 2.69, 95% CI 1.37-5.28) at the index procedure was the only independent predictor of necessary multiple procedures. Among patients with non-PV ectopic beats initiating AF at the index procedure, the presence of ligament of Marshall triggers (P = 0.001, odds ratio 6.74, 95% CI 2.13-21.32) could predict the necessity of multiple procedures., Conclusions: The need for multiple catheter ablation procedures can be predicted by the presence of non-PV ectopic beats initiating AF at the index procedure. However, PV-initiated AF remains the major cause of AF recurrence despite multiple catheter ablation procedures., (© 2015 Wiley Periodicals, Inc.)

A 44-year-old man with structurally normal heart underwent catheter ablation of left ventricular summit tachycardia. The initial mapping revealed the origin of tachycardia at the junction of great cardiac vein and anterior interventricular vein. During ablation the exit site shifted to the nearby regions, which was recognized by subtle changes of 12-lead ECG. Mapping and ablating at different exit sites rendered the tachycardia noninducible., (© 2014 Wiley Periodicals, Inc.)

Introduction: The characteristics of endocardial electrograms needed to detect the overlying abnormal epicardial substrates in arrhythmogenic right ventricular cardiomyopathy with epicardial ventricular tachycardia (VT) remain unclear. This study investigated which of the endocardial electrogram characteristics could predict the overlying abnormal epicardial substrates., Methods and Results: In 20 consecutive patients (median age: 46 years, 11 men) undergoing epicardial VT ablation, detailed endocardial and epicardial mappings were obtained by using the CARTO 3 system. The endocardial electrographic characteristics (unipolar peak-to-peak voltage, unipolar peak-negative-voltage, bipolar voltage, and bipolar electrogram duration) of the opposite endocardium and epicardium in RV were retrospectively investigated (N = 1,697 paired points, 84 ± 60 pairs/patient). Endocardial predictors of the presence of epicardial dense scar (<0.5 mV), low voltage zones (LVZ; ≤1.5 mV), and ablation targets (by using activation mapping, entrainment mapping, and pace mapping) were analyzed., Results: In the multivariable analysis, (1) unipolar peak-negative voltage independently predicted the presence of epicardial LVZ, epicardial dense scar, and ablation targets; (2) bipolar voltage could not predict epicardial lesions; and (3) bipolar electrogram duration predicted epicardial LVZ, but not dense scar or ablation targets. The endocardial unipolar peak-negative voltage of <1.66 mV (89% sensitivity and 53% specificity) was the optimal cutoff point for predicting epicardial dense scar., Conclusions: In patients with RV epicardial VT, the presence of unipolar peak-negative voltage of <1.66 mV in the endocardium predicted the presence of epicardial dense scar (<0.5 mV) and potential ablation targets in the overlying epicardium., (© 2014 Wiley Periodicals, Inc.)

Introduction: The optimal substrate ablation approach in patients with persistent atrial fibrillation (Per AF) remains unclear. This was a prospective randomized study comparing the efficacy of limited (continuous complex fractionated atrial electrogram, CFAE: <60 milliseconds) versus extensive (continuous CFAE plus variable CFAE: <120 milliseconds) atrial substrate modification in Per AF patients., Methods and Results: We enrolled 120 Per AF patients in the study, and 30 patients with AF termination after pulmonary vein isolation (PVI) were excluded. In the remaining 90 patients, 45 were treated with limited approach (Group 1) and 45 with an extensive approach (Group 2). The end point of the study was the incidence of an atrial arrhythmia recurrence postblanking period. The patients were followed up for 15 months with 3-month clinical reviews, electrograms (ECGs), Holter recordings, and echocardiographic monitoring. Procedural AF termination and the single procedural efficacy were statistically comparable between the 2 groups (48.9% vs. 63.4% in Groups 1 and 2, respectively, P = 0.289). During the follow-up, patients who received limited ablation had a lower incidence of recurrent AFL (P = 0.04), and better reverse remodeling of the left atrium (LA, P = 0.04). After 2 procedures, the freedom from any atrial arrhythmia was better in Group 2 (62.2% vs. 87.8%, P = 0.009). Those with longstanding AF and a larger baseline LA size responded better to the extensive ablation., Conclusions: In the Per AF patients who failed to achieve AF termination after PVI alone, a specific atrial substrate modification approach targeting only continuous CFAEs could be considered as an initial ablation strategy., (© 2014 Wiley Periodicals, Inc.)

Introduction: Antitachycardia pacing (ATP), a quick, painless, and effective therapy available in implantable cardioverter-defibrillators (ICDs), can terminate most, but not all, sustained ventricular tachycardias (VTs). This study investigated the possible ventricular electrogram (EGM) factors for predicting the effectiveness of ATP therapy from ICD recordings., Methods and Results: In this study, we analyzed 113 EGMs of VT episodes acquired from 20 patients who received ATP or shock to terminate tachyarrhythmias during follow-up after ICD implantations. The relationship between the outcome of ATP and VT EGM features (such as voltage, width, cycle length, and beat-to-beat morphologic variation) was investigated. The divergence (beat-to-beat morphologic variation) of the VT EGMs was determined by calculating the total deviation of all EGMs away from the average template after all VT EMGs were aligned. In total, 72 (63.7%) successful (Group I) and 41 (36.3%) unsuccessful (Group II) ATP therapy episodes were analyzed. The mean amplitude, cycle length, and EGM width were similar between these 2 groups (P > 0.05). A multivariate analysis demonstrated that the only predictor of successful ATP was the divergence among the VT EGMs (0.56 ± 0.32 vs 1.07 ± 0.64, P < 0.001, for Groups 1 and 2, respectively). The optimal cutoff value for determining a successful ATP therapy was 0.73 (with an area under the curve of 0.769, sensitivity of 81.9% [95% CI = 71.1-90.0], and specificity of 65.9% [95% CI = 49.4-79.9], P < 0.0001)., Conclusion: Signal analyses from stored EGMs of VT can predict the response of ATP therapy in patients with ICD implantations. A lesser ventricular beat-to-beat morphologic variation in the intracardiac recordings from ICDs correlated with a higher probability of a successful ATP., (© 2013 Wiley Periodicals, Inc.)

Introduction: Autonomic modulation of the cardiac activity plays an important role in the pathogenesis of atrial fibrillation (AF). The aim of this study was to assess the differences in the atrial electrical and structural properties between patients with vagal and sympathetic AF., Methods: The study included 30 patients (53 ± 12 years old, male 26) with frequent attacks of symptomatic paroxysmal AF. All cases underwent 24-hour ambulatory Holter monitoring before the catheter ablation. The onset of AF accompanied with an increased HF component and decreased L/H ratio was designated as a vagal type (group 1, n = 12), whereas a decreased HF component and increased L/H ratio was classified as a sympathetic type (group 2, n = 18). Electrical and structural properties were evaluated during the ablation procedure., Results: All patients had AF originating from PVs. There was a higher incidence of non-PV triggers in group 2 patients than that in group 1 (44% vs 8%, P = 0.04). Group 1 had a higher bipolar peak-to-peak voltage and mean DF of the global left atrium (LA), shorter total activation time, and smaller LA volume than group 2, whereas the electrical and structural properties in the right atrium were similar. After a follow-up of 15 ± 7 months, there was a lower incidence of AF recurrence in group 1 than that in group 2 (0% vs 28%, P = 0.02)., Conclusion: There are better electrical properties and a smaller LA volume in patients with vagal-type AF. In contrast, the LA substrate is worse, and coexisting non-PV triggers and recurrence following ablation are more prevalent in patients with the sympathetic-type AF., (© 2013 Wiley Periodicals, Inc.)

Introduction: Heart failure (HF) increases the susceptibility to atrial fibrillation (AF) and is associated with altered cardiomyocyte connexin. The regional remodeling of connexin(s) may contribute to the spatiotemporal organization of AF. This study sought to investigate the regional differences in connexin(s) and fibrosis in specific atrial regions and correlate that with the electrogram properties., Methods and Results: Biatrial electroanatomic mapping during sinus rhythm (electrogram voltage and velocity) and AF (dominant frequency, DF) was performed in 6 ventricular pacing-induced HF dogs (at 252 beats/minute for 6 weeks) and 6 controls. Atrial tissues were sampled from 7 specific sites for analysis of the connexin and fibrosis. HF caused marked atrial dilatation, and increased the induced AF duration (P < 0.001). Remodeled connexins, including a lower expression and more lateralization of both connexin40 (Cx40) and Cx43 as well as increased regional dispersion of Cx40, in the presence of diffuse enhanced atrial fibrosis, characterized the atrial substrate of the HF dogs (P < 0.01). Regional analysis showed abnormal velocity and low electrogram voltage in the areas with downregulated Cx40 and Cx43 was enhanced in the presence of marked atrial fibrosis (>30% of area, P < 0.01). During AF, lower expression of the Cx40 was associated with higher DF in areas of less and more fibrosis, respectively (R = 0.67 and 0.58, P < 0.01)., Conclusions: An altered expression of connexins correlated with the electrogram properties in the existence of diffuse enhanced atrial fibrosis associated with HF. The regional remodeling of Cx40 is likely an important factor in the maintenance of AF in HF., (© 2013 Wiley Periodicals, Inc.)

Introduction: Atrial fibrillation (AF) is associated with increased risk of embolic stroke. Catheter ablation of AF provides an effective therapy for patients with symptomatic and drug-refractory AF. The aim of this study was to evaluate whether the atrial electromechanical interval is useful in identifying patients at risk of stroke after successful catheter ablation., Methods and Results: A total of 279 AF patients who received catheter ablation and showed no evidence of recurrences were enrolled. Electromechanical interval (PA-PDI) was determined as the time interval from the initiation of P wave deflection to the peak of mitral inflow A wave on pulse wave Doppler imaging. The PA-PDI interval was measured for each patient after the 3-month blanking period of catheter ablation. The clinical endpoint was the occurrence of ischemic stroke. During the follow-up of 46.5 ± 17.2 months, 6 patients suffered from ischemic strokes. Patients with strokes had higher CHA2DS2-VASc scores and longer PA-PDI intervals (138.7 ± 12.4 ms vs 161.2 ± 7.7 ms, P value < 0.001) compared to those without strokes. At a cutoff point of 150 ms identified by ROC curve, the positive and negative predictive values of the PA-PDI interval to predict stroke were 86.7% and 100%, respectively. The PA-PDI interval improved the predictive performance of the CHA2DS2-VASc score, and the area under the ROC curve increased from 0.75 to 0.85., Conclusions: Our results suggest that the PA-PDI interval is a useful tool to identify patients with high risk of stroke after successful catheter ablation of AF., (© 2012 Wiley Periodicals, Inc.)

Introduction: Data regarding the long-term outcome of catheter ablation in patients with nonpulmonary vein (NPV) ectopy initiating atrial fibrillation (AF) are limited. We aimed to evaluate the long-term result of patients with AF who had NPV triggers and underwent catheter ablation., Methods and Results: The study included 660 consecutive patients (age 54 ± 11 years old, 477 males) who had undergone catheter ablation for AF. Group 1 consisted of 132 patients with AF initiating from the NPV, and group 2 consisted of 528 patients with AF initiating from pulmonary vein (PV) triggers only. Patients from Group 1 were younger than those from Group 2 (51 ± 12 years old vs 54 ± 11 years old, P = 0.001) and were more likely to be females (34.4% vs 25.8%, P = 0.049). The incidences of nonparoxysmal AF (36.4% vs 16.3%, P < 0.001) and right atrial (RA) enlargement (31.3% vs 19%, P = 0.004) were higher, and the biatrial substrates were worse in Group 1 than those in Group 2 (left atrial voltage 1.5 ± 0.7 mV vs 1.9 ± 0.7 mV, P < 0.001, RA voltage 1.6 ± 0.5 mV vs 1.8 ± 0.6 mV, P = 0.014). During a follow-up period of 46 ± 23 months, there was a higher AF recurrence rate in Group 1 than in Group 2 (57.6% vs 38.8%, P < 0.001). The independent predictors of AF recurrence were NPV trigger (P < 0.001, HR 2, 95% CI 1.4-2.85), nonparoxysmal AF (P = 0.021, HR 1.55, 95% CI 1.07-2.24), larger left atrial diameter (P = 0.002, HR 1.04, 95% CI 1.02-1.07) and worse left atrial substrate (P = 0.028, HR 1.3, 95% CI 1.03-1.64)., Conclusion: Compared to AF originating from the PV alone, AF originating from the NPV ectopy showed a worse outcome., (© 2012 Wiley Periodicals, Inc.)

Introduction: Currently, the identification of complex fractionated atrial electrograms (CFEs) in the substrate modification is mostly based on cycle length-derived algorithms. The characteristics of the fibrillation electrogram morphology and their consistency over time are not clear. The aim of this study was to optimize the detection algorithm of crucial CFEs by using nonlinear measure electrogram similarity., Methods and Results: One hundred persistent atrial fibrillation patients that underwent catheter ablation were included. In patients who required CFE ablation (79%), the time-domain fibrillation signals (6 seconds) were acquired for a linear analysis (mean fractionation interval and dominant frequency [DF]) and nonlinear-based waveform similarity analysis of the local electrograms, termed the similarity index (SI). Continuous CFEs were targeted with an endpoint of termination. Predictors of the various signal characteristics on the termination and clinical outcome were investigated. Procedural termination was observed in 39% and long-term sinus rhythm maintenance in 67% of the patients. The targeted CFEs didn't differ based on the linear analysis modalities between the patients who responded and did not respond to CFE ablation. In contrast, the average SI of the targeted CFEs was higher in termination patients, and they had a better outcome. Multivariate regression analysis showed that a higher SI independently predicted sites of termination (≥ 0.57; OR = 4.9; 95% CI = 1.33-18.0; P = 0.017)., Conclusions: In persistent AF patients, a cycle length-based linear analysis could not differentiate culprit CFEs from bystanders. This study suggested that sites with a high level of fibrillation electrogram similarity at the CFE sites were important for AF maintenance., (© 2012 Wiley Periodicals, Inc.)

Introduction: Pulmonary vein isolation (PVI) is the primary ablation therapy in patients with atrial fibrillation (AF). We hypothesized that high dominant frequency (DF) sites (AF nests during sinus rhythm [SR]) adjacent to the PV ostia are associated with the atrial substrate that maintains AF, and PVI incorporating the high-frequency AF nests may have a higher efficacy., Methods and Results: In a prospective and randomized comparison, 126 symptomatic paroxysmal AF patients that underwent PVI were enrolled. We compared the efficacy of a modified PVI (ablation line: 1.0-1.5 cm from the PV ostium with encircling the AF nests [spectral analysis with DF >70 Hz during SR, Group II]) versus the anatomy-guided conventional PVI (Group I). In Group II, the DF value along the PV ostium was lower than 70 Hz after the PVI. The primary endpoint was the freedom from symptomatic atrial arrhythmias after a single procedure. We also followed the autonomic function by a time-domain analysis of the heart rate variability. In both groups, AF nests were observed and electric isolation was successfully obtained in all patients. With a mean duration of 16 ± 6.1 months of follow-up, Group II had a higher single procedure efficacy without drugs (78.7% vs 66.1%, log-rank test: P = 0.02), and fewer repeat procedures (6.6% vs 23%; P = 0.04), as compared to Group I., Conclusion: PVI incorporating the high frequency AF nests adjacent to the PV ostia had a better single procedure efficacy., (© 2012 Wiley Periodicals, Inc.)

Unlabelled: Long-Term Outcome of SVC AF Ablation., Introduction: Data of the long-term clinical outcome after superior vena cava (SVC) isolation are limited. We aimed to evaluate the long-term outcome in patients with atrial fibrillation (AF) who had triggers originating from the SVC and received catheter ablation of AF., Methods and Results: The study consisted of 68 patients (age 56 ± 12 years old, 32 males) who underwent the ablation procedure for drug-refractory, symptomatic paroxysmal AF originating from the SVC since 1999. Group 1 consisted of 37 patients with AF initiated from the SVC only, and group 2 consisted of 31 patients with both SVC and pulmonary vein (PV) triggers. During a follow-up period of 88 ± 50 months, the AF recurrence rate was 35.3% after a single procedure. The freedom-from-AF rates were 85.3% at 1 year and 73.3% at 5 years. In the baseline study, group 2 had larger left atrium (38 ± 4 mm vs 36 ± 5 mm, P = 0.04), left ventricle (50 ± 5 mm vs 46 ± 5 mm, P = 0.003), and PV diameters. Kaplan-Meier survival analysis showed a higher AF recurrence rate in group 2 compared to that in group 1 (P = 0.012). The independent predictor of an AF recurrence was a larger SVC diameter (P = 0.02, HR 1.4, 95% CI 1.1-1.8)., Conclusion: Among the patients with paroxysmal AF originating from the SVC, 73% remained free of AF for 5 years after a single catheter ablation procedure. Superior vena cava isolation without PV isolation is an acceptable therapeutic strategy in those patients with AF originating from the SVC only. The SVC diameter was an independent predictor of AF recurrence. (J Cardiovasc Electrophysiol, Vol. 23, pp. 955-961, September 2012)., (© 2012 Wiley Periodicals, Inc.)

Introduction: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a major cause of sudden cardiac death due to tachyarrhythmias. The purpose of this study was to investigate the long-term prognosis in patients with ARVC and the incidence of rapid ventricular arrhythmias during follow-up., Methods: Thirty ARVC patients (19 male, 63.3%, mean age 48 ± 15 years) fulfilling modified Task Force criteria 2010 were included. Of them, 13 patients (43.3%) received implantable cardioverter-defibrillator (ICD) implantation. Rapid ventricular arrhythmia was defined as electrical storm or the occurrence of ventricular tachycardia (VT) or ventricular fibrillation (VF) with a cycle length of 240 ms or less that necessitate shock delivery to 2 or more times within a 24-hour period., Results: With a mean follow-up of 68 ± 10 months, 6 patients (20%) with ICD implantation had recurrent rapid VT/VF. One (3.3%) of them died of multiple shocks and SCD, and 5 (16.7%) had multiple ICD therapies due to VT/VF and electrical storm. The interval between the diagnosis of ARVC and occurrence of rapid VT/VF was 13.4 ± 4.9 months. Most (5/6, 83.3%) events of recurrent rapid VT/VF occurred within 2 years. Ablated patients who did not receive an ICD implant were totally free of rapid VT/VF., Conclusions: For patients with ARVC, long-term prognosis is favorable. During a long-term follow-up, patients meeting the criteria for ICD implantation have a higher rate of rapid and potentially life-threatening arrhythmias. However, early and clustered recurrence of rapid VT/VF in patients with an ICD is common, whereas late occurrence of rapid VT/VF is very rare., (© 2012 Wiley Periodicals, Inc.)

Background: The atrial substrate in chronic atrial fibrillation (AF) patients with a left atrial spontaneous echo contrast (LASEC) has not been previously reported. The aim of this study was to investigate the atrial substrate properties and long-term follow-up results in the patients who received catheter ablation of chronic AF., Methods: Of 36 consecutive patients with chronic AF who received a stepwise ablation approach, 18 patients with an LASEC (group I) were compared with 18 age-gender-left atrial volume matched patients without an LASEC (group II). The atrial substrate properties including the weighted peak-to-peak voltage, total activation time during sinus rhythm (SR), dominant frequency (DF), and complex fractionated electrograms (CFEs) during AF in the bi-atria were evaluated., Result: The left atrial weighted bipolar peak-to-peak voltage (1.0 ± 0.6 vs 1.6 ± 0.7 mV, P = 0.04), total activation time (119 ± 20 vs 103 ± 13 ms, P < 0.001) and DF (7.3 ± 1.3 vs 6.6 ± 0.7 Hz, P < 0.001) differed between group I and group II, respectively. Those parameters did not differ in the right atrium. The bi-atrial CFEs (left atrium: 89 ± 24 vs 92 ± 25, P = 0.8; right atrium: 92 ± 25 vs 102 ± 3, P = 0.9) did not differ between group I and group II, respectively. After a mean follow-up of 30 ± 13 month, there were significant differences in the antiarrhythmic drugs (1.1 ± 0.3 vs 0.7 ± 0.5, P = 0.02) needed after ablation, and recurrence as persistent AF (92% vs 50%, P = 0.03) between group I and group II, respectively. After multiple procedures, there were more group II patients that remained in SR, when compared with group I (78% vs 44%, P = 0.04)., Conclusion: There was a poorer atrial substrate, lesser SR maintenance after catheter ablation and need for more antiarrhythmic drugs in the chronic AF patients with an LASEC when compared with those without an LASEC., (© 2011 Wiley Periodicals, Inc.)

Introduction: It is difficult to discriminate patients with and without paroxysmal atrial fibrillation (PAF). The atrial electromechanical interval determined by the transthoracic echocardiogram is demonstrated to be a predictor of new onset AF. The aim of our study was to investigate whether the electromechanical interval is a useful parameter to identify patients with PAF., Methods and Results: A total of 297 patients (PAF group = 103; control group = 194) with mean age of 59.4 ± 12.4 years were enrolled. The electromechanical interval (PA-PDI) defined as the time interval from the initiation of the P-wave deflection to the peak of the mitral inflow A wave on the pulse-wave Doppler imaging was measured for every patient. Patients with PAF had significantly longer PA-PDI intervals compared with that of patients without it (152.7 ± 13.8 ms vs 133.4 ± 16.8 ms). The area under ROC curve based on the PA-PDI interval to diagnose PAF was 0.803 (95% confidence interval = 0.755-0.851, P < 0.001). At the cut-off value of 142 ms, the sensitivity and specificity in identifying PAF were 77.7% and 80.1%, respectively. In the PAF group, the PA-PDI interval was closely associated with the CHADS(2) score and inversely related with the peak velocity of left atrial appendage., Conclusions: The PA-PDI interval may be a useful parameter to identify patients with PAF. Further studies are necessary to evaluate the usefulness of PA-PDI intervals in diagnosing PAF in addition to the current methods and tools., (© 2011 Wiley Periodicals, Inc.)

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: It has been demonstrated that intrinsic cardiac autonomic activation of ganglionated plexi (GPs) exhibits a frequency gradient from the center to the periphery with limited mapping., Objective: We aimed to use a global mapping tool (Ensite Array) to identify the frequency distribution and clarify the interaction between the extrinsic/intrinsic autonomic systems., Methods: A mid sternal thoractomy was performed in anesthetized dogs. High frequency stimulation (20 Hz, 0.1 ms duration) was applied to locate the GPs and achieve vagosympathetic stimulation (VNS). There were 4 major GPs, which were located near the 4 pulmonary vein (PV) ostia, and a third fat pad (SVC-Ao) GP that was located near the superior vena cava (SVC)-right atrial (RA) junction., Results: Without VNS (n = 12), the left atrial (LA) mean (8.20 ± 0.11 vs 7.95 ± 0.30 Hz, P = 0.04) and max (9.86 ± 0.28 vs 9.43 ± 0.29 Hz, P = 0.03) DFs were higher during the PV ostial GP stimulation than the SVC-Ao GP stimulation. The LA max DFs were located not only at the primary GPs but also the nearby secondary PV ostial GPs. The RA mean DF (8.36 ± 0.05 vs 7.99 ± 0.19 Hz, P = 0.04) was higher during SVC-Ao GP stimulation than PV ostial GP stimulation. The max DF was located inside the SVC during SVC-Ao GP stimulation and at the RA septum during PV ostial GP stimulation. With VNS (n = 12), the LA mean and max DFs between the PV ostial and SVC-Ao GP stimulation were similar. The DF distribution shifted to non-GP LA sites during both the PV ostial and SVC-Ao GP stimulation., Conclusion: The findings indicate that the AF was caused by an interaction between the PV ostial GPs during intrinsic autonomic stimulation, whereas the non-GP LA sites were responsible for the AF induced by an extrinsic neural input. , (© 2011 Wiley Periodicals, Inc.)

Atrial arrhythmias are a common sequel after surgery for congenital heart disease, and often eventually cause late morbidity and mortality. Nowadays, percutaneous catheter ablation of atrial flutter (AFL) is widely practised, and is highly successful and safe. Patients with a tricuspid valve replacement (TVR) represent a distinct group for whom the appropriate nonpharmacologic therapy for AFL has not yet been established. We report a case of a 55-year-old woman with a history of a total correction of tetralogy of Fallot (ToF) who developed AFL before and after receiving a tricuspid valve prosthesis. Based on the results of the activation mapping, counterclockwise and clockwise AFL were identified. Completion of a cavotricuspid isthmus (CTI) line on the atrial side successfully terminated the AFL, with resumption of sinus rhythm. Guided by a 3D mapping system, CTI ablation is feasible and safe in patients with a prosthetic tricuspid valve., (© 2011 Wiley Periodicals, Inc.)

Multiple origins of focal atrial tachycardia (AT) located at the left lateral isthmus is a rare case. We present a case of a 31-year-old female with incessant AT. During radiofrequency ablation, 3 origins of AT located in the lateral mitral ishtmus from a lower to a higher position were identified with changes of the ECG morphology and earliest activation on 3D mapping. Ablation of the AT origins can terminate the tachycardia., (© 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.)

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.)

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: 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.)