Paroxysmal and persistent atrial fibrillation ablation outcomes with the pulmonary vein ablation catheter GOLD duty-cycled phased radiofrequency ablation catheter: quality of life and 12-month efficacy results from the GOLD Atrial Fibrillation Registry.

AIMS: The GOLD AF Registry has been designed to prospectively assess the population, indications, and outcomes using second-generation phased radiofrequency (RF) ablation (pulmonary vein ablation catheter GOLD) in a global examination of standard-of-care use for the treatment of paroxysmal and persistent atrial fibrillation (AF). METHODS AND RESULTS: GOLD AF (NCT02433613) is a prospective, observational, multi-centre registry designed to characterize efficacy and safety of phased RF ablation in patients with AF. The primary endpoint was freedom from AF recurrence at 12-month follow-up after a 90-day blanking period. Ancillary objectives include safety, procedural efficiency, and quality of life (QoL). The QoL assessment using the Atrial Fibrillation Effect on QualiTy-of-Life (AFEQT) and the European Heart Rhythm Association (EHRA) Score of AF-related symptoms was collected at baseline and 12 months. In total, 1054 patients were included in this analysis (age 60.6, 67.6% male, 26.5% PersAF). Kaplan-Meier estimate of freedom from AF recurrence was 77.7% at 12 months. Peri-procedural device or procedure-related complications were observed in 26 (2.5%) patients, with a low stroke rate of 0.3%. One-year post-ablation, the EHRA AF Symptom score decreased in 68% of patients. The AFEQT score improvement was observed in 88.4% and 90.4% of patients who completed the questionnaire in-person or interviewed by phone at 12 month follow-up, respectively. CONCLUSION: Phased RF ablation for the treatment of paroxysmal and persistent AF demonstrated a 77.7% freedom from AF recurrence at 12 months in addition to a significant reduction in arrhythmia symptoms and clinically meaningful improved QoL. Low peri-procedural complication rate of <3% was reported.

Leadless pacing using the transcatheter pacing system (Micra TPS) in the real world: initial Swiss experience from the Romandie region.

AIMS: Leadless pacemakers are implanted in Switzerland since June 2015. Large worldwide registries have shown high implant success, low complication rates, and good electrical parameters up to 12 months' follow-up. However, data are scarce outside the investigational setting. The purpose of this study is to assess the real-world experience regarding clinical safety and efficacy of Micra TPS (transcatheter pacing system) leadless pacemakers. METHODS AND RESULTS: Retrospective observational, multi-centre study designed to assess initial safety and efficacy of the Micra TPS in the Swiss Romande region. A total of 92 patients were included from four different centres with an implantation success rate of 97.8% (90 of 92). Thresholds were overall low at implantation (median 0.38 V/0.24 ms, ranging from 0.13 to 2.88 V/0.24 ms) and remained stable over 1-year follow-up. The perioperative serious adverse event rate was 6.5% in six patients which lead to prolonged hospitalization in five patients and death in one patient. In addition, three further major events (3.3%) occurred during an average follow-up of 1 year, requiring implantation of a standard transvenous pacemaker in two patients, and surgical explantation of the Micra TPS in one patient due to intractable ventricular tachycardia. CONCLUSION: Leadless pacemakers are a valuable adjunct for treating selected patients requiring single-chamber pacing. However, in this initial experience, major complication rates were high (9.8%). The implant procedure requires proper training and should be performed in an adequate setting.

Long-term follow-up after left atrial appendage occlusion with comparison of transesophageal echocardiography versus computed tomography to guide medical therapy and data about postclosure cardioversion.

AIMS: The use of left atrial appendage (LAA) occluders in atrial fibrillation is increasing. There are few data on the comparison between transesophageal echocardiography (TEE) and computed tomography (MDCT) assessing peridevice flow and outcome of electrical cardioversion (ECV) in these patients. METHODS AND RESULTS: Single-center prospective registry from 2009 to 2015 including all LAA occluders to analyze success and complications during implantation and follow-up. Patients having ≥1 ECV were further analyzed. TEE was performed during implantation and at 6 weeks. In a subgroup of 77 patients, we compared MDCT with TEE at 6 weeks. Overall, 135 patients (69 ± 9 years; 70% male; CHA2 DS2 -VASc score: 3.6 ± 1.4; HAS-BLED score: 2.5 ± 0.6) received a LAA occluder (Watchman, n = 73; ACP-1, n = 59; Amulet, n = 3; PVI + LAA occluder, n = 91; and LAA occluder only, n = 44). Device implantation was successful in 131 (97%). Eight patients (5.9%) had major periprocedural complications (ischemic stroke/transient ischemic attacks, n = 4, tamponade, n = 2, device thrombosis, n = 2, Dressler syndrome, n = 1). The periprocedural complication rate was similar between concomitant procedure and LAA occluder only (8/91 vs. 5/44; P = 0.6). Twelve patients (9%) died (procedure-related, n = 2; 1%) during follow-up of 44 months (IQR: 43). MDCT (n = 77) at 6 weeks showed similar peridevice flow compared to TEE (TEE: 1.5 ± 1.9 mm vs. MDCT: 1.1 ± 2.2 mm, P = 0.25). Thromboembolic events occurred in 3 patients (CVA, n = 1; TIA, n = 2) during follow-up. In total, 41 ECV were performed in 26 patients (1.6 ± 0.9/patient), 13 months (IQR: 24) after implantation (<1 month: n = 8). No ECV-related clinical complications were observed. CONCLUSION: LAA occlusion is feasible with an acceptable safety profile and few events during long-term follow-up. ECV after LAA occlusion is feasible. MDCT could help to evaluate peridevice flow.

Safety and efficacy of the nMARQ catheter for paroxysmal and persistent atrial fibrillation.

AIMS: Circular irrigated radiofrequency ablation using the nMARQ catheter has recently been introduced for the treatment of atrial fibrillation (AF). The aim of this study is to report the safety and efficacy of catheter ablation using this technology in patients with paroxysmal and persistent AF. METHODS AND RESULTS: The data of a prospective registry describing the experience of a single operator using this technology on 327 consecutive patients were analysed. The mean procedure time was 69 ± 22 min for paroxysmal AF (n = 228) and 75 ± 23 min for persistent AF (n = 97). Follow-up was available for 206 (63%) patients for 6 ± 5 months (range 1-23, median 3.3). Single procedure success off antiarrhythmic drugs was 75% in paroxysmal AF and 52% in persistent AF. Including the 5% redo cases and those on antiarrhythmic medication, freedom from AF was documented in 90 and 83% of paroxysmal and persistent AF patients, respectively. There were no serious complications in the first 325 patients, but the last two consecutive patients (0.6%) developed atrio-oesophageal fistulas and had a fatal outcome. The catheter has been recalled from market. CONCLUSION: The nMARQ catheter is a highly effective tool for treatment of paroxysmal and persistent AF. Nevertheless, the occurrence of life-threatening oesophageal fistulas is of major concern and requires further investigation.

Investigation into causes of abnormal cerebral MRI findings following PVAC duty-cycled, phased RF ablation of atrial fibrillation.

INTRODUCTION: Left atrial catheter ablation of the pulmonary veins (PVs) is an established option for patients with atrial fibrillation (AF). Asymptomatic cerebral emboli (ACE) detected by diffusion weighted MRI (DW-MRI) following AF ablation has been reported at varying rates. This variability may be linked to procedural variables and demographic risk factors. Animal studies with the multielectrode pulmonary vein ablation catheter (PVAC) have identified potential sources of emboli, including air introduced during PVAC introduction, inadequate anticoagulation, and high current densities when the distal (E1) and proximal (E10) electrodes are in contact. We sought to evaluate the incidence, size, and number of DW-MRI findings with procedural modifications that potentially reduce the embolic load. METHODS: Thirty-seven AF patients (59 ± 10 years, 73% male, all with paroxysmal AF, left atrial [LA] diameter 44 ± 7 mm, left ventricular ejection fraction 57 ± 7%) underwent MRI sequences preceding ablation, within 24 hours postablation, and at 4-6 weeks. During the procedure all patients were on uninterrupted phenprocoumon, an attempted activated clotting time (ACT) level >300 seconds, had the PVAC introduced under saline, and antral ablation was started with a 2:1 bipolar/unipolar mode. Files from the ablation unit (GENius v14.4) were retrospectively analyzed to determine the relationship between E1 and E10 in close proximity and DW-MRI findings. RESULTS: Post procedure, 10/37 patients (27%) were positive for new DWI cerebral lesions. Nine of 10 patients had a single lesion, and 1/10 patient had 2 lesions. Average lesion size was 3.1 ± 3.9 mm (2-14 mm). One of 10 (10%) had lesions at MRI follow-up. No neurological symptoms were observed. Eighteen of 37 (49%) of procedures had evidence of E1/E10 interaction. In the subgroup of patients with and without E1 and E10 in close proximity, the DW-MRI rate was 8/18 (44%) and 2/19 (11%), respectively (P = 0.029). CONCLUSIONS: The source of positive DW-MRI findings in LA ablation involves several factors. Controlling anticoagulation and careful sheath management helps to reduce the number and size of DW-MRI lesions. With the PVAC catheter, an ablation with the E1 and E10 in close proximity increases the risk of a DW-MRI finding. In the future, electrodes E1 and E10 should be kept apart to help reduce the incidence of acute ACE.

[Fermeture de l'oreillette gauche - une alternative à l'anticoagulation permanente en cas de fibrillation auriculaire?] / Vorhofohrverschluss links ­ eine Alternative zur Dauerantikoagulation bei Vorhofflimmern?

Left Atrial Appendage Closure- An Alternative to Continuous Anticoagulation for Atrial Fibrillation? Abstract. Approximately 25% of all ischemic insults are caused by cardiac emboli in atrial fibrillation. Therefore, in patients with atrial fibrillation, oral anticoagulation is initiated or transesophageal echocardiography is performed before electroconversion to exclude blood clots in the heart. This shows that virtually all cardiac thrombi (>90%) are localized in the atrial ear. Therefore, for many decades surgeons have been removing the atrial tube during open heart surgery to eliminate it as a source of emboli. As a minimally invasive alternative, various screens for percutaneous closure of the atrial ear have been developed in the past 10-20 years. The requirements, techniques, and results will be discussed in the following article.

Correlation between conduction velocity and frequency analysis in patients with atrial fibrillation using high-density charge mapping.

Spectral analysis of atrial signals has been used to identify regions of interest in atrial fibrillation (AF). However, the relationship to the atrial substrate is unclear. In this study, we compare regions with dominant frequency (DF), simultaneously determined in the left atrium (LA) by a novel noncontact mapping system using unipolar charge density signals, to the zones of slow conduction (SZ) during AF.In 19 AF patients the conduction during AF was assessed by a validated algorithm and SZ compared to the DF and the DF ratio between the DF peak and the area under the total spectrum (DFR). The results were compared in five different regions of the LA. The reproducibility of SZ location at different time measurements was higher than for DF or DFR. The SZs are mainly confined at the anterior and posterior wall of the LA. There was no statistically significant correlation between SZ and DF or DFR across the atrium.

Barlow disease: effect of mitral valve repair on ventricular arrhythmias in 82 patients in a retrospective long-term study.

BACKGROUND: Patients (pt) with mitral valve prolapse (MVP) due to Barlow disase (BD) have an increased incidence of ventricular arrhythmias (VA; including ventricular tachycardias VT) and sudden cardiac death (SCD). Data on the effect of MV repair on VA are scarce. METHODS: Pre- and postoperative VA in severe mitral regurgitation (MR) with MVP due to BD undergoing surgical mitral valve repair were analyzed. Patients with degenerative mitral valve disease not fulfilling BD criteria were excluded. Information was from charts, ECG/Holter ECG and/or pacemaker/ implantable cardioverter defibrillator (ICD) data. SCD, sustained VT>30 sec and/or ventricular fibrillation necessitating an ICD-shock were considered major events. Event probability was calculated using the Kaplan-Meier estimator throughout the follow-up period of 20.7 years. RESULTS: There were 82 pts (61% males), mean age at surgery 62±14 years. Bileaflet MVP was present in 54%, mitral annular dysjunction (MAD) in 37% and left ventricular ejection fraction (LVEF) <50% in 12%. MV repair included ring annuloplasty in all and artificial chords in 48%. Mean follow-up was 3.1 years (0.2 to 14.2 years). Postoperative rhythm surveillance by Holter ECG and/or pacemaker was available in 67%. A VA load of ≥10% and/or any VT was noted in 26% before and 32% after surgery (P=0.44). Postoperative VA load was not predicted by MAD, artificial chords, LVEF of <50%, age at surgery >50 years and/or residual ≥moderate MR (all P<0.05), it correlated only with bileaflet MVP (P=0.009). Major events occurred in 3 pts: SCD in 2 pts and ICD for sustained polymorphic VT in 1 pt (incidence 1.2%/year). The event probability of receiving a SCD or an ICD-shock was 4.9%. CONCLUSIONS: VA burden does not seem to change after MV repair in MVP due to BD. The occurrence of major arrhythmic events can not be predicted reliably, thus, patients with MVP due to BD may need lifelong postoperative follow-up, especially in bileaflet MVP which was an independent risk factor for increased VA burden in this retrospective long-term study in a small but well selected patient group.

Initial results of linear duty-cycled radiofrequency for atypical flutter and atrial tachycardia.

BACKGROUND: Duty-cycled radiofrequency (DCRF) is increasingly used for ablation of atrial fibrillation (AF). Many patients also have atrial flutter (AFL). Recently, a linear multielectrode has been shown to create linear block at the cavotricuspid isthmus and in the left atrium (LA). OBJECTIVE: To map and ablate atypical AFL and atrial tachycardias (ATs) in the right and LA using a linear multielectrode with DCRF. METHODS: The linear multielectrode delivers DCRF at 20-45 W maximum in 1:1 unipolar/bipolar temperature-controlled mode. Target temperatures were manually titrated to 60 °C in the LA, if power >5W indicated adequate passive cooling. RESULTS: A total of 76 AT/AFL were targeted in 57 patients. Acute success was reached in 14/15 (93%) right AT, in 17/22 (77%) left atrial roof AFL, in 5/6 (83%) septal AFL, in 9/9 (100%) other left atrial AT, but only in 8/23 (35%) AFL from the mitral isthmus (which rose to 13/23 [57%] with additional use of irrigated radiofrequency). Nevertheless, freedom of AF/AFL 10 ± 6 months after a single procedure was documented in 92% of right AT, 71% of roof AFL, 73% for mitral AFL, and 60% of septal or other LA AT/AFL. No char formation was noted. However, frequent induction of AF and one case of asystole occurred during delivery of DCRF in a pacemaker patient. CONCLUSION: The linear multielectrode allows mapping and ablation of atypical AFL/AT. Freedom of AF/AT was reached in 60%-92% depending on localization and number of arrhythmias. Technical modifications will improve safety and efficacy.

Linear ablation with duty-cycled radiofrequency energy at the cavotricuspid isthmus.

BACKGROUND: Multielectrode catheters using duty-cycled radiofrequency (RF) have been developed to treat atrial fibrillation (AF). Many of these patients also have atrial flutter. Therefore, a linear multielectrode has been developed using the same RF energy. OBJECTIVE: The concept and acute results of linear ablation using duty-cycled RF were tested in the cavotricuspid isthmus (CTI). METHODS: The CTI was targeted in 75 patients, in 68 (90%) among them as an adjunct to AF ablation with the same technology. A linear electrode catheter with a 4-mm tip and five 2-mm ring electrodes was connected to a generator titrating duty-cycled RF at 20-45 W up to a target temperature of 70 degrees C in 1:1 unipolar/bipolar mode. RESULTS: During a mean procedure time of 20 +/- 12 minutes, complete CTI block was achieved by 4 +/- 3 applications of duty-cycled RF in 69 (92%) patients. No more than three RF applications were necessary in 60% of patients. During the initial learning curve, standard RF had to be used in five (7%) patients. Complete block was not achieved in one patient with frequent episodes of AF. Char was observed in five (7%) patients with poor electrode cooling; consequently, the temperature ramp-up was slowed and manually turned off in the event of low-power delivery. Two groin hematomas occurred; otherwise, no clinical complications were observed. CONCLUSION: Multielectrode catheters delivering duty-cycled RF can effectively ablate the CTI with few RF applications with promising acute results. Further modifications are necessary to improve catheter steering and prevent char formation. (PACE 2010; 444-450).

Image-guided ablation of scar-related ventricular tachycardia: towards a shorter and more predictable procedure.

PURPOSE: The aim of this study was to analyze the feasibility and reproducibility of using image integration software at a remote setting over the MUSIC network to perform image-guided VT ablation. Furthermore, we analyzed the efficacy of a focused workflow with electroanatomical mapping (EAM) limited to imaging-defined scar. METHODS: In a prospective two-centre study, consecutive patients undergoing image integration-guided VT ablation (magnetic resonance [DE-MRI] and/or multidetector computed tomography [MDCT]) were included. Patients were divided into two groups (Group 1, complete EAM; Group 2, EAM limited to imaging-defined substrate). RESULTS: Forty-nine patients (62 ± 15 years; 90% male; LVEF 41 ± 14%; ischemic 69%) who underwent image integration-guided VT ablation were included (MDCT 98%; DE-MRI in 35%). Total procedure time was 172 ± 48 min (ablation 31 ± 17 min; fluoroscopy 23 ± 13 min). Procedure time was shorter in Group 2 as compared to Group 1 (Group 2 [n = 26] vs. Group 1 [n = 23]; procedure time: 151 ± 33 vs. 180 ± 53 min, P = 0.01). Non-inducibility of all VT was achieved in 37 (76%), with no difference between Group 1 and 2 (Group 2 vs. Group 1; VT non-inducibility 71 vs. 74%, P = 0.8). During a follow-up period of 19 ± 8 months, 13 patients (27%) had a VT recurrence. Two patients (4%) died during follow-up. There were no differences in VT-free survival between Group 1 and Group 2 (p = 0.77). CONCLUSION: Image-integrated VT ablation is feasible through a network between highly experienced centers and remotely located centers. Focused image integration-guided VT ablation is associated with short and predictable procedure duration, achieving high-long term success rates.

High-resolution noncontact charge-density mapping of endocardial activation.

BACKGROUND: Spatial resolution in cardiac activation maps based on voltage measurement is limited by far-field interference. Precise characterization of electrical sources would resolve this limitation; however, practical charge-based cardiac mapping has not been achieved. METHODS: A prototype algorithm, developed from first principles of electrostatic field theory, derives charge density (CD) as a spatial representation of the true sources of the cardiac field. The algorithm processes multiple, simultaneous, noncontact voltage measurements within the cardiac chamber to inversely derive the global distribution of CD sources across the endocardial surface. RESULTS: Comparison of CD to an established computer-simulated model of atrial conduction demonstrated feasibility in terms of spatial, temporal, and morphologic metrics. Inverse reconstruction matched simulation with median spatial errors of 1.73 mm and 2.41 mm for CD and voltage, respectively. Median temporal error was less than 0.96 ms and morphologic correlation was greater than 0.90 for both CD and voltage. Activation patterns observed in human atrial flutter reproduced those established through contact maps, with a 4-fold improvement in resolution noted for CD over voltage. Global activation maps (charge density-based) are reported in atrial fibrillation with confirmed reduction of far-field interference. Arrhythmia cycle-length slowing and termination achieved through ablation of critical points demonstrated in the maps indicates both mechanistic and pathophysiological relevance. CONCLUSION: Global maps of cardiac activation based on CD enable classification of conduction patterns and localized nonpulmonary vein therapeutic targets in atrial fibrillation. The measurement capabilities of the approach have roles spanning deep phenotyping to therapeutic application. TRIAL REGISTRATION: ClinicalTrials.gov NCT01875614. FUNDING: The National Institute for Health Research (NIHR) Translational Research Program at Royal Papworth Hospital and Acutus Medical.

[The Old-Age Heart]. / Das Herz im Alter.

The Old-Age Heart Abstract. Knowledge of cardiovascular changes in old age and their therapeutic options is important. Old age can lead to hypertrophy of the left ventricle, diastolic dysfunction, heart valve changes and pulmonary hypertension. Patients often develop arterial hypertension. Valvular changes are common in people over 100 years of age (aortic stenosis and mitral insufficiency). The risk of coronary heart disease is 35 % for men and 24 % for women. In old age, sinus node dysfunction and atrial fibrillation are common. 25 % of all strokes are cardiac embolisms in atrial fibrillation. Cardiac interventions in the elderly are increasingly frequent and include coronary catheter revascularization or valve interventions (percutaneous aortic valve replacement or MitraClip). Optimal therapy in old age includes not only cardiovascular interventions also include drugs and a lifestyle modification and mainly serves to improve the quality of life.

Catheter ablation for paroxysmal atrial fibrillation: segmental pulmonary vein ostial ablation versus left atrial ablation.

BACKGROUND: Segmental ostial catheter ablation (SOCA) to isolate the pulmonary veins (PVs) and left atrial catheter ablation (LACA) to encircle the PVs both may eliminate paroxysmal atrial fibrillation (PAF). The relative efficacy of these 2 techniques has not been directly compared. METHODS AND RESULTS: Of 80 consecutive patients with symptomatic PAF (age, 52+/-10 years), 40 patients underwent PV isolation by SOCA and 40 patients underwent LACA to encircle the PVs. During SOCA, ostial PV potentials recorded with a ring catheter were targeted. LACA was performed by encircling the left- and right-sided PVs 1 to 2 cm from the ostia and was guided by an electroanatomic mapping system; ablation lines also were created in the mitral isthmus and posterior left atrium. The mean procedure and fluoroscopy times were 156+/-45 and 50+/-17 minutes for SOCA and 149+/-33 and 39+/-12 minutes for LACA, respectively. At 6 months, 67% of patients who underwent SOCA and 88% of patients who underwent LACA were free of symptomatic PAF when not taking antiarrhythmic drug therapy (P=0.02). Among the variables of age, sex, duration and frequency of PAF, ejection fraction, left atrial size, structural heart disease, and the ablation technique, only an increased left atrial size and the SOCA technique were independent predictors of recurrent PAF. The only complication was left atrial flutter in a patient who underwent LACA. CONCLUSIONS: In patients undergoing catheter ablation for PAF, LACA to encircle the PVs is more effective than SOCA.

Diagnosis of sleep-related breathing disorders by visual analysis of transthoracic impedance signals in pacemakers.

BACKGROUND: Minute ventilation sensors of cardiac pacemakers measure ventilation by means of transthoracic impedance changes between the pacemaker case and the electrode tip. We investigated whether this technique might detect sleep-related breathing disorders. METHODS AND RESULTS: In 22 patients, analog waveforms of the transthoracic impedance signal measured by the pacemaker minute ventilation sensor over the course of a night were visualized, scored for apnea/hypopnea events, and compared with simultaneous polysomnography. Analysis of transthoracic impedance signals correctly identified the presence or absence of moderate to severe sleep apnea (apnea/hypopnea index, AHI >20 h(-1)) in all patients (receiver operating characteristics, ROC=1.0). The ROC for AHI scores of > or =5 h(-1) and > or =10 h(-1) showed an area under the curve of 0.95, P<0.005, and 0.97, P<0.0001, respectively. Accuracy over time assessed by comparing events per 5-minute epochs was high (Cronbach alpha reliability coefficient, 0.85; intraclass correlation, 0.73). Event-by-event comparison within +/-15 seconds revealed agreement in 81% (kappa, 0.77; P<0.001). CONCLUSIONS: Detection of apnea/hypopnea events by pacemaker minute ventilation sensors is feasible and accurate compared with laboratory polysomnography. This technique might be useful to screen and monitor sleep-related breathing disorders in pacemaker patients.

Pulmonary vein isolation for paroxysmal and persistent atrial fibrillation.

BACKGROUND: The pulmonary veins (PVs) have been demonstrated to often play an important role in generating atrial fibrillation (AF). The purpose of this study was to determine the safety and efficacy of segmental PV isolation in patients with paroxysmal or persistent AF. METHODS AND RESULTS: In 70 consecutive patients (mean age, 53 +/- 11 years) with paroxysmal (58) or persistent (12) AF, segmental PV isolation guided by ostial PV potentials was performed. The left superior, left inferior, and right superior PVs were targeted for isolation in all patients, and the right inferior PV was isolated in 20 patients. Among the 230 targeted PVs, 217 (94%) were completely isolated, with a mean of 6.5 +/- 4.2 minutes of radiofrequency energy applied at a maximum power setting of 35 W. A second PV isolation procedure was performed in 6 patients (9%). At 5 months of follow-up, 70% of patients with paroxysmal and 22% of patients with persistent AF were free from recurrent AF (P<0.001), and 83% of patients with paroxysmal AF were either free of symptomatic AF or had significant improvement. Among various clinical characteristics, only paroxysmal AF was an independent predictor of freedom from recurrence of AF (P<0.05). One patient developed unilateral quadrantopsia after the procedure. There were no other complications. CONCLUSIONS: With a segmental isolation approach that targets at least 3 PVs, a clinically satisfactory result can be achieved in >80% of patients with paroxysmal AF. The clinical efficacy of pulmonary vein isolation is much lower when AF is persistent than when it is paroxysmal.

Segmental ostial ablation to isolate the pulmonary veins during atrial fibrillation: feasibility and mechanistic insights.

BACKGROUND: The purpose of this study was to determine the feasibility and mechanistic implications of segmental pulmonary vein (PV) ostial ablation during atrial fibrillation (AF). METHODS AND RESULTS: Forty consecutive patients underwent PV isolation for AF. Among 125 PVs targeted for isolation, ablation was performed during AF in 70 veins and during sinus rhythm in 55 veins. A decapolar Lasso catheter was positioned near the ostium. During AF, ostial ablation was performed near the Lasso catheter electrodes that recorded a tachycardia with a cycle length shorter than in the adjacent left atrium. During sinus rhythm, ostial ablation was guided by PV potentials. Complete PV isolation was achieved in 70 PVs (100%) ablated during AF and in 53 PVs (96%) ablated during sinus rhythm (P=0.4). The mean durations of radiofrequency energy needed for isolation were 7.4+/-4.4 and 5.2+/-3.9 minutes during AF and sinus rhythm, respectively (P<0.01). Before ablation, an immediate recurrence of AF (IRAF), occurred after cardioversion in 18 of 40 patients, and IRAF was consistently abolished by PV isolation. The probability of AF termination during isolation of a PV was directly related to the extent of tachycardia in that vein. As more PVs were isolated, induction of persistent AF by rapid pacing became less likely. CONCLUSIONS: Segmental ostial ablation guided by PV tachycardia during AF is feasible and as efficacious as during sinus rhythm. The responses to cardioversion, ablation, and rapid pacing observed in this study imply that IRAF is triggered by the PVs and that PV tachycardias may play an important role in the perpetuation of AF.

Clinical significance of inducible atrial flutter during pulmonary vein isolation in patients with atrial fibrillation.

OBJECTIVES: This study was designed to determine the prevalence and clinical significance of atrial flutter (AFL) that occurs during catheter ablation for atrial fibrillation (AF). BACKGROUND: Atrial flutter frequently occurs in patients with AF. METHODS: Pulmonary vein isolation was performed in 133 consecutive patients (age 52 +/- 11 years) for paroxysmal (n = 112) or persistent (n = 21) AF. A clinical episode of AFL was documented in 40 of the 133 patients (30%). During the ablation procedure, AFL occurred in 86 patients (65%), either spontaneously (n = 36) or by rapid atrial pacing (n = 50), with AFL being typical in the majority (80%). Cavo-tricuspid isthmus ablation was performed in 28 of the 133 patients. RESULTS: Among the 105 patients who did not undergo isthmus ablation, 25 patients (24%) were documented to have symptomatic AFL during a mean follow-up of 609 +/- 252 days. Among the clinical variables of age, gender, history of clinical AFL, ejection fraction, left atrial diameter, duration of AF, and occurrence of AFL during ablation, only a history of clinical AFL (p = 0.05) and occurrence of typical AFL during the ablation (p = 0.01) were independent predictors of symptomatic AFL during follow-up. The incidence of symptomatic AFL during follow-up was similar among patients who did and did not have long-term freedom from recurrent AF. CONCLUSIONS: In patients with AF who have either a history of AFL or an episode of typical AFL during an electrophysiologic study, symptomatic AFL is common after pulmonary vein isolation. Therefore, cavo-tricuspid isthmus ablation is appropriate during pulmonary vein isolation if AFL has been observed clinically or in the electrophysiology laboratory.

Rate-dependent effect of verapamil on atrial refractoriness.

OBJECTIVES: The purpose of this study was to determine whether verapamil has rate-dependent effects on the atrial effective refractory period (AERP). BACKGROUND: Block of calcium current (I(Ca)) and rapid component of the delayed rectifier potassium current (I(Kr)) by verapamil is frequency-dependent. This may result in variable effects of verapamil on the AERP, depending on the rate. METHODS: The subjects of this study were 30 adults with a mean age of 45 +/- 13 years who did not have structural heart disease. In 20 subjects, the AERP was measured at basic drive cycle lengths (BDCLs) of 650 to 250 ms, in 50 ms decrements, before and after infusion of 0.1 mg/kg verapamil. The effective refractory periods (ERPs) were measured in the setting of autonomic blockade in 10 subjects and without autonomic blockade in 10 subjects. Ten subjects served as a control group and received a saline infusion instead of verapamil. RESULTS: Verapamil significantly prolonged the AERP at BDCLs of 650 to 500 ms (p < 0.01 or p < 0.05) and significantly shortened the ERP at BDCLs of 300 and 250 ms (p < 0.01). In the control group, there were no significant differences between the baseline and post-saline measurements of ERP. CONCLUSIONS: Verapamil prolongs AERP at slow rates and shortens AERP at rapid rates. These findings are consistent with a predominant effect on I(Ca) at rapid rates and a predominant effect on I(Kr) at slow rates.