Clinical mapping approach to diagnose electrical rotors and focal impulse sources for human atrial fibrillation

Computational Mapping of Rotors and Focal Impulses in Human AF. Introduction: The perpetuating mechanisms for human atrial fibrillation (AF) remain undefined. Localized rotors and focal beat sources may sustain AF in elegant animal models, but there has been no direct evidence for localized sources in human AF using traditional methods. We developed a clinical computational mapping approach, guided by human atrial tissue physiology, to reveal sources of human AF. Methods and Results: In 49 AF patients referred for ablation (62 ± 9 years; 30 persistent), we defined repolarization dynamics using monophasic action potentials (MAPs) and recorded AF activation from 64‐pole basket catheters in left atrium and, in n = 20 patients, in both atria. Careful positioning of basket catheters was required for optimal mapping. AF electrograms at 64–128 electrodes were combined with repolarization and conduction dynamics to construct spatiotemporal AF maps. We observed sustained sources in 47/49 patients, in the form of electrical rotors (n = 57) and focal beats (n = 11) that controlled local atrial activation with peripheral wavebreak (fibrillatory conduction). Patients with persistent AF had more sources than those with paroxysmal AF (2.1 ± 1.0 vs 1.5 ± 0.8, P = 0.02), related to shorter cycle length (163 ± 19 milliseconds vs 187 ± 25 milliseconds, P < 0.001). Approximately one‐quarter of sources lay in the right atrium. Conclusions: Physiologically guided computational mapping revealed sustained electrical rotors and repetitive focal beats during human AF for the first time. These localized sources were present in 96% of AF patients, and controlled AF activity. These results provide novel mechanistic insights into human AF and lay the foundation for mechanistically tailored approaches to AF ablation. (J Cardiovasc Electrophysiol, Vol. 23, pp. 447‐454, May 2012)     

Clinical Benefit of Ablating Localized Sources for Human Atrial Fibrillation: The Indiana University FIRM Registry

Background

Mounting evidence shows that localized sources maintain atrial fibrillation (AF). However, it is unclear in unselected “real-world” patients if sources drive persistent atrial fibrillation (PeAF), long-standing persistent atrial fibrillation (LPeAF), or paroxysmal atrial fibrillation (PAF); if right atrial sites are important; and what the long-term success of source ablation is.

Ablation of Atrial Fibrillation at the Time of Cavotricuspid Isthmus Ablation in Patients With Atrial Flutter Without Documented Atrial Fibrillation Derives a Better Long‐Term Benefit

AF Ablation in Patients With Only Documentation of Atrial Flutter. Objectives: The aim of the study was to evaluate whether isolation of the pulmonary veins (PVs) at the time of cavotricuspid isthmus (CTI) ablation is beneficial in patients with lone atrial flutter (AFL). Background: A high proportion of patients with lone persistent AFL have recurrent episodes of atrial fibrillation (AF) after CTI ablation. However, the benefit of AF ablation in patients with only documentation of AFL has not been determined. Methods: Forty‐eight patients with typical lone persistent AFL (age 56 ± 6; 90% male) were randomized to CTI ablation (Group A; n = 25) or to CTI + PV isolation (PVI) (Group B; n = 23). In addition to PVI, some patients in group B underwent ablation of complex fractionated electrograms and/or creation of left atrial roof and mitral isthmus ablation line in a stepwise approach when AF was induced and sustained for more than 2 minutes. Mean follow‐up was 16 ± 4 months with a 48‐hour ambulatory monitor every 2 months. Results: There were no recurrences of AFL in either group. Six patients in group B (22%) underwent a stepwise ablation protocol. AF organized and terminated in 5 patients during ablation (83%). Complication rate was not significantly different among the groups. Twenty patients in group B (87%) and 11 patients in group A (44%) were free of arrhythmias on no medications at the end of follow‐up (P < 0.05). Conclusions: Ablation of AF at the time of CTI ablation results in a significantly better long‐term freedom from arrhythmias. (J Cardiovasc Electrophysiol, Vol. 22, pp. 34‐38, January 2011)     

Time to Cardioversion of Recurrent Atrial Arrhythmias After Catheter Ablation of Atrial Fibrillation and Long‐Term Clinical Outcome

Introduction: It is unclear whether early restoration of sinus rhythm in patients with persistent atrial arrhythmias after catheter ablation of atrial fibrillation (AF) facilitates reverse atrial remodeling and promotes long‐term maintenance of sinus rhythm. The purpose of this study was to determine the relationship between the time to restoration of sinus rhythm after a recurrence of an atrial arrhythmia and long‐term maintenance of sinus rhythm after radiofrequency catheter ablation of AF. Methods and Results: Radiofrequency catheter ablation was performed in 384 consecutive patients (age 60 ± 9 years) for paroxysmal (215 patients) or persistent AF (169 patients). Transthoracic cardioversion was performed in all 93 patients (24%) who presented with a persistent atrial arrhythmia: AF (n = 74) or atrial flutter (n = 19) at a mean of 51 ± 53 days from the recurrence of atrial arrhythmia and 88 ± 72 days from the ablation procedure. At a mean of 16 ± 10 months after the ablation procedure, 25 of 93 patients (27%) who underwent cardioversion were in sinus rhythm without antiarrhythmic therapy. Among the 46 patients who underwent cardioversion at ≤30 days after the recurrence, 23 (50%) were in sinus rhythm without antiarrhythmic therapy. On multivariate analysis of clinical variables, time to cardioversion within 30 days after the onset of atrial arrhythmia was the only independent predictor of maintenance of sinus rhythm in the absence of antiarrhythmic drug therapy after a single ablation procedure (OR 22.5; 95% CI 4.87–103.88, P < 0.001). Conclusion: Freedom from AF/flutter is achieved in approximately 50% of patients who undergo cardioversion within 30 days of a persistent atrial arrhythmia after catheter ablation of AF.     

Importance of Sinus Rhythm as Endpoint of Persistent Atrial Fibrillation Ablation

Endpoint of Persistent AF Ablation . Background: The endpoint of persistent atrial fibrillation (AF) ablation is still a matter of debate. The purpose of this study was to evaluate if sinus rhythm (SR) as endpoint of persistent AF ablation has a better long‐term outcome compared to atrial tachycardia (AT) or AF at the end of the procedure. Methods and Results: Between 2008 and 2011, 191 consecutive patients undergoing de novo catheter ablation for symptomatic persistent and long‐standing persistent AF using a sequential ablation approach (including pulmonary vein isolation, ablation of complex fractionated electrograms and linear lesions) were included in the study. According to the result at the end of ablation procedure, patients were classified into 3 groups: patients with termination of AF into SR (Group 1, n = 62), patients with AT undergoing cardioversion (CV) (Group 2, n = 47), or patients with AF undergoing CV (Group 3, n = 82). The primary endpoint was freedom from any atrial tachyarrhythmia off antiarrhythmic drugs at 12 months. At 12 months, estimated proportions of patients free from any arrhythmia recurrence were 42% for Group 1, 13% for Group 2, and 25% for Group 3 (P = 0.002). In a Cox regression analysis only termination into SR was associated with a lower risk of arrhythmia recurrence (HR: 0.62; P = 0.04). Conclusion: If SR is achieved as endpoint of persistent and long‐standing persistent AF ablation using a sequential ablation approach it is associated with the highest long‐term single procedure success rate compared to AT or AF at the end of the procedure. (J Cardiovasc Electrophysiol, Vol. 24, pp. 388‐395, April 2013)     

Long‐Term Outcome of Atrial Fibrillation Ablation: Impact and Predictors of Very Late Recurrence

Long‐Term Outcome of AF Ablation. Introduction: Ablation eliminates atrial fibrillation (AF) in studies with 1 year follow‐up, but very late recurrences may compromise long‐term efficacy. In a large cohort, we sought to describe the determinants of delayed recurrence after AF ablation. Methods and Results: Seven hundred and seventy‐four patients with AF (428 paroxysmal [PAF, 55%] and 346 persistent or longstanding persistent [PersAF, 45%]) underwent wide area circumferential ablation (WACA, 62%) or pulmonary vein isolation (38%). Over 3.0 ± 1.9 years, there were 135 recurrences in PAF patients and 142 in PersAF patients. AF elimination was achieved in 61% of patients with PersAF at 2 years after last ablation and in 71% of patients with PAF (P = 0.04). This finding was related to a higher initial rate of very late recurrence in PersAF. From 1.0 to 2.5 years, the recurrence increased by 20% (from 37% to 57%) in PersAF patients versus only 12% (from 27% to 39%) in PAF patients. Independent predictors of overall recurrence included diabetes (HR 1.9 [1.3–2.9], P = 0.002) and PersAF (HR 1.6 [1.2–2.0], P < 0.001). Independent predictors of very late recurrence included PersAF (HR 1.7 [1.1–2.7], P = 0.018) and WACA (HR 1.8 [1.1–2.7], P = 0.018), while diabetes came close to significance. In PAF patients, left atrial size >45 mm was identified as an AF‐type specific predictor (HR 2.4 [1.3–4.7], P = 0.009), whereas in PersAF patients, no unique predictors were identified. Conclusion: Late recurrences reduced the long‐term efficacy of AF ablation, particularly in patients with PersAF and underlying cardiovascular diseases. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1071‐1078)     

Catheter Ablation of Long‐Standing Persistent Atrial Fibrillation: A Lesson from Circumferential Pulmonary Vein Isolation

Catheter Ablation of Long‐Standing Persistent AF. Introduction: Circumferential pulmonary vein isolation (CPVI) is associated with a high success rate in patients with paroxysmal and persistent atrial fibrillation (AF). However, in patients with long‐standing persistent AF, the ideal ablation strategy still remains a matter of debate. Methods and Results: Two‐hundred and five patients underwent catheter ablation for long‐standing persistent AF defined as continuous AF of more than 1‐year duration. In a first step, all patients underwent CPVI. If direct‐current cardioversion failed following CPVI, ablation of complex fractionated atrial electrograms (CFAEs) was performed. The goal was conversion into sinus rhythm (SR) or, alternatively, atrial tachycardia (AT) with subsequent ablation. A total of 340 procedures were performed. CPVI alone was performed during 165 procedures in 124 of 205 (60.5%) patients. In the remaining 81 patients, additional CFAE ablation was performed in 45, left linear lesions for recurrent ATs in 44 and SVC isolation in 15 patients, respectively, resulting in inadvertent left atrial appendage isolation in 9 (4.4%) patients. After the initial ablation procedure, 67 of 199 patients remained in SR during a mean follow‐up of 19 ± 11 months. Six patients were lost to follow‐up. After a mean of 1.7 ± 0.8 procedures, 135 of 199 patients (67.8%) remained in SR. Eighty‐six patients (43.2%) remained in SR following CPVI performed as the sole ablative strategy. Conclusions: CPVI alone is sufficient to restore SR in 43.2% of patients with long‐standing persistent AF. Multiple procedures and additional ablation strategies with a significant risk of inadvertent left atrial appendage isolation are often required to maintain stable SR. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1085‐1093)     

Intraprocedural Use of Ibutilide to Organize and Guide Ablation of Complex Fractionated Atrial Electrograms: Preliminary Assessment of a Modified Step‐Wise Approach to Ablation of Persistent Atrial Fibrillation

Ibutilide Guided CFAE Ablation. Introduction: While able to achieve clinical success, the current step‐wise approach to persistent atrial fibrillation (AF) ablation requires considerable “substrate” ablation and frequently mandates multiple procedures to address consequent atrial tachycardias (ATs). An alternative strategy minimizing the amount of ablation while maintaining clinical success would be desirable. We hypothesize that intraprocedural administration of a low‐dose antiarrhythmic drug (AAD) during AF will organize areas of passive activation and not affect areas critical to AF maintenance, thereby potentially minimizing the ablation lesion set. Methods and Results: Eleven patients (age = 55 ± 6 years; LA = 48 ± 15 mm; median AF duration = 3 years) with persistent AF undergoing catheter ablation were enrolled in this exploratory prospective observational study. After pulmonary vein (PV) isolation, a mean cycle length (mCL) map was created and areas with mCL <120 ms were considered to represent complex fractionated atrial electrograms (CFAE). Ibutilide (0.25–1.0 mg) was then administered and a second mCL map created. Ablation lesions were placed at CAFE sites identified after ibutilide administration. Activation and/or entrainment mapping was employed to address ATs. The endpoint of ablation was achieving sinus rhythm. The average LA mCL increased (146 vs 165 ms, P = 0.01) and the LA CFAE surface area decreased after ibutilide administration. Additional ablation organized AF to either sinus rhythm or AT in 10/11 (91%) patients. After a median follow up of 455 days, 8 of 11 (72%) patients were free from AF. Three patients underwent a repeat ablation procedure (average 1.27 ablations/patient). Conclusions: Ibutilide administration may organize atrial activity and facilitate AF termination during ablation while minimizing the ablation lesion set. (J Cardiovasc Electrophysiol, Vol. 21, pp. 608‐616, June 2010)     

Right Atrial Mapping and Linear Ablation for Paroxysmal Atrial Fibrillation

Objective: Catheter ablation techniques to cure atrial fibrillation (AF) are under investigation. This study evaluates a mapping-based, individualized approach to right atrial (RA) linear ablation in patients with paroxysmal AF. Methods: In this prospective observational study, 29 patients with recurrent symptomatic AF refractory to medical therapy, underwent linear ablation between May 1998 and December 1999. Inclusion criteria were symptomatic paroxysmal AF, failure of at least 2 antiarrhythmic medications, and informed consent. Radiofrequency ablation was performed in the RA using a 3.3 French multielectrode catheter, ablating through sequential electrodes to establish linear lesions. Lesions were delivered during sustained AF, guided by an empiric mapping scheme, targeting arrhythmogenic areas noted during electrophysiologic testing in sinus rhythm and areas of most disorganization during AF. Reinduction of AF was attempted at the end of successful ablation. Results: The mean age was 58 years. There were 15 male and 14 female patients. Sustained AF was inducible in all patients at electrophysiology study. Acute success was achieved in 24 patients (83%). Long term success (maintaining sinus rhythm off antiarrhythmic medications) was seen in 23 (79%) over a mean follow-up of 19.7 months. Ablation lines varied from patient to patient. There were no complications. Conclusions: Individualized linear ablation in the RA using a multielectrode catheter system can produce effective suppression of paroxysmal AF. Ablation during AF, and testing to reinduce AF at the end of the procedure, make this study unique.     

Image‐Integration of Intraprocedural Rotational Angiography‐Based 3D Reconstructions of Left Atrium and Pulmonary Veins into Electroanatomical Mapping: Accuracy of a Novel Modality in Atrial Fibrillation Ablation

DynaCT Cardiac Integration into Electroanatomical Mapping. Introduction: Exact visualization of complex left atrial (LA) anatomy is crucial for safety and success rates when performing catheter ablation of atrial fibrillation (AF). The aim of our study was to validate the accuracy of integrating rotational angiography‐based 3‐dimensional (3D) reconstructions of LA and pulmonary vein (PV) anatomy into an electroanatomical mapping (EAM) system. Methods and Results: In 38 patients (62 ± 8 years, 25 females) undergoing catheter ablation of paroxysmal (n = 19) or persistent (n = 19) AF, intraprocedural rotational angiography of LA and PVs was performed. The subsequent 3D reconstruction and segmentation of LA and PVs was transferred to the EAM system and registered to the EAM. The distances of all EAM points to corresponding points on the LA syngo® DynaCT Cardiac surface were calculated. Segmentation of LA with clear visualization of adjacent structures was possible in all patients. Also, the integrated segmentation of the LA was used to guide the encirclement of ipsilateral veins, which resulted in PV isolation in all patients. Integration into the 3D mapping system was achieved with a distance error of 2.2 ± 0.4 mm when compared with the EAM surface. Subgroups with paroxysmal and persistent AF showed distance errors of 2.3 ± 0.3 mm and 2.1 ± 0.4 mm, respectively (P = n.s.). Conclusion: Intraprocedural registration of LA and PV anatomy by contrast enhanced rotational angiography was feasible and accurate. There were no differences between patients with paroxysmal or persistent AF. Therefore, integration of rotational angiography‐based reconstructions into 3D EAM systems might be helpful to guide catheter ablation for AF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 278–283, March 2010)     

Mapping and ablating stable sources for atrial fibrillation: summary of the literature on Focal Impulse and Rotor Modulation (FIRM)

Atrial fibrillation (AF) is the most common sustained arrhythmia and the most common indication for catheter ablation. However, despite substantial technical advances in mapping and energy delivery, ablation outcomes remain suboptimal. A major limitation to AF ablation is that the areas targeted for ablation are rarely of proven mechanistic importance, in sharp contrast to other arrhythmias in which ablation targets demonstrated mechanisms in each patient. Focal impulse and rotor modulation (FIRM) is a new approach to demonstrate the mechanisms that sustain AF (“substrates”) in each patient that can be used to guide ablation then confirm elimination of each mechanism. FIRM mapping reveals that AF is sustained by 2–3 rotors and focal sources, with a greater number in patients with persistent than paroxysmal AF, lying within spatially reproducible 2.2?±?1.4-cm² areas in diverse locations. This temporospatial reproducibility, now confirmed by several groups using various methods, changes the concepts regarding AF-sustaining mechanisms, enabling localized rather than widespread ablation. Mechanistically, the role of rotors and focal sources in sustaining AF has been demonstrated by the acute and chronic success of source (FIRM) ablation alone. Clinically, adding FIRM to conventional ablation substantially improves arrhythmia freedom compared with conventional ablation alone, and ongoing randomized trials are comparing FIRM—ablation with and without conventional ablation to conventional ablation alone. In conclusion, ablation of patient-specific AF-sustaining mechanisms (substrates), as exemplified by FIRM, may be central to substantially improving AF ablation outcomes.     

Different patterns of atrial remodeling after catheter ablation of chronic atrial fibrillation

Atrial Substrate Remodeling After Chronic AF Ablation . 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 cm³ vs 72 ± 8 cm³, 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. (J Cardiovasc Electrophysiol, Vol. 22, pp. 385‐393)     

Intracardiac Echocardiography Improves Procedural Efficiency During Cryoballoon Ablation for Atrial Fibrillation: A Pilot Study

Intracardiac Echocardiography Guided Cryoballoon Ablation. Background: Cryoballoon ablation is increasingly used for pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF). This new technique aims to perform PVI safer and faster. However, procedure and fluoroscopy times were similar to conventional RF approaches. We compared ICE plus fluoroscopy versus fluoroscopy alone for anatomical guidance of PVI. Methods: Forty‐three consecutive patients with paroxysmal AF were randomly assigned to ICE plus fluoroscopy (n = 22) versus fluoroscopy alone (n = 21) for guidance of cryoballoon PVI. A “single big balloon” procedure using a 28 mm cryoballoon was performed. The optimal ICE‐guided position of the cryoballoon was assessed by full ostial occlusion and loss of Doppler coded reflow to the left atrium (LA). Any further freezes were ICE‐guided only without use of fluoroscopy or contrast media injection. Results: A total of 171 pulmonary veins could be visualized with ICE. 80% of ICE‐guided freezes were performed with excellent ICE quality. Acute procedural success and AF recurrence rate at 6 months were similar in both groups (AF recurrence: ICE‐guided = 27% vs Fluoroscopy = 33%; P = ns). Patients without ICE guidance had significantly longer procedure (143 ± 27 minutes vs 130 ± 19 minutes; P = 0.05) and fluoroscopy times (42 ± 13 minutes vs 26 ± 10, P = 0.01). The total amount of contrast used during the procedure was significantly lower in patients with ICE guidance (88 ± 31 mL vs 169 ± 38 mL, P < 0.001). Conclusion: Additional ICE guidance appears to be associated with lower fluoroscopy, contrast, and procedure times, with similar efficacy rates. Specifically, ICE allows for better identification of the PV LA junction and more precise anatomically guided cryoballoon ablations. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1202‐1207, November 2010)     

Long-term results of catheter ablation for atrial fibrillation in 866 patients

PurposeThis study presents eight-year experience with ablation techniques, recurrent arrhythmias, and long-term outcomes in patients undergoing catheter ablation for atrial fibrillation (AF).MethodsCatheter ablation of AF was performed in 866 consecutive patients in a total of 1272 ablation procedures. Ablation strategy and procedure endpoints were left at the operator's discretion. Total study population and groups of paroxysmal (n=508/59%), persistent (n=102/12%), and long-standing persistent AF (n=256/29%) were evaluated.ResultsPulmonary vein isolation alone or with cavo-tricuspid isthmus ablation was accomplished in 36% of the patients. It was significantly more often used in paroxysmal AF than in persistent or long-standing persistent AF (both p<0.001). More extensive ablation prevailed in persistent AF types. Ablation was repeated in 307 (35%) patients. Patients with long-standing persistent AF underwent significantly more repeat procedures than patients with paroxysmal AF (p<0.001) or persistent AF (p=0.001). Recurrent AF dominated before the first repeat ablation in 68% cases, while recurrent atrial tachycardia (AT) prevailed before the second (73%), and third (93%) repeat ablation. Patients with long-standing persistent AF presented with recurrent AT in 50% of the cases already before the first repeat ablation. At the end of 49±26 month follow-up, 83% of the patients remained in stable sinus rhythm (SR); 70% of the patients without antiarrhythmic drugs. SR maintenance was insignificantly superior in long-standing persistent AF group (91%) compared to paroxysmal AF (82%) and persistent AF patients (68%).ConclusionPatients with persistent AF types underwent more extensive initial ablation. Patients with long-standing persistent AF experienced best long-term outcome likely as a consequence of higher number of repeat ablation procedures.     

Robotic navigation in catheter ablation for paroxysmal atrial fibrillation: midterm efficacy and predictors of postablation arrhythmia recurrences

Robotic Navigation in Ablation of Paroxysmal AF . Introduction: Remote navigation systems represent a novel strategy for catheter ablation of atrial fibrillation (AF). The goal of this study is to describe a single‐center experience with the electromechanical robotic system (Sensei, Hansen Medical) in treatment of patients with paroxysmal AF. Methods: Out of 200 patients who underwent robotically guided ablation for AF between 2007 and 2009 at our institute, 100 patients (29 women, age 56.5 ± 10 years) had paroxysmal AF refractory to antiarrhythmic drugs. Electroanatomic mapping using NavX system (St. Jude Medical) provided anatomical shell for subsequent circumferential ablation with robotic catheter (Artisan) loaded with a 3.5‐mm, open‐irrigation, cooled‐tip ablation catheter. Results: A mean of 69 radiofrequency current applications (duration 2082 ± 812 seconds) were delivered to achieve circumferential electrical isolation of pulmonary venous antra. Total procedural time reached 222 ± 54 minutes. The mean fluoroscopic time was 11.9 ± 7.8 minutes. There were no major procedure‐related complications. After a median follow‐up of 15 months (range 3‐28 months), 63% of the patients were free from any atrial arrhythmias ≥ 30 seconds after the single procedure. Success rate increased to 86% after 1.2 procedures. Multivariate analysis revealed that only predictor of recurrent AF/AT was shorter overall procedural time (207 ± 36 vs 236 ± 64 minutes in patients with and without recurrences, respectively, P = 0.0068). Conclusions: This study demonstrates feasibility and safety of robotic navigation in catheter ablation for paroxysmal AF. Midterm follow‐up documents success rate comparable to other technologies and potential for improvement in more extensive ablation along the ridges with thicker myocardium. (J Cardiovasc Electrophysiol, Vol. 22, pp. 534‐540 May 2011)     

Incidence and Electrophysiologic Properties of Dissociated Pulmonary Vein Activity Following Pulmonary Vein Isolation During Catheter Ablation of Atrial Fibrillation

Dissociated PV Activity During AF Ablation. Introduction: Pulmonary veins (PV) play an important role in the arrhythmogenesis of atrial fibrillation (AF). Catheter‐based PV isolation is one of the primary treatments for symptomatic drug refractory AF. Following electrical isolation, isolated rhythms in the PV are encountered. The aim of this study was to assess the frequency of postisolation PV activity and classify the different rhythms observed. Methods and Results: This single center prospective study sought to assess the dissociated activity in the PVs following their isolation during AF ablation. In 100 consecutive patients (60 paroxysmal, 40 persistent) undergoing AF ablation, dissociated PV activity was recorded using a multielectrode mapping catheter following antral PV isolation. The dissociated PV activity was classified as (1) silent, (2) isolated ectopic beats, (3) ectopic rhythm, and (4) PV fibrillation. All the PVs were successfully isolated in all the patients. In 91 of 100 patients, there was dissociated activity in at least 1 isolated ipsilateral PV group. There was no significant difference in spontaneous PV activity between patients with paroxysmal and persistent AF (91.7% vs 90%, P = 1.0). Among the 200 isolated ipsilateral PV groups, 64 of 200 (32%) were silent, 86 of 200 (43%) demonstrated isolated ectopic beats, 41 of 200 (20.5%) had ectopic rhythms and 9 of 200 (4.5%) had PV fibrillation. The average cycle length of the PV ectopic rhythm was 2594 ± 966 ms (range 1193–4750 ms). Conclusions: Following PV isolation, a majority of patients demonstrate dissociated activity in at least 1 PV. This finding was evident in patients with both paroxysmal and persistent AF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1338‐1343, December 2010)     

Outcomes of Ablation of Paroxysmal Atrial Fibrillation in Patients on Chronic Hemodialysis

AF Ablation in HD Patients . Introduction: It is not common for patients on chronic hemodialysis (HD) to undergo catheter ablation of atrial fibrillation (AF). We aimed to show the outcomes of AF ablation in the HD patients. Methods and Results: Thirty HD patients who underwent pulmonary vein (PV) isolation for drug refractory paroxysmal AF were retrospectively studied, and their AF recurrence free rate and frequency of periprocedural complications were compared to 60 age‐ and gender‐matched control patients not requiring HD. A nonirrigated ablation catheter was used in both patient groups. During a mean follow‐up period of 821 ± 218 days, 16 (54%) of the HD patients remained free from AF recurrence without any antiarrhythmic agents versus 47 (78%) of the control patients with an initial ablation (P = 0.013). A second ablation procedure was performed in 12 patients with an AF recurrence, and consequently 20 (67%) of the HD patients were in sinus rhythm compared to 53 (88%) of the controls during a follow‐up duration of 747 ± 221 after the last ablation (P = 0.012). Bleeding from the venipuncture site requiring a prolonged hospital stay was identified in 2 HD patients and 1 control subject, while no life‐threatening complications were observed in either patient group. Conclusion: Although the success rate of the PV isolation in HD patients was far from satisfactory, it may be considered as one of the therapeutic options for them. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1289‐1294, December 2012)     

Substrate and procedural predictors of outcomes after catheter ablation for atrial fibrillation in patients with hypertrophic cardiomyopathy

Background: Hypertrophic cardiomyopathy (HCM) is often accompanied by atrial fibrillation (AF) due to diastolic dysfunction, elevated left atrial pressure, and enlargement. Although catheter ablation for drug‐refractory AF is an effective treatment, the efficacy in HCM remains to be established. Methods: Thirty‐three consecutive patients (25 male, age 51 ± 11 years) with HCM underwent pulmonary vein (PV) isolation (n = 8) or wide area circumferential ablation with additional linear ablation (n = 25) for drug‐refractory AF. Twelve‐lead and 24‐hour ambulating ECGs, echocardiograms, event monitor strips, and SF 36 quality of life (QOL) surveys were obtained before ablation and for routine follow‐up. Results: Twenty‐one (64%) patients had paroxysmal AF and 12 (36%) had persistent/permanent AF for 6.2 ± 5.2 years. The average ejection fraction was 0.63 ± 0.12. The average left atrial volume index was 70 ± 24 mL/m 2 . Over a follow‐up of 1.5 ± 1.2 years, 1‐year survival with AF elimination was 62%(Confidence Interval [CI]: 66‐84) and with AF control was 75%(CI: 66‐84). AF control was less likely in patients with a persistent/chronic AF, larger left atrial volumes, and more advanced diastolic disease. Additional linear ablation may improve outcomes in patient with severe left atrial enlargement and more advanced diastolic dysfunction. Two patients had a periprocedureal TIA, one PV stenosis, and one died after mitral valve replacement from prosthetic valve thrombosis. QOL scores improved from baseline at 3 and 12 months. Conclusion: Outcomes after AF ablation in patients with HCM are favorable. Diastolic dysfunction, left atrial enlargement, and AF subtype influence outcomes. Future studies of rhythm management approaches in HCM patients are required to clarify the optimal clinical approach.     

Effect of catheter ablation on progression of paroxysmal atrial fibrillation

Ablation and Progression of Atrial Fibrillation. Objective: The objective was to determine the effect of radiofrequency catheter ablation (RFA) on progression of paroxysmal atrial fibrillation (AF). Background: Progression to persistent AF may occur in up to 50% of patients with paroxysmal AF receiving pharmacological therapy. Hypertension, age, prior transient ischemic event, chronic obstructive pulmonary disease, and heart failure (HATCH score) have been identified as independent risk factors for progression of AF. Methods: RFA was performed in 504 patients (mean age: 58 ± 10 years) to eliminate paroxysmal AF. A repeat RFA procedure was performed in 193 patients (38%). Clinical variables predictive of outcome and their relation to progression of AF after RFA were assessed using multivariate analysis. Results: At a mean follow‐up of 27 ± 12 months after RFA, 434/504 patients (86%) were in sinus rhythm; 49/504 patients (9.5%) continued to have paroxysmal AF; and 14 (3%) were in atrial flutter. Among the 504 patients, 7 (1.5%) progressed to persistent AF. In patients with recurrent AF after RFA, paroxysmal AF progressed to persistent AF in 7/56 (13%, P < 0.001). The progression rate of AF was 0.6% per year after RFA (P < 0.001 compared to 9% per year reported in pharmacologically treated patients). Age >75 years, duration of AF >10 years and diabetes were independent predictors of progression to persistent AF. The HATCH score was not significantly different between patients with paroxysmal AF who did and did not progress to persistent AF (0.7 ± 0.8 vs 1.0 ± 0.5, P = 0.3). Conclusions: Compared to a historical control group of pharmacologically treated patients with paroxysmal AF, RFA appears to reduce the rate of progression of paroxysmal AF to persistent AF. Age, duration of AF, and diabetes are independent risk factors for progression to persistent AF after RFA. (J Cardiovasc Electrophysiol, Vol. 23, pp. 9‐14, January 2012)     

Persistence of Pulmonary Vein Isolation After Robotic Remote‐Navigated Ablation for Atrial Fibrillation and its Relation to Clinical Outcome

Robotic Remote Ablation for AF . Aims: A robotic navigation system (RNS, Hansen?) has been developed as an alternative method of performing ablation for atrial fibrillation (AF). Despite the growing application of RNS‐guided pulmonary vein isolation (PVI), its consequences and mechanisms of subsequent AF recurrences are unknown. We investigated the acute procedural success and persistence of PVI over time after robotic PVI and its relation to clinical outcome. Methods and Results: Sixty‐four patients (60.7 ± 9.8 years, 53 male) with paroxysmal AF underwent robotic circumferential PVI with 3‐dimensional left atrial reconstruction (NavX?). A voluntary repeat invasive electrophysiological study was performed 3 months after ablation irrespective of clinical course. Robotic PVI was successful in all patients without complication (fluoroscopy time: 23.5 [12–34], procedure time: 180 [150–225] minutes). Fluoroscopy time demonstrated a gradual decline but was significantly reduced after the 30th patient following the introduction of additional navigation software (34 [29–45] vs 12 [9–17] minutes; P < 0.001). A repeat study at 3 months was performed in 63% of patients and revealed electrical conduction recovery in 43% of all PVs. Restudied patients without AF recurrence (n = 28) showed a significantly lower number of recovered PVs (1 (0–2) vs 2 (2–3); P = 0.006) and a longer LA‐PV conduction delay than patients with AF recurrences (n = 12). Persistent block of all PVs was associated with freedom from AF in all patients. At 3 months, 67% of patients were free of AF, while reablation of recovered PVs led to an overall freedom from AF in 81% of patients after 1 year. Conclusion: Robotic PVI for PAF is safe, effective, and requires limited fluoroscopy while yielding comparable success rates to conventional ablation approaches with PV reconduction as a common phenomenon associated with AF recurrences. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1079‐1084)