Catheter ablation vs. amiodarone plus losartan for prevention of atrial fibrillation recurrence in patients with paroxysmal atrial fibrillation.

BACKGROUND: Although amiodarone plus angiotensin II receptor blockers (ARBs) and catheter ablation may improve sinus rhythm maintenance of paroxysmal atrial fibrillation (AF), their clinical efficacies have not been compared. This prospective cohort study was designed to compare clinical efficacy of catheter ablation and amiodarone plus losartan on sinus rhythm maintenance in patients with paroxysmal AF. MATERIALS AND METHODS: A total of 240 patients with paroxysmal AF were assigned to four groups. CPVA group (n = 60) was treated with circumferential pulmonary vein ablation (CPVA), SPVI group (n = 60) with segmental pulmonary vein isolation, AMIO group (n = 60) with amiodarone and AMIO + LO group (n = 60) with amiodarone plus losartan. The endpoint was documented recurrence of AF > 30 s by Holter or conventional 12-lead ECG in the 1-year follow-up period. RESULTS: During 12 months of follow-up, the primary end point was reached in 28 patients in CPVA group, 14 patients in SPVI group, 25 patients in AMIO group and 13 patients in AMIO + LO group, respectively. The sinus rhythm in SPVI and AMIO + LO group were significant higher than that in CPVA and AMIO group (P < 0.01 and 0.025), and no difference between CPVA and AMIO group. The maintenance rate of sinus rhythm in SPVI group was similar to that in AMIO + LO group. CONCLUSIONS: This study demonstrates that segmental pulmonary vein isolation in preventing AF recurrence is similar to amiodarone plus losartan, but it is superior to CPVA and amiodarone alone in patients with paroxysmal AF. Larger multicentre studies are needed to confirm its long-term outcomes.

[Use of the NavX navigation system in ablation of atrial fibrillation]. / Einsatz des Navigationssystems NavX bei der Ablationsbehandlung von Vorhofflimmern.

Catheter ablation, notably the electric isolation of pulmonary veins, has become a well-established therapeutic approach in symptomatic atrial fibrillation. The NavX navigation system has been described to facilitate pulmonary vein isolation in patients with AF. EnSite NavX (Endocardial Solutions, St. Jude Medical, Inc., St. Paul, MN, USA) is a novel navigation system that measures the local voltage on every standard intra-cardiac electrode and calculates the electrode position in three-dimensional (3D) space. Any individual electrode of each catheter in 3D-space can be displayed and labelled individually. The geometry of any cardiac chamber can be reconstructed and additional information, e.g. electrical activation spreading, can be displayed colour coded on the surface. Recent studies investigating the possible advantages of this system in the ablation of persistent or paroxysmal atrial fibrillation are summarized. All reports showed a significant reduction in fluoroscopy and procedure time by the use of the NavX system compared to conventional fluoroscopic catheter guidance. This benefit can be obtained with simple visualisation of all intracardiac catheters alone or with additional reconstruction of the left atrium and pulmonary veins.

[Magnetic navigation in invasive electrophysiological diagnostic and therapy]. / Magnetische Navigation in der elektrophysiologischen Diagnostik und Therapie.

Electrophysiological stimulation and ablation is currently performed with manually deflectable catheters of different lengths and curves. Disadvantages of conventional therapy are catheter stiffness, limited local stability, risk of dislocation or perforation, and reduced tissue contact in regions with difficult access. Fluoroscopy to control catheter movement and position may require substantial radiation times. Magnetic navigation was first applied for right heart catherization in congenital heart disease in 1991; the first electrophysiological application took place in 2003. Today, an ablation electrode with small magnets is aligned in the patient's heart by two external magnets positioned at both sides of the thorax. Antegrade and retrograde movement of the distal catheter tip are performed via an external device on the patient's thigh. Three-dimensional MRI scans acquired before intervention can be merged with electroanatomical reconstruction, leading to further reductions of radiation burden. During treatment of supraventricular tachyarrhythmias high local precision of magnetically guided catheters, good local stability, and a substantially reduced radiation time have been reported. First applications in ventricular tachyarrhythmias and complex congenital cardiac defects indicate a comparable effect. Limitations of this therapy are the application in left atrial procedures (open irrigated ablation catheters not yet available), difficult transaortic retrograde approach (high lead flexibility), and the considerable costs. Magnet-assisted navigation is feasible during percutaneous coronary interventions of tortuous coronary arteries and in positioning guidewires in coronary sinus side branches for resynchronisation therapy. Future applications will be complex left atrial procedures, magnetically guided cardiac stem cell therapy, local drug application, and extracardiac vessel therapy.

[Selective increase of ventricular pacing threshold with complete exit block following DC cardioversion in a patient with a dual chamber pacemaker]. / Selektiver ventrikulärer Reizschwellenanstieg mit komplettem Exitblock nach elektiver externer Elektrokardioversion bei implantiertem Zweikammerschrittmacher.

We report the case of a 78-year old patient with a dual chamber pacemaker, who was admitted for cardioversion of atrial tachycardia. Transthoracic DC shock of 160 J was followed by transient loss of ventricular capture with complete exit-block and severe nodal bradycardia. Subsequent analysis of stimulation thresholds revealed a marked rise in the ventricular threshold only, whereas atrial threshold was unchanged. The selective dysfunction of ventricular capture is most likely caused by current-induced tissue damage at the electrode-endomyocardial interface by preferential shunting of high electrical energy into the ventricular lead as compared to the atrial lead. High output pacing prior to elective DC cardioversion is recommended to ensure consistent capture, particularly in pacemaker-dependent patients, and careful evaluation of pacemaker function after shock delivery should performed.

Dissimilar atrial rhythms: coexistence of reentrant atrial tachycardia, atrioventricular nodal reentrant tachycardia and interatrial conduction block.

We report a patient in whom mapping of the right atrium with multipolar catheters and electroanatomic mapping revealed the presence of three dissimilar rhythms: a reentrant atrial tachycardia in the antero-lateral wall of the right atrium and an atrioventricular nodal reentrant tachycardia (AVNRT) isolated from each other and a conduction disturbance at the interatrial septum resulting in a rate-related interatrial block and a slow left atrial rhythm. The AVNRT was stopped with intravenous adenosine (6 mg) and induced repeatedly by atrial extrastimuli associated with a critical atrioventricular delay and dual atrioventricular nodal pathways. Electroanatomic mapping disclosed extensive fibrosis isolating viable myocardium of the antero-lateral wall from the rest of the right atrium. The viable myocardium in the antero-lateral wall was activated by a reentrant rhythm circulating around an islet of fibrosis located in the middle of the viable tissue. The AVNRT was ablated by a standard approach and the reentrant atrial tachycardia by producing a linear lesion bridging the central islet of fibrosis with the anterior tricuspid annulus. This case highlights the complicated nature of some dissimilar atrial rhythms and the power of electroanatomic mapping tools to reveal the exact mechanism and guide radiofrequency ablation.

Internal atrial defibrillation during electrophysiological studies and focal atrial fibrillation ablation procedures.

Induction of sustained AF during electrophysiological studies requires electrical cardioversion to restore sinus rhythm for continuation of the electrophysiological study and mapping procedure. The study included 104 consecutive patients (age 59 +/- 12 years, 74 men), who were in stable sinus rhythm at the beginning of the electrophysiological study, underwent internal atrial defibrillation (IAD) of AF (> 15 minutes) that was induced during electrophysiological study. In 21 patients, AF was regarded to be the clinical problem (group I), and in the remaining 83 patients other arrhythmias represented the primary target of the electrophysiological study (group II). A 7.5 Fr cardioversion catheter (EP Medical) equipped with a distal array was used and placed in the left pulmonary artery and a proximal array of the same size was located along the lateral right atrial wall. All patients were successfully cardioverted with a mean energy of 6.2 +/- 4.0 1. In 18 (78%) of 21 group I patients and in 12 (14%) of 81 group II patients, AF recurred 3.7 +/- 3.4 and 2.4 +/- 1.4 times during electrophysiological study, respectively. The IAD shock did not suppress focal activity, thus the mapping of atrial foci responsible for AF could be continued even after several IADs. No IAD related complications occurred during the study. In conclusion, (1) IAD can be safely and successfully performed during electrophysiological study without using narcotic drugs or high electric energies; (2) IAD does not suppress focal activity; and (3) even if AF recurs frequently during the electrophysiological study, IAD can be performed several times without significant time delay.

Modes of initiation of paroxysmal atrial fibrillation from analysis of spontaneously occurring episodes using a 12-lead Holter monitoring system.

Although new, possibly curative radiofrequency ablation techniques for atrial fibrillation (AF) have been developed in recent years, little is known about the mechanisms of spontaneous onset of AF episodes. Using a 12-lead 24-hour Holter monitoring system, we aimed to characterize such episodes. A total of 297 spontaneous episodes of AF in 33 patients with intermittent AF (mean age of 59 +/- 11 years) were analyzed. Two hundred seventy-six episodes (93%) were initiated by atrial premature complexes (APCs), whereas 19 episodes (6.4%) were preceded by typical atrial flutter and 2 (0.7%) by atrial tachycardia. Based on 12-lead electrocardiographic criteria, the origin of ectopic beats initiating AF was classified in 230 episodes (77.5%) as being of left atrial origin, in 6 episodes (2.0%) as being of right atrial origin and in 40 episodes (13.5%) the exact location could not be determined. In 16 of 23 patients (70%) with multiple episodes of AF, ectopic beats that initiated AF were consistently monomorphic. In the 120 seconds (6.2 APCs/min for a 30-second period) before onset of AF, frequency of ectopic beats increased from 0.8 APCs/min in AF-free intervals to 4.1/min (6.2 APCs/min for a 30-second period), (p = 0.003 and p = 0.016, respectively). In 209 of 254 episodes (82%), AF onset occurred during normal sinus rate (60 to 100 beats/min). Thus, paroxysmal AF is triggered most frequently by monomorphic left APCs. In most AF episodes, the increase in the number of ectopic beats that initiated episodes of AF occurred at a normal sinus rate.

Electrophysiologic characteristics of paroxysmal and chronic atrial fibrillation in human right atrium.

OBJECTIVES: The aim of the study was to analyze the electrophysiologic characteristics of paroxysmal (PAF) and chronic (CAF) atrial fibrillation (AF) in the human right atrium (RA). BACKGROUND: Differences that exist between PAF and CAF and the mechanisms of self-sustenance of these arrhythmias are incompletely understood. METHODS: A total of 53 patients with PAF (25 patients, mean age 59 +/- 6.1 years, 3 women) and CAF (28 patients, mean age 59 +/- 13 years, 7 women) underwent multisite mapping of the RA during ongoing AF using a 64-electrode basket catheter. Quantitative evaluation and three-dimensional activation patterns were performed using a computerized system. RESULTS: Patients with PAF, as compared with patients with CAF, had significantly longer AF cycle length, shorter time intervals with type III AF throughout the RA and a smaller number of endocardial breakthroughs (mean 51 +/- 19 vs. 104 +/- 40, p < 0.001). The majority of endocardial breakthrough points (88% in PAF patients and 98% in CAF patients) were located in the septal region and coincided anatomically with major interatrial connection routes. Coexistence of re-entrant and apparently focal activation determined maintenance of AF in the RA in PAF, whereas random re-entry was documented more frequently in patients with CAF. In patients with CAF, the duration of arrhythmia (in years) correlated strongly with the percentage of time during which type III AF was observed in the lateral wall of the RA (r = 0.71). CONCLUSIONS: Clinical PAF and CAF, as recorded in the RA, have, at least quantitatively, distinct electrophysiologic features and different mechanisms of maintenance.

Activation patterns in the left atrium during counterclockwise and clockwise atrial flutter.

INTRODUCTION: Activation of the left atrium (LA) in patients with isthmus-dependent right atrial flutter (AFL) has not yet been studied. The aim of this study was to analyze the activation patterns in the LA in patients with counterclockwise and clockwise AFL. METHODS AND RESULTS: The study population consisted of 12 patients (10 men and 2 women; mean age 61+/-13 years) with documented AFL and atrial fibrillation referred for ablation. The LA was mapped with a 64-electrode basket catheter inserted through a transseptal approach (10 patients) or an open foramen ovale (2 patients). In patients with counterclockwise AFL (10 episodes), the LA was activated for a mean of 133+/-28 msec. Two endocardial breakthroughs of earliest activity on the left side of the interatrial septum, separated in time by an interval of 38+/-15 msec, were observed in 9 episodes (90%). Two wavefronts originated from these breakthroughs, which activated the posterior and the anterior LA walls, respectively. In one patient, the entire LA was activated from the inferior breakthrough. In patients with clockwise AFL (five episodes), the LA activation time was 130+/-13 msec. During ongoing episodes, two early electrical breakthroughs, separated in time by an interval of 41+/-15 msec, appeared in the high anteroseptal and low posteroseptal LA regions. The superior wavefront that emerged from the high anterolateral LA region was the dominant activation pathway in 4 (80%) of 5 episodes. CONCLUSION: In patients with AFL, the LA is activated by two wavefronts originating from the high anterior and the low posterior regions of the interatrial septum. The sequence of activation of these interatrial connections in counterclockwise or clockwise AFL and the conductive properties of the LA conduction pathways determine the activation patterns in the LA.

Inappropriate shock delivery due to ventricular double detection with a biventricular pacing implantable cardioverter defibrillator.

This report describes a patient with advanced heart failure, pronounced intraventricular conduction delay, and ventricular tachycardias who underwent implantation of a multisite pacing ICD. Pacing leads were placed in the right atrium, right ventricular apex, and to the left ventricular posterior wall via a coronary sinus vein. The system proved to have correct sensing and pacing function in an atrial synchronized biventricular pacing mode and an appropriate detection of ventricular fibrillation. However, 1 month after implantation the patient received an inappropriate shock delivery due to double detection of ventricular premature beats. The inherent detection problem of dual ventricular sensing is discussed.

Dissociation between coronary sinus and left atrial conduction in patients with atrial fibrillation and flutter.

INTRODUCTION: Coronary sinus (CS) recordings are routinely used during electrophysiologic studies for various supraventricular and ventricular arrhythmias with the understanding that they represent left atrial (LA) activity. However, the behavior of CS electrical activity during atrial arrhythmias has not drawn any special attention beyond standard considerations. METHODS AND RESULTS: The study population consisted of 9 patients (3 women; mean age 59 +/- 11 years) with atrial fibrillation (AF) and atrial flutter (AFL) who developed dissociation of conduction between the CS and posterior LA during spontaneous AF and AFL. In all patients, the LA and the CS were mapped using a 64-electrode basket catheter and a multipolar electrode catheter, respectively. The right atrium (RA) was mapped simultaneously using a 24-polar electrode catheter (7 patients) or a 64-electrode basket catheter (2 patients). Eight patients showed stable double potentials in CS recordings during AF (9 episodes) and AFL (3 episodes). During ongoing arrhythmias, the first row of potentials maintained a constant relationship with the RA activity, whereas the second row of potentials was discordant with the posterior wall of the LA in 7 patients and concordant in 2 patients. In 1 patient with counterclockwise AFL, CS activation was isolated from the posterior wall of the RA until it reached the distal portion of the CS, after which it entered the lateral region of the LA. In 1 patient, a macroreentrant LA tachycardia involving CS muscle was observed. Rapid atrial pacing from the proximal CS and extrastimuli produced longitudinal dissociation of CS activation in all patients. CONCLUSION: Conduction between the CS and posterior LA can be dissociated during spontaneous atrial arrhythmias and provocative proximal CS pacing.

Incidence of electromagnetic interference in implantable cardioverter defibrillators.

Electromagnetic interference (EMI) with ICDs can lead to temporary inhibition of the device or to inappropriate delivery of antitachycardia pacing and shocks. The incidence of interactions between electronic devices and the current generation of ICDs is not known. In a retrospective study of 341 patients (665 patient-years) who underwent a regular follow-up every 3 months, five episodes of EMI were detected in four different patients. The risk for receiving inappropriate shocks due to EMI is < 1% per year and patient. In conclusion, although inappropriate delivery of shocks by ICDs due to EMI rarely occurs, patient information should emphasize the avoidance of situations of possible interference. Further efforts concerning lead technology and detection algorithms are necessary to minimize the risk of EMI.

Reentry circuit location and left atrial three-dimensional activation patterns in left atrial flutter.

We report the case of a patient with left atrial flutter (LAF) in whom the reentry circuit location was mapped with a 64-electrode basket catheter deployed in the left atrium. Left atrial three-dimensional activation patterns were constructed with a software program and presented as color-coded isochrones. The reentrant activation traveled preferentially around the mitral annulus in a clockwise direction. It consisted of a single reentry confined anteriorly by the mitral annulus and posteriorly by an anatomic-functional barrier composed of a functional conduction block extending between pulmonary veins and surrounding a part of the posterior wall of the left atrium. The lower portion of the posterior wall and the anterior wall in close proximity to mitral annulus were preferentially used by the reentrant impulse.

Do current dual chamber cardioverter defibrillators have advantages over conventional single chamber cardioverter defibrillators in reducing inappropriate therapies? A randomized, prospective study.

INTRODUCTION: Supraventricular tachyarrhythmias are the main cause of inappropriate therapies in patients with conventional single chamber implantable cardioverter defibrillators (VVI-ICD). It was anticipated that dual chamber cardioverter defibrillators (DDD-ICD), with their capacity to analyze atrial and ventricular rhythm, could substantially reduce inappropriate therapies. METHODS AND RESULTS: Our prospective study included 92 patients (87 men; mean age 61 +/- 12.7 years) who were randomly assigned to a VVI-ICD (45 patients) or a DDD-ICD (47 patients). Both groups were followed for 7.5 +/- 3.5 and 7.6 +/- 4.1 months, respectively. During the follow-up period, overall 725 ventricular tachycardia (VT)/ventricular fibrillation (VF) episodes were recorded in 45 (49%) of 92 patients. Of these episodes, 404 (56%) occurred in the VVI-ICD group and 321 (44%) episodes occurred in the DDD-ICD group. Twenty-three (51%) patients in the VVI-ICD group and 22 (47%) patients in the DDD-ICD group (P = 0.8) developed VT/VF. Overall, 73 (10%) of 725 treated episodes were inappropriate in 6 (13%) patients in the VVI group and in 10 (21%) patients in the DDD-ICD group (P = 0.2). There were 22 (31%) inappropriately treated episodes in the VVI-ICD group and 51 (69%) in the DDD-ICD group. Thirty-two of the 51 inappropriate episodes in the DDD-ICD patients resulted from intermittent atrial sensing problems that led to failure of the respective dual chamber algorithms. Nonfatal complications occurred in 6 (13%) patients in the VVI-ICD group and in 3 (6%) patients in the DDD-ICD group (P = 0.7). CONCLUSION: We conclude that the implanted DDD-ICD and conventional VVI-ICD are equally safe and effective for therapy of life-threatening ventricular tachyarrhythmias. Although DDD-ICDs allow better rhythm classification, the applied detection algorithms do not offer benefits in avoiding inappropriate therapies during supraventricular tachyarrhythmias.

Noncontact mapping-guided ablation of atrial flutter and enhanced-density mapping of the inferior vena caval-tricuspid annulus isthmus.

Three-dimensional visualization of cardiac activation has become important in providing further insights into pathophysiological mechanisms of arrhythmias and to increase the efficacy of catheter ablation. The noncontact mapping enables a single beat analysis in a reconstructed geometry of the cardiac chamber. The aim of the study was to describe three-dimensional activation patterns and inferior vena caval-tricuspid annulus (IVC-TA) isthmus conduction characteristics in patients with atrial flutter and the noncontact guidance of the radiofrequency ablation of this arrhythmia. In 34 patients with atrial flutter, the noncontact probe was deployed in the RA. The global three-dimensional activation and the isthmus conduction (enhanced density mapping) were delineated during ongoing a trial flutter and paced rhythms. Ablation was performed nonfluoroscopically based on reconstructed anatomy and conduction patterns. Noncontact mapping was compared and validated with conventional multielectrode technique. IVC-TA isthmus ablation was completed successfully in 33 (97%) of 34 patients. In one patient a lower loop reentry around the inferior vena cava was depicted as a mechanism of atrial flutter. In another patient with positive flutter waves in inferior leads, an activation pattern typical of counterclockwise flutter was demonstrated in propagation maps. During a follow-up of 15.9 +/- 5.9 months, two atrial flutter recurrences occurred (5.8%). A gap of the resumed conduction through the IVC-TA isthmus was delineated as a mechanism of recurrence and ablated with one and three radiofrequency applications. Noncontact mapping allows construction of the global activation patterns in typical and atypical atrial flutter. It enables the nonfluoroscopic guidance of atrial flutter ablation and a comprehensive evaluation of the ablation results.

Pseudotermination of intermittent atrial fibrillation by a pacemaker algorithm: antitachycardia pacing without capture miscounted as successful termination of fibrillation episodes.

A patient is described with intermittent AF and an implanted pacemaker which provides preventive pacing and overdrive stimulation designated to terminate atrial arrhythmias. The case highlights the possibility of false estimation of therapeutic efficacy and possible proarrhythmic effect of this therapeutic modality.