Primary prevention of atrial fibrillation: does the atrial lead position influence the incidence of atrial arrhythmias in patients with sinus node dysfunction? Results from the PASTA Trial.

INTRODUCTION: PASTA (pacing of the atria in sinus node disease) is a prospective and randomized trial, assessing the effect of different atrial lead positions on the atrial fibrillation (AF) incidence in patients with sinus node disease (SND). METHOD: The atrial lead position is randomized to: (a) free right atrial wall, (b) right atrial appendage (RAA), (c) coronary sinus ostium (CS-Os), or (d) dual site right atrial pacing (CS-Os + RAA). The pacemakers (Vitatron Selection 9000 or Prevent AF, Vitatron B.V., Arnhem, The Netherlands) are programmed in DDDR 70 mode and the total follow-up duration is 24 months. To describe the atrial rhythm state, pacemaker-derived data (arrhythmia counter) were assessed for AF episodes. AF was considered as evident, if the AF burden (time in AF related to follow-up interval) was >1% (i.e., 15 min/d). Follow-up data after 24 months were evaluated. RESULTS: The analysis evaluates 142 patients (77 male, 74.5 +/- 7.8 years). There was no statistical significant difference with respect to the occurrence of AF between the four groups after 24 months (A: 36%; B: 38%, C: 32%, D: 48%). The percentage of atrial/ventricular pacing was in A: 78/76%, in B: 84/81%, in C: 70/65%, and in D: 79/69%. These differences were not significant. CONCLUSION: The evaluation of the AF burden >1% and the total AF burden after 24 months did not show differences in the incidence of AF in patients with dual chamber pacemaker therapy for SND. We were not able to demonstrate a significant influence of right atrial lead position on the incidence of AF recurrence.

Pulmonary-vein isolation for atrial fibrillation in patients with heart failure.

BACKGROUND: Pulmonary-vein isolation is increasingly being used to treat atrial fibrillation in patients with heart failure. METHODS: In this prospective, multicenter clinical trial, we randomly assigned patients with symptomatic, drug-resistant atrial fibrillation, an ejection fraction of 40% or less, and New York Heart Association class II or III heart failure to undergo either pulmonary-vein isolation or atrioventricular-node ablation with biventricular pacing. All patients completed the Minnesota Living with Heart Failure questionnaire (scores range from 0 to 105, with a higher score indicating a worse quality of life) and underwent echocardiography and a 6-minute walk test (the composite primary end point). Over a 6-month period, patients were monitored for both symptomatic and asymptomatic episodes of atrial fibrillation. RESULTS: In all, 41 patients underwent pulmonary-vein isolation, and 40 underwent atrioventricular-node ablation with biventricular pacing; none were lost to follow-up at 6 months. The composite primary end point favored the group that underwent pulmonary-vein isolation, with an improved questionnaire score at 6 months (60, vs. 82 in the group that underwent atrioventricular-node ablation with biventricular pacing; P<0.001), a longer 6-minute-walk distance (340 m vs. 297 m, P<0.001), and a higher ejection fraction (35% vs. 28%, P<0.001). In the group that underwent pulmonary-vein isolation, 88% of patients receiving antiarrhythmic drugs and 71% of those not receiving such drugs were free of atrial fibrillation at 6 months. In the group that underwent pulmonary-vein isolation, pulmonary-vein stenosis developed in two patients, pericardial effusion in one, and pulmonary edema in another; in the group that underwent atrioventricular-node ablation with biventricular pacing, lead dislodgment was found in one patient and pneumothorax in another. CONCLUSIONS: Pulmonary-vein isolation was superior to atrioventricular-node ablation with biventricular pacing in patients with heart failure who had drug-refractory atrial fibrillation. (ClinicalTrials.gov number, NCT00599976.)

Atrial fibrillation ablation using a robotic catheter remote control system: initial human experience and long-term follow-up results.

OBJECTIVES: We present the initial clinical human experience with the use of a robotic remote navigation system (Hansen Medical, Mountain View, California), to perform left and right atrial mapping and radiofrequency ablation of atrial fibrillation (AF) and atrial flutter (AFL). BACKGROUND: Catheter ablation is an established curative modality for various arrhythmias. A robotic steerable sheath system (SSS) (Hansen Medical) allows better catheter stability and greater degrees of freedom of catheter movement. METHODS: A total of 40 patients (mean age 57 years) with antiarrhythmic drug (AAD)-refractory AF (23 had also concomitant documented typical AFL) were studied. Three-dimensional reconstruction of the corresponding atrial chamber anatomy was performed with the CARTO electroanatomic mapping system (Biosense Webster, Diamond Bar, California or the EnSite NavX system (St. Jude Medical, Minneapolis, Minnesota) in combination with the Artisan catheter (Hansen Medical). In patients undergoing AF ablation, 2 transseptal punctures were performed under intracardiac ultrasound (ICE) guidance, with one of the punctures being performed using SSS. Pulmonary vein antrum isolation was performed with a 3.5-mm thermocool catheter manipulated with the use of the SSS and was verified by circular mapping. Patients were followed clinically for recurrence of arrhythmia with an event transmitter and ambulatory holter monitoring. Clinical recurrence of AF/AFL was defined as AF/AFL episodes >1 min in duration. RESULTS: Pulmonary vein antrum isolation was performed in 40 patients, including 23 with concomitant typical AFL ablation. All pulmonary veins, including the superior vena cava, were successfully isolated. In 23 of 40 patients, cavotricuspid ablation was also performed with bidirectional block obtained. At 1-year follow-up, 34 patients (86%) and 5 patients were free from atrial arrhythmia off AADs and on AADs, respectively. CONCLUSIONS: This preliminary human experience suggests that mapping and ablation of AFL and AF using this novel robotic catheter with remote control system is feasible with similar results to conventional approach.

Incidence of oesophageal wall injury post-pulmonary vein antrum isolation for treatment of patients with atrial fibrillation.

AIMS: Oesophageal injury has been reported with delivery of radio-frequency lesions at the left atrium posterior wall in catheter ablation procedures for atrial fibrillation (AF). In this observational study we prospectively assessed endoscopical oesophageal wall changes after pulmonary vein antrum isolation (PVAI) in patients presenting for treatment of AF. METHODS AND RESULTS: Twenty eight patients (18 men; mean age 55 +/- 11 years) were ablated using either a cooled-tip or an 8 mm tip ablation catheter. Endoscopy of the oesophagus was performed 24 h after PVAI. If oesophageal wall changes were detected post ablation, a proton-pump inhibitor (PPI) was started and repeat endoscopy was considered. Within 24 h post ablation oesophageal wall changes were confirmed in 47% of our study patients. Erythema was identified in 29% and necrotic or ulcer-like changes in 18% of patients. None of study patients experienced left atrial-oesophageal fistula. A significant correlation between Reflux-like symptoms and oesophageal wall changes was demonstrated. Complete recovery of oesophageal lesions was shown in all study patients 2-4 weeks post ablation. CONCLUSION: A significant number of patients experienced oesophageal wall injury post PVAI. Initiating PPIs in this group of patients might facilitate recovery of oesophageal wall injuries caused by radio-frequency energy delivery.

Randomized comparison between open irrigation technology and intracardiac-echo-guided energy delivery for pulmonary vein antrum isolation: procedural parameters, outcomes, and the effect on esophageal injury.

INTRODUCTION: We performed a prospective study to compare efficacy and safety of both open irrigation tip (OIT) technology with intracardiac echo (ICE)-guided energy delivery in patients presenting for PVAI. METHODS AND RESULTS: Fifty-three patients presenting for PVAI were randomized to ablation using an OIT catheter (Group 1, 26 patients; temperature and power were set at 50 degrees and 50 W, respectively, with a saline pump flow rate of 30 mL/min) or radiofrequency (RF) energy delivery under ICE guidance (Group 2, 27 patients; energy was titrated based on microbubbles formation). The mean procedure time and fluoroscopy exposure were lower in Group 1 (164 +/- 42 min and 7,560 +/- 2,298 microGray m2 vs 204 +/- 47 min and 12,240 +/- 4,356 microGray m2; P = 0.005 and 0.008, respectively). Moreover, the durations of RF lesions applied per PV antrum was lower in Group 1 compared with Group 2 (5.1 +/- 2.2 min vs 9.2 +/- 3.2 min, P = 0.03, respectively). Within 24 hours after PVAI in 35.7% (all erythema) of Group 1 and 57.1% (21.4% erythema and 35.7% necrosis) of Group 2, patients' esophageal wall changes were documented. After 14 +/- 2 months of follow up, recurrences were documented in 19.2% of Group 1 and 22.2% of Group 2 patients. CONCLUSION: Although both OIT and ICE-guided energy delivery possess a similar effect in treating AF, OIT seems to be superior in terms of achieving isolation and shortening fluoroscopy exposure. Moreover, a lower incidence of esophageal wall injury was observed utilizing OIT for PVAI.

A new method to investigate the response to the morphology discrimination algorithm in patients with ICD.

BACKGROUND: Inappropriate therapy for supraventricular tachyarrhythmia is still a major problem in implantable cardioverter defibrillators (ICD). The morphology discrimination algorithm compares the morphology of a tachycardia electrogram with a stored template on a beat-to-beat basis. However, algorithm responders could not yet be identified prior to the occurrence of first tachycardia episodes. We analyzed whether rapid atrial pacing and/or exercise testing can be used for identification of responders and compared the results with ICD detected tachycardia. METHODS: 22 patients (16 male, 61+/-14 years) with dual-chamber ICDs have been enrolled. Patients underwent a standardized bicycle exercise testing and an atrial pacing protocol. For both tests, morphology match scores of 8 consecutive beats were analyzed for each 10-bpm-step increment above sinus rhythm. Patients were categorized as responders, if morphology match was > or = 90% of tested heart rates. During follow-up, ICD stored episodes with morphology discrimination activated were evaluated. RESULTS: There were no significant differences between morphology match (85+/-29% vs. 84+/-27%) and linear regression slope B (-0.19+/-0.87 vs. -0.20+/-0.48) during exercise testing and atrial pacing. 16 patients (73%) were classified as responders. During follow-up (739+/-338 days) 121 sustained supraventricular (n=88) and ventricular tachycardia (n=33) were detected in 10 patients (45%). Specificity for tachycardia discrimination was 78% overall, 100% in responders and 22% in non-responders. CONCLUSION: Exercise testing and atrial pacing were equally suitable for identification of patients who seem to respond to the morphology discrimination algorithm with a high specificity for ventricular tachycardia discrimination. Thus, morphology match tests are suggested to optimize tachycardia discrimination and to reduce inadequate therapies.

Management of far-field R wave sensing for the avoidance of inappropriate mode switch in dual chamber pacemakers: results of the FFS-test study.

BACKGROUND AND OBJECTIVE: Far-field R wave sensing (FFS) in the atrial channel of dual chamber pacemakers is a relevant source for inappropriate mode switch from the DDD mode to the DDI or VDI mode. Inappropriate loss of atrioventricular synchrony due to false positive mode switch is hemodynamically disadvantageous, may induce atrial tachyarrhythmias, can lead to pacemaker syndrome, and impairs the reliability of pacemaker Holter data. The aim of the study was to determine whether individual adjustment of the postventricular atrial blanking period (PVAB) based on an additional test is effective in avoiding inappropriate mode switch due to FFS when compared with standard programming of the PVAB. METHODS: A total of 207 patients were supplied with a St. Jude Medical Identity DR or Identity ADx DR dual chamber pacemaker for sinus nodal disease (n = 84), atrioventricular block (n = 79), binodal disease (n = 35), or other indications (n = 9). At hospital discharge, they were randomized to an individually optimized PVAB (n = 100) or to a control group with the PVAB left at the nominal of 100 msec (n = 107). Primary endpoint was the occurrence of inappropriate mode switch due to FFS within 3 months after pacemaker implantation assessed by stored electrograms of the pacemaker. RESULTS: At the 3-month follow-up, 28/107 (26%) patients with the standard programming of the PVAB showed at least one episode of inappropriate mode switch due to FFS versus 10/100 (10%) patients with optimized PVAB (P < 0.01). The optimized PVAB was shorter than the nominal PVAB in about one-third of patients and longer in about two-third of patients. Different atrial lead localizations were not associated with the occurrence of inappropriate mode switch. CONCLUSIONS: Individual adjustment of the PVAB significantly reduces the incidence of inappropriate mode switch due to FFS.

Assessment of temperature, proximity, and course of the esophagus during radiofrequency ablation within the left atrium.

BACKGROUND: Left atrioesophageal fistula is a devastating complication of atrial fibrillation ablation. There is no standard approach for avoiding this complication, which is caused by thermal injury during ablation. The objectives of this study were to evaluate the course of the esophagus and the temperature within the esophagus during pulmonary vein antrum isolation (PVAI) and correlate these data with esophagus tissue damage. METHODS AND RESULTS: Eight-one patients presenting for PVAI underwent esophagus evaluation that included temperature probe placement. Esophagus course was obtained with computed tomography, 3D imaging (NAVX), or intracardiac echocardiography. For each lesion, the power, catheter and esophagus temperature, location, and presence of microbubbles were recorded. Lesion location and esophagus course were defined with 6 predetermined left atrial anatomic segments. Endoscopy evaluated tissue changes during and after PVAI. Of 81 patients, the esophagus coursed near the right pulmonary veins in 23 (28.4%), left pulmonary veins in 31 (38.3%), and mid-posterior wall in 27 (33%). Esophagus temperature was significantly higher during left atrial lesions along its course than with lesions elsewhere (38.9+/-1.4 degrees C, 36.8+/-0.5 degrees C, P<0.01). Lesions that generated microbubbles had higher esophagus temperatures than those without (39.3+/-1.5 degrees C, 38.5+/-0.9 degrees C, P<0.01). Power was not predictive of esophagus temperatures. Distance between the esophagus and left atrium was 4.4+/-1.2 mm. CONCLUSIONS: Lesions near the course of the esophagus that generated microbubbles significantly increased esophagus temperature compared with lesions that did not. Power did not correlate with esophagus temperatures. Esophagus variability makes the avoidance of lesions along its course difficult. Rather than avoiding posterior lesions, emphasis could be placed on better esophagus monitoring for creation of safer lesions.

Relationship between selected overdrive parameters and the therapeutic outcome and tolerance of atrial overdrive pacing.

There is a paucity of information on the influence of selected overdrive parameters on the clinical efficacy and tolerance of atrial overdrive algorithms to suppress atrial tachyarrhythmias. Data from a completed clinical trial investigating a new DDD+ overdrive algorithm implemented in a permanent pacemaker were analyzed. One-hundred patients with standard pacing indications and atrial tachyarrhythmias were enrolled and followed for 6 months in DDD and 6 months in DDD+ mode in a randomized, crossover fashion. The overdrive step size was programmed at the discretion of the investigators between 4 and 12 beats/min, overdrive plateau length between 10 and 32 beats, and maximum overdrive rate between 100 and 160 beats/min. The effects of DDD+ versus DDD mode on burden and incidence of atrial tachyarrhythmias stored in the mode switch memory were examined as a function of the programmed overdrive parameters. An overdrive step size between 7 and 12 beats/min, and higher a maximum overdrive rate between 121 and 160 beats/min were slightly more effective than lower programmed values, though > 500 randomized, crossover observations would have been necessary to verify statistical significance. Overdrive pacing related symptoms mandated early manual deactivation of overdrive pacing in 4.7% of 85 evaluated patients. Overdrive was disabled without testing tolerability of less aggressive overdrive values. There was no link between patient symptoms and programmed overdrive step size or overdrive plateau length values.

Pacing of the atria in sick sinus syndrome trial: preventive strategies for atrial fibrillation.

This study examines the effects of various atrial lead positions in physiological pacing on the incidence of AF in patients with sick sinus syndrome. The lead is implanted in the RA free wall, in the RA appendage, near the coronary sinus ostium (CSO) or, in dual site RA pacing, in the appendage and the CSO. Since CSO and dual site right atrial pacing aim at modifying the pathological substrate, pacing of two-thirds of all cardiac cycles is attempted by adapting the basic rate and the rate response option. The results of this study are expected to assist in the development of guidelines for the placement of atrial pacing leads in sick sinus syndrome.

The influence of concomitant drug therapy on the efficacy of atrial overdrive stimulation for prevention of atrial tachyarrhythmias.

Data from the completed "Suppression of Atrial Fibrillation by DDD+ Overdrive Pacing with Inos2 CLS (closed-loop system) Pacemakers" multicenter trial were retrospectively evaluated to examine the influence of concomitant antiarrhythmic drugs on the clinical success of conventional single site right atrial overdrive pacing compared with DDD pacing. The DDD+ overdrive algorithm provided > 90% atrial pacing at a rate slightly above the intrinsic atrial rate. Seventy-five patients with conventional pacing indications and paroxysmal, recurrent atrial tachyarrhythmia have completed the study. They were randomized to 6 months of DDD or DDD+ pacing, followed by mode crossover and an additional 6-month follow-up in the alternate mode. The incidence of atrial tachyarrhythmia during each period was compared using data on sustained (> 60 s) mode switch episodes stored in the pacemaker memory. A stable antiarrhythmic drug regimen was allowed during the study. beta-Adrenergic blockers and Class III antiarrhythmics, prescribed to 54.7% and 40.0% of patients respectively, were linked to minimal or no benefit of overdrive pacing compared with DDD pacing. In contrast, patients untreated with beta-adrenergic blockers or Class III drugs had a significant reduction in atrial tachyarrhythmia burden of > 5 hours/patient per week (P < 0.05) during overdrive. Changes with Class I and Class IV antiarrhythmic drugs, prescribed to 18.7% and 13.3% of patients, respectively, were insignificant. Our data indicate that clinical trials that prohibit the use of beta-adrenergic blockers may record more favorable outcomes with dynamic atrial overdrive algorithms versus conventional DDDR pacing, than studies allowing concomitant beta-adrenergic blockade.