Cryoablation versus radiofrequency energy for the ablation of atrioventricular nodal reentrant tachycardia (the CYRANO Study): results from a large multicenter prospective randomized trial.

BACKGROUND: Cryoablation has emerged as an alternative to radiofrequency catheter ablation (RFCA) for the treatment of atrioventricular (AV) nodal reentrant tachycardia (AVNRT). The purpose of this prospective randomized study was to test whether cryoablation is as effective as RFCA during both short-term and long-term follow-up with a lower risk of permanent AV block. METHODS AND RESULTS: A total of 509 patients underwent slow pathway cryoablation (n=251) or RFCA (n=258). The primary end point was immediate ablation failure, permanent AV block, and AVNRT recurrence during a 6-month follow-up. Secondary end points included procedural parameters, device functionality, and pain perception. Significantly more patients in the cryoablation group than the RFCA group reached the primary end point (12.6% versus 6.3%; P=0.018). Whereas immediate ablation success (96.8% versus 98.4%) and occurrence of permanent AV block (0% versus 0.4%) did not differ, AVNRT recurrence was significantly more frequent in the cryoablation group (9.4% versus 4.4%; P=0.029). In the cryoablation group, procedure duration was longer (138±54 versus 123±48 minutes; P=0.0012) and more device problems occurred (13 versus 2 patients; P=0.033). Pain perception was lower in the cryoablation group (P<0.001). CONCLUSIONS: Cryoablation for AVNRT is as effective as RFCA over the short term but is associated with a higher recurrence rate at the 6-month follow-up. The risk of permanent AV block does not differ significantly between cryoablation and RFCA. The potential benefits of cryoenergy relative to ablation safety and pain perception are counterbalanced by longer procedure times, more device problems, and a high recurrence rate. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00196222.

Very late relapse of atrial fibrillation after pulmonary vein isolation: incidence and results of repeat ablation.

BACKGROUND: There are few data about the incidence of very late (>12 months) arrhythmia relapse after pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (AF) and about the success rate of repeat ablation procedures in this population. METHODS: All patients treated with PVI for paroxysmal AF were screened in the institution's electrophysiology database. Follow-up data at 1, 3, 6, and 12 months and yearly thereafter including repetitive (7 days or 1 day) Holter electrocardiograms were assessed as well as the technique and success rate of repeat ablations. RESULTS: Overall, 24 of 356 (6.7%) patients experienced their first AF recurrence more than 12 months after PVI. Of these 24 patients, 14 underwent reablation for paroxysmal (11 patients) or persistent AF (three patients). Repeat ablation included re-PVI in all 14 patients (43 of 48 initially isolated PVs with recovered left atrial-PV conduction). Ablation of complex fractionated atrial electrograms or left/right atrial lines was performed in eight patients, including the three patients with persistent AF. During follow-up of 15.1 ± 9 months after the second ablation, 10 of 14 (71%) reablated patients remained in sinus rhythm. CONCLUSIONS: After PVI for paroxysmal AF, very late arrhythmia recurrence occurs in less than 10% of patients. The success rate of the repeat procedure is high.

The modified anterior line: an alternative linear lesion in perimitral flutter.

INTRODUCTION: Ablation of left atrial flutter (LAF) is often limited by the need for technically demanding linear lesions. We evaluated the safety and efficacy of a new modified anterior line (MAL), connecting the anterior/anterolateral mitral annulus with the left superior pulmonary vein for ablation of perimitral flutter. METHODS AND RESULTS: MAL was performed in 65 patients (15 females, age 63.6 +/- 9.8 years) with perimitral flutter using 3D mapping systems (70.8% Carto, 29.2% NavX). Perimitral flutter was either the presenting arrhythmia (73.8%) or an intermediate organized rhythm during atrial fibrillation ablation. Follow-up included repetitive 7-day Holter with 93.8% of patients off antiarrhythmics. MAL was acutely effective in 63/65 patients (96.9%). Termination to sinus rhythm occurred in 36 of 65 patients (55.4%), and in 27 of 65 patients (41.5%) there was a change to another LAF type. Bidirectional block across the MAL was achieved in 56 of 65 patients (86.1%). After 6 months of follow-up, 20 of 41 patients (48.8%) had a LAF recurrence, with 6 patients undergoing a reablation. In all redo patients the MAL was still complete and LAF mechanism was different to the initially targeted. No major complication occurred during the ablation procedures or in the postablation period. CONCLUSION: The MAL is a safe and effective linear lesion for the treatment of perimitral LAF. Its value compared to more established linear lesions as the mitral isthmus line has to be evaluated in larger studies.

Long-term follow-up of patients supplied with single-chamber or dual-chamber cardioverter defibrillators.

INTRODUCTION: In patients who have an indication for an implantable cardioverter defibrillator (ICD) a dual-chamber device is indicated in the case of concomitant significant sinus node disease or atrioventricular block. It is a matter of debate whether dual-chamber ICD may be beneficial for patients with preserved sinus and atrioventricular nodal function as data from prospective randomized trials are limited. Mid- or long-term follow-up data are unavailable. METHODS AND RESULTS: One hundred patients (age 60+/-12 years, 11 women) with the indication for the implantation of an ICD and without antibradycardia pacing indication were randomly assigned to either receive a dual-chamber ICD (n=52) or a single-chamber ICD (n=48). Patients were followed-up for a mean of 52+/-14 months. Mortality and arrhythmogenic morbidity were assessed. All-cause mortality was 21% for single-chamber and 31% for dual-chamber ICD recipients, respectively (P=0.26). Cardiovascular mortality was 13% for single-chamber ICD recipients versus 21% in the dual-chamber group (P=0.25). Subgroup analysis using 35% of ventricular paced beats as cutoff value in the dual-chamber ICD group revealed a 42% mortality rate for the patients with frequent ventricular pacing compared to 10% of patients with a low rate of ventricular pacing (P=0.05, relative risk 4.21, 95% confidence interval: 0.9-19.8). As for arrhythmogenic morbidity, the difference in the ventricular tachyarrhythmia load was not different in both groups (single chamber: 23+/-74 VT episodes, dual chamber: 54+/-134 VT episodes, P=0.17). CONCLUSION: In ICD recipients without conventional indication for dual-chamber pacing, dual chamber compared to single-chamber ICD has no advantage concerning mortality and arrhythmogenic morbidity in a long-term follow-up. In these patients the implantation of a single-chamber device is sufficient.

Left atrial tachycardia after circumferential pulmonary vein ablation for atrial fibrillation: incidence, electrophysiological characteristics, and results of radiofrequency ablation.

AIMS: To investigate the incidence, electrophysiological properties, and ablation results for left atrial (LA) tachycardia as a sequel to the circumferential pulmonary vein ablation (CPVA) for atrial fibrillation (AF). METHODS AND RESULTS: Sixty-seven patients with AF underwent CPVA. Sustained LA tachycardia developed in 21/67 (31%) patients and in 16/21 symptomatic patients 55 LA tachycardias (3.4+/-2.4 per patient) were mapped: 18 (33%) tachycardias were related to macro-re-entry around the mitral valve (7) or pulmonary vein(s) (11). In 20 tachycardias (36%), a 'small-loop' LA re-entrant tachycardia (LART) was identified; gaps in prior ablation lines (7 LART) or an area of extremely slow conduction adjacent to the CPVA lesions (13 LART) were crucial for these re-entries. Seventeen tachycardias (31%) were too unstable for complete mapping. Ablation was a primary success in 34 of 38 (89%) mapped LART, but in eight of 21 procedures, cardioversion was necessary to achieve sinus rhythm. CONCLUSION: LART develops in a high percentage of patients after CPVA. Small-loop re-entry, which is difficult to map, may arise and patients suffer from several and/or unstable variants of LART. Thus, mapping and ablation of these LART is challenging and the overall success is yet not satisfactory.

Freedom from atrial tachyarrhythmias after catheter ablation of atrial fibrillation: a randomized comparison between 2 current ablation strategies.

BACKGROUND: Data on the comparative value of the circumferential pulmonary vein and the segmental pulmonary vein ablation for interventional treatment of atrial fibrillation are limited. We hypothesized that the circumferential pulmonary vein ablation approach was superior to the segmental pulmonary vein ablation approach. METHODS AND RESULTS: One hundred patients with highly symptomatic atrial fibrillation were randomly assigned to undergo either circumferential (n=50) or segmental pulmonary vein ablation (n=50). Freedom from atrial tachyarrhythmias in a 7-day Holter monitoring at 6 months was the primary end point. Secondary end points were freedom of arrhythmia-related symptoms and a composite of pericardial tamponade, thromboembolic complications, and pulmonary vein stenosis (safety end point). On the basis of the results of the 7-day Holter monitoring at 6 months, 21 patients (42%) after circumferential pulmonary vein ablation and 33 patients (66%) after segmental pulmonary vein ablation (P=0.02) were free of atrial tachyarrhythmia episodes. During the 6-month follow-up period, 27 patients (54%) after circumferential pulmonary vein ablation and 41 patients (82%) after segmental pulmonary vein ablation remained free of arrhythmia-related symptoms (P<0.01). No significant difference was found in the safety end point (6 versus 7 events; P=0.77) in the circumferential versus segmental pulmonary vein ablation group, respectively. CONCLUSIONS: This study demonstrates no superiority of the circumferential pulmonary vein ablation over segmental pulmonary vein ablation for treatment of atrial fibrillation in terms of efficacy and safety.

LocaLisa catheter navigation reduces fluoroscopy time and dosage in ablation of atrial flutter: a prospective randomized study.

INTRODUCTION: Catheter ablation has become a well-established therapy for isthmus-dependent right atrial flutter (AFL). Recently, mapping and ablation of AFL have been performed using sophisticated three-dimensional mapping systems, such as electroanatomic and noncontact mapping systems. The LocaLisa system enables nonfluoroscopic navigation of intracardiac electrode catheters based on impedance changes related to catheter movements in transthoracic current fields. The aim of this randomized prospective study was to compare the efficacy of the LocaLisa system with the conventional mapping/ablation approach for radiofrequency ablation of AFL. METHODS AND RESULTS: Fifty consecutive patients with AFL (39 men and 11 women; age 65 +/- 10 years) were studied. The patients were randomly assigned to undergo radiofrequency ablation guided by a conventional fluoroscopy-based approach (24 patients) or by the LocaLisa system (26 patients). Ablation success rate and documentation of bidirectional isthmus block were 100% in both groups. Compared with fluoroscopy-guided approaches, LocaLisa-guided procedures demonstrated a reduction in total fluoroscopy time from 15.9 +/- 10.6 minutes to 7.5 +/- 6.5 minutes (P < 0.005). Total fluoroscopy dosage was reduced from 21.0 +/- 19.8 to 8.7 +/- 9.5 Gycm2 (P < 0.05). Fluoroscopy time required for ablation was significantly shortened in the LocaLisa group (2.6 +/- 2.6 min) compared with the conventional approach group (11 +/- 10 min, P < 0.0005). In 9 (35%) of 26 patients, the ablation could be performed with a fluoroscopy time < or = 1 minute. There were no significant differences with regard to the number of radiofrequency applications, fluoroscopy time needed for diagnostic reasons, total procedure time, or other ablation data. CONCLUSION: Compared with the conventional approach, the LocaLisa system significantly reduces the fluoroscopy times needed for ablation of typical AFL.

Do airport metal detectors interfere with implantable pacemakers or cardioverter-defibrillators?

OBJECTIVES: The aim of this study was to determine whether airport metal detector gates (AMDGs) interfere with pacemakers (PMs) or implantable cardioverter-defibrillators (ICDs). BACKGROUND: It is currently unknown whether AMDGs interfere with implanted PMs or ICDs. METHODS: A total of 348 consecutive patients (200 PM and 148 ICD recipients) have been tested for the occurrence of electromagnetic interference (EMI) within the electromagnetic field of a worldwide-used airport metal detector. RESULTS: No interference, such as pacing or sensing abnormalities, was observed in any of the 200 PM and 148 ICD patients; also no reprogramming occurred. CONCLUSIONS: In vivo testing of PM and ICD systems showed no EMI with a standard AMDG. Clinically relevant interactions with implanted PMs or ICDs seem unlikely.

Pulmonary vein internal electrical activity does not contribute to the maintenance of atrial fibrillation.

Whether the electrical activity generated in the pulmonary veins (PVs) during atrial fibrillation (AF) contributes to the maintenance of arrhythmia is not known. The study population consisted of 22 patients (mean age 58 +/- 9.5 years, 16 men) with persistent (12 patients) or intermittent (10 patients) AF. Mapping of the left atrium (LA) was performed with a 64-electrode basket catheter. PVs were mapped simultaneously with the LA with a quadripolar catheter. PV were defined as arrhythmogenic (if frequent ectopic activity induced AF) or nonarrhythmogenic (if no ectopic activity was observed during the procedure). AF cycle lengths in arrhythmogenic and nonarrhythmogenic PV were 130 +/- 50 ms and 152 +/- 42 ms, respectively (P < 0.001). Both were significantly longer than simultaneous AF activity recorded from the posterior wall of the LA (116 +/- 49 ms, P < 0.001). AF cycle lengths in arrhythmogenic PVs as compared to nonarrhythmogenic PVs were: right superior PV 125 +/- 49 ms versus 148 +/- 51 ms; left superior PV 140 +/- 52 ms versus 161 +/- 30 ms; left inferior PV 127 +/- 48 ms versus 147 +/- 45 ms; and right inferior PV 129 +/- 38 versus 152 +/- 44 ms (P < 0.001 for all four comparisons). AF activity in the PV was more organized than in the posterior wall of the LA and the veins were activated in a proximal-to-distal direction during sustained AF episodes. In patients with AF not related to rheumatic heart disease, the posterior wall of the LA has faster activity than the PVs. The AF activity generated inside the PV during sustained AF episodes originates from the posterior wall of the LA rather than from focal firing.

Simultaneous multisite endocardial mapping of sustained and non-sustained atrial fibrillation in humans.

The aim of this study was to investigate the differences between sustained and non-sustained forms of human atrial fibrillation (AF) using multielectrode endocardial recordings. Methods. Sixty-four pole basket catheters were deployed in the right atrium (RA) of 3 groups of patients: 1) patients with persistent AF (> 48 hours); 2) induced sustained AF (> 15 minutes); and 3) induced non-sustained AF (< 15 minutes). Beat to beat AF intervals (FF) were evaluated for each bipole. On the basis of signal characteristics and direction of wavefront propagation, the degree of spatial and temporal organization of AF was assessed. Results. Persistent AF showed the shortest FF intervals (161 ms) and lowest overall degree of AF organization, induced non-sustained AF the longest FF intervals (192 ms) and highest degree of organization. FF intervals of induced sustained AF were only slightly longer (169 ms) compared to persistent AF. Within each AF group, the lateral wall showed the highest degree of organization, the septal region the lowest. Conclusion. In humans, FF interval and overall degree of AF organization were found to increase significantly from sustained to non-sustained AF. Persistent and induced sustained AF, however, only slightly differed in these parameters.

Impact of atrial fibrillation on the voltage of bipolar signals acquired from the left and right atria.

A detailed analysis of the impact of atrial fibrillation (AF) on the voltage of the atrial signals acquired from various right and left atrial regions has not been reported. Thirteen patients (mean age 55 +/- 11 years, range 39-67 years, 5 women) with AF were included in this study. Mapping of the left and the right atrium was performed with 64-electrode basket catheters. AF cycle lengths were calculated over 10-second time intervals using a custom-made software. Voltage of the bipolar signals during AF was calculated by measuring the amplitudes of 30 consecutive signals in the left and the right atria. During sinus rhythm voltage differences between the left (3 +/- 2.9 mV) and the right atrium (2.8 +/- 2.4 mV, P = 0.15) were insignificant. During AF, as compared to sinus rhythm, voltages of the bipolar signals were significantly reduced in the left (0.9 +/- 0.6 mV) and the right (1.3 +/- 1.1 mV) atria (P < 0.001 compared with sinus rhythm). In the left atrium, the posterior wall showed the most pronounced voltage reduction (1.1 +/- 0.8 mV vs 5.3 +/- 4.6 mV, P < 0.001). In the right atrium the septal wall showed the greatest reduction in voltage amplitude (0.8 +/- 0.6 mV vs 2.5 +/- 1.5 mV, P < 0.001). There was a close correlation between the voltage values and the AF cycle length. The smallest voltage values and greatest amplitude reductions were observed during faster and more disorganized AF activity. It is concluded that during AF, the voltage of bipolar signals is significantly reduced as compared to sinus rhythm. The reduction in voltage expresses atrial and regional disparity and correlates strongly with local AF cycle lengths and the degree of AF disorganization.

Single chamber atrial fibrillation involving only the left atrium: implications for maintenance and radiofrequency ablation therapy.

Due to the anatomic and the functional interatrial relationship, AF is a biatrial process. Whether one of the atria could sustain AF is not known. This study included 11 patients (mean age 57 +/- 10 years, 7 men) with AF who showed a distinct activation pattern, characterized by regular activity in the right atrium (RA) and irregular fibrillatory activity confined to the left atrium (LA) throughout the AF episodes. Each of the atria was mapped with 64-electrode basket catheters. AF was monitored for 74 +/- 26 minutes. Complex and irregular activity with a cycle length of 138 +/- 43 ms was observed in the LA throughout the monitoring time. The posterior and the roof of the LA showed the highest degree of disorganization. RA was activated by regular wavefronts with a cycle length of 194 +/- 22 ms (P < 0.001, compared with LA). No fibrillatory activity was observed in the RA. All wavefronts that activated the RA were of septal origin: high anteroseptal 52%, low posteroseptal 22%, mid-septal 18, and dual wavefronts (from the high anteroseptal and low posteroseptal pathways) 8%. The lateral wall of the RA was activated in a superoinferior direction in 82% of all activations. A left-to-right conduction block during AF and a rotor of fibrillatory activity located in the posterior wall of the LA were observed in two patients. Isolated AF in the LA showed various surface electrocardiographic patterns. It is concluded that LA alone without participation of the RA can sustain AF. These data have implications for mechanisms and the ablative therapy of AF.

Acute and long-term results of radiofrequency ablation of common atrial flutter and the influence of the right atrial isthmus ablation on the occurrence of atrial fibrillation.

AIMS: The purpose of this study was to evaluate the acute success rate and long-term efficacy of radiofrequency ablation of common type atrial flutter (AFL) by using a standardised anatomical approach in a large series of patients and to assess the influence of right atrial isthmus ablation on the occurrence of atrial fibrillation. There are no large scale prospective or retrospective multicentre studies for radiofrequency ablation of AFL. METHODS AND RESULTS: The study population consisted of 363 consecutive patients with AFL (mean age 58+/-16 years, 265 men) who underwent radiofrequency ablation at the inferior vena cava-tricuspid annulus (IVC-TA) isthmus using a standardised anatomic approach. Bidirectional isthmus block at the IVC-TA was achieved in 328 patients (90%). Following radiofrequency ablation, 343 patients (95%) were followed for a mean of 496+/-335 days. During the follow-up period, 310 patients (90%) remained free of AFL recurrences. Multivariate analysis identified five independent predictors of AFL recurrence: fluoroscopy time (p<0.001), atrial fibrillation after AFL ablation (p=0.01), lack of bidirectional block (p=0.02), reduced left ventricular function (p=0.035) and right atrial dimensions (p=0.046). Atrial fibrillation occurrence was significantly reduced after AFL ablation (112 in 343 patients, 33%) as compared to occurrence of atrial fibrillation before radiofrequency ablation (198 in 363 patients, 55%, p<0.001). CONCLUSIONS: The current anatomical ablation approach for AFL and criteria for evaluation of the IVC-TA isthmus block is associated with an acute success rate of 90% and a long-term recurrence rate of 10%. Radiofrequency ablation of common AFL results in a significant reduction in the occurrence of atrial fibrillation.

Application of right atrial contiguous linear lesions: an in vivo efficacy validation of multipolar ablation catheters in an animal model.

Catheter ablation of atrial flutter and catheter Maze procedures require the creation of linear lesions. The efficacy of different multipolar catheters to create linear contiguous transmural lesions was studied in a sheep model. In 19 sheep a multipolar ablation catheter was inserted into the right atrium. In nine sheep a steerable 7 Fr catheter (C1) with six 6-mm electrodes and in five sheep a steerable 7 Fr catheter (C2) with four 5-mm electrodes were placed. In five sheep a 3.7 Fr catheter (C3) with eight electrodes of 6-mm length was deployed (steerable sheath). A total of 72 linear lesions were created and evaluated. Catheter types C1, C2, and C3 produced continuous lesions with at least two adjacent electrodes in 45%, 79%, and 87% of the lesions. The mean lesion length achieved by C3 was longer compared to C1 and C2 (27 +/- 14 vs 10 +/- 5 and 11 +/- 6 mm; P < 0.05). The ability to produce contiguous lesions by all available electrodes was low: C1, 5%; C2, 5%; and C3, 6%. C3 was most effective in exerting transmural lesions (93% vs C1 75% and C2 57%; P < 0.0001). Microscopic endocardial fibrinous adhesions and macroscopic mild electrode carbonizations were caused by all catheter types. In conclusion, (1) all three catheter types do not create contiguous lesions along all electrodes. Gaps of viable tissue remain in most instances; (2) lesion depths and transmurality varies with different catheters; and (3) potentially hazardous thrombotic material was observed during radiofrequency ablation with all three catheters.

Electrophysiologic characteristics of the spontaneous onset and termination of atrial fibrillation.

Electrophysiologic characterization of the onset and termination of atrial fibrillation (AF) is poorly defined. Our study population consisted of 21 consecutive patients (mean age 58 +/- 9 years, 6 women) with intermittent (10 patients) or persistent (11 patients) AF. Mapping of the left atrium (LA) and the right atrium (RA) during initiation and termination of AF was performed with a 64-electrode basket catheter. A total of 92 spontaneous AF onsets (in 16 patients) and 63 spontaneous AF terminations were analyzed. Irrespective of the origin of the triggering atrial premature complex (APC), the onset of AF was preceded by an intermediary rhythm that consisted of repetitive firing from the focus that generated the initial APC, reentry around the mitral annulus, or typical atrial flutter. The earliest fibrillatory activity was constantly produced by circumvented regions (generators) localized most frequently in the posterior wall of the LA. Generators of fibrillatory activity were not observed in the RA for any of the patients. In the RA, AF is maintained by a mixture of macro-reentry and driving wave fronts of left atrial origin. Four modes of AF termination were observed: a multifocal rhythm (19 episodes, 30%), left atrial tachycardia (17 episodes, 27%), direct conversion to sinus rhythm (15 episodes, 24%), and conversion to typical atrial flutter (12 episodes, 19%). A repetitive rapid rhythm initiated most often by APCs plays a crucial role in the initiation of AF via activation of the generators of fibrillatory activity. The LA plays a central role in the initiation of AF by serving as a substrate for generators of fibrillatory activity. Termination of AF consists of a heterogenous group of unstable rhythms.

Direct and indirect catheter-to-catheter carbonization caused by high power radiofrequency delivery via a large tip ablation electrode.

We report two cases of directly and indirectly induced catheter carbonizations by radiofrequency application via a large tip ablation catheter. We assume that during a large tip high power delivery of more than 50 watts, an adjacent, smaller-sized, low resistance electrode produces a local increase in the intensity of the current field that is sufficient to elevate the tissue temperature above 100 degrees C. Due to the potential risk of embolism, this may have an impact on ablation procedures in the left atrium and ventricle using similar mapping configurations.

Characterization of paroxysmal and persistent atrial fibrillation in the human left atrium during initiation and sustained episodes.

INTRODUCTION: Atrial fibrillation (AF) in the left atrium (LA) is poorly defined in terms of regional differences in the degree of organization, characteristics of paroxysmal and persistent variants, and electrophysiologic events that develop at the onset of episodes. METHODS AND RESULTS: The study population consisted of 21 patients (15 men and 6 women; mean age 58+/-9.4 years) with paroxysmal (10 patients) or persistent (11 patients) AF. Mapping of the LA during sustained episodes and the onset of AF was performed with a 64-electrode basket catheter. At the onset of AF, repetitive beats starting with atrial premature complexes and ending with generation of the earliest fibrillatory activity were defined as intermediary rhythm. Patients with paroxysmal AF had longer AF cycle lengths and more pronounced regional differences than patients with persistent AF. In total, AF cycle lengths in the LA in patients with persistent AF were 20% shorter than in patients with paroxysmal AF. Initiation of AF was preceded by an intermediary rhythm of 5.5+/-2.5 cycles (6.3+/-2.7 cycles in paroxysmal AF vs 4.2+/-1.0 cycles in persistent AF; P = 0.026). At the onset of AF, the earliest generators of fibrillatory activity were located more frequently in the posterior wall of the LA. CONCLUSION: AF in the LA displays substantial regional differences in terms of AF cycle lengths and degree of organization. Patients with persistent AF have shorter cycle lengths and a higher degree of disorganized activity than patients with paroxysmal AF. Intermediary rhythms play an important role in initiation of AF via activation of generator regions in the LA.

Biatrial multisite mapping of atrial premature complexes triggering onset of atrial fibrillation.

Pulmonary veins are considered to be the most common origin of the focal activity that triggers the onset of atrial fibrillation (AF). However, little is known about the importance of ectopic activity located outside the pulmonary veins. This study included 45 patients (8 women and 37 men, mean age 55 +/- 12 years) with paroxysmal (n = 25) and persistent (n = 20) AF in whom multisite mapping of the right and left atria was performed using a 64-electrode basket catheter (n = 21) or a noncontact mapping system (n = 24). Spontaneous or orciprenaline-induced atrial premature complexes (APCs) were mapped. In all, 94 AF onsets from 38 distinct foci in 30 patients were observed and analyzed. Of these foci, 20 (53%) were located in pulmonary veins and 18 (47%) were located outside the pulmonary veins in other parts of the atria. In 22 patients (73%), AF was reproducibly induced by APCs from a single focus (59 episodes). In 8 patients (27%), AF originated from 2 distinct foci (35 episodes). Additionally, 20 of 30 patients (67%) who developed AF had APCs in different locations not inducing AF. APCs inducing AF had shorter coupling intervals than APCs not inducing AF (307 +/- 54 vs 409 +/- 76 ms, p <0.001). This study showed that 47% of ectopic foci triggering the onset of AF were located outside the pulmonary veins in extravenous parts of the left atrium and the right atrium, and 27% of patients had AF onsets of bifocal origin. These data challenge the current opinion that extrapulmonary foci play a minor role in inducing AF.