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Objectives: The purpose of this study was to assess whether additional ablation in the right atrium (RA) improves termination rate in long-lasting persistent atrial fibrillation (PsAF)., Background: Prolongation of atrial fibrillation (AF) cycle length (CL) measured from the left atrial appendage predicts favorable outcome during catheter ablation of PsAF. However, in some patients, despite prolongation of AF CL in the left atrium (LA) with ablation, AF persists. We hypothesized that this persistence is due to RA drivers, and that these patients may benefit from RA ablation., Methods: In all, 148 consecutive patients undergoing catheter ablation of PsAF (duration 25 +/- 32 months) were studied. AF CL was monitored in both atria during stepwise ablation commencing in the LA. Ablation was performed in the RA when all LA sources in AF had been ablated and an RA-LA gradient existed. The procedural end point was AF termination., Results: Two distinct patterns of AF CL change emerged during LA ablation. In 104 patients (70%), there was parallel increase of AF CL in LA and RA culminating in AF termination (baseline: LA 153 ms [range 140 to 170 ms], RA 155 ms [range 143 to 171 ms]; after ablation: LA 181 ms [range 170 to 200 ms], RA 186 ms [range 175 to 202 ms]). In 24 patients (19%), RA AF CL did not prolong, creating a right-to-left frequency gradient (baseline: LA 142 ms [range 143 to 153 ms], RA 145 ms [range 139 to 162 ms]; after ablation: LA 177 ms [range 165 to 185 ms], RA 152 ms [range 147 to 175 ms]). These patients had a longer AF history (23 months vs. 12 months, p = 0.001), and larger RA diameter (42 mm vs. 39 mm, p = 0.005), and RA ablation terminated AF in 55%. In the remaining 20 patients, biatrial ablation failed to terminate AF., Conclusions: A divergent pattern of AF CL prolongation after LA ablation resulted in a right-to-left gradient, demonstrating that the right atrium is driving AF in approximately 20% of PsAF., (Copyright (c) 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Aims: To evaluate the contribution of the posterior left atrium (LA) to chronic atrial fibrillation (AF)., Methods and Results: Twenty-seven patients with chronic-AF were studied. After pulmonary vein (PV) isolation, the posterior-LA was isolated by ablation joining the right- and left-PVs using an irrigated-tip catheter. Isolation was demonstrated by absent/dissociated posterior-LA activity and the inability to pace the region. Ablation impact was determined by the effect on cycle length (CL) and AF termination. Posterior-LA isolation was achieved using 35 +/- 12 min of radiofrequency with total fluoroscopic and procedural durations of 64 +/- 16 and 199 +/- 46 min, resulting in abolition of electrograms (n = 21) or autonomous activity (n = 6; CL 820 +/- 343 ms). AFCL increased from 156 +/- 28 ms to 162 +/- 27 ms with PV-isolation and to 175 +/- 32 ms by posterior-LA exclusion (P < 0.0001). AF persisted in all after PV-isolation and terminated in 5 (19%) during posterior-LA-isolation. After 10 +/- 6 months, 12 patients developed atrial tachycardia (four) or AF (eight); four underwent repeat posterior-LA-isolation, while the others required additional ablation/antiarrhythmics. After 21 +/- 5 months, 17 (63%) were in sinus rhythm following posterior-LA-isolation., Conclusion: This study demonstrates the feasibility of complete posterior-LA exclusion by catheter ablation. This strategy results in maintenance of sinus rhythm in 63% at 2 years follow-up.

Background: Left atrial (LA) linear lesions are effective in substrate modification for atrial fibrillation (AF). However, achievement of complete conduction block remains challenging and conduction recovery is commonly observed. The aim of the study was to investigate the localization of gap sites of recovered LA linear lesions., Methods and Results: Forty-eight patients with paroxysmal (n = 26) and persistent/permanent (n = 22) AF underwent repeat ablation after pulmonary vein (PV) isolation and LA linear ablation at the LA roof and/or mitral isthmus due to recurrences of AF or flutter. In 35 patients, conduction through the mitral isthmus line (ML) had recovered whereas roof-line recovery was observed in 30 patients. The gaps within the ML were distributed to the junction between left inferior PV and left atrial appendage in 66%, the middle part of the ML in 20%, and in 8% to the endocardial aspect of the ML while only 6% of lines showed an epicardial site of recovery. The RL predominantly recovered close to the right superior PV (54%) and less frequently in the mid roof or close to the left PV (both 23%). Reablation of lines required significantly shorter RF durations (ML: 7.24 +/- 5.55 minutes vs 24.08 +/- 9.38 minutes, RL: 4.24 +/- 2.34 minutes vs 11.54 +/- 6.49 minutes; P = 0.0001). Patients with persistent/permanent AF demonstrated a significantly longer conduction delay circumventing the complete lines than patients with paroxysmal AF (228 +/- 77 ms vs 164 +/- 36 ms, P = 0.001)., Conclusions: Gaps in recovered LA lines were predominantly located close to the PVs where catheter stability is often difficult to achieve. Shorter RF durations are required for reablation of recovered linear lesions. Conduction times around complete LA lines are significantly longer in patients with persistent/permanent AF as compared to patients with paroxysmal AF.

Background: Areas of complex fractionated atrial electrograms (CFAEs) have been implicated in the atrial substrate of atrial fibrillation (AF). The mechanisms underlying CFAE in humans are not well investigated., Objectives: The purpose of this study was to investigate the regional activation pattern associated with CFAE using a high-density contact mapping catheter., Methods: Twenty patients with paroxysmal AF were mapped using a high-density multielectrode catheter. CFAE were mapped at 10 different sites (left atrium [LA]: inferior, posterior, roof, septum, anterior, lateral; right atrium [RA]: anterior, lateral, posterior, septum). Local atrial fibrillation cycle length (AFCL) was measured immediately before and after the occurrence of CFAE, and the longest electrogram duration (CFAEmax) was assessed., Results: Longer electrogram durations were recorded in the LA compared with the RA (CFAEmax 118 +/- 21 ms vs 104 +/- 23 ms, P = .001). AFCL significantly shortened before the occurrence of CFAEmax compared with baseline (LA: 174 +/- 32 ms vs 186 +/- 32 ms, P = .0001; RA: 177 +/- 31 ms vs 188 +/- 31 ms, P = .0001) and returned to baseline afterwards. AFCL shortened by >or=10 ms in 91% of mapped sites. Two different local activation patterns were associated with occurrence of CFAEmax: a nearly simultaneous activation in all spines in 84% indicating passive activation, and a nonsimultaneous activation sequence suggesting local complex activation or reentry., Conclusion: Fractionated atrial electrograms during AF demonstrate dynamic changes that are dependent on regional AFCL. Shortening of AFCL precedes the development of CFAE; thus, cycle length is a major determinant of fractionation during AF. High-density mapping in AF may help to differentiate passive activation of CFAE from CFAE associated with an active component of the AF process.

Background: There are no reports describing the technique, electrophysiological evaluation, and clinical consequences of complete linear block at roofline joining the superior pulmonary veins (PVs) in patients with paroxysmal atrial fibrillation (AF)., Methods and Results: Ninety patients with drug-refractory paroxysmal AF undergoing radiofrequency ablation were prospectively randomized into 2 ablation strategies: (1) PV isolation (n=45) or (2) PV isolation in combination with linear ablation joining the 2 superior PVs (roofline; n=45). In both groups, the cavotricuspid isthmus, fragmented peri-PV-ostial electrograms, and spontaneous non-PV foci were ablated. Roofline ablation was performed at the most cranial part of the left atrium (LA) with complete conduction block demonstrated during LA appendage pacing by the online mapping of continuous double potential and an activation detour propagating around the PVs to activate caudocranially the posterior wall of the LA. The effect of ablation at the LA roof was evaluated by the change in fibrillatory cycle length, termination and noninducibility of AF, and clinical outcome. PV isolation was achieved in all patients with no significant differences in the radiofrequency duration, fluoroscopy, or procedural time between the groups. Roofline ablation required 12+/-6 (median 11, range 3 to 25) minutes of radiofrequency energy delivery with a fluoroscopic duration of 7+/-2 minutes and was performed in 19+/-7 minutes. Complete block was confirmed in 43 patients (96%) and resulted in an activation delay that was shorter circumventing the left than the right PVs during LA appendage pacing (138+/-15 versus 146+/-25 ms, respectively; P=0.01). Roofline ablation resulted in a significant increase in the fibrillatory cycle length (198+/-38 to 217+/-44 ms; P=0.0005), termination of arrhythmia in 47% (8/17), and subsequent noninducibility of AF in 59% (10/17) of the patients inducible after PV isolation. However, LA flutter, predominantly perimitral, could be induced in 10 patients (22%) after roofline ablation. At 15+/-4 months, 87% of the roofline group and 69% with PV isolation alone are arrhythmia free without antiarrhythmics (P=0.04)., Conclusions: This prospective randomized study demonstrates the feasibility of achieving complete linear block at the LA roof. Such ablation resulted in the prolongation of the fibrillatory cycle, termination of AF, and subsequent noninducibility and is associated with an improved clinical outcome compared with PV isolation alone.

Objectives: The goal of this study was to characterize the origin of focal atrial tachycardias (AT)., Background: Focal ATs originate from a small area and spread centrifugally; however, activation at the AT origin has not been characterized., Methods: Twenty patients with AT having failed prior ablation or occurring after atrial fibrillation ablation were studied. After excluding macro-re-entry, AT was mapped using a 20-pole catheter (five radiating spines; diameter 3.5 cm), performing vector mapping to identify the earliest activity followed by high-density mapping at the AT origin. Localized re-entry was considered if >85% of the tachycardia cycle length (CL) was observed within the mapping field and was confirmed by entrainment., Results: A total of 27 ATs were mapped to the pulmonary vein ostia (n = 5), and left (n = 16) and right atria (n = 6). A localized focus was evidenced at the site of origin in 19 ATs (70%), whereas in 8 (30%), localized re-entry was evidenced by 95.2 +/- 4.5% of the tachycardia CL recorded within the mapping field and entrainment showed a post-pacing interval <20 ms longer than tachycardia CL (6 of 6 tested). Localized re-entry had a shorter CL (p = 0.009), slowed conduction at its origin (fractionated potential 115 +/- 19 ms vs. 64 +/- 22 ms, representing 49 +/- 10% and 20 +/- 10% of tachycardia CL, respectively; p < 0.0001), and were more often contiguous with regions of electrical silence or conduction abnormalities (88% vs. 32%; p = 0.01). In addition, mapping documented varying degrees of intra-atrial conduction block, preferential conduction (n = 5), and rapid bursts of myocardial activity (n = 1). At 11 +/- 7 months, none have had recurrence of AT., Conclusions: High-density multielectrode mapping can be used to perform vector mapping to localize complex AT. It provides novel insight into the mechanisms of focal AT, distinguishing focal AT from localized re-entry.

Objectives: We assessed the anatomical distribution and electrogram characteristics of breakthrough from the left atrium (LA) to the pulmonary veins (PVs)., Background: Localization of LA-PV breakthrough is an important technique for PV ablation in patients with atrial fibrillation (AF)., Methods: A total of 157 patients with paroxysmal AF underwent PV disconnection guided by mapping with a circumferential 10-electrode catheter. Radiofrequency (RF) current was delivered ostially at the site(s) of earliest activation (113 patients) or electrogram polarity reversal defined by opposite polarity across adjacent bipoles (44 patients). Breakthrough sites were proved by changes in pulmonary vein potential activation sequence occurring as a result of localized RF delivery and were classified into four segments around the ostium (top, bottom, anterior, posterior). Results of mapping and ablation were compared between the two groups., Results: A total of 99% of 411 targeted PVs were successfully disconnected in both groups. Breakthroughs were most frequent at the bottom of superior PVs (85% prevalence) and the top of inferior PVs (75% prevalence). A wide activation front (>5 synchronous bipoles) indicating broad breakthrough was observed in 18% of PVs. Polarity reversal occurred with 88% sensitivity and 91% specificity at breakthrough sites. Polarity reversal was restricted to fewer bipoles (2.0 +/- 0.4 bipoles vs. 3.4 +/- 2.0 bipoles, p < 0.01) compared with earliest activation. Shorter RF application time was required to disconnect PVs with wide synchronous activation using polarity reversal compared with using conventional earliest activity (10.3 +/- 3.0 min vs. 12.3 +/- 3.4 min, p < 0.05)., Conclusions: Bipolar electrogram polarity reversal allows more precise localization of breakthrough compared with the earliest activation, particularly in cases of wide synchronous PV activation.

This report describes two patients who exhibited far-field oversensing of the P wave by the ventricular channel of a DDD biventricular pacemaker implanted for the treatment of congestive heart failure. Oversensing probably occurred secondary to slight displacement of the left ventricular lead in the coronary venous system. Long-term reliable pacing was restored by decreasing the sensitivity of the ventricular channel.

Background: The extent of ostial ablation necessary to electrically disconnect the pulmonary vein (PV) myocardial extensions that initiate atrial fibrillation from the left atrium has not been determined., Methods and Results: Seventy patients underwent PV mapping with a circumferential 10-electrode catheter during sinus rhythm or left atrial pacing. After assessment of perimetric distribution and activation sequence of PV potentials, ostial ablation was performed at segments showing earliest activation, with the end point of PV disconnection. A total of 162 PVs (excluding right inferior PVs) were ablated. PV potentials were present at 60% to 88% of their perimeter, but PV muscle activation was always sequential from a segment with earliest activation (breakthrough). Radiofrequency (RF) application at this breakthrough eliminated all PV potentials in 34 PVs, whereas a secondary breakthrough required RF applications at separate segments in 77; in others, >2 segments were ablated. A median of 5, 6, and 4 bipoles from the circular catheter were targeted in the right superior, left superior, and inferior PVs, respectively, to achieve PV disconnection. Early recurrence of arrhythmia was observed in 31 patients as a result of new venous or atrial foci or recovery of previously targeted PVs, most related to a single recovered breakthrough that was reablated with local RF application., Conclusions: Although PV muscle covers a large extent of the PV perimeter, there are specific breakthroughs from the left atrium that allow ostial PV disconnection by use of partial perimetric ablation.

Pulmonary vein potentials (PVPs), though obvious during ectopic activity, are frequently invisible during sinus rhythm when they need to be distinguished from left atrial (LA) potentials to perform successful ablation procedures. Thirty-six patients with paroxysmal atrial fibrillation underwent circumferential PV mapping with a circular ten-electrode catheter during sinus rhythm, and during pacing from the right atrium, proximal and distal coronary sinus (CS), and LA. Ablation was performed at the ostium of the PV, the procedural endpoint consisting of electrical disconnection of the PV from the LA. A total of 93 PVs (excluding the right inferior PV) were mapped. During sinus rhythm, distinct right PVPs were present in all instances, while they were concealed within the electrograms recorded from the left inferior and superior PV in 23 (64%) patients. Distal CS or LA appendage pacing unmasked and separated left PV from LA potentials by a mean of 19 +/- 14 ms; the LA-to-left-PV potential interval measured 36 +/- 14 ms. The number of deflections also increased from 2.1 +/- 0.7 during sinus rhythm to 3 +/- 1.4 during LA stimulation. However, in the right superior PV, pacing caused overlapping of atrial potentials with right superior PVPs. RF ablation of the left PVPs was performed during distal or LA pacing in 23 patients, while in the right superior PV it was performed during sinus rhythm eliminating all, including unmasked, left PVPs, providing proof of their PV origin. Distal CS or LA pacing is required to recognize left PVPs in approximately 2/3 of patients and facilitates RF ablation.

Background: The full circuit of common atrial flutter using conventional methods of sequential or multielectrode activation mapping is not completely understood., Methods and Results: We performed three-dimensional right atrial endocardial activation mapping during common counterclockwise atrial flutter in 17 patients (16 men, 1 woman; mean age, 53+/-11 years) by using the Cordis-Biosense EP Navigation system and assessed the distribution of estimated conduction velocities and double and fractionated potentials. ECG flutter wave morphologies were compared with activation patterns. Points (91+/-29) were sequentially acquired covering 88+/-11% of the flutter cycle length of 239+/-22 ms. A wide and variable posterior zone of double and fractionated potentials coincided with blocking and colliding wave fronts and formed the posterior limit of the circuit. A progressively widening septal (sep) wave front ascending from just beyond the coronary sinus ostium, passed cranially as a broad front anterior to the superior vena cava (SVC) in 14 patients, whereas fusion around the SVC formed the superior (sup) limb of the circuit in 3. Bounded anteriorly by the tricuspid valve, the wave front descended down the lateral (lat) aspect of the right atrium before completing the circuit in all cases through the inferior vena cava-tricuspid annulus isthmus. The estimated conduction velocity in the medial isthmus (0.6+/-0.3 m/s) was lower than in the other limbs of the circuit (sup=1+/-0.5 m/s, lat=1+/-0.5 m/s, sep=0.9+/-0.4 m/s, P=.05). Double and fractionated potentials were constant and more prevalent in the posterior right atrium. ECG flutter wave morphology did not correlate with three-dimensional activation maps., Conclusions: Interindividual variations occur in the right atrial circuit of common atrial flutter, with constant activation through the cavotricuspid isthmus. A variable zone of block forms the posterior limit. Fusion around the SVC can occur, and ascending medial septal activation does not follow a consistent pattern.