Inverse relationship between fractionated electrograms and atrial fibrosis in persistent atrial fibrillation: combined magnetic resonance imaging and high-density mapping

OBJECTIVES This study sought to evaluate the relationship between fibrosis imaged by delayed-enhancement (DE) magnetic resonance imaging (MRI) and atrial electrograms (Egms) in persistent atrial fibrillation (AF). BACKGROUND Atrial fractionated Egms are strongly related to slow anisotropic conduction. Their relationship to atrial fibrosis has not yet been investigated. METHODS Atrial high-resolution MRI of 18 patients with persistent AF (11 long-lasting persistent AF) was registered with mapping geometry (NavX electro-anatomical system (version 8.0, St. Jude Medical, St. Paul, Minnesota)). DE areas were categorized as dense or patchy, depending on their DE content. Left atrial Egms during AF were acquired using a high-density, 20-pole catheter (514 ± 77 sites/map). Fractionation, organization/regularity, local mean cycle length (CL), and voltage were analyzed with regard to DE. RESULTS Patients with long-lasting persistent versus persistent AF had larger left atrial (LA) surface area (134 ± 38 cm(2) vs. 98 ± 9 cm(2), p = 0.02), a higher amount of atrial DE (70 ± 16 cm(2) vs. 49 ± 10 cm(2), p = 0.01), more complex fractionated atrial Egm (CFAE) extent (54 ± 16 cm(2) vs. 28 ± 15 cm(2), p = 0.02), and a shorter baseline AF CL (147 ± 10 ms vs. 182 ± 14 ms, p = 0.01). Continuous CFAE (CFEmean [NavX algorithm that quantifies Egm fractionation] <80 ms) occupied 38 ± 19% of total LA surface area. Dense DE was detected at the left posterior left atrium. In contrast, the right posterior left atrium contained predominantly patchy DE. Most CFAE (48 ± 14%) occurred at non-DE LA sites, followed by 41 ± 12% CFAE at patchy DE and 11 ± 6% at dense DE regions (p = 0.005 and p = 0.008, respectively); 19 ± 6% CFAE sites occurred at border zones of dense DE. Egms were less fractionated, with longer CL and lower voltage at dense DE versus non-DE regions: CFEmean: 97 ms versus 76 ms, p < 0.0001; local CL: 153 ms versus 143 ms, p < 0.0001; mean voltage: 0.63 mV versus 0.86 mV, p < 0.0001. CONCLUSIONS Atrial fibrosis as defined by DE MRI is associated with slower and more organized electrical activity but with lower voltage than healthy atrial areas. Ninety percent of continuous CFAE sites occur at non-DE and patchy DE LA sites. These findings are important when choosing the ablation strategy in persistent AF.

Pattern and timing of the coronary sinus activation to guide rapid diagnosis of atrial tachycardia after atrial fibrillation ablation

BACKGROUND Atrial tachycardias (AT) during or after ablation of atrial fibrillation frequently pose a diagnostic challenge. We hypothesized that both the patterns and the timing of coronary sinus (CS) activation could facilitate AT mapping. METHODS AND RESULTS A total of 140 consecutive postpersistent atrial fibrillation ablation patients with sustained AT were investigated by conventional mapping. CS activation pattern was defined as chevron or reverse chevron when the activations recorded on both the proximal and the distal CS dipoles were latest or earliest, respectively. The local activation of mid-CS was timed with reference to Ppeak-Ppeak (P-P) interval in lead V1. A ratio, mid-CS activation time to AT cycle length, was computed. Of 223 diagnosed ATs, 124 were macroreentrant (56%) and 99 were centrifugal (44%). When CS activation was chevron/reverse chevron (n=44; 20%), macroreentries were mostly roof dependent. With reference to P-P interval, mid-CS activation timing showed specific consistency for peritricuspid and perimitral AT. Proximal to distal CS activation pattern and mid-CS activation at 50% to 70% of the P-P interval (n=30; 13%) diagnosed peritricuspid AT with 81% sensitivity and 89% specificity. Distal to proximal CS activation and mid-CS activation at 10% to 40% of the P-P interval (n=44; 20%) diagnosed perimitral AT with 88% sensitivity and 75% specificity. CONCLUSIONS The analysis of the patterns and timing of CS activation provides a rapid stratification of most likely macroreentrant ATs and points toward the likely origin of centrifugal ATs. It can be included in a stepwise diagnostic approach to rapidly select the most critical mapping maneuvers.

The effectiveness and safety of d,l-sotalol in the ambulatory treatment of atrial fibrillation and flutter

Data on short and long term efficacy and safety of d,l sotalol in patients with atrial fibrillation or atrial flutter is limited. The aims of this study were to (1) assess the antiarrhythmic efficacy of d,l sotalol maintaining normal sinus rhythm in patients with refractory atrial fibrillation or flutter, (2) evaluate the efficacy of d,l sotalol in preventing recurrences of paroxysmal atrial fibrillation or flutter, (3) evaluate the control of ventricular rate in patients with paroxysmal or refractory atrial fibrillation or flutter unsuccessfully treated with other antiarrhythmic agents, (4) determine predictors of efficacy (5) assess the safety of d,l sotalol in this setting. Two hundred patients with chronic or paroxysmal atrial fibrillation or atrial flutter or both, who had failed one to six previous antiarrhythmic drug trials were treated with d,l sotalol 80 to 440 mg/day orally. Fifty four percent was female, age 47 +/- 16 years (range 7-79), follow up period 7 +/- 7 months (range 1 to 14 months), 79% of patients had the arrhythmia for more than one year. The atrial fibrillation in 37.5% of patients was chronic and paroxysmal in 23.5. The atrial flutter was chronic in 31% of patients and paroxysmal in 8%. Eighty two percent of patients was in functional class I (NYHA) and 82% had cardiac heart disease: left atrial (LA) size 44 +/- 10 mm, right atrial (RA) size 37 +/- 7 mm and left ventricular ejection fraction (LVEF) 58 +/- 8%. Total success was achieved in 58% of patients (atrial fibrillation 40% and 18% in atrial flutter), partial success in 38% (atrial fibrillation in 18% and 20% in atrial flutter) and 4% of patients failure. It was p < 0.07 when compared total success vs partial success among atrial fibrillation and atrial flutter groups. Patients with cardiac heart disease responded worst (p = 0.10) to the drug than those without it, specially if the heart was dilated. We concluded that d,l sotalol has moderate efficacy to convert and maintain normal sinus rhythm, as well as it acts controlling paroxysmal relapses and ventricular heart rate.

Effects of Gender on the Incidence of Cardiac Tamponade Following Catheter Ablation of Atrial Fibrillation: Results from a Worldwide Survey in 34,943 AF Ablation Procedures.

BACKGROUND -Cardiac tamponade is the most dramatic complication observed during atrial fibrillation (AF) ablation and the leading cause of procedure-related mortality. Female gender is a known risk factor for complications during AF ablation; however, it is unknown whether women have a higher risk of tamponade. METHODS AND RESULTS -A systematic Medline search was used to locate academic electrophysiologic (EP) centers that reported cases of tamponade occurring during AF ablation. Centers were asked to provide information on cases of acute tamponade according to gender and their mode of management including any case of related mortality. Nineteen EP centers provided information on 34,943 ablation procedures involving 25,261 (72%) males. Overall 289 (0.9%) cases of tamponade were reported: 120 (1.24%) in females and 169 (0.67%) in males (odds ratio 1.83, P<0.001). There was a reciprocal association between center volume and the occurrence of tamponade with substantial lower risk in high volume centers. Most cases of tamponade occurred during catheter manipulation or ablation; females tended to develop more tamponades during transseptal catheterization. No gender difference in the mode of management was observed. However, 16% cases of tamponade required surgery with lower rates in high volume centers. Three cases of tamponade (1%) culminated in death. CONCLUSIONS -Tamponade during AF ablation procedures is relatively rare. Women have an almost twofold higher risk for developing this complication. The risk of tamponade among women decreases substantially in high volume centers. Surgical back-up and acute management skills for treating tamponade are important in centers performing AF ablation.

Value of different follow-up strategies to assess the efficacy of circumferential pulmonary vein ablation for the curative treatment of atrial fibrillation.

BACKGROUND The objective of this study was to compare transtelephonic ECG every 2 days and serial 7-day Holter as two methods of follow-up after atrial fibrillation (AF) catheter ablation for the judgment of ablation success. Patients with highly symptomatic AF are increasingly treated with catheter ablation. Several methods of follow-up have been described, and judgment on ablation success often relies on patients' symptoms. However, the optimal follow-up strategy objectively detecting most of the AF recurrences is yet unclear. METHODS Thirty patients with highly symptomatic AF were selected for circumferential pulmonary vein ablation. During follow-up, a transtelephonic ECG was transmitted once every 2 days for half a year. Additionally, a 7-day Holter was recorded preablation, after ablation, after 3 and 6 months, respectively. With both, procedures symptoms and actual rhythm were correlated thoroughly. RESULTS A total of 2,600 transtelephonic ECGs were collected with 216 of them showing AF. 25% of those episodes were asymptomatic. On a Kaplan-Meier analysis 45% of the patients with paroxysmal AF were still in continuous SR after 6 months. Simulating a follow-up based on symptomatic recurrences only, that number would have increased to 70%. Using serial 7-day ECG, 113 Holter with over 18,900 hours of ECG recording were acquired. After 6 months the percentage of patients classified as free from AF was 50%. Of the patients with recurrences, 30-40% were completely asymptomatic. The percentage of asymptomatic AF episodes stepwise increased from 11% prior ablation to 53% 6 months after. CONCLUSIONS The success rate in terms of freedom from AF was 70% on a symptom-only-based follow-up; using serial 7-day Holter it decreased to 50% and on transtelephonic monitoring to 45%, respectively. Transtelephonic ECG and serial 7-day Holter were equally effective to objectively determine long-term success and to detect asymptomatic patients.

Perception of atrial fibrillation before and after radiofrequency catheter ablation: relevance of asymptomatic arrhythmia recurrence.

BACKGROUND The objective of this study was to assess the incidence and impact of asymptomatic arrhythmia in patients with highly symptomatic atrial fibrillation (AF) who qualified for radiofrequency (RF) catheter ablation. METHODS AND RESULTS In this prospective study, 114 patients with at least 3 documented AF episodes together with corresponding symptoms and an ineffective trial of at least 1 antiarrhythmic drug were selected for RF ablation. With the use of CARTO, circumferential lesions around the pulmonary veins and linear lesions at the roof of the left atrium and along the left atrial isthmus were placed. A continuous, 7-day, Holter session was recorded before ablation, right after ablation, and after 3, 6, and 12 months of follow-up. During each 7-day Holter monitoring, the patients recorded quality and duration of any complaints by using a detailed symptom log. More than 70,000 hours of ECG recording were analyzed. In the 7-day Holter records before ablation, 92 of 114 patients (81%) had documented AF episodes. All episodes were symptomatic in 35 patients (38%). In 52 patients (57%), both symptomatic and asymptomatic episodes were recorded, whereas in 5 patients (5%), all documented AF episodes were asymptomatic. After ablation, the percentage of patients with only asymptomatic AF recurrences increased to 37% (P<0.05) at the 6-month follow-up. An analysis of patient characteristics and arrhythmia patterns failed to identify a specific subset who were at high risk for the development of asymptomatic AF. CONCLUSIONS Even in patients presenting with highly symptomatic AF, asymptomatic episodes may occur and significantly increase after catheter ablation. A symptom-only-based follow-up would substantially overestimate the success rate. Objective measures such as long-term Holter monitoring are needed to identify asymptomatic AF recurrences after ablation.

Trigger activity more than three years after left atrial linear ablation without pulmonary vein isolation in patients with atrial fibrillation.

OBJECTIVES The aim of this study was to analyze trigger activity in the long-term follow-up after left atrial (LA) linear ablation. BACKGROUND Interventional strategies for curative treatment of atrial fibrillation (AF) are targeted at the triggers and/or the maintaining substrate. After substrate modification using nonisolating linear lesions, the activity of triggers is unknown. METHODS With the LA linear lesion concept, 129 patients were treated using intraoperative ablation with minimal invasive surgical techniques. Contiguous radiofrequency energy-induced lesion lines involving the mitral annulus and the orifices of the pulmonary veins without isolation were placed under direct vision. RESULTS After a mean follow-up of 3.6 +/- 0.4 years, atrial ectopy, atrial runs, and reoccurrence of AF episodes were analyzed by digital 7-day electrocardiograms in 30 patients. Atrial ectopy was present in all patients. Atrial runs were present in 25 of 30 patients (83%), with a median number of 9 runs per patient/week (range 1 to 321) and a median duration of 1.2 s/run (range 0.7 to 25), without a significant difference in atrial ectopy and atrial runs between patients with former paroxysmal (n = 17) or persistent AF (n = 13). Overall, 87% of all patients were completely free from AF without antiarrhythmic drugs. CONCLUSIONS A detailed rhythm analysis late after specific LA linear lesion ablation shows that trigger activity remains relatively frequent but short and does not induce AF episodes in most patients. The long-term success rate of this concept is high in patients with paroxysmal or persistent AF.

Topographic variability of the esophageal left atrial relation influencing ablation lines in patients with atrial fibrillation.

UNLABELLED Topography of the esophagus in atrial fibrillation ablation. INTRODUCTION The close anatomic relationship of the posterior wall of the left atrium (LA) and the thermosensitive esophagus creates a potential hazard in catheter ablation procedures. METHODS AND RESULTS In 30 patients (pts) with atrial fibrillation (AF) undergoing catheter ablation, we prospectively studied the course and contact of the esophagus in relation to LA and the topographic proximity to ablation lines encircling the right-sided and left-sided pulmonary veins (PV) as well as to the posterior line connecting the encircling lines using the electromagnetic mapping system for reconstruction of LA and for tagging of the esophagus. This new technique of anatomic tagging of the esophagus was validated against the CT scan as a standard imaging procedure. The esophageal course was highly variable, extending from courses in direct vicinity to the left- or right-sided PV as well as in the midportion of the posterior LA. In order to avoid energy application in direct proximity to the esophagus, adjustments of the left and right PV encircling lines were necessary in 14/30 pts (47%) and 3/30 (10%). In 30 pts (100%), the mid- to inferior areas of the posterior LA revealed contact with the esophagus. Therefore, posterior and inferior linear ablation lines were abandoned and shifted to superior in 29 pts (97%). CONCLUSIONS Anatomic tagging of esophagus revealed a highly variable proximity to different areas of the posterior LA suggesting individual adjustment of encircling and linear ablation lines in AF ablation procedures to avoid the life threatening complication of esophagus perforation.

Late recurrent arrhythmias after ablation of atrial fibrillation: incidence, mechanisms, and treatment.

OBJECTIVES The aim of the study was to determine the incidence of atrial flutter and other arrhythmia recurrences (other than atrial fibrillation [AF]) during long-term follow-up after left atrial substrate modification by percutaneous radiofrequency (RF) ablation of AF. BACKGROUND RF ablation is an effective treatment for patients with AF. However, late recurrent arrhythmias may complicate the patient's course. METHODS One hundred fifty consecutive patients with paroxysmal or persistent AF were included in this prospective study. The incidence of arrhythmia recurrences after AF ablation was analyzed during long-term follow-up using repetitive 7-day ECG recording. RESULTS In 28 of 150 patients (18.7%), stable regular arrhythmias other than AF were detected during follow-up. Left atrial flutter observed in 10 patients (6.7%) was treated by recompletion of the ablation lines in all 10 patients. Left atrial flutter was associated with recurrence of AF in all 10 patients. Nine of 10 patients (90%) were free from atrial flutter and 6 of 10 patients were free from AF after the second intervention. Typical right atrial flutter occurred in 10 patients (6.7%) and was treated successfully by percutaneous RF ablation without recurrence in all patients. Additionally, atrial flutter was documented during follow-up in 7 patients (4.7%); however, invasive electrophysiologic evaluation was not performed due to various reasons. CONCLUSIONS Left atrial flutter is a relevant complication after RF catheter ablation of AF and was always associated with AF recurrence in our study population. Prevention of left atrial flutter can be achieved by induction of ablation lines as continuous and transmural as possible. However, left atrial flutter that does occur late after ablation is amenable to interventional treatment with good prospects of success.

Stable secondary arrhythmias late after intraoperative radiofrequency ablation of atrial fibrillation: incidence, mechanism, and treatment.

INTRODUCTION Intraoperative radiofrequency (RF) ablation is an effective treatment of atrial fibrillation (AF). However, secondary arrhythmias late after ablation may complicate the patient's course. We report on the incidence, mechanisms, and treatment of gap-related atrial flutter and other secondary arrhythmias during long-term follow-up. METHODS AND RESULTS In 129 patients who underwent intraoperative RF ablation with placement of left atrial linear lesions using minimally invasive surgical techniques, secondary arrhythmias were analyzed during long-term follow-up (20 +/- 6 months). Transient atrial arrhythmias during the first 3 postoperative months were excluded. In 8 (6.2%) of 129 patients, sustained stable secondary arrhythmias were documented. Left atrial, gap-related atrial flutter was observed in 4 patients (3.1%). The flutter was treated by percutaneous RF ablation in 3 patients (2.3%) and with drugs in 1 patient (0.8%). In 2 patients (1.6%), right atrial isthmus-dependent atrial flutter occurred and was treated successfully by percutaneous RF ablation. In 2 patients (1.6%), ectopic right atrial tachycardias occurred and were treated with percutaneous RF ablation. CONCLUSION Late after intraoperative RF ablation of atrial fibrillation, three types of stable secondary arrhythmias were observed in 6% of patients: left atrial gap-related atrial flutter, right atrial isthmus-dependent atrial flutter, and ectopic atrial tachycardia. Gaps after intraoperative RF ablation due to noncontinuous or nontransmural linear lesions may lead to stable left atrial macroreentrant tachycardias, requiring new interventional therapy.

Time courses and quantitative analysis of atrial fibrillation episode number and duration after circular plus linear left atrial lesions: trigger elimination or substrate modification: early or delayed cure?

OBJECTIVES We sought to analyze the time course of atrial fibrillation (AF) episodes before and after circular plus linear left atrial ablation and the percentage of patients with complete freedom from AF after ablation by using serial seven-day electrocardiograms (ECGs). BACKGROUND The curative treatment of AF targets the pathophysiological corner stones of AF (i.e., the initiating triggers and/or the perpetuation of AF). The pathophysiological complexity of both may not result in an "all-or-nothing" response but may modify number and duration of AF episodes. METHODS In patients with highly symptomatic AF, circular plus linear ablation lesions were placed around the left and right pulmonary veins, between the two circles, and from the left circle to the mitral annulus using the electroanatomic mapping system. Repetitive continuous 7-day ECGs administered before and after catheter ablation were used for rhythm follow-up. RESULTS In 100 patients with paroxysmal (n = 80) and persistent (n = 20) AF, relative duration of time spent in AF significantly decreased over time (35 +/- 37% before ablation, 26 +/- 41% directly after ablation, and 10 +/- 22% after 12 months). Freedom from AF stepwise increased in patients with paroxysmal AF and after 12 months measured at 88% or 74% depending on whether 24-h ECG or 7-day ECG was used. Complete pulmonary vein isolation was demonstrated in <20% of the circular lesions. CONCLUSIONS The results obtained in patients with AF treated with circular plus linear left atrial lesions strongly indicate that substrate modification is the main underlying pathophysiologic mechanism and that it results in a delayed cure instead of an immediate cure.

Prognostic role of subsequent atrial tachycardias occurring during ablation of persistent atrial fibrillation: a prospective randomized trial

BACKGROUND The role of subsequent atrial tachycardias (AT) in the context of persistent atrial fibrillation (AF) remains undetermined. This study evaluated the prognostic role of subsequent ATs for arrhythmia recurrences after catheter ablation of persistent AF. METHODS AND RESULTS A total of 110 patients with persistent AF (63±9 years; 22 women; 61 long-lasting persistent AF) underwent pulmonary vein isolation followed by electrogram-guided ablation. After AF terminated to AT, patients were separated by the randomization protocol to receive either direct cardioversion (group A) or further ablation of subsequent ATs to sinus rhythm (group B). After a mean follow-up of 20.1±13.3 months after the first procedure, significantly more group B patients were in sinus rhythm as compared with patients in group A (30 [57%] versus 18 [34%]; P=0.02). Moreover, recurrences of AF were significantly less frequent of group B than in group A patients (10 [19%] versus 26 [49%]; P=0.001). After the last procedure (follow-up, 34.0±6.4 months), significantly more group B patients were free of AF as compared with patients of group A (49 [92%] versus 39 [74%]; P=0.01). The proportion of AT recurrences did not differ between the 2 groups after the first and final procedures. The strongest predictor for an arrhythmia-free survival after a single procedure was randomization to the procedural end point of termination to sinus rhythm by elimination of subsequent ATs (P=0.004). CONCLUSIONS Catheter ablation of subsequent ATs increases freedom from AF but not AT, suggesting a contributing role of subsequent ATs in the mechanisms of persistent AF. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT01896570.

Catheter ablation of persistent and long-standing persistent atrial fibrillation. Strategies and results

Catheter ablation for paroxysmal atrial fibrillation is a meanwhile established therapy option, which is most frequently performed using radiofrequency ablation. Mid-term success rate of 70 % are achievable with a single ablation procedure. However, the mechanistics of persistent atrial fibrillation are less well understood and catheter ablation is a far more challenging procedure. Different ablation approaches are being performed to treat persistent atrial fibrillation ranging from sole pulmonary vein isolation to additional ablation of fractionated electrograms aiming for termination of atrial fibrillation. Thus far, it has not been investigated which strategy is most successful in treating persistent atrial fibrillation. After extended ablation of atrial fibrillation, occurrence of organized atrial arrhythmias is not uncommon and can be successfully ablated. These consecutive arrhythmias can be considered as a next step towards stable sinus rhythm after repeat ablation. Improvement of mapping methods as well as a better understanding of mechanisms of atrial fibrillation may increase success rate of catheter ablation of persistent atrial fibrillation and may also help to improve success rate of these complex procedures.