Complexity and Distribution of Drivers in Relation to Duration of Persistent Atrial Fibrillation.

BACKGROUND: The underlying mechanisms sustaining human persistent atrial fibrillation (PsAF) is poorly understood. OBJECTIVES: This study sought to investigate the complexity and distribution of AF drivers in PsAF of varying durations. METHODS: Of 135 consecutive patients with PsAF, 105 patients referred for de novo ablation of PsAF were prospectively recruited. Patients were divided into 3 groups according to AF duration: PsAF presenting in sinus rhythm (AF induced), PsAF <12 months, and PsAF >12 months. Patients wore a 252-electrode vest for body surface mapping. Localized drivers (re-entrant or focal) were identified using phase-mapping algorithms. RESULTS: In this patient cohort, the most prominent re-entrant driver regions included the pulmonary vein (PV) regions and inferoposterior left atrial wall. Focal drivers were observed in 1 or both PV regions in 75% of patients. Comparing between the 3 groups, with longer AF duration AF complexity increased, reflected by increased number of re-entrant rotations (p < 0.05), number of re-entrant rotations and focal events (p < 0.05), and number of regions harboring re-entrant (p < 0.01) and focal (p < 0.05) drivers. With increased AF duration, a higher proportion of patients had multiple extra-PV driver regions, specifically in the inferoposterior left atrium (p < 0.01), superior right atrium (p < 0.05), and inferior right atrium (p < 0.05). Procedural AF termination was achieved in 70% of patients, but decreased with longer AF duration. CONCLUSIONS: The complexity of AF drivers increases with prolonged AF duration. Re-entrant and focal drivers are predominantly located in the PV antral and adjacent regions. However, with longer AF duration, multiple drivers are distributed at extra-PV sites. AF termination rate declines as patients progress to longstanding PsAF, underscoring the importance of early intervention.

Slow pathway modification in patients presenting with only two consecutive AV nodal echo beats.

BACKGROUND: Slow pathway modification (SPM) is the therapy of choice for AV-nodal reentry tachycardia (AVNRT). When AVNRT is not inducible, empirical ablation can be considered, however, the outcome in patients with two AV nodal echo beats (AVNEBs) is unknown. METHODS: Out of a population of 3003 patients who underwent slow pathway modification at our institution between 1993 and 2013, we retrospectively included 32 patients with a history of symptomatic tachycardia, lack of paroxysmal supraventricular tachycardia (pSVT) inducibility but occurrence of two AVNEBs. RESULTS: pSVT documentation by electrocardiography (ECG) was present in 20 patients. The procedural endpoint was inducibility of less than two AVNEBs. This was reached in 31 (97%) patients. Long-term success was assessed by a telephone questionnaire (follow-up time 63±9 months). A total 94% of the patients benefited from the procedure (59% freedom from symptoms; 34% improvement in symptoms). Among those patients in whom ECG documentation was not present, 100% benefited (58% freedom from symptoms, 42% improvement). CONCLUSION: This is the first collective analysis of a group of patients presenting with symptoms of pSVT and inducibility of only two AVNEBs. Procedural success and clinical long-term follow-up were in the range of the reported success rates of slow pathway modification of inducible AVNRT, independent of whether ECG documentation was present. Thus, SPM is a safe and effective therapy in patients with two AVNEBs.

Incidence and management of inadvertent puncture and sheath placement in the aorta during attempted transseptal puncture.

AIMS: Transseptal punctures (TSP) are routinely performed in cardiac interventions requiring access to the left heart. While pericardial effusion/tamponade are well-recognized complications, few data exist on accidental puncture of the aorta and its management and outcome. We therefore analysed our single centre database for this complication. METHODS AND RESULTS: We assessed frequency and outcome of inadvertent aortic puncture during TSP in consecutive patients undergoing ablation procedures between January 2005 and December 2014. During the 10-year period, two inadvertent aortic punctures occurred among 2936 consecutive patients undergoing 4305 TSP (0.07% of patients, 0.05% of TSP) and in one Mustard patient during attempted baffle puncture. The first two patients required left ventricular access for catheter ablation of ventricular tachycardia. In both cases, an 11.5F steerable sheath (inner diameter 8.5F) was accidentally placed in the ascending aorta just above the aortic valve. In the presence of surgical standby, the sheaths were pulled back with a wire left in the aorta. Under careful haemodynamic and echocardiographic observation, this wire was also pulled back 30 min later. None of the patients required a closing device or open heart surgery. None of the patients suffered complications from the accidental aortic puncture and sheath placement. CONCLUSION: Inadvertent aortic puncture and sheath placement are rare complications in patients undergoing TSP for interventional procedures. Leaving a guidewire in place during the observation period may allow introduction of sheaths or other tools in order to control haemodynamic deterioration.

Lower rate of left atrial tachycardia after pulmonary vein isolation with PVAC versus irrigated-tip circumferential antral ablation.

BACKGROUND: Left atrial tachycardias (LAT) occur in about 5% of patients after irrigated-tip circumferential antral (CA) pulmonary vein isolation (PVI). They may cause debilitating symptoms in the patient and may be very difficult to treat. OBJECTIVE: To assess the incidence of LAT after PVI with the multielectrode phased-radiofrequency pulmonary vein ablation catheter (PVAC) compared to circumferential antral PVI with an irrigated-tip catheter. METHODS: We analyzed data from our ablation database. A total of 150 patients who underwent their first PVI with the PVAC system and 300 patients who underwent their first PVI with irrigated-tip circumferential antral (CA) radiofrequency ablation were matched by age and sex, as well as by type of atrial fibrillation. RESULTS: Of 150 PVAC patients, only 1 patient (0.7%) developed LAT during mean follow-up of 21 ± 14 months. The mechanism was macroreentry and the patient underwent successful ablation at our institution. Eleven of 300 irrigated-tip CA PVI patients (3.7%) developed LAT during mean follow-up of 22 ± 14 months and subsequently underwent ablation (P = .05). CONCLUSION: LAT occurs more frequently after irrigated-tip CA PVI compared to single-shot-device ablation with PVAC. Apart from being less technically demanding, lower incidence of LAT may influence choice of ablation technology.

Esophageal and Mediastinal Lesions Following Multielectrode Duty-Cycled Radiofrequency Pulmonary Vein Isolation: Simple Equals Safe?

BACKGROUND: The development of esophageal lesions following atrial fibrillation (AF) ablation has frequently been reported. Mediastinal tissue layers and the posterior wall of the left atrium are in close proximity to the site of ablation. Hence, mucosal lesions might solely represent the "tip of the iceberg." We therefore investigated patients undergoing multielectrode phased radiofrequency (RF) ablation (PVAC®, Medtronic Inc., Minneapolis, MN, USA) for symptomatic AF by radial endosonography (EUS) in conjunction with conventional endoscopy esophago-gastro-duodenoscopy (EGD) to visualize potential mediastinal injuries following pulmonary vein isolation (PVI). METHODS AND RESULTS: Eighteen patients (six women, mean age 52.8 ± 12.8 years, range 32-72 years) underwent PVI using multielectrode phased RF ablation and EGD and EUS following PVI within 48 hours. Postablation periesophageal lesions were detected by EUS in 10 out of 18 patients (56%). Four out of 10 lesions consisted of mild changes like small pericardial effusions, whereas six out of 10 patients had more severe lesions of the mediastinum, including one patient with changes of the esophageal mucosa. No atrio-esophageal fistula developed during follow-up (FU; mean FU 215 ± 105 days). CONCLUSIONS: Mediastinal and esophageal structural changes occurred in a substantial number of patients. These findings highlight the necessity of close FU and the awareness of the potential development of an atrio-esophageal fistula also after multielectrode catheter ablation.

Data on procedural handling and complications of pulmonary vein isolation using the pulmonary vein ablation catheter GOLD®.

AIMS: The second-generation multi-electrode-phased radiofrequency pulmonary vein ablation catheter (PVAC GOLD(®)) was redesigned with the intent to improve its safety and efficacy. METHODS AND RESULTS: Using a prospectively designed single-centre database, we retrospectively analysed 128 consecutive patients (102 paroxysmal and 43 female) who underwent their first pulmonary vein isolation with the PVAC GOLD(®). The analysis focused on procedural data as well as in-hospital complications. Baseline characteristics of the patient collective were as follows: mean age 57.9 years, mean CHA2DS2-VASC was 1.73 ± 1.30; structural heart disease was present in seven patients. The PVAC GOLD(®) exhibited procedure durations of 123.1 min ± 27.9, duration of energy delivery was 18.3 min ± 11.4, and fluoroscopy duration was 16.0 min ± 7.7. The redesigned catheter shows major complication [major bleeding, transitory ischaemic attack (TIA), and pericardial tamponade] rates of 2.3% (n = 3). The overall rate of adverse events was 5.4% (n = 7). Bleeding complications were observed in three patients (2.3%), in particular there were two cases (1.6%) of minor bleeding and one case (0.8%) of major bleeding. Two patients suffered pericardial effusion, but there was no need for pericardiocentesis. Besides one TIA, there was no other thrombo-embolic event. Furthermore, one case of post-procedural fever was observed. No deaths, stroke, or haemorrhagic shock occurred. Of the 510 pulmonary veins, 508 could be reached with the PVAC GOLD(®) device using a non-steerable long sheath. CONCLUSION: The PVAC GOLD(®) seems to have an acceptable safety profile. The handling is comparable with the previous generation PVAC(®).

Persistent Atrial Fibrillation From the Onset: A Specific Subgroup of Patients With Biatrial Substrate Involvement and Poorer Clinical Outcome.

OBJECTIVES: This study sought to characterize the clinical characteristics, atrial substrate, and prognosis in a subgroup of patients with persistent atrial fibrillation (AF) from the onset (PsAFonset). BACKGROUND: Patients with AF frequently progress from trigger-driven paroxysmal arrhythmias to substrate-dependent persistent arrhythmias. METHODS: Patients referred for persistent AF (PsAF) ablation were enrolled from 3 centers. Consecutive patients with PsAFonset (n = 129) were compared with patients with PsAF that progressed from paroxysmal AF (n = 231). In addition, 90 patients (30 patients with PsAFonset and 60 control subjects) were studied with noninvasive mapping to characterize the AF drivers. The degree of fractionation and endocardial voltages were assessed invasively. RESULTS: Patients with PsAFonset were younger (p = 0.047) and more obese (p < 0.001); there were more men (p = 0.034), more patients with hypertension (p = 0.044), and these patients had larger left (p < 0.05) and right atria (p < 0.05). Baseline AF cycle length was shorter in the PsAFonset group (p < 0.01); the degree of fractionation was higher (p < 0.001 for both atria), and the endocardial voltage was lower (p < 0.05 for both atria). Patients with PsAFonset had higher a number of re-entrant driver regions (p < 0.001) and extrapulmonary vein regions that had re-entrant drivers (p < 0.05), whereas control subjects displayed more focal driver regions (p = 0.029). The acute AF termination rate was lower in the PsAFonset group (42% vs. 81%; p < 0.001). During a mean follow-up of 17 ± 11 months from the last procedure, patients with PsAFonset had significantly higher AF, atrial tachycardia (AT), and AF/AT recurrence rates (p < 0.01). CONCLUSIONS: Patients with PsAFonset represent a distinct subgroup defined by specific demographics, underlying diffuse biatrial substrate disease, and worse clinical outcome. The findings highlight the importance of defining criteria for early detection of atrial substrate disease.

Persistent atrial fibrillation ablation: conventional versus driver-guided strategy.

While pulmonary vein isolation for paroxysmal atrial fibrillation (AF) is highly effective, catheter ablation for persistent AF remains a challenge with varying clinical success reported. Several ablation techniques have been proposed to target persistent AF, with the additional ablation of complex fractionated electrograms and linear lesions shown to provide incremental success to pulmonary vein isolation alone. Recently, several studies have suggested the presence of localized drivers (re-entrant or focal) in AF. By targeting these drivers, clinical outcomes may be maintained while minimizing the extent of ablation. This article will focus on the conventional stepwise ablation approach for persistent AF versus driver-guided ablation with the use of newer mapping technologies.

Impact of Substrate-Based Ablation of Ventricular Tachycardia on Cardiac Mortality in Patients With Implantable Cardioverter-Defibrillators.

INTRODUCTION: This study sought to determine if the acute procedural outcome of ventricular tachycardia (VT) substrate ablation is associated with a mortality benefit in patients with implantable cardioverter-defibrillators (ICD). METHODS AND RESULTS: A total of 195 ICD recipients (65 ± 11years) with ischemic or nonischemic dilated cardiomyopathy underwent substrate-based ablation targeting elimination of local abnormal ventricular activities (LAVA). Acute procedural success, which was defined as elimination of all identified LAVA in addition to the lack of VT inducibility, was achieved in 95 (49%) patients. During a median follow-up of 23 months, patients with acute procedure success had a significantly lower incidence of ICD shocks compared to those with ablation failure (8% vs. 30%, P < 0.001). In multivariate analysis, acute procedural success was associated with a lower risk of VT recurrence (hazard ratio [HR] 0.30, 95% confidence interval [CI] 0.18-0.49, P < 0.001) and all-cause mortality (HR 0.32, 95% CI 0.17-0.60, P < 0.001). While the impact of ablation success on mortality was not statistically significant in patients with LVEF > 35% (HR 0.45, 95% CI 0.15-1.34, P = 0.15) and those with NYHA class I/II (HR 0.63, 95% CI 0.29-1.40, P = 0.26), it was marked in patients with LVEF ≤ 35% (HR 0.30, 95% CI 0.14-0.62, P = 0.001) and NYHA class III/IV (HR 0.17, 95% CI 0.05-0.57, P = 0.004). CONCLUSIONS: LAVA elimination in addition to VT noninducibility as a procedural outcome for substrate-based ablation is associated with reduced mortality and better VT-free survival during follow-up. This prognostic benefit may be most pronounced in patients with severe heart failure as indicated by severely depressed LV function and NYHA class III/IV symptoms.

Outcome predictors of empirical slow pathway modulation: clinical and procedural characteristics and long-term follow-up.

OBJECTIVE: Catheter-based modulation of the slow pathway is the first-line therapy of atrioventricular nodal reentrant tachycardia (AVNRT), the most common supraventricular tachycardia (SVT). In patients with a typical history, in whom AVNRT is not inducible during an electrophysiological study, the current guidelines allow consideration of empirical slow pathway modulation (ESPM) under the precondition that both, dual nodal pathway physiology (DNPP) and an ECG documentation compatible with AVNRT exist. This recommendation is based on small series. Furthermore, it is unknown whether ESPM is beneficial in the presence of ECG documentation but the absence of DNPP or vice versa in the presence of DNPP but absence of ECG documentation. METHODS: Out of 3003 patients who underwent slow pathway modulation from 1993 to 2013, we included 116 patients (68 female; median age 47.0 years) with symptomatic tachycardia who had non-inducible SVT. All patients either had ECG documentation of SVT (66 %) or DNPP (89 %) or both (54 %). All patients underwent ESPM. No severe complications occurred. RESULTS: After a follow-up time of 64 ± 5.3 months, 81 % of all patients had benefited from ESPM (49 % freedom of symptoms, 32 % improvement). In patients with ECG documentation but absence of DNPP 100 % benefited (85 % freedom of symptoms; 15 % improvement). In patients with DNPP but absence of ECG documentation 75 % benefited (40 % freedom of symptoms, 35 % improvement). CONCLUSION: In a large cohort of patients, ESPM is a safe procedure that improves clinical symptoms in the majority of patients during long-term follow-up. We show for the first time that this also applies for cases where there is no DNPP but a characteristic ECG documentation, and vice versa.

Noninvasive mapping to guide atrial fibrillation ablation.

Atrial fibrillation (AF) is a dynamic rhythm. Noninvasive mapping overcomes many previous barriers to mapping such a dynamic rhythm, by providing a beat-to-beat, biatrial, panoramic view of the AF process. Catheter ablation of AF drivers guided by noninvasive mapping has yielded promising clinical results and has advanced understanding of the underlying pathophysiologic processes of this common heart rhythm disorder.

Noninvasive mapping of ventricular arrhythmias.

Several decades of research has led to the development of a 252-lead electrocardiogram-based three-dimensional imaging modality to refine noninvasive diagnosis and improve the management of heart rhythm disorders. This article reviews the clinical potential of this noninvasive mapping technique in identifying the sources of electrical disorders and guiding the catheter ablation of ventricular arrhythmias (premature ventricular beats and ventricular tachycardia). The article also briefly refers to the noninvasive electrical imaging of the arrhythmogenic ventricular substrate based on the electrophysiologic characteristics of postinfarction ventricular myocardium.

Distinct localized reentrant drivers in persistent atrial fibrillation identified by noninvasive mapping: relation to f-wave morphology.

Noninvasive mapping overcomes previous barriers to provide panoramic beat-to-beat mapping during atrial fibrillation (AF). This article demonstrates the utility of noninvasive mapping in identifying localized driving sources in persistent AF. Reentrant driver activity detected by noninvasive mapping from specific regions correlated with distinct f-wave morphologies. Ablation targeting these drivers resulted in progressive AF cycle length prolongation and termination of the arrhythmia.

[Complications associated with catheter ablation of atrial fibrillation]. / Komplikationen der Katheterablation von Vorhofflimmern.

The past years catheter ablation has gained significant importance in the treatment of atrial fibrillation (AF), hence procedure numbers have risen worldwide. Initially, data concerning complications were only available through surveys and single center reports but international classification of diseases (ICD) code-based data have recently been published representing real world conditions. The rate of overall acute complications is 6.3 % and has risen slightly in the past 10 years whereby cardiac complications occurred most frequently, followed by vascular, respiratory and neurological complications. Risk factors for a higher complication rate are advanced age (> 80 years), female gender and less experienced investigators and hospitals.

Characterization of contact force during endocardial and epicardial ventricular mapping.

BACKGROUND: The optimal contact force (CF) for ventricular mapping and ablation remains unvalidated. We assessed CF in different endocardial and epicardial regions during ventricular tachycardia substrate mapping using a CF-sensing catheter (Smartouch; Biosense-Webster) and compared the transseptal versus retroaortic approach. METHODS AND RESULTS: In total, 8979 mapping points with CF, and force vector orientation (VO) were recorded in 21 patients, comprising 13 epicardial, 12 left ventricular (6 transseptal and 6 retroaortic approach), and 12 right ventricular endocardial maps. VO was defined as adequate when the vector was directed toward the myocardium. During epicardial mapping, 46% of the points showed an adequate VO and a median CF of 8 (4-13) g, however, with significant differences among the 8 regions. When VO was inadequate, median CF was higher at 16 (10-24) g (P<0.0001). During left ventricular and right ventricular endocardial mapping, 94% of VO were adequate. Median CF of adequate VO was higher in the left ventricular and right ventricular endocardium than in the epicardium (15 [8-25] and 13 [7-22] g versus 8 [4-13] g, respectively; both P<0.001). Global median left ventricular CF with transseptal approach was not statistically different from retroaortic approach, but CF in the apicoinferior and apicoseptal regions was higher with transseptal approach (P<0.001). CONCLUSIONS: Ventricular mapping demonstrates important regional variations in CF, but in general, CF is higher endocardially than epicardially where poor catheter orientation is associated with higher CF. A transseptal approach may lead to improved contact particularly in the apicoseptal and inferior regions.

Driver domains in persistent atrial fibrillation.

BACKGROUND: Specific noninvasive signal processing was applied to identify drivers in distinct categories of persistent atrial fibrillation (AF). METHODS AND RESULTS: In 103 consecutive patients with persistent AF, accurate biatrial geometry relative to an array of 252 body surface electrodes was obtained from a noncontrast computed tomography scan. The reconstructed unipolar AF electrograms acquired at bedside from multiple windows (duration, 9±1 s) were signal processed to identify the drivers (focal or reentrant activity) and their cumulative density map. The driver domains were catheter ablated by using AF termination as the procedural end point in comparison with the stepwise-ablation control group. The maps showed incessantly changing beat-to-beat wave fronts and varying spatiotemporal behavior of driver activities. Reentries were not sustained (median, 2.6 rotations lasting 449±89 ms), meandered substantially but recurred repetitively in the same region. In total, 4720 drivers were identified in 103 patients: 3802 (80.5%) reentries and 918 (19.5%) focal breakthroughs; most of them colocalized. Of these, 69% reentries and 71% foci were in the left atrium. Driver ablation alone terminated 75% and 15% of persistent and long-lasting AF, respectively. The number of targeted driver regions increased with the duration of continuous AF: 2 in patients presenting in sinus rhythm, 3 in AF lasting 1 to 3 months, 4 in AF lasting 4 to 6 months, and 6 in AF lasting longer. The termination rate sharply declined after 6 months. The mean radiofrequency delivery to AF termination was 28±17 minutes versus 65±33 minutes in the control group (P<0.0001). At 12 months, 85% patients with AF termination were free from AF, similar to the control population (87%,); P=not significant. CONCLUSIONS: Persistent AF in early months is maintained predominantly by drivers clustered in a few regions, most of them being unstable reentries.

Pulmonary vein isolation using a circular, open irrigated mapping and ablation catheter (nMARQ): a report on feasibility and efficacy.

AIMS: Pulmonary vein isolation (PVI) is the mainstay of interventional treatment of paroxysmal atrial fibrillation (PAF). We report on the feasibility and efficacy of a novel, open-irrigated mapping and radiofrequency (RF) ablation catheter. METHODS AND RESULTS: Thirty-nine consecutive patients (pts; age 60 ± 10 years, 8 females) suffering from drug-refractory PAF referred for PVI were included in this prospective study. Pulmonary vein isolation was performed with the use of a novel 10-pole circular, open-irrigated mapping and ablation catheter (nMARQ, Biosense Webster). Outcome parameters were the acute success rate in establishing complete PVI and the rate of sustained sinus rhythm (SR) during follow-up (FU). Ten patients underwent a repeat procedure for recurrent AF. Ninety-eight percent of the PVs could be acutely isolated using solely the nMARQ catheter by applying a mean total of 10.0 ± 4.6 min of RF energy. The mean total procedure duration was 86 ± 29 min, and the mean fluoroscopy time was 22.2 ± 6.5 min, respectively. Transient reconnection provoked by adenosine was observed in 10 of 24 patients, most frequently in the right superior PV. Cardiac tamponade related to transseptal puncture occurred in one patient. Reconnected PVs could be identified as a source of recurrent AF in 9 of 10 patients undergoing a repeat procedure. Single and multiple procedure success rates during a mean FU of 140 ± 75 days were 66 and 77%, respectively. CONCLUSION: Irrigated multi-electrode RF ablation is fast and effective, providing a high rate of isolated PVs without the need of touch-up lesions. Success rates were comparable with other techniques with a low complication rate. Recurrences of AF were mainly due to recovered pulmonary vein/left atrium conduction.