The 'double transition': a novel electrocardiogram sign to discriminate posteroseptal accessory pathways ablated from the right endocardium from those requiring a left-sided or epicardial coronary venous approach.

AIMS: The precise localization of manifest posteroseptal accessory pathways (APs) often poses diagnostic challenges considering that a small area may encompass AP that may be ablated from the right or left endocardium, or epicardially within the coronary sinus (CS). We sought to explore whether the QRS transition pattern in the precordial lead may help to discriminate the necessary ablation approach. METHODS AND RESULTS: Consecutive patients who underwent a successful ablation of a single manifest AP over a 5-year period were included. Standard 12-lead electrocardiograms were reviewed. A total of 273 patients were identified. Mean age was 31 ± 15 years and 62% were male. Of the 110 identified posteroseptal AP, 64 were ablated from the right endocardium, 33 from the left endocardium, and 13 inside the CS. While a normal precordial QRS transition was most often observed, a subset of 33 patients presented an atypical 'double transition' pattern which specifically identified right endocardial AP. The combination of a q wave in V1 with a proportion of the positive QRS component in V1 < V2 > V3, predicted a right endocardial AP with a 100% specificity. In case of a positive QRS sum in V2, this 'double transition' pattern predicted a posteroseptal right endocardial AP with 99.5% specificity and 44% sensitivity. The positive predictive value was 97%. The only false positive was a midseptal AP. In the case of a negative or isoelectric QRS sum in V2, APs were located more laterally on the tricuspid annulus. CONCLUSION: The combination of a q wave in V1 with a double QRS transition pattern in the precordial leads is highly specific of a right endocardial AP and rules out the need for CS or left-sided mapping.

Useful Electrocardiographic Features to Help Identify the Mechanism of Atrial Tachycardia Occurring After Persistent Atrial Fibrillation Ablation.

OBJECTIVES: The purpose of this study was to describe and identify useful electrocardiographic characteristics to help identify the mechanism of atrial tachycardia (AT) occurring after persistent atrial fibrillation (PsAF) ablation. BACKGROUND: Electrocardiographic analysis to help identify the mechanism of AT after PsAF ablation is much limited by the fact that remodeling and ablation alter the normal activation pattern. METHODS: All consecutive patients who underwent mapping and ablation of AT after PsAF ablation were included. Surface P waves were analyzed during higher (>2:1) grades of atrioventricular block. RESULTS: One hundred ninety-six ATs with visible P waves were identified in 127 patients (macro-re-entry in 57%, centrifugal AT in 43%). One-third displayed low-voltage P waves (≤0.1 mV). An isoelectric line >80 ms was more common in centrifugal compared with macro-re-entrant AT (47% vs. 24%; p < 0.001), but its positive predictive value was limited (60%). A minority of peritricuspid ATs displayed the classic saw-tooth pattern (27% [n = 22]). However, the "precordial transition" (a gradual transition from an upright component in lead V1 to a negative component with progression across the precordium) remained often observed and specifically identified peritricuspid AT (specificity, 98%; sensitivity, 59%). Only 2 unique features could help identify perimitral AT (n = 60). First, the presence of a negative or negative-positive P-wave in any of leads V2 to V6 identified perimitral AT with 97% specificity and 30% sensitivity. Second, a "notched" negative component at the beginning of a positive P-wave in the inferior leads specifically identified clockwise perimitral AT (specificity, 98%; sensitivity, 25%). CONCLUSIONS: Only few unique electrocardiographic characteristics help identify the mechanism of AT after PsAF ablation. Knowledge of these characteristics may aid in planning and performing ablation.

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.

Polymorphic Ventricular Tachycardia/Ventricular Fibrillation and Sudden Cardiac Death in the Normal Heart.

Primary electrical diseases manifest with polymorphic ventricular tachycardia (PMVT) and ventricular fibrillation (VF) and along with idiopathic VF contribute to about 10% of sudden cardiac deaths (SCDs) overall. These disorders include long QT syndrome, Brugada syndrome, catecholaminergic polymorphic ventricular tachycardia, short QT syndrome, and early repolarization syndrome. This article reviews the clinical electrophysiological management of PMVT/VF in a structurally normal heart affected with these disorders.

Intermittent drivers anchoring to structural heterogeneities as a major pathophysiological mechanism of human persistent atrial fibrillation.

The mechanisms responsible for perpetuation of human persistent atrial fibrillation (AF) are controversial and probably vary between individuals. A wide spectrum of mechanisms have been described in experimental studies, ranging from a single localized stable (focal/reentrant) source, to multiple sources, up to diffuse bi-atrial wavelets. We characterized AF drivers in patients with persistent AF (lasting less than 1 year) using novel high resolution mapping, imaging and modelling approaches with the objective of evaluating their relationship to atrial structural heterogeneities. Using panoramic non-invasive mapping in humans, focal or reentrant sources driving AF waves were identified, originating from multiple distinct regions and exhibiting short lifespans and periodic recurrences in the same locations. The reentrant driver regions harboured long, fractionated electrograms covering most of the fibrillatory cycle lengths with varying beat-to-beat sequences suggestive of unstable trajectories attached to slow conducting heterogeneous tissue. MRI atrial imaging demonstrated that such drivers preferentially clustered at the borders of fibrotic atrial regions. In patient-specific computer simulations, sustained AF was shown to be driven by meandering transitory reentries attached to fibrosis borders expressing specific metrics in density and extent. Finally, random microstructural alterations devoid of cellular electrical changes were modelled, showing that a percolation mechanism could also explain atrial reentries and complex fractionated electrograms. These data from clinical, imaging and computational studies strongly suggest that intermittent and spatially unstable drivers anchoring to structural heterogeneities are a major pathophysiological mechanism in human persistent atrial fibrillation.

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.

Non-invasive cardiac mapping in clinical practice: Application to the ablation of cardiac arrhythmias.

Ten years ago, electrocardiographic imaging (ECGI) started to demonstrate its efficiency in clinical settings. The initial application to localize focal ventricular arrhythmias such as ventricular premature beats was probably the easiest to challenge and validates the concept. Our clinical experience in using this non-invasive mapping technique to identify the sources of electrical disorders and guide catheter ablation of atrial arrhythmias (premature atrial beat, atrial tachycardia, atrial fibrillation), ventricular arrhythmias (premature ventricular beats) and ventricular pre-excitation (Wolff-Parkinson-White syndrome) is described here.

Focal Arrhythmia Ablation Determined by High-Resolution Noninvasive Maps: Multicenter Feasibility Study.

INTRODUCTION: A noninvasive 3D mapping technique (ECVUE™, CardioInsight Inc., Cleveland) maps the origin and mechanisms of various arrhythmias without catheterizing the heart. METHODS: Thirty-three patients (3 centers, mean 45.0 ± 14.6 years,) with symptomatic premature ventricular complexes (24 PVCs), focal atrial tachycardias (2 ATs), and manifest accessory pathways (7 WPW syndromes) were prospectively explored using 3D, noninvasive bedside electrocardiomapping. The location of origin of the focal arrhythmia was first determined using noninvasive mapping. Subsequently, a stimulus artifact was delivered at this site to confirm and evaluate the precise location of the mapped focal origin. The procedural parameters and clinical efficacy were studied. RESULTS: Ablation was successful in 32/33 (97%) patients (PVCs: 13 right, 10 left, 1 septal; WPW: 3 left, 3 right; ATs: 2 left) without complications. The time from catheterization to permanent arrhythmia elimination/termination, RF duration, skin-to-skin procedural duration, and fluoroscopic exposure were median 16, 3.98, 71, and 11.9 minutes (for n = 29), respectively. At mean 24.7 ± 3.7 months of follow-up, 31 patients remain arrhythmia-free after a single procedure. One patient (right WPW syndrome) required repeat ablation 1 month later. One patient had recurrence of PVCs and is now deceased. The cumulative radiation (CT scan and fluoroscopy) exposure was median 7.57 mSv. CONCLUSION: ECVUE(TM) is a noninvasive tool allowing rapid preprocedural localization of focal arrhythmia and enables the electrophysiologist with highly specific information to direct RF delivery at the source of the arrhythmia with minimal intracardiac mapping.

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.

Recurrent spontaneous clinical perimitral atrial tachycardia in the context of atrial fibrillation ablation.

BACKGROUND: Recurrent perimitral atrial tachycardia (AT) is a challenging arrhythmia and is frequently encountered in the context of atrial fibrillation (AF) ablation. OBJECTIVE: The purpose of this study was to investigate the clinical characteristics and the procedural and clinical outcomes in patients with recurrent perimitral atrial tachycardia (PMAT) after AF ablation. METHODS: Among 520 consecutive ablation procedures for recurrent AT/AF after AF ablation, 40 procedures (patients) were performed for clinically recurrent PMAT 12.1 ± 13.6 months after the last procedure (total 2.2 ± 1.3 procedures). Previously, mitral isthmus (MI) linear ablation was performed in 26 of 40 procedures, including 13 procedures with complete block and 13 with 159.0 ± 23.0 ms of conduction delay without block. As a reference group, conduction delay was evaluated in 55 patients with incomplete MI block and absence of spontaneous PMAT during the follow-up period. RESULTS: Recurrent PMATs were terminated by MI linear ablation in 26 of 40 patients. Bidirectional block across the MI and anterior line joining the mitral annulus and left atrial roof was achieved in 33 (82.5%) and 2 (5%) patients, respectively. At mean follow-up of 26.7 ± 14.5 months, 2 patients (5%) underwent reablation for spontaneously recurrent PMAT. At 12 months after the ablation procedure for PMAT, 73.5% of the patients were free from AT/AF. Conduction delay >149 ms predicted the occurrence of spontaneous PMAT with 80.0% sensitivity and 87.3% specificity. CONCLUSION: PMAT can recur even after successful bidirectional MI linear block. Substantial conduction delay without block across the MI from a previous procedure(s) could predispose to recurrent PMAT. Although most clinical PMATs can be successfully treated by catheter ablation, very late recurrence is possible.

Body Surface Mapping to Guide Atrial Fibrillation Ablation.

Atrial fibrillation (AF) is the most common rhythm disorder, and is strongly associated with thromboembolic events and heart failure. Over the past decade, catheter ablation of AF has advanced considerably with progressive improvement in success rates. However, interventional treatment is still challenging, especially for persistent and long-standing persistent AF. Recently, AF analysis using a non-invasive body surface mapping technique has been shown to identify localised reentrant and focal sources, which play an important role in driving and perpetuating AF. Non-invasive mapping-guided ablation has also been reported to be effective for persistent AF. In this review, we describe new clinical insights obtained from non-invasive mapping of persistent AF to guide catheter ablation.

Five-year outcome of catheter ablation of persistent atrial fibrillation using termination of atrial fibrillation as a procedural endpoint.

BACKGROUND: This study aimed to determine 5-year efficacy of catheter ablation for persistent atrial fibrillation (AF) using AF termination as a procedural end point. METHODS AND RESULTS: One hundred fifty patients (57±10 years) underwent persistent AF ablation using a stepwise ablation approach (pulmonary vein isolation, electrogram-guided, and linear ablation) with the desired procedural end point being AF termination. Repeat ablation was performed for recurrent AF or atrial tachycardia. AF was terminated by ablation in 120 patients (80%). Arrhythmia-free survival rates after a single procedure were 35.3%±3.9%, 28.0%±3.7%, and 16.8%±3.2% at 1, 2, and 5 years, respectively. Arrhythmia-free survival rates after the last procedure (mean 2.1±1.0 procedures) were 89.7%±2.5%, 79.8%±3.4%, and 62.9%±4.5%, at 1, 2, and 5 years, respectively. During a median follow-up of 58 (interquartile range, 43-73) months after the last ablation procedure, 97 of 150 (64.7%) patients remained in sinus rhythm without antiarrhythmic drugs. Another 14 (9.3%) patients maintained sinus rhythm after reinitiation of antiarrhythmic drugs, and an additional 15 (10.0%) patients regressed to paroxysmal recurrences only. Failure to terminate AF during the index procedure (hazard ratio 3.831; 95% confidence interval, 2.070-7.143; P<0.001), left atrial diameter≥50 mm (hazard ratio 2.083; 95% confidence interval, 1.078-4.016; P=0.03), continuous AF duration≥18 months (hazard ratio 1.984; 95% confidence interval, 1.024-3.846; P<0.04), and structural heart disease (hazard ratio 1.874; 95% confidence interval, 1.037-3.388; P=0.04) predicted arrhythmia recurrence. CONCLUSIONS: In patients with persistent AF, an ablation strategy aiming at AF termination is associated with freedom from arrhythmia recurrence in the majority of patients over a 5-year follow-up period. Procedural AF nontermination and specific baseline factors predict long-term outcome after ablation.

Contemporary challenges of catheter ablation for atrial fibrillation.

PURPOSE: Catheter ablation of atrial fibrillation (AF) is now one of the most frequently performed ablation procedures, but there are currently 2 important challenges: achieving permanent/durable rather than transient pulmonary vein isolation (PVI) and improving the results of ablation for the wider patient population with persistent AF. METHODS: Recent technical advances in the technique of ablation and the results of clinical trials aimed at achieving more permanent and durable PVI are reviewed. We also summarize recent advances in identifying atrial fibrosis and in understanding the pathophysiology of AF relevant to selecting patients for ablation of persistent AF. FINDINGS: The use of contact force-sensing technology, adenosine testing after ablation, and pace capture-guided ablation all have the potential for achieving more durable ablation. Selection of patients suitable for ablation of persistent AF may be improved by assessing the extent of atrial fibrosis with delayed enhancement imaging with cardiac magnetic resonance or by assessing the pattern of atrial electrical activity with the use of complex atrial electrograms. Advances in treatment are likely to result from the recognition of localized rotors and focal sources as primary sustaining mechanisms for all types of human AF and in the use of noninvasive mapping for their identification. Linear ablation to supplement PVI may improve the results of AF ablation. IMPLICATIONS: Rapidly unfolding advances in the techniques of AF ablation and the understanding of mechanisms of AF hold promise for improving the durability of PVI and for extending the technique to carefully selected patients with persistent AF.

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.

Diagnostic value of isoproterenol testing in arrhythmogenic right ventricular cardiomyopathy.

BACKGROUND: Although the Task Force Criteria for arrhythmogenic right ventricular cardiomyopathy (ARVC) have recently been updated, the diagnosis remains challenging in the early stages. The aim of this study was to evaluate the diagnostic value of ß-adrenergic stimulation in ARVC. METHODS AND RESULTS: We evaluated 412 consecutive patients (213 men, age 41.5±16 years) referred for premature ventricular contractions evaluation or suspected ARVC. Isoproterenol testing was performed with continuous infusion of isoproterenol (45 µg/min) for 3 minutes. It was considered positive if there were either (1) polymorphic premature ventricular contractions with ≥1 couplet or (2) sustained or nonsustained ventricular tachycardia with left bundle branch block excluding right ventricular outflow tract ventricular tachycardia. ARVC was diagnosed in 35 patients at initial evaluation (23 men, aged 42±15 years). Isoproterenol testing was positive in 32 of 35 (91.4%) patients with ARVC and in 42 of 377 (11.1%) patients without ARVC (P<0.0001). Sensitivity, specificity, positive, and negative predictive values of isoproterenol testing to diagnose ARVC were 91.4%, 88.9%, 43.2%, and 99.1%, respectively. During a mean follow-up period of 5.6±4.4 years, 6 additional patients met diagnostic criteria for ARVC. Importantly, initial isoproterenol testing was positive in 6 of 6 (100%) of these patients. Survival free from ARVC diagnosis was significantly lower in the positive isoproterenol group than in the negative isoproterenol group (P<0.0001, exact log-rank test). CONCLUSIONS: Ventricular arrhythmogenicity during isoproterenol testing is highly sensitive (sensitivity, 91.4%) for the diagnosis of ARVC, particularly in its early stages.

Pulmonary veins to left atrium cycle length gradient predicts procedural and clinical outcomes of persistent atrial fibrillation ablation.

BACKGROUND: Rapid pulmonary vein (PV) activity has been shown to maintain paroxysmal atrial fibrillation (AF). We evaluated in persistent AF the cycle length (CL) gradient between PVs and the left atrium (LA) in an attempt to identify the subset of patients where PVs play an important role. METHODS AND RESULTS: Ninety-seven consecutive patients undergoing first ablation for persistent AF were studied. For each PV, the CL of the fastest activation was assessed over 1 minute (PVfast) using Lasso recordings. The PV to LA CL gradient was quantified by the ratio of PVfast to LA appendage (LAA) AF CL. Stepwise ablation terminated AF in 73 patients (75%). In the AF termination group, the PVfast CL was much shorter than the LAA CL resulting in lower PVfast/LAA ratios compared with the nontermination group (71±10% versus 92±7%; P<0.001). Within the termination group, PVfast/LAA ratios were notably lower if AF terminated after PV isolation or limited adjunctive substrate ablation compared with patients who required moderate or extensive ablation (63±6% versus 75±8%; P<0.001). PVfast/LAA ratio <69% predicted AF termination after PV isolation or limited substrate ablation with 74% positive predictive value and 95% negative predictive value. After a mean follow-up of 29±17 months, freedom from arrhythmia recurrence off-antiarrhythmic drugs was achieved in most patients with PVfast/LAA ratios <69% as opposed to the remaining population (80% versus 43%; P<0.001). CONCLUSIONS: The PV to LA CL gradient may identify the subset of patients in whom persistent AF is likely to terminate after PV isolation or limited substrate ablation and better long-term outcomes are achieved.

Non Invasive ECG Mapping To Guide Catheter Ablation.

Since more than 100 years, 12-lead electrocardiography (ECG) is the standard-of-care tool, which involves measuring electrical potentials from limited sites on the body surface to diagnose cardiac disorder, its possible mechanism and the likely site of origin. Several decades of research has led to the development of a 252-lead-ECG and CT-scan based, three dimensional, electro-imaging modality to non-invasively map abnormal cardiac rhythms including fibrillation. These maps provide guidance towards ablative therapy and thereby help advance the management of complex heart rhythm disorders. Here, we describe the clinical experience obtained using non-invasive technique in mapping the electrical disorder and guide the catheter ablation of atrial arrhythmias (premature atrial beat, atrial tachycardia, atrial fibrillation), ventricular arrhythmias (premature ventricular beats) and ventricular pre-excitation (Wolff-Parkinson-White syndrome).