Fragmented Electrograms Research Articles

Ultra-high density mapping and ablation of localized microreentrant tachycardias: insight from the CHARISMA registry

Abstract Background The optimal criteria for distinguishing microreentrant atrial tachycardias (mAT) from macroreentrant atrial arrhythmias (MAT) in clinical practice have not been definitively established. Recent advancements in ultra-high-density mapping featuring automated functionalities, has enhanced our understanding of mAT circuits and the precise localization of foci. Purpose Our intent was to observe the diagnostic support provided by high density mapping and Lumipoint algorithm in mAT as well as the ablation outcomes. Methods Consecutive patients eligible for atrial tachycardia (AT) ablation in 22 Italian centres were prospectively enrolled. all ATs were comprehensively mapped in either the left or right atrium utilizing the Rhythmia mapping system and the 64-pole Orion basket catheter. A mAT was defined as an AT characterized by slow, continuous, low fragmented potentials covering a minimum of 50% of the tachycardia cycle length (CL) within a confined area (defined as a circuit within < 1 cm2), enclosed by a couple of closed splines of the Orion catheter, and exhibiting a centrifugal activation pattern to the rest of the atria. The Lumipoint tool was systematically employed to confirm electrogram fragmentation within this defined area. Results Among 159 ATs analysed, 97 (61.0%) were identified as MAT, 50 (31.4%) as focal atrial tachycardias and 12 (7.5%) as mAT. Of these latter, 6 patients (50%) had a previous history of atrial ablation procedure. Concerning the mAT group, the predominant origin site was the left atrium (10 mAT, 83,3%); the targeted activity was localized in the anterior wall in 4 cases (33.3%), in proximity to PVs in 3 cases (25%), along the left ridge in 2 cases (16.6%) and at the roof in 1 case (8,3%). In the remaining right mAT, the foci were found in the free wall and along the CTI in 1 case (8.3% each). The electrical activity spanning the whole CL was detected by 2.7±1.8 pairs of close bipoles of the Orion catheter, was confined to a region of 0.36±0.3cm2 with the longest component of fractionated EGM per spline equal to 64.7±17% of the CL. Low voltage areas (<0.1 mV) were detected in all mAT cases and colocalized with the origin site. Voltage level was 0.2±0.1mV at the site of longest duration of the fragmented potential. A single shot RF delivery terminated each arrhythmia at targeted location. Consolidative RF ablations were then delivered in the adjacent area. Over a median of 288 [248-349] days of follow-up, 5 (3.1%) patients suffered from an AT/AF arrhythmia recurrence and of these, 3 (3.1%) were in the MAT group, 1 (2%) in the focal AT and 1 (8.3%) in the mAT group. No complications were observed. Conclusions A novel automated algorithm for microreentrant atrial tachycardia identification, coupled with the identification of matched areas of electrogram fractionation by the Orion catheter, may restrict the extent of required ablation and result in a low arrhythmia recurrence.

Distinct Electrogram Features and Ventricular Arrhythmia Induction Modes Between Repolarization and Conduction Heterogeneities

BackgroundRecent clinical studies have indicated the presence of localized electrical abnormalities in idiopathic ventricular fibrillation and J-wave syndrome patients. ObjectivesThis study aims to characterize the specific electrical signatures of localized repolarization and conduction heterogeneities and their respective role in vulnerability to arrhythmias. MethodsOptical mapping was performed in porcine right ventricles with local: 1) repolarization shortening; 2) conduction slowing; or 3) structural heterogeneity induced by locally perfusing: 1) pinacidil (20 μmol/L, n = 13); or 2) flecainide (2 μmol/L, n = 13) via an epicardial catheter; or 3) by local epicardial tissue destruction (9 radiofrequency lesions n = 12). Electrograms were recorded (n = 5 in each group) and spontaneous and induced arrhythmias were quantified and optically mapped. ResultsElectrograms were normal in (1) but showed local fragmentation in 40% of preparations in (2) with greater effects observed at high pacing frequencies dependent on the wavefront direction. In (3), the structural substrate alone increased the width and number of peaks in the electrograms, and addition of flecainide induced pronounced fragmentation (≥3 peaks and ≥70 ms) in all cases. Occurrence of spontaneous arrhythmias was significantly increased in (1) and (2) (P < 0.0001 and 0.05, respectively, vs baseline) and were triggered by ectopies. Vulnerability to arrhythmias at high pacing frequencies (≥2 Hz) was the lowest in (1) and greatest in (2). ConclusionsMicrostructural substrates have the most pronounced impact on electrograms, especially when combined with sodium channel blockers, whereas local action potential duration shortening does not lead to electrogram fragmentation even though it is associated with the highest prevalence of spontaneous arrhythmias.

Targeting confluent areas of slow conduction and electrogram fragmentation for atrioventricular node re-entrant tachycardia ablation.

Targeting confluent areas of slow conduction and electrogram fragmentation for atrioventricular node re-entrant tachycardia ablation.

Association between the number of altered late potential criteria and increased arrhythmic risk in Brugada syndrome patients.

Brugada syndrome (BrS) is associated with abnormal electrophysiological properties at right ventricular epicardium, consisting of fragmented electrograms extending well beyond QRS termination. We aimed to evaluate the utility of signal-averaged electrocardiogram (SA-ECG) for the noninvasive assessment of late potentials (LP) and risk stratification of BrS patients. A prospective, observational, single-center study of BrS patients is submitted to SA-ECG with the determination of the total filtered QRS duration (fQRS), root mean square voltage of the 40ms terminal portion of the QRS (RMS40), and duration of the low-amplitude electric potential component of the terminal portion of the QRS (LAS40). LP were considered positive when above standard cut-offs: fQRS > 114ms, RMS40 < 20µV, and LAS40 > 38ms. The rates of malignant arrhythmic events (MAEs), defined as sudden death or appropriate shocks, were compared in relation to clinical characteristics and SA-ECG findings. A total of 106 BrS patients (mean age, 48 ± 12years, 67.9% male) were studied, 49% with type-1 spontaneous pattern and 81% asymptomatic. During a median follow up of 4.7years, 10 patients (7.1%) suffered MAEs, including 4 sudden deaths. The presence of LP was significantly associated with the arrhythmic risk, which increased with the number of altered LP criteria. In comparison to the patients who had none or 1 altered LP criterium, MAE risk was 4.7 times higher in those with 2 altered criteria and 9.4 times higher in those with 3 altered LP criteria. SA-ECG may be a useful tool for risk stratification in BrS. The presence of 2 or 3 abnormal LP criteria could identify a subset of asymptomatic patients at high risk of arrhythmic events.

Functional mapping to reveal slow conduction and substrate progression in atrial fibrillation.

The aim of our study was to analyse the response to short-coupled atrial extrastimuli to identify areas of hidden slow conduction (HSC) and their relationship with the atrial fibrillation (AF) phenotype. Twenty consecutive patients with paroxysmal AF and persistent AF (10:10) underwent the first pulmonary vein isolation procedure. Triple short-coupled extrastimuli were delivered in sinus rhythm (SR), and the evoked response was analysed: sites exhibiting double or highly fragmented electrograms (EGM) were defined as positive for HSC (HSC+). The delta of the duration of the bipolar EGM was analysed, and bipolar EGM duration maps were built. High-density maps were acquired using a multipolar catheter during AF, SR, and paced rhythm. Spatial co-localization of HSC+ and complex fractionated atrial EGMs (CFAE) during AF was evaluated. Persistent AF showed a higher number and percentage of HSC+ than paroxysmal AF (13.9% vs. 3.3%, P < 0.001). The delta of EGM duration was 53 ± 22 ms for HSC+ compared with 13 ± 11 (10) ms in sites with negative HSC (HSC-) (P < 0.001). The number and density of HSC+ were lower than CFAE during AF (19 vs. 56 per map, P < 0.001). The reproducibility and distribution of HSC+ in repeated maps were superior to CFAE (P = 0.19 vs. P < 0.001). Sites with negative and positive responses showed a similar bipolar voltage in the preceding sinus beat (1.65 ± 1.34 and 1.48 ± 1.47 mV, P = 0.12). Functional mapping identifies more discrete and reproducible abnormal substrates than mapping during AF. The HSC+ sites in response to triple extrastimuli are more frequent in persistent AF than in paroxysmal AF.

Triggers of Ventricular Fibrillation in Patients With Inferolateral J-Wave Syndrome

BackgroundThere are few data on ventricular fibrillation (VF) initiation in patients with inferolateral J waves. ObjectivesThis multicenter study investigated the characteristics of triggers initiating spontaneous VF in inferolateral J-wave syndrome. MethodsA total of 31 patients (age 37 ± 14 years, 24 male) with spontaneous VF episodes associated with inferolateral J waves were evaluated to determine the origin and characteristics of triggers. The J-wave pattern was recorded in inferior leads in 11 patients, lateral leads in 3, and inferolateral leads in 17. ResultsThe VF triggers (n = 37) exhibited varying QRS durations (176 ± 21 milliseconds, range 119-219 milliseconds) and coupling intervals (339 ± 46 milliseconds, range 250-508 milliseconds) with a right (70%) or left (30%) bundle branch block (BBB) pattern. Trigger patterns were associated with J-wave location: left BBB triggers with inferior J waves and right BBB triggers with lateral J waves. Electrophysiologic study was performed for 22 VF triggers in 19 patients. They originated from the left or right Purkinje system in 6 and from the ventricular myocardium in 10 and were undetermined in 6. Purkinje vs myocardial triggers showed distinct electrocardiographic characteristics in coupling interval and QRS-complex duration and morphology. Abnormal epicardial substrate associated with fragmented electrograms was identified in 9 patients, with triggers originating from the same region in 7 patients. Catheter ablation resulted in VF suppression in 15 patients (79%). ConclusionsVF initiation in inferolateral J-wave syndrome is associated with significant individual heterogeneity in trigger characteristics. Myocardial triggers have electrocardiographic features distinct from Purkinje triggers, and their origin often colocalizes with an abnormal epicardial substrate.

Arrhythmogenic substrate elimination for safe testosterone therapy in symptomatic Brugada syndrome patients.

Brugada Syndrome (BrS) is a cardiogenetic disease known for its association with sudden cardiac death (SCD) in individuals with structurally normal hearts. The prevalence of BrS is higher in males, who also face a greater risk of SCD. Its higher prevalence and worse outcome in male subjects may be due to testosterone effects on ion channels expression and function. The influence of testosterone on cardiac action potentials, both genomically and non-genomically, underscores its potential role in unmasking the syndrome and triggering life-threatening arrhythmias. Notably, testosterone replacement therapy (TRT), used for hypogonadism and gender reassignment, has been linked to BrS unmasking. The role of epicardial ablation in symptomatic BrS patients where hormonal therapy cannot be discontinued is unknown. In this study we describe the first two cases of substrate mapping and ablation in BrS patients experiencing arrhythmic events while on TRT. In both cases, high-density epicardial mapping revealed abnormal areas of prolonged and fragmented electrograms in the right ventricular (RV) outflow tract and anterior wall. These abnormalities were completely abolished by radiofrequency ablation (RFA). After ablation, both patients showed a persistent normalization of the ECG and were free from ventricular arrhythmias at follow-up, despite ongoing TRT. RFA can be considered as a therapeutic option in symptomatic BrS patients with a high-risk profile who cannot discontinue TRT, being essential for restoring their normal physiology or preserving their sexual identity. As testosterone use is increasing, further studies are warranted to define a standardized diagnostic and therapeutic strategy in this specific subset of BrS patients.

Left Ventricular Abnormal Substrate in Brugada Syndrome

BackgroundSlow-conductive structural abnormalities located in the epicardium of the right ventricle (RV) underlie Brugada syndrome (BrS). The extent of such substrate in the left ventricle (LV) has not been investigated. ObjectivesThis study sought to characterize the extent of epicardial substrate abnormalities in BrS. MethodsWe evaluated 22 consecutive patients (mean age 46 ± 11 years, 21 male) referred for recurrent ventricular arrhythmias (mean 10 ± 13 episodes) in the setting of BrS. The patients underwent clinical investigations and wide genetic screening to identify SCN5A mutations and common risk variants. High-density biventricular epicardial mapping was performed to detect prolonged (>70 ms) fragmented electrograms, indicating abnormal substrate area. ResultsAll patients presented with abnormal substrate in the epicardial anterior RV (27 ± 11 cm2). Abnormal substrate was also identified on the LV epicardium in 10 patients (45%), 9 at baseline and 1 after ajmaline infusion, covering 15 ± 11 cm2. Of these, 4 had severe LV fascicular blocks. Patients with LV substrate had a longer history of arrhythmia (11.4 ± 6.7 years vs 4.3 ± 4.3 years; P = 0.003), longer PR (217 ± 24 ms vs 171 ± 14 ms; P < 0.001) and HV (60 ± 12 ms vs 46 ± 5 ms; P = 0.005) intervals, and abnormal substrate also extending into the inferior RV (100% vs 33%; P = 0.001). SCN5A mutation was present in 70% of patients with LV substrate (vs 25%; P = 0.035). SCN5A BrS patients with recurrent ventricular arrhythmias present a higher polygenic risk score compared with a nonselected BrS population (median of differences: −0.86; 95% CI: −1.48 to −0.27; P = 0.02). ConclusionsA subset of patients with BrS present an abnormal substrate extending onto the LV epicardium and inferior RV that is associated with SCN5A mutations and multigenic variants.

Identification of atrial complex electrograms by short-coupled extrastimuli in paroxysmal and persistent atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): - Health Council of the Andalusian Regional Government through the project "PI-0057-2017". - European Regional Development Fund/European Social Fund. Introduction Electrogram fractionation during atrial fibrillation (AF) and sinus rhythm have been studied as marker of atrial remodeling and potential target for ablation. Objective The aim of our study was to analyze the response to closely coupled atrial extrastimuli and try to identify areas of hidden slow conduction (HSC) that can promote reentry and AF maintenance in paroxysmal and persistent AF. Methods Twenty consecutive patients with paroxysmal AF and persistent AF (10:10) underwent first PVI procedure. During sinus rhythm triple short coupled extrastimuli was delivered. Locations showing double or highly fragmented electrograms in response to triple extrastimuli were defined as positive electrogram (HSC-EGM) (Figure 1). Increase in duration (delta) of the bipolar EGM was recorded. Two consecutive high-density maps were acquired using a multipolar catheter during AF, sinus and paced rhythms. Spatial correlation of HSC-EGM and complex atrial fractionation (CFAEs) during AF were evaluated. Results Patients with persistent AF showed a higher number and percentage of HSC-EGM than paroxysmal AF (13,9% vs 3,3%, p&amp;lt;0.001) (Figure 2). Delta of EGM duration was 53 ± 22 ms compared to 16 ± 14 ms in sites with a negative response (p&amp;lt;0.001). The number of HSC-EGM distinguished with extrastimuli was lower than that of CFAEs during AF (19 vs 56 per map, p&amp;lt;0.01). The reproducibility of the extension and distribution of HSC-EGM in the repeated maps was superior to that of the CFAEs. The distribution of the HSC-EGM was comparable with those found in the initial map (p=0,32), however, there were significant differences in the distribution of CFAEs between the first map and the remap (p=0.003). Conclusion HSC-EGM in response to triple extrastimuli are more frequent in persistent AF. This type of evoked response could reveal the presence of slow conduction areas and could be considered a potential target for ablation of persistent atrial fibrillation. More studies are needed to confirm this hypothesis.

Role of localized repolarization and conduction heterogeneities in ventricular arrhythmias and sudden cardiac death

Recent clinical studies have indicated the presence of localized tissue abnormalities in sudden cardiac death (SCD) survivors without apparent structural heart disease, including idiopathic ventricular fibrillation (VF) and J-wave Syndromes. The origin of these abnormalities, showing distinct electrical features on contact mapping, and mechanisms of associated arrhythmias are still a matter of debate. To determine the respective role of localized repolarization and conduction heterogeneities in vulnerability to arrhythmias and SCD, and to characterize their specific electrical signatures. Optical mapping was performed on porcine right ventricular models of either local (i) repolarization shortening, (ii) conduction slowing, or (iii) micro-structural heterogeneity which were created by locally perfusing (i) pinacidil (20 μM n = 13) or (ii) flecainide (2 μM n = 13) via an epicardial catheter (branch of right coronary artery), or (iii) by local epicardial tissue destruction through radiofrequency application (9 micro lesions 30W 1 sec n = 13). Pseudo-ECG were assessed and the number of induced and spontaneous arrhythmias were quantified and mapped in each preparation. An HD grid mapping catheter was used to record bipolar electrograms (n = 5 in each group). Electrograms were normal in model (i), but showed local fragmentation in 40% of preparations in model (ii) with greater effects observed at high pacing frequencies (3 Hz). In model (iii), the structural substrate alone increased the width and number of peaks in the electrograms, and addition of flecainide (2 μM) in this model induced pronounced fragmentation (≥ 3 peaks and ≥ 70ms duration) in 100% of the cases. Arrhythmogenicity was significantly increased in models (i) and (ii) which presented 82% and 45% more spontaneous arrhythmias (P < 0.0001 and 0.05 vs. baseline) and a reduced pacing frequency threshold to induce arrhythmias (−69% and −50%, P < 0.001 vs. baseline). In these models, the frequency of spontaneous activity was increased (+411% P < 0.01 and +181% P < 0.05 vs. baseline) and originated near the heterogeneous area. Microstructural substrates have the most pronounced impact on electrograms, especially when combined with sodium channel blockers, while repolarization heterogeneities do not lead to electrogram fragmentation but are associated with the highest prevalence of spontaneous arrhythmias. Both heterogeneities show increased ectopic activity.

Electrophysiological characteristics and long-term outcome of substrate-based catheter ablation for left posterior fascicular ventricular tachycardia targeting fragmented antegrade Purkinje potentials during sinus rhythm.

The aim of this study was to investigate the electrophysiological characteristics and long-term outcome of patients undergoing substrate-based ablation of left posterior fascicular ventricular tachycardia (LPF-VT) guided by targeting of fragmented antegrade Purkinje potentials (FAPs) during sinus rhythm. This study retrospectively analysed 50 consecutive patients referred for ablation. Substrate mapping during sinus rhythm was performed to identify the FAP that was targeted by ablation. FAPs were recorded in 48 of 50 (96%) patients during sinus rhythm. The distribution of FAPs was located at the proximal segment of posterior septal left ventricle (LV) in two (4.2%) patients, middle segment in 33 (68.8%) patients, and distal segment in 13 (27.1%) patients. In 32 of 48 (66.7%) patients, the FAP displayed a continuous multicomponent fragmented electrogram, while a fragmented, split, and uncoupled electrogram was recorded in 16 (33.3%) patients. Entrainment attempts at FAP region were performed successfully in seven patients, demonstrating concealed fusion and the critical isthmus of LPF-VT. Catheter ablation targeting at the FAPs successfully terminated the LPF-VT in all 48 patients in whom they were seen. Left posterior fascicular (LPF) block occurred in four (8%) patients after ablation. During a median follow-up period of 61.2 ± 16.8 months, 47 of 50 (94%) patients remained free from recurrent LPF-VT. Ablation of LPF-VT targeting FAP during sinus rhythm results in excellent long-term clinical outcome. FAPs were commonly located at the middle segment of posterior septal LV. Region with FAPs during sinus rhythm was predictive of critical site for re-entry.

Automatic identification of areas with low-voltage fragmented electrograms for the detection of the critical isthmus of atypical atrial flutters.

Critical isthmuses of atypical atrial flutters (AAFLs) are usually located at slow conduction areas that exhibit fractionated electrograms. We tested a novel software, intended for integration with a commercially available navigation system, that automatically detects fractionated electrograms, to identify the critical isthmus in patients with AAFL ablation. All available patients were analyzed; 27 patients with 33 AAFLs were included. The PentaRay NAV catheter (Biosense Webster) was used for mapping. The novel software was retrospectively applied; fractionated points with duration ≥80 ms and bipolar voltage between 0.05 and 0.5 mV were highlighted on the surface of maps. In 10 randomly chosen AAFLs, an expert electrophysiologist evaluated the positive predictive value of the algorithm to detect true fractionation: 74.4%. We tested the capacity of the software to identify areas of fractionation (defined as clusters of ≥3 adjacent points with fractionation) at the critical isthmus of the AAFLs (defined using conventional mapping criteria). An area of fractionation was identified at the critical isthmus in 30 cases (91%). Globally, 144 areas of fractionation (median number per AAFL 4 [3-6]) were identified. Duration of the fractionation or the surface of the areas was not different between areas at critical isthmuses and the rest. Setting the fractionation score filter of the software in nine provided best performance. The novel software detected areas of fractionation at the critical isthmus in most AAFLs, which may help identify the critical isthmus in clinical practice.

Combined Use of Voltage Mapping and Speckle-tracking Analysis for the Characterization of Arrhythmogenic Right Ventricular Cardiomyopathy: A Case Report

A 38-year-old man was admitted to our hospital after ventricular tachycardia. Endocardial bipolar and unipolar voltage mapping were performed and findings were integrated with data from intracardiac echocardiography (ICE) right ventricular (RV) speckle-tracking analysis. A reduction in the strain analysis was stored in correspondence of the fragmented electrogram area. The definitive diagnosis was arrhythmogenic RV cardiomyopathy (ARVC). The integration of ICE-derived RV strain and voltage mapping could represent a successful strategy to improve the results of ablation in ARVC.

94 Combined use of voltage mapping and speckle tracking echocardiography for the early diagnosis of ARVC/D: a case report

Abstract A 38 years-old man was admitted to our hospital after ventricular tachycardia with left-bundle-branch block and inferior axis morphology. After undergoing different examinations the criteria for the diagnosis of arrhythmogenic right ventricular cardiomyopathy (ARVC) were met. An electrophysiological study was then performed together with endocardial bipolar and unipolar voltage map. Unipolar and bipolar voltage mapping of the right ventricle showed low voltage areas and corresponding fragmented potentials from the tricuspid annulus to the inferior apex. On the right ventricular outer tract (RVOT), the bipolar voltage mapping was normal while the unipolar mapping showed low-voltage areas in the antero-septal outer tract. An off-line map was used to perform speckle tracking analysis on intracardiac echocardiography (ICE) clips of right ventricle and standard echocardiography. A reduction of the strain analysis was stored in correspondence of the fragmented electrograms area, in particular, speckle tracking analysis on ICE views showed a reduction of the RV LS in the segments below tricuspid valve, in the three different myocardial layers. The endocardial longitudinal strain was reduced from sub-tricuspidalic segments to the RV apex in accordance with the fragmentated potentials stored during voltage mapping. On the contrary, at anterior RVOT wall, the unipolar voltage mapping showed fragmented potentials and the STE analysis revealed a reduced epicardial LS. This case report lays emphasis on the importance of the integration of ICE-derived right ventricular strain and voltage mapping in the improvement of the sensibility of an early diagnosis of the ARVC.

Procedural and short-term results of electroanatomic-mapping-guided ganglionated plexus ablation by first-time operators: A multicenter study.

Single-center observational studies have shown promising results with fragmented electrogram (FE)-guided ganglionated plexus (GP) ablation in patients with vagally mediated bradyarrhythmia (VMB). We aimed to compare the acute procedural characteristics during FE-guided GP ablation in patients with VMB performed by first-time operators and those of a single high-volume operator. This international multicenter cohort study included data collected over 2 years from 16 cardiac hospitals. The primary operators were classified according to their prior GP ablation experience: a single high-volume operator who had performed > 50 GP ablation procedures (Group 1), and operators performing their first GP ablation cases (Group 2). Acute procedural characteristics and syncope recurrence were compared between groups. Forty-seven consecutive patients with VMB who underwent FE-guided GP ablation were enrolled, n = 31 in Group 1 and n = 16 in Group 2. The mean number of ablation points in each GP was comparable between groups. The ratio of positive vagal response during ablation on the left superior GP was higher in Group 1 (90.3% vs. 62.5%, p = .022). Ablation of the right superior GP increased heart rate acutely without any vagal response in 45 (95.7%) cases. The procedure time was longer in group 2 (83.4 ± 21 vs. 118.0 ± 21 min, respectively, p < .001). Over a mean follow-up duration of 8.0 ± 3 months (range 2-24 months), none of the patients suffered from syncope. This multi-center pilot study shows for the first time the feasibility of FE-guided GP ablation across a large group of procedure-naïve operators.

Risk stratification in patients with Brugada syndrome: the role of the late potentials evaluated by signal-averaged ECG

Abstract Introduction Brugada syndrome (BS) is a relevant cause of sudden death in individuals without structural heart disease. The accuracy of the available methods for risk stratification is very limited and the investigation of new methodologies to improve the identification of patients at risk is under intensive investigation. Recently the pathophysiological relevance of anomalous, fragmented and prolonged electrograms on the epicardial surface of the right ventricular outflow tract (RVOT) has been described. Therefore, the study of signal-averaged ECG (SA-ECG) has become attractive since it may allow the non-invasive evaluation of these electrical anomalies. In order to maximize the detection capacity and to focus the evaluation in the RVOT, we developed an alternative methodology of electrode positioning directed to this area of interest. Purpose To characterize the study of late potentials (LP) by SA-ECG in patients with SB and to evaluate its association with the occurrence of arrhythmia events. Methods Prospective single centre study of patients (pts) with BS. LP were evaluated by SA-ECG with determination of the total filtered QRS duration (fQRS), root mean square voltage of the 40 ms terminal portion of the QRS (RMS40) and duration of the low amplitude electric potential component (40 microV) of the terminal portion of the QRS (LAS40) in conventional and modified leads (addressed to RVOT). The association of LP with the risk of definite malignant dysrhythmias due to sudden death, ventricular fibrillation, ventricular tachycardia or appropriate shock of the implantable cardioverter defibrillator (ICD) was evaluated and the acuity of the prognostic stratification was determined by the area under the receiver operator characteristic curve (ROC). Results A total of 76 pts (69.7% men, age 48±12 years) were studied, of which 33 had a spontaneous type 1 pattern and 43 had a type 1 pattern induced by flecainide. During a median follow-up of 1.6 years, 13 pts (17.1%) had symptoms potentially related to BS and 6 (10.5%) had malignant arrhythmias [including two pts who suffered sudden death (2.6%). The pts who had malignant dysrhythmias presented higher values of fQRS (125±23 vs. 108±18, p=0.046) and LAS40 (54±13 vs. 40±11, p=0.014), and lower values of RMS40 only in the modified leads (11±5 vs. 22±19, p=0.041). The parameters of the SA-ECG were significant prognostic predictors. The acuity of each of the parameteres alone was moderate and the parameters that were identified as more powerful predictors of risk were those derived from the modified leads (Figure). Conclusion The LP evaluated by SA-ECG may be relevant in the prognostic stratification of patients with BS, since it seems to be associated with the risk of malignant ventricular arrhythmias. Funding Acknowledgement Type of funding sources: None.

High-density mapping with fragmentation analysis in patients with reentrant atrial tachycardias (MAP-FLURHY study).

Reentrant atrial tachycardias (ATs) use areas of slow conduction that can be visualized as fragmented electrograms. We aimed to test an ablation strategy based on the identification and ablation of spots with fragmented electrograms in reentrant ATs, using Rhythmia navigation system. All consecutive patients from June 2016 to June 2019 were included. The IntellaMap ORION Catheter was used to detect sites with fragmentation, arbitrarily defined as fragmented electrograms > 70ms. Entrainment was used to check if these areas belonged to the AT circuit. Ablation targeted the longest fragmented electrogram within the circuit: focal ablation for microreentries and lines for macroreentries. Ablation success was defined from each AT as conversion to sinus rhythm or another AT. Twenty-seven consecutive patients with 44 mappable ATs were included. All ATs showed sites with fragmented electrograms (104 sites; 2.4 sites per AT); 43/44 ATs had fragmented electrograms within the circuit, which were the target of ablation. Ablation success: 34/36 ATs (94%); success could not be assessed in 8 circuits, in 6 due to mechanical conversion to sinus rhythm at the target fragmented site. Fragmented electrograms within the AT circuits were longer than electrograms outside the circuits (110 ± 30 vs 90 ± 15ms, p < 0.001). A fragmentation duration > 100ms/ > 40% of the AT cycle length predicted to be a successful site for ablation with 72.3%/73.8% specificity, respectively. Sixty-two percent of the patients were free from atrial arrhythmias at 1year. Most ATs had detectable fragmented electrograms within the circuit, which could be the target of ablation with high efficacy.

Why is neuromodulation effect of pulmonary vein isolation not same in all cases?

Abstract Funding Acknowledgements Type of funding sources: None. Background Cardiac ganglionated plexi (GPs) of the autonomic system are primarily located in major epicardial fat pads adjacent to the left atrium and pulmonary vein junctions. These structures may play a central role in both the initiation and maintenance of atrial fibrillation (AF). Previous studies reported modification of GPs during pulmonary vein isolation (PVI) may increase rate of sinus node and AF-free survival. However, a deficiency certainly existed why is modification of GPs observed in some patients during PVI but not in others? Purpose We aimed to evaluate ratio of ablation points within classical antral circumferential ablation lines for PVI and distribution of 4 major atrial ganglionated plexus. Methods Thirty-eight consecutive patients undergoing ablation of GP for vagally mediated bradyarrhythmias were evaluated. All GP sites were detected by using previously defined fragmented electrogram based strategy which is a validated tool when compared with a combination of spectral analysis and high frequency stimulation to detect GPs. Estimated ablation lines for antral circumferential ablation was defined as a circumferential isolation line performed ≥1 cm away from the pulmonary vein ostium as identified by 3D electroanatomical reconstruction (Figure 1). The total number of ablation points in each GP sites and ratio of ablation points within estimated antral circumferential ablation lines were recorded. Results The great majority of ablation points were detected at the insertion of the right pulmonary veins. Number of ablation points in each GP site in descending order is as follows: (1) the right superior GP = 13.6 ± 6; (2) the left superior GP = 10.5 ± 5; (3) the right inferior GP = 5.9 ± 4; and (4) the left inferior GP = 2.5 ± 3. The ratio of ablation points within estimated antral circumferential ablation lines was higher in right-sided GPs (50.5%±24 for the right superior GP and 30.2%±31 for the right inferior GP vs 18.3%±24 for the left superior GP and 11.6%±26 for the left inferior GP. Figure 2 demonstrates total number of ablation points and the ratio of ablation points within estimated antral circumferential ablation lines in each GP site. Conclusions The present study shows that individual variability of distribution of GPs and how antral ablation was done during PVI might be the main contributors of neuromodulation effect. Further randomized, controlled and multicenter studies should be performed to confirm these findings. Abstract Figure 1

The role of marshall bundle epicardial connections in atrial tachycardias after atrial fibrillation ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background Atrial tachycardias (ATs) are often seen in the context of AF ablation. Objectives We evaluated the role of the Marshall bundle (MB) network in left atrial (LA) ATs using high-density high-spatial resolution 3D mapping. Methods 199 post-AF ablation LA tachycardias were mapped in 140 consecutive patients (112 (80%) males, mean age: 61.8 years); 133 (66.8%) were macro-reentrant and 66 (33.2%) were scar-related re-entry. MB-dependent perimitral AT (PMAT) was diagnosed where the difference between the post pacing interval and the tachycardia cycle length (PPI-TCL) was &amp;lt;20ms in parts of the expected MB-dependent perimitral circuit (within the VOM, the ridge between the left pulmonary veins and LA appendage (LAA), the anterior LA and between 6- and 11-o’clock of the mitral annulus) and the PPI-TCL was &amp;gt;20ms in areas bypassed by the VOM (the distal coronary sinus (CS), the posterior LA and the mitral isthmus). MB-related re-entry was diagnosed by PPI-TCL &amp;lt;20ms at the left lateral ridge, posterior base of LAA, inferolateral LA or VOM ostium; and PPI-TCL &amp;gt;20ms in the septal annulus. Typically, in MB-dependent localized re-entry, the earliest activation was found along the MB-LA endocardial connection or MB-CS epicardial connection. Results The MB network was found to participate in 60 (30.2%) re-entrant ATs, 31 PMATs and 29 localized re-entries. High-frequency multiphasic fragmented electrograms with long duration were often recorded endocardially or epicardially at the MB-LA or MB-CS connections. The amplitude and duration of these signals were 0.5 ± 0.79 mV and 65 ± 40 ms for MB-PMATs and 0.26 ± 0.28mV and 122 ± 67 ms for MB-localized re-entries. Unipolar EGMs at the site of endocardial-epicardial breakthrough had a rS pattern in all MB-related ATs. Of 60 MB-related ATs, 49 (81.6%) terminated with RF ablation, 44 (73.3%) at the MB-LA junction and 5 (8.3%) at the MB-CS junction, while 9 (15%) terminated after 2.5-5 cc of alcohol infusion inside the vein of Marshall (VOM). Of the 31 MB-related macroreentrant ATs, 17 (54.8%) terminated at the MB-LA junction, 5 (16.1%) at the MB-CS junction and 7 (22.6%) with alcohol infusion inside the VOM. Two macroreentries (6.5%) using the MB did not terminate with RF energy either endocardially at the MB-LA junction or epicardially at the MB-CS junction, and we were unable to identify or cannulate the VOM for ethanol infusion. Of the 29 localized re-entrant ATs using the MB, 27 (93.1%) terminated at the MB-LA junction, none terminated at the MB-CS junction and 2 (6.9%) terminated after alcohol infusion. After a mean follow up of 12 months, only 4 patients (6.7%) had AT recurrence. Conclusions MB re-entrant ATs accounted for up to 29% of the left ATs after AF ablation. Ablation of the MB-LA or CS-MB connections or alcohol infusion inside the VOM is required to treat these arrhythmias. Abstract Figure.

Effect of general and local anesthesia on the vagal response characteristics during ganglionated plexus ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background The effect of different anesthetics on the function of the autonomic nervous system (ANS) is not well known. As a relatively new treatment option, ganglionated plexus (GP) ablation aims to modify the behavior of the cardiac ANS to prevent some/all of the autonomic processes occurring in vasovagal syncope (VVS) by using endocardial ablation techniques. Purpose The purpose of this study was to determine the effects midazolam and propofol on the vagal response (VR) characteristics during GP ablation in patients with vasovagal syncope (VVS). Methods Forty consecutive patients undergoing GP ablation for VVS were divided to receive local anesthesia with midazolam (group 1, n = 29) or general anesthesia with propofol (group EA, n = 11). All GP sites were detected by using previously defined fragmented electrogram based strategy. VR was defined on 3 levels: 1) R-R interval increased by 50% (level 1); 2) R-R interval increased by 20-50% (level 2); and 3) R-R interval increase lower than 20% (level 3). Results Baseline characteristics and mean follow-up times were comparable between groups. In both groups, the left superior GP (LSGP) was the most common GP site at which a VR was observed. However, there was a significant difference between groups for level of VR. While ablation on the LSGP caused a level 1 VR in 89.6% of cases in group 1, level 1 VR was seen in 22.2% of cases in group 2 (p &amp;lt; 0.0001). Similarly, ratio of level 1 VR during ablation on the left inferior GP (LIGP) was significantly lower in group 2 (44.8% vs 9%, p = 0.034). Once cut-off for VR was decreased to level 2, the ratio of (+) VR increased to 90.9% during ablation on the LSGP in group 2. Level 2 VR was detected in 45.4% of cases during ablation on the LIGP. Ratio of positive VRs in any level was lower than 20% during ablation on the right superior and inferior GPs in both groups. During a mean follow-up time of 12.1 ± 7 months, all but 2 (5%) of 40 patients were free of syncope. Conclusions The autonomic nervous tone might be affected in different ways by local and general anesthesia. Propofol may reveal a shift in the sympathovagal balance toward sympathetic predominance which may cause a blunting on VR during GP ablation. Further randomized, controlled and multicenter studies should be performed to confirm these findings.