Outcomes after stepwise ablation for persistent atrial fibrillation in patients with heart failure

AbstractBackgroundThere is limited data regarding the outcomes after stepwise ablation for persistent atrial fibrillation (AF) in patients with heart failure (HF).Methods and resultsPatients without structural heart disease undergoing stepwise ablation for persistent AF (continuous AF≤1 year) were studied (n=108; age, 61±10 years) and 32 patients had a history of HF. The HF patients were further grouped on the basis of left ventricular ejection fraction (LVEF)≤45% (n=15) and >45% (n=17). During a median follow-up period of 2.2 years, repeated ablations were necessary in 65 patients. The proportion of patients that were arrhythmia free 1 year after the last ablation was 67% in patients with LVEF≤45%, 86% in LVEF>45%, and 91% in no HF (p=0.0009). In patients with LVEF≤45%, the AF burden was reduced to less than one paroxysmal episode per month, and patients with and without recurrences both showed significant increases in LVEF over the follow-up period (38±7% to 60±10% and 37±6% to 53±10%, respectively).ConclusionsHF patients with LVEF≤45% had lower chances to remain free from arrhythmias after stepwise ablation for persistent AF than those with LVEF>45%. Nevertheless, LVEF also improved in patients with recurrences, reflecting the observed reduction in AF burden and emphasizing the benefits of ablation

Early Repolarization Syndrome: Diagnostic and Therapeutic Approach

An early repolarization pattern can be observed in 1% up to 13% of the overall population. Whereas, this pattern was associated with a benign outcome for many years, several more recent studies demonstrated an association between early repolarization and sudden cardiac death, so-called early repolarization syndrome. In early repolarization syndrome patients, current imbalances between epi- and endo-cardial layers result in dispersion of de- and repolarization. As a consequence, J waves or ST segment elevations can be observed on these patients' surface ECGs as manifestations of those current imbalances. Whereas, an early repolarization pattern is relatively frequently found on surface ECGs in the overall population, the majority of individuals presenting with an early repolarization pattern will remain asymptomatic and the isolated presence of an early repolarization pattern does not require further intervention. The mismatch between frequently found early repolarization patterns in the overall population, low incidences of sudden cardiac deaths related to early repolarization syndrome, but fatal, grave consequences in affected patients remains a clinical challenge. More precise tools for risk stratification and identification of this minority of patients, who will experience events, remain a clinical need. This review summarizes the epidemiologic, pathophysiologic and diagnostic background and presents therapeutic options of early repolarization syndrome

Atrial Fibrillation Mechanisms and Implications for Catheter Ablation

AF is a heterogeneous rhythm disorder that is related to a wide spectrum of etiologies and has broad clinical presentations. Mechanisms underlying AF are complex and remain incompletely understood despite extensive research. They associate interactions between triggers, substrate and modulators including ionic and anatomic remodeling, genetic predisposition and neuro-humoral contributors. The pulmonary veins play a key role in the pathogenesis of AF and their isolation is associated to high rates of AF freedom in patients with paroxysmal AF. However, ablation of persistent AF remains less effective, mainly limited by the difficulty to identify the sources sustaining AF. Many theories were advanced to explain the perpetuation of this form of AF, ranging from a single localized focal and reentrant source to diffuse bi-atrial multiple wavelets. Translating these mechanisms to the clinical practice remains challenging and limited by the spatio-temporal resolution of the mapping techniques. AF is driven by focal or reentrant activities that are initially clustered in a relatively limited atrial surface then disseminate everywhere in both atria. Evidence for structural remodeling, mainly represented by atrial fibrosis suggests that reentrant activities using anatomical substrate are the key mechanism sustaining AF. These reentries can be endocardial, epicardial, and intramural which makes them less accessible for mapping and for ablation. Subsequently, early interventions before irreversible remodeling are of major importance. Circumferential pulmonary vein isolation remains the cornerstone of the treatment of AF, regardless of the AF form and of the AF duration. No ablation strategy consistently demonstrated superiority to pulmonary vein isolation in preventing long term recurrences of atrial arrhythmias. Further research that allows accurate identification of the mechanisms underlying AF and efficient ablation should improve the results of PsAF ablation

Mapping and Ablation of Idiopathic Ventricular Fibrillation

Idiopathic ventricular fibrillation (IVF) is the main cause of unexplained sudden cardiac death, particularly in young patients under the age of 35. IVF is a diagnosis of exclusion in patients who have survived a VF episode without any identifiable structural or metabolic causes despite extensive diagnostic testing. Genetic testing allows identification of a likely causative mutation in up to 27% of unexplained sudden deaths in children and young adults. In the majority of cases, VF is triggered by PVCs that originate from the Purkinje network. Ablation of VF triggers in this setting is associated with high rates of acute success and long-term freedom from VF recurrence. Recent studies demonstrate that a significant subset of IVF defined by negative comprehensive investigations, demonstrate in fact subclinical structural alterations. These localized myocardial alterations are identified by high density electrogram mapping, are of small size and are mainly located in the epicardium. As reentrant VF drivers are often colocated with regions of abnormal electrograms, this localized substrate can be shown to be mechanistically linked with VF. Such areas may represent an important target for ablation

A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu

Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe3+ to Fe2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (–OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss

The impact of novel technologies on ablation therapy in scar-related tachycardia

Les innovations telle que les cathéters irrigués et le contact force ont largement amélioré la sécurité et l'efficacité de l’ablation, et plusieurs technologies de ballon comme le cryoballon ont également raccourci le temps de procédure. L'électroporation permettrait de réduire considérablement les complications tout en conservant la durabilité et la transmuralité de la lésion. Cependant, de tels développements dans les techniques d'ablation mais aussi dans les technologies de cartographie sont indispensables pour de meilleurs résultats du traitement de l'arythmie. Un circuit de tachycardie atriale (TA) ou de tachycardie ventriculaire (TV) a normalement un isthme critique pour maintenir la tachycardie. L’identification cet isthme ainsi que la formation d’une lésion durable peuvent être des facteurs limitants dans l'efficacité du traitement par ablation de ces tachyarythmies. En plus de certaines techniques d'ablation, plusieurs technologies de cartographie permettant de guider l’ablation ont récemment vu le jour. L'amélioration considérable des cathéters de cartographie et des technologies d'imagerie peut notamment avoir un impact sur le diagnostic du mécanisme de la tachycardie et sur l'identification de substrats et de circuits de tachycardies, conduisant à une meilleure efficacité de l’ablation. Les cathéters multipolaires de cartographie sont de plus en plus utilisés pour l’analyse du substrat. Cependant, l'impact clinique de l'espacement inter-électrodes et de la taille des électrodes sur les électrogrammes locaux n'a pas été systématiquement étudié. De plus, l'efficacité clinique de l'utilisation d'un système de cartographie à ultra haute résolution / haute densité et de cathéters multipolaires et à espace inter-électrodes réduits n'a pas été complètement analysé. Les données issues de l’imagerie cardiaque par résonnance magnétique (IRM) et de la tomodensitométrie (par exemple zone de cicatrice, épaisseur de paroi) peuvent être combinées avec les informations électroanatomiques du système de cartographie tridimensionnelle par un nouveau procédé de calcul 'MUSIC'. Toutefois, le véritable impact clinique de cette technologie n'a pas été étudié. Par conséquent, les objectifs de ce projet de recherche sont (1) de préciser en quoi les signaux sont affectés par la différence de taille d'électrode et d'espacement inter-électrodes, et de démontrer les caractéristiques de chaque cathéter multipolaire dans un modèle animal (2) afin de pouvoir observer le bénéfice clinique de l’utilisation d’un système de cartographie ultra haute résolution / haute densité et des cathéters multipolaires à mini électrode espacées pour identifier une stratégie pratique permettant de détecter l'isthme du circuit de tachycardie et de le traiter à l'aide de ces technologies, (3) d'évaluer le rapport entre les données d'imagerie et de voltage pour chaque cathéter multipolaire, et (4) d'élucider l'impact clinique de l’ablation d’une TV guidée par l’imagerie avec le système MUSIC. Pour élucider ces points, nous avons mené trois études principales comprenant une série d'expérimentations sur des animaux et deux séries d'études cliniques. La première série de 4 expériences sur animaux a démontré l'effet de la taille des électrodes, de l'espacement inter-électrodes, de l’orientation de l’activation des électrogrammes locaux et du seuil de voltage déterminant les zones de cicatrices. La partie clinique est composée de deux études principales. Premièrement, nous avons élucidé l'efficacité de l'utilisation du nouveau système de cartographie à ultra haute résolution / haute densité, «RhtymiaTM», associé au cathéter multipolaire Orion TM muni de mini électrodes et d’un espacement inter-électrodes, dans le diagnostic de plusieurs formes de TA complexes post-FA.[...]Recent improvement in ablation such as irrigation catheter and contact force has been dramatically raised a safety and efficacy, and several balloon technologies such as cryoballoon has significantly shorten the procedure time. Electroporation may remarkably decrease complications with maintaining a lesion durability and transmurality. However, not only such developments in ablation technologies but also those in mapping technologies are mandatory for the best outcome of an arrhythmia treatment. A circuit of atrial tachycardia (AT) and ventricular tachycardia (VT) normally has a critical isthmus to maintain the tachycardia. Successful detection of this isthmus as well as a durable lesion formation can be a limiting factor in the efficacy of ablation therapy for these tachyarrhythmias. In addition to some ablation technologies, several mapping technologies for guiding ablation therapy have recently emerged. In particular, the remarkable improvement of mapping catheters and imaging technologies may have an impact on diagnosing a tachycardia mechanism and identifying substrates and circuits of tachycardias, leading to a procedural efficacy. Multipolar mapping catheters are increasingly utilized for substrate delineation. However, the clinical impact of inter-electrode spacing and size of the electrode on the local electrograms has not been systematically examined. Additionally, the clinical efficacy of using an ultra high resolution/high-density mapping system and multipolar catheters with small electrodes and spacing has not been fully examined. Imaging information from Cardia Magnetic Resonance (CMR) and computerized tomography (CT) scan (e.g. scar area, wall thickness) can be combined with the elecroanatomical information from the 3 dimensional mapping system by a novel computational tool ‘MUSIC’ system. However, the true clinical impact of this technology has not been reported. Therefore, the aims of this research project are to (1) clarify how the signals are affected by the difference of electrode length and interelectrode spacing, and demonstrate the characteristics of each multipolar catheter in an animal model (2) to observe a clinical advantage of using an ultra high resolution/high-density mapping system and multipolar catheters with small electrodes and spacing in identifying a practical strategy to detect the isthmus of the tachycardia circuit and treat it based on these technologies, (3) to evaluate the relation between the information from imaging and voltages in each multipolar catheter, and (4) to elucidate the clinical impact of an imaging guided-VT ablation therapy with the MUSIC system. To elucidate these points, we conducted three main studies including one series of animal experiments and two series of clinical studies. The first series of 4 animal experiments demonstrated the effect of electrode size, inter-electrode spacing, and activation orientation on the local electrograms and voltage threshold determining scars. The clinical parts composed of two main studies. First, we elucidated the efficacy of using the novel ultra highresolution/high-density mapping system, 'RhtymiaTM', with the Orion TM multipolar catheter with small electrodes and inter-elecotrode spacing catheter, in diagnosing several forms of complex post-AF ATs. The second part of the clinical study describes the relationship between wall thickness distribution on CT imaging and substrate mapping on the electroanatomical mapping system in patients with ventricular tachycardias based on ischemic cardiomyopathy. [...

L'impact des nouvelles technologies de cartographie sur la thérapie d'ablation dans la tachycardie liée à la cicatrice.

Recent improvement in ablation such as irrigation catheter and contact force has been dramatically raised a safety and efficacy, and several balloon technologies such as cryoballoon has significantly shorten the procedure time. Electroporation may remarkably decrease complications with maintaining a lesion durability and transmurality. However, not only such developments in ablation technologies but also those in mapping technologies are mandatory for the best outcome of an arrhythmia treatment. A circuit of atrial tachycardia (AT) and ventricular tachycardia (VT) normally has a critical isthmus to maintain the tachycardia. Successful detection of this isthmus as well as a durable lesion formation can be a limiting factor in the efficacy of ablation therapy for these tachyarrhythmias. In addition to some ablation technologies, several mapping technologies for guiding ablation therapy have recently emerged. In particular, the remarkable improvement of mapping catheters and imaging technologies may have an impact on diagnosing a tachycardia mechanism and identifying substrates and circuits of tachycardias, leading to a procedural efficacy. Multipolar mapping catheters are increasingly utilized for substrate delineation. However, the clinical impact of inter-electrode spacing and size of the electrode on the local electrograms has not been systematically examined. Additionally, the clinical efficacy of using an ultra high resolution/high-density mapping system and multipolar catheters with small electrodes and spacing has not been fully examined. Imaging information from Cardia Magnetic Resonance (CMR) and computerized tomography (CT) scan (e.g. scar area, wall thickness) can be combined with the elecroanatomical information from the 3 dimensional mapping system by a novel computational tool ‘MUSIC’ system. However, the true clinical impact of this technology has not been reported. Therefore, the aims of this research project are to (1) clarify how the signals are affected by the difference of electrode length and interelectrode spacing, and demonstrate the characteristics of each multipolar catheter in an animal model (2) to observe a clinical advantage of using an ultra high resolution/high-density mapping system and multipolar catheters with small electrodes and spacing in identifying a practical strategy to detect the isthmus of the tachycardia circuit and treat it based on these technologies, (3) to evaluate the relation between the information from imaging and voltages in each multipolar catheter, and (4) to elucidate the clinical impact of an imaging guided-VT ablation therapy with the MUSIC system. To elucidate these points, we conducted three main studies including one series of animal experiments and two series of clinical studies. The first series of 4 animal experiments demonstrated the effect of electrode size, inter-electrode spacing, and activation orientation on the local electrograms and voltage threshold determining scars. The clinical parts composed of two main studies. First, we elucidated the efficacy of using the novel ultra highresolution/high-density mapping system, 'RhtymiaTM', with the Orion TM multipolar catheter with small electrodes and inter-elecotrode spacing catheter, in diagnosing several forms of complex post-AF ATs. The second part of the clinical study describes the relationship between wall thickness distribution on CT imaging and substrate mapping on the electroanatomical mapping system in patients with ventricular tachycardias based on ischemic cardiomyopathy. [...]Les innovations telle que les cathéters irrigués et le contact force ont largement amélioré la sécurité et l'efficacité de l’ablation, et plusieurs technologies de ballon comme le cryoballon ont également raccourci le temps de procédure. L'électroporation permettrait de réduire considérablement les complications tout en conservant la durabilité et la transmuralité de la lésion. Cependant, de tels développements dans les techniques d'ablation mais aussi dans les technologies de cartographie sont indispensables pour de meilleurs résultats du traitement de l'arythmie. Un circuit de tachycardie atriale (TA) ou de tachycardie ventriculaire (TV) a normalement un isthme critique pour maintenir la tachycardie. L’identification cet isthme ainsi que la formation d’une lésion durable peuvent être des facteurs limitants dans l'efficacité du traitement par ablation de ces tachyarythmies. En plus de certaines techniques d'ablation, plusieurs technologies de cartographie permettant de guider l’ablation ont récemment vu le jour. L'amélioration considérable des cathéters de cartographie et des technologies d'imagerie peut notamment avoir un impact sur le diagnostic du mécanisme de la tachycardie et sur l'identification de substrats et de circuits de tachycardies, conduisant à une meilleure efficacité de l’ablation. Les cathéters multipolaires de cartographie sont de plus en plus utilisés pour l’analyse du substrat. Cependant, l'impact clinique de l'espacement inter-électrodes et de la taille des électrodes sur les électrogrammes locaux n'a pas été systématiquement étudié. De plus, l'efficacité clinique de l'utilisation d'un système de cartographie à ultra haute résolution / haute densité et de cathéters multipolaires et à espace inter-électrodes réduits n'a pas été complètement analysé. Les données issues de l’imagerie cardiaque par résonnance magnétique (IRM) et de la tomodensitométrie (par exemple zone de cicatrice, épaisseur de paroi) peuvent être combinées avec les informations électroanatomiques du système de cartographie tridimensionnelle par un nouveau procédé de calcul 'MUSIC'. Toutefois, le véritable impact clinique de cette technologie n'a pas été étudié. Par conséquent, les objectifs de ce projet de recherche sont (1) de préciser en quoi les signaux sont affectés par la différence de taille d'électrode et d'espacement inter-électrodes, et de démontrer les caractéristiques de chaque cathéter multipolaire dans un modèle animal (2) afin de pouvoir observer le bénéfice clinique de l’utilisation d’un système de cartographie ultra haute résolution / haute densité et des cathéters multipolaires à mini électrode espacées pour identifier une stratégie pratique permettant de détecter l'isthme du circuit de tachycardie et de le traiter à l'aide de ces technologies, (3) d'évaluer le rapport entre les données d'imagerie et de voltage pour chaque cathéter multipolaire, et (4) d'élucider l'impact clinique de l’ablation d’une TV guidée par l’imagerie avec le système MUSIC. Pour élucider ces points, nous avons mené trois études principales comprenant une série d'expérimentations sur des animaux et deux séries d'études cliniques. La première série de 4 expériences sur animaux a démontré l'effet de la taille des électrodes, de l'espacement inter-électrodes, de l’orientation de l’activation des électrogrammes locaux et du seuil de voltage déterminant les zones de cicatrices. La partie clinique est composée de deux études principales. Premièrement, nous avons élucidé l'efficacité de l'utilisation du nouveau système de cartographie à ultra haute résolution / haute densité, «RhtymiaTM», associé au cathéter multipolaire Orion TM muni de mini électrodes et d’un espacement inter-électrodes, dans le diagnostic de plusieurs formes de TA complexes post-FA.[...

Sudden manifestation of sinus arrest nine months after catheter ablation treatment for persistent atrial fibrillation

A 39-year-old man with a seemingly non-remodeled, small heart suffered persistent atrial fibrillation (AF). Extensive isolation of the pulmonary vein, superior vena cava, and posterior left atrium, in conjunction with right atrium focal ablation, was performed to ablate multiple AF foci during two catheter ablation sessions. Sinus arrest occurred suddenly during follow-up, despite the absence of recurrent AF, ultimately necessitating pacemaker implantation. This case underscores the necessity of careful follow-up after catheter ablation, highlighting the risk of sudden, severe sinus node dysfunction, even in young AF patients with small hearts