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Catheter ablation has brought major advances in the management of patients with atrial fibrillation (AF). As evidenced by multiple randomized trials, AF catheter ablation can reduce the risk of recurrent AF and improve quality of life. In some studies, AF ablation significantly reduced cardiovascular hospitalizations. Despite the existing data on AF catheter ablation, numerous knowledge gaps remain concerning this intervention. This report is based on a recent virtual workshop convened by the National Heart, Lung, and Blood Institute to identify key research opportunities in AF ablation. We outline knowledge gaps related to emerging technologies, the relationship between cardiac structure and function and the success of AF ablation in patient subgroups in whom clinical benefit from ablation varies, and potential platforms to advance clinical research in this area. This report also considers the potential value and challenges of a sham ablation randomized trial. Prioritized research opportunities are identified and highlighted to empower relevant stakeholders to collaborate in designing and conducting effective, cost-efficient, and transformative research to optimize the use and outcomes of AF ablation.

Transient Atrial-His Block during Wide QRS-Complex Tachycardia with 1:1 Ventriculoatrial Relationship: What is the Diagnosis?

Persistent left superior vena cava (LSVC) is the most common thoracic venous anomaly. It is frequently implicated in atrial fibrillation initiation and maintenance in patients who harbor them, as exemplified by this case study. The LSVC is in continuity with the CS and can be disconnected from the left atrium to which it is connected by multiple myocardial bridges, creating an ideal substrate for rapid reentry.

We present a 40-year old patient with symptomatic persistent AF. This case illustrates the importance of thoracic veins in the pathogenesis of atrial fibrillation. In this case, PV isolation resulted in a drastic cycle length prolongation with AF persisting with periods of organized activation sequence allowing for localization of the culprit area: a bursting SVC, whose isolation led to sinus resumption.

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.

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.

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.

Background— Complex-fractionated atrial electrograms and atrial fibrosis are associated with maintenance of persistent atrial fibrillation (AF). We hypothesized that pulmonary vein isolation (PVI) plus ablation of selective atrial low-voltage sites may be more successful than PVI only. Methods and Results— A total of 85 consecutive patients with persistent AF underwent high-density atrial voltage mapping, PVI, and ablation at low-voltage areas (LVA70% of AF cycle length on a single electrode (fractionated activity) or multiple electrodes around the circumferential mapping catheter (rotational activity) or discrete rapid local activity (group I). The procedural end point was AF termination. Arrhythmia freedom was compared with a control group (66 patients) undergoing PVI only (group II). PVI alone was performed in 23 of 85 (27%) patients of group I with low amount (P P =0.42). Conclusions— Ablation of sites with distinct activation characteristics within/at borderzones of LVA in addition to PVI is more effective than conventional PVI-only strategy for persistent AF. PVI only seems to be sufficient to treat patients with left atrial low voltage

Objectif Confirmer qu’une antibiotherapie orale d’emblee est aussi efficace qu’une antibiotherapie sequentielle intraveineuse puis orale pour prevenir les cicatrices renales chez des enfants de 1 a 36 mois ayant un premier episode de pyelonephrite aigue (PNA).

Objective To evauluate the relationship between propionic acidemia (PA) and cardiomyopathy. Study design We retrospectively compared clinical and metabolic results of patients with PA with and without cardiomyopathy. Results Of 26 patients with PA who survived the first year of age, a dilated cardiomyopathy developed in 6 (group 1) at a median age of 7 years (range, 5-11 years). They were compared with 14 patients without cardiomyopathy for whom data were available (group 2). Their median age at the time of the study was 11 years (range, 3-21 years). PA was diagnosed in the neonatal period in 5 of 6 patients in group 1 and 11 of 14 patients in group 2. All patients received similar medical treatment. Two patients in group 1 died of cardiac arrest. In 2 patients, the cardiomyopathy was reversed during the year after orthotopic liver transplantation (OLT). In 2 other patients, OLT was contraindicated because of severe heart disease. The number of metabolic distress episodes was similar in both groups. Excretion of propionate metabolites in urine did not correlate with the occurrence of cardiomyopathy. Conclusion Dilated cardiomyopathy, a frequent complication of PA, develops independent of any specific metabolic profile and is reversible after OLT.

International audience; AIMS: The ALternate Site Cardiac ResYNChronization (ALSYNC) study evaluated the feasibility and safety of left ventricular endocardial pacing (LVEP) using a market-released pacing lead implanted via a single pectoral access by a novel atrial transseptal lead delivery system. METHODS AND RESULTS: ALSYNC was a prospective clinical investigation with a minimum of 12-month follow-up in 18 centres of cardiac resynchronization therapy (CRT)-indicated patients, who had failed or were unsuitable for conventional CRT. The ALSYNC system comprises the investigational lead delivery system and LVEP lead. Patients required warfarin therapy post-implant. The primary study objective was safety at 6-month follow-up, which was defined as freedom from complications related to the lead delivery system, implant procedure, or the lead ≥70%. The ALSYNC study enrolled 138 patients. The LVEP lead implant success rate was 89.4%. Freedom from complications meeting the definition of primary endpoint was 82.2% at 6 months (95% CI 75.6-88.8%). In the study, 14 transient ischaemic attacks (9 patients, 6.8%), 5 non-disabling strokes (5 patients, 3.8%), and 23 deaths (17.4%) were observed. No death was from a primary endpoint complication. At 6 months, the New York Heart Association class improved in 59% of patients, and 55% had LV end-systolic volume reduction of 15% or greater. Those patients enrolled after CRT non-response showed similar improvement with LVEP. CONCLUSIONS: The ALSYNC study demonstrates clinical feasibility, and provides an early indication of possible benefit and risk of LVEP. CLINICAL TRIAL: NCT01277783

Early repolarization (ER) involving the inferolateral leads, previously considered a benign electrocardiographic (ECG) phenomenon, has recently been associated with sudden cardiac death. Although the mechanisms underlying early repolarization are unknown, ER is the latest of the primary electrical cardiac disease discovered to have significantly high prevalence in SCD cases and contribute to increased risk of death from cardioarrhythmic cause. Population-based studies have demonstrated an association between early repolarization and sudden death, primarily when the ECG demonstrates ≥0.2 mV of ST elevation. Risk stratification, especially for asymptomatic patient, remains challenging. However, clinical features as personal history of syncope, familial history of sudden cardiac death and characteristics of the J-wave (>0.2 mV, wide distribution, horizontal/descending ST segment) should be considered at higher risk.

OBJECTIVE: To confirm whether oral antibiotic treatment is as efficacious as sequential intravenous/oral antibiotic treatment in the prevention of renal scarring in children with acute pyelonephritis and scintigraphy-documented acute lesions. METHODS: In a prospective multicenter trial, children aged 1 to 36 months with their first case of acute pyelonephritis, a serum procalcitonin concentration ≥0.5 ng/mL, no known uropathy, and a normal ultrasound exam were randomized into 2 treatment groups. They received either oral cefixime for 10 days or intravenous ceftriaxone for 4 days followed by oral cefixime for 6 days. Patients with acute renal lesions detected on early dimercaptosuccinic acid scintigraphy underwent a follow-up scintigraphy 6 to 8 months later. RESULTS: The study included 171 infants and children. There were no significant differences between the 2 groups in any clinical characteristic. Initial scintigraphy results were abnormal for 119 children. Ninety-six children were measured for renal scarring at the follow-up scintigraphy (per protocol analysis population). The incidence of renal scarring was 30.8% in the oral treatment group and 27.3% for children who received the sequential treatment. CONCLUSIONS: Although this trial does not statistically demonstrate the noninferiority of oral treatment compared with the sequential treatment, our study confirmed the results of previously published reports and therefore supports the use of an oral antibiotic treatment of primary episodes of acute pyelonephritis in infants and young children.

As in atrial fibrillation (AF), while both triggers and substrate may theoretically be the target of catheter ablation strategies, the presently published literature on catheter ablation of ventricular fibrillation (VF), including isolated case reports, has focused on targeting triggers.1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11The large mass of ventricular myocardium, the importance of maintaining normal mechanical ventricular function, and the risk of creating other forms of malignant arrhythmias mean that ablation strategies aimed at substrate modification are not suitable using the currently available technology. However, previous work in AF has shown that both triggers and substrate may share a close structural relationship. The pulmonary veins play an important role in the initiation and maintenance of AF,12 and recent studies have shed light on their role in the maintenance of AF in some patients. Similarly, several experimental studies demonstrated that Purkinje fibers act as initiators and perpetuators of VF.13,14 Hence, by ablating an area in which the triggering ectopics are found to originate, an additional effect might be substrate modification if the area is implicated in the maintenance of VF.

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in humans, occurring in 2% of the unselected adult population, increasing with each decade of life to a prevalence of 5.9% in the population older than 65 years. It results in an increased mortality rate and significant morbidity rate related to thromboembolic stroke, loss of atrial systole, and tachycardia-mediated atrial and ventricular cardiomyopathy. 1 Management strategies have been two tiered, either using palliative measures of rate control coupled with anticoagulation or the restoration and maintenance of sinus rhythm. Emerging evidence suggests that the pharmacologic maintenance of sinus rhythm has limited efficacy and value, at least in older patients and in those with persistent AF or structural heart disease. 2 3 4 Consequently, there is heightened interest in the nonpharmacologic, catheter-based approaches to maintain sinus rhythm that may prevent the significant adverse consequences associated with this arrhythmia. This chapter focuses on the current mapping techniques and the advantages and limitations of catheter ablation techniques targeting the triggers and substrate of AF.

Different approaches have been described [1–12] for ablating the slow ‘pathway’ (SP) in patients with atrioventricular nodal reentrant tachycardia (AVNRT). In one approach, electrogram patterns are used to identify the ablation site [1,4], whereas in the other approach, the ablating site is selected on anatomical criteria. Both approaches appear effective, but no study (except one preliminary abstract [8]) comparing the two techniques has been published. In the following study, we analyze the results of these different techniques and investigated the prevalence of electrogram patterns and their relation to a successful outcome in a series of 164 patients.