Cryocure-VT: the safety and effectiveness of ultra-low-temperature cryoablation of monomorphic ventricular tachycardia in patients with ischaemic and non-ischaemic cardiomyopathies.

AIMS: The ultra-low-temperature cryoablation (ULTC) ablation system using -196°C N2 cryogen has been reported to create lesions with freeze duration-dependent depth titratable to over 10 mm with minimum attenuation by scar. Cryocure-VT (NCT04893317) was a first-in-human clinical trial evaluating the safety and efficacy of a novel, purpose-built ULTC catheter in endocardial ablation of scar-dependent ventricular tachycardias (VTs). METHODS AND RESULTS: This prospective, multi-centre study enrolled patients referred for de novo or second ablations of recurrent monomorphic VT of both ischaemic and non-ischaemic aetiologies. Primary safety and efficacy endpoints of the study were freedom from device- or procedure-related major adverse events (MAEs) up to 30 days post-ablation, acute non-inducibility of clinical VTs at the end of the procedure, and freedom from sustained VT or implantable defibrillator intervention at 6 months. Ultra-low-temperature cryoablation was performed in 64 patients (age 67 ± 11 years, 78% ischaemic, ejection fraction = 35 ± 10%) at 9 centres. The primary acute effectiveness endpoint was achieved in 94% (51/54) of patients in whom post-ablation induction was attempted. There were no protocol-defined MAEs; four procedure-related serious adverse events resolved without clinical sequelae. At 6-month follow-up, 38 patients (60.3%) remained VT-free, and freedom from defibrillator shock was 81.0%, with no significant difference between ischaemic and non-ischaemic cohorts. In 47 patients with defibrillator for at least 6 months prior to the ablation, the VT burden was reduced from median of 4, inter-quartile range (IQR, 1-9) to 0, IQR (0-2). CONCLUSION: In this first-in-human multi-centre experience, endocardial ULTC ablation of monomorphic VT appears safe and effective in patients with both ischaemic-cardiomyopathy and non-ischaemic-cardiomyopathy. CLINICAL TRIAL REGISTRATION: NCT04893317.

Atrial Fibrillation Burden: Impact on Stroke Risk and Beyond.

Atrial fibrillation (AF) is an important independent risk factor for stroke. Current guidelines handle AF as a binary entity with risk driven by the presence of clinical risk factors, which guides the decision to treat with an oral anticoagulant. Recent studies in the literature suggest a dose-response relationship between AF burden and stroke risk, in both clinical AF and subclinical atrial fibrillation (SCAF), which differs from current guidance to disregard burden and utilize clinical risk scores alone. Within clinical classification and at the same risk levels in various scores, the risk of stroke increases with AF burden. This opens the possibility of incorporating burden into risk profiles, which has already shown promise. Long-term rhythm monitoring is needed to elucidate SCAF in patients with stroke. Recent data from randomized trials are controversial regarding whether there is an independent risk from AF episodes with a duration of less than 24 h, including the duration of SCAF greater than six minutes but less than 24 h.

Ultra-Low-Temperature Cryoablation for Ventricular Tachycardia: An Early Single-Centre Report of Acute Results.

Background: Endocardial catheter ablation for ventricular tachycardia (VT) may fail because of the inability to deliver transmural lesions. Ultra-low-temperature cryoablation (ULTC) uses near-critical nitrogen and can generate temperatures as low as -196 °C. We report a series of 18 patients who underwent ULTC at the McGill University Health Centre (MUHC), representing the largest single-centre experience to date. Methods: Eighteen patients with monomorphic drug-refractory VT underwent VT ablation with ULTC at our institution as part of the first-in-human CryoCure-VT trial (NCT04893317). After voltage map, the mapping catheter was replaced with the ULTC catheter, and lesions were applied over a fixed duration of time (60-180 seconds), followed by a 60-second thaw and another application at the original duration (freeze-thaw-freeze). Duration of ablation time was selected depending on the wall thickness of the left ventricle monitored with intracardiac echo to achieve tissue depths of 4.5 to 7.5 mm. Results: Baseline left ventricular ejection fraction was 32%, mean age 71 years, 94% were male. A total of 32 sustained VTs were induced in 16 of 18 patients. A total of 177 cryoablation lesions were delivered (9.8 lesions per patient). Of the 16 patients with inducible VT, 15 (94%) were rendered noninducible postablation, and 1 was inducible only for a nonclinical VT. Complications included 1 pericardial effusion that required drainage. From 18 patients, 16 (89%) were discharged within the first 24 hours postablation. Conclusions: ULTC is feasible and permits acute control of monomorphic VT during VT ablation procedures in drug-refractory patients.

Contexte: L'ablation endocardique par cathéter pour traiter la tachycardie ventriculaire (TV) peut être un échec, en raison de l'incapacité à créer des lésions transmurales. La cryoablation à ultra-basse température (ULTC, pour ultra-low-temperature cryoablation) réalisée au moyen d'azote près de son point critique liquide-vapeur peut produire des températures aussi basses que ­196 °C. Nous faisons état d'une série de 18 patients ayant subi une ULTC au Centre universitaire de santé McGill (CUSM), ce qui représente la plus importante expérience menée dans un seul établissement jusqu'à ce jour. Méthodologie: Au total, 18 patients atteints de TV monomorphe pharmacorésistante ont subi une ablation de la TV par ULTC à notre établissement, dans le cadre du premier essai mené chez l'humain sur la guérison par cryothérapie de la TV (NCT04893317). Après l'obtention de la carte électrophysiologique, le cathéter de cartographie a été remplacé par le cathéter d'ULTC, qui a permis de créer des lésions par l'application de froid pendant une durée fixe (de 60 à 180 secondes), suivie d'une période de dégel de 60 secondes, puis d'une autre application de froid pendant la même durée que la première application (cycle gel-dégel-gel). La durée de l'ablation a été déterminée en fonction de l'épaisseur de la paroi du ventricule gauche surveillée par échocardiographie endocavitaire afin d'obtenir des profondeurs tissulaires de 4,5 à 7,5 mm. Résultats: La fraction d'éjection du ventricule gauche initiale était de 32 %, l'âge moyen des sujets était de 71 ans et 94 % d'entre eux étaient de sexe masculin. Au total, 32 TV soutenues ont été induites chez 16 patients sur 18. Dans l'ensemble, 177 lésions de cryoablation ont été créées (soit 9,8 lésions par patient). Après l'ablation, nous avons été incapables d'induire une TV chez 15 (94 %) des 16 patients chez qui nous en avions induit avant l'intervention et, chez le patient restant, nous avons pu induire une TV non clinique seulement. Les complications comprenaient un cas d'épanchement péricardique ayant nécessité un drainage. Au total, 16 (89 %) des 18 patients ont reçu leur congé de l'hôpital dans les 24 heures suivant l'ablation. Conclusions: L'ULTC est réalisable et permet une maîtrise rigoureuse de la TV monomorphe lors des interventions d'ablation de la TV chez les patients dont la TV est pharmacorésistante.

Meta-analysis evaluating apixaban in patients with atrial fibrillation and end-stage renal disease requiring dialysis.

Background: Warfarin is considered the primary oral anticoagulant for patients with atrial fibrillation and end-stage renal disease (ESRD) requiring dialysis. Although warfarin can offer significant stroke prevention in this population, the accompanying major bleeding risks make warfarin nearly prohibitive. Apixaban was shown to be superior to warfarin in preventing stroke or systemic embolism, with a lower risk of bleeding and mortality in a large, randomized trial of individuals with mostly normal renal function but none with ESRD. Methods: We systematically reviewed evidence comparing apixaban versus warfarin for atrial fibrillation in this population, and evaluated outcomes of stroke or systemic embolism, and major bleeding using random-effects models. The main safety outcome was major bleeding, and the main effectiveness outcome was stroke or systemic embolism. Results: We found five observational studies of 10 036 patients (2638 receiving apixaban, and 7398 receiving warfarin) meeting inclusion criteria. Pooled analysis demonstrated a significant reduction in major bleeding with apixaban as compared to warfarin (odds ratio [OR] 0.51, 95% confidence interval [CI] 0.42-0.61; p < .0001). Apixaban was also associated with a reduction in intracranial bleeding (OR 0.58, 95% CI 0.37-0.92; p = .02) and in gastrointestinal bleeding (OR 0.61, 95% CI 0.51-0.73; p < .0001). Furthermore, apixaban was associated with a reduction in stroke/systemic embolism (OR 0.64, 95% CI 0.50-0.82; p < .0001). Conclusion: Apixaban was associated with superior outcomes and reduced adverse events compared to warfarin in observational studies of patients with atrial fibrillation on dialysis. Randomized controlled studies are needed to confirm these findings.

Cardioneuroablation as a strategy to prevent pacemaker implantation in young patients with vasovagal syncope.

Background: Cardioneuroablation (CNA) is an ablation technique that targets epicardial ganglionic plexi to reduce syncope burden and avoid pacemaker implantation in patients with cardioinhibitory vasovagal syncope (VVS). This study aims to demonstrate feasibility and safety of CNA in high-risk refractory VVS patients using continuous monitoring with an implantable loop recorder (ILR). Methods: Data was collected prospectively for patients undergoing CNA. Patients were required to have recurrent syncope with documented asystole, refractory to conservative measures. Ganglionic plexi (GPs) were identified by fragmented signals and high frequency stimulation (HFS). Ablation was performed until loss of positive response to HFS, Wenckebach cycle shortening was achieved, or an increase in sinus rate of > 20 bpm. Follow-up was performed through remote and clinic follow-up of their ILRs. Results: Between December 2020 and July 2023 six patients (mean age 29 ± 3, 67 % female)underwent CNA. The baseline heart rate and Wenckebach cycle length was 63.2 ± 15 bpm and 582 ms before and 91 ± 5 bpm and 358 ms after ablation respectively. During a median follow-up of 13.4 months, 3/5 patients had no further syncopal episodes, 1 had a recurrence, underwent repeat CNA with no further episodes at 1 year, and 1 had 5 syncopal events, which was a dramatic reduction from nearly daily episodes pre-CNA. There were no procedure related complications. Conclusions: A dramatic reduction in documented pauses and syncope burden was noted post CNA. Appropriate patient selection with rigorous objective follow-up in an experienced center is necessary. Larger studies are required to confirm these findings.

Fibrilação atrial durante taquicardia por reentrada nodal atrioventricular: achado sugestivo da presença de via superiorcomum nodal / Atrial fibrillation during atrioventricular nodal reentry tachycardia: a suggestive finding favoring the presence of the upper common nodal pathway

Na taquicardia por reentrada nodal atrioventricular, a necessidade do átrio para a manutenção da taquicardia é controverso. Descrevemos um caso de fibrilação atrial ocorrendo durante taquicardia por reentrada nodal atrioventricular sem afetar o ciclo da arritmia, e discutimos as evidências favorecendo a presença de umavia comum superior.

In Atrioventricular Nodal Reentry Tachycardia the requirement of the atrium for the maintenance oftachycardia is controversial. We describe a case of atrial fibrillation that occurred during Atrioventricular Nodal Reentry Tachycardia without affecting the arrhythmia cycle, and discuss the evidences favoring the presence ofan upper common pathway.